--- /dev/null
- sqlite3_free(azCol);
+
+#if defined(SQLITE_ENABLE_SESSION) && defined(SQLITE_ENABLE_PREUPDATE_HOOK)
+#include "sqlite3session.h"
+#include <assert.h>
+#include <string.h>
+
+#ifndef SQLITE_AMALGAMATION
+# include "sqliteInt.h"
+# include "vdbeInt.h"
+#endif
+
+typedef struct SessionTable SessionTable;
+typedef struct SessionChange SessionChange;
+typedef struct SessionBuffer SessionBuffer;
+typedef struct SessionInput SessionInput;
+
+/*
+** Minimum chunk size used by streaming versions of functions.
+*/
+#ifndef SESSIONS_STRM_CHUNK_SIZE
+# ifdef SQLITE_TEST
+# define SESSIONS_STRM_CHUNK_SIZE 64
+# else
+# define SESSIONS_STRM_CHUNK_SIZE 1024
+# endif
+#endif
+
+typedef struct SessionHook SessionHook;
+struct SessionHook {
+ void *pCtx;
+ int (*xOld)(void*,int,sqlite3_value**);
+ int (*xNew)(void*,int,sqlite3_value**);
+ int (*xCount)(void*);
+ int (*xDepth)(void*);
+};
+
+/*
+** Session handle structure.
+*/
+struct sqlite3_session {
+ sqlite3 *db; /* Database handle session is attached to */
+ char *zDb; /* Name of database session is attached to */
+ int bEnable; /* True if currently recording */
+ int bIndirect; /* True if all changes are indirect */
+ int bAutoAttach; /* True to auto-attach tables */
+ int rc; /* Non-zero if an error has occurred */
+ void *pFilterCtx; /* First argument to pass to xTableFilter */
+ int (*xTableFilter)(void *pCtx, const char *zTab);
+ sqlite3_session *pNext; /* Next session object on same db. */
+ SessionTable *pTable; /* List of attached tables */
+ SessionHook hook; /* APIs to grab new and old data with */
+};
+
+/*
+** Instances of this structure are used to build strings or binary records.
+*/
+struct SessionBuffer {
+ u8 *aBuf; /* Pointer to changeset buffer */
+ int nBuf; /* Size of buffer aBuf */
+ int nAlloc; /* Size of allocation containing aBuf */
+};
+
+/*
+** An object of this type is used internally as an abstraction for
+** input data. Input data may be supplied either as a single large buffer
+** (e.g. sqlite3changeset_start()) or using a stream function (e.g.
+** sqlite3changeset_start_strm()).
+*/
+struct SessionInput {
+ int iNext; /* Offset in aData[] of next change */
+ u8 *aData; /* Pointer to buffer containing changeset */
+ int nData; /* Number of bytes in aData */
+
+ SessionBuffer buf; /* Current read buffer */
+ int (*xInput)(void*, void*, int*); /* Input stream call (or NULL) */
+ void *pIn; /* First argument to xInput */
+ int bEof; /* Set to true after xInput finished */
+};
+
+/*
+** Structure for changeset iterators.
+*/
+struct sqlite3_changeset_iter {
+ SessionInput in; /* Input buffer or stream */
+ SessionBuffer tblhdr; /* Buffer to hold apValue/zTab/abPK/ */
+ int bPatchset; /* True if this is a patchset */
+ int rc; /* Iterator error code */
+ sqlite3_stmt *pConflict; /* Points to conflicting row, if any */
+ char *zTab; /* Current table */
+ int nCol; /* Number of columns in zTab */
+ int op; /* Current operation */
+ int bIndirect; /* True if current change was indirect */
+ u8 *abPK; /* Primary key array */
+ sqlite3_value **apValue; /* old.* and new.* values */
+};
+
+/*
+** Each session object maintains a set of the following structures, one
+** for each table the session object is monitoring. The structures are
+** stored in a linked list starting at sqlite3_session.pTable.
+**
+** The keys of the SessionTable.aChange[] hash table are all rows that have
+** been modified in any way since the session object was attached to the
+** table.
+**
+** The data associated with each hash-table entry is a structure containing
+** a subset of the initial values that the modified row contained at the
+** start of the session. Or no initial values if the row was inserted.
+*/
+struct SessionTable {
+ SessionTable *pNext;
+ char *zName; /* Local name of table */
+ int nCol; /* Number of columns in table zName */
+ const char **azCol; /* Column names */
+ u8 *abPK; /* Array of primary key flags */
+ int nEntry; /* Total number of entries in hash table */
+ int nChange; /* Size of apChange[] array */
+ SessionChange **apChange; /* Hash table buckets */
+};
+
+/*
+** RECORD FORMAT:
+**
+** The following record format is similar to (but not compatible with) that
+** used in SQLite database files. This format is used as part of the
+** change-set binary format, and so must be architecture independent.
+**
+** Unlike the SQLite database record format, each field is self-contained -
+** there is no separation of header and data. Each field begins with a
+** single byte describing its type, as follows:
+**
+** 0x00: Undefined value.
+** 0x01: Integer value.
+** 0x02: Real value.
+** 0x03: Text value.
+** 0x04: Blob value.
+** 0x05: SQL NULL value.
+**
+** Note that the above match the definitions of SQLITE_INTEGER, SQLITE_TEXT
+** and so on in sqlite3.h. For undefined and NULL values, the field consists
+** only of the single type byte. For other types of values, the type byte
+** is followed by:
+**
+** Text values:
+** A varint containing the number of bytes in the value (encoded using
+** UTF-8). Followed by a buffer containing the UTF-8 representation
+** of the text value. There is no nul terminator.
+**
+** Blob values:
+** A varint containing the number of bytes in the value, followed by
+** a buffer containing the value itself.
+**
+** Integer values:
+** An 8-byte big-endian integer value.
+**
+** Real values:
+** An 8-byte big-endian IEEE 754-2008 real value.
+**
+** Varint values are encoded in the same way as varints in the SQLite
+** record format.
+**
+** CHANGESET FORMAT:
+**
+** A changeset is a collection of DELETE, UPDATE and INSERT operations on
+** one or more tables. Operations on a single table are grouped together,
+** but may occur in any order (i.e. deletes, updates and inserts are all
+** mixed together).
+**
+** Each group of changes begins with a table header:
+**
+** 1 byte: Constant 0x54 (capital 'T')
+** Varint: Number of columns in the table.
+** nCol bytes: 0x01 for PK columns, 0x00 otherwise.
+** N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
+**
+** Followed by one or more changes to the table.
+**
+** 1 byte: Either SQLITE_INSERT, UPDATE or DELETE.
+** 1 byte: The "indirect-change" flag.
+** old.* record: (delete and update only)
+** new.* record: (insert and update only)
+**
+** The "old.*" and "new.*" records, if present, are N field records in the
+** format described above under "RECORD FORMAT", where N is the number of
+** columns in the table. The i'th field of each record is associated with
+** the i'th column of the table, counting from left to right in the order
+** in which columns were declared in the CREATE TABLE statement.
+**
+** The new.* record that is part of each INSERT change contains the values
+** that make up the new row. Similarly, the old.* record that is part of each
+** DELETE change contains the values that made up the row that was deleted
+** from the database. In the changeset format, the records that are part
+** of INSERT or DELETE changes never contain any undefined (type byte 0x00)
+** fields.
+**
+** Within the old.* record associated with an UPDATE change, all fields
+** associated with table columns that are not PRIMARY KEY columns and are
+** not modified by the UPDATE change are set to "undefined". Other fields
+** are set to the values that made up the row before the UPDATE that the
+** change records took place. Within the new.* record, fields associated
+** with table columns modified by the UPDATE change contain the new
+** values. Fields associated with table columns that are not modified
+** are set to "undefined".
+**
+** PATCHSET FORMAT:
+**
+** A patchset is also a collection of changes. It is similar to a changeset,
+** but leaves undefined those fields that are not useful if no conflict
+** resolution is required when applying the changeset.
+**
+** Each group of changes begins with a table header:
+**
+** 1 byte: Constant 0x50 (capital 'P')
+** Varint: Number of columns in the table.
+** nCol bytes: 0x01 for PK columns, 0x00 otherwise.
+** N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
+**
+** Followed by one or more changes to the table.
+**
+** 1 byte: Either SQLITE_INSERT, UPDATE or DELETE.
+** 1 byte: The "indirect-change" flag.
+** single record: (PK fields for DELETE, PK and modified fields for UPDATE,
+** full record for INSERT).
+**
+** As in the changeset format, each field of the single record that is part
+** of a patchset change is associated with the correspondingly positioned
+** table column, counting from left to right within the CREATE TABLE
+** statement.
+**
+** For a DELETE change, all fields within the record except those associated
+** with PRIMARY KEY columns are set to "undefined". The PRIMARY KEY fields
+** contain the values identifying the row to delete.
+**
+** For an UPDATE change, all fields except those associated with PRIMARY KEY
+** columns and columns that are modified by the UPDATE are set to "undefined".
+** PRIMARY KEY fields contain the values identifying the table row to update,
+** and fields associated with modified columns contain the new column values.
+**
+** The records associated with INSERT changes are in the same format as for
+** changesets. It is not possible for a record associated with an INSERT
+** change to contain a field set to "undefined".
+*/
+
+/*
+** For each row modified during a session, there exists a single instance of
+** this structure stored in a SessionTable.aChange[] hash table.
+*/
+struct SessionChange {
+ int op; /* One of UPDATE, DELETE, INSERT */
+ int bIndirect; /* True if this change is "indirect" */
+ int nRecord; /* Number of bytes in buffer aRecord[] */
+ u8 *aRecord; /* Buffer containing old.* record */
+ SessionChange *pNext; /* For hash-table collisions */
+};
+
+/*
+** Write a varint with value iVal into the buffer at aBuf. Return the
+** number of bytes written.
+*/
+static int sessionVarintPut(u8 *aBuf, int iVal){
+ return putVarint32(aBuf, iVal);
+}
+
+/*
+** Return the number of bytes required to store value iVal as a varint.
+*/
+static int sessionVarintLen(int iVal){
+ return sqlite3VarintLen(iVal);
+}
+
+/*
+** Read a varint value from aBuf[] into *piVal. Return the number of
+** bytes read.
+*/
+static int sessionVarintGet(u8 *aBuf, int *piVal){
+ return getVarint32(aBuf, *piVal);
+}
+
+/*
+** Read a 64-bit big-endian integer value from buffer aRec[]. Return
+** the value read.
+*/
+static sqlite3_int64 sessionGetI64(u8 *aRec){
+ return (((sqlite3_int64)aRec[0]) << 56)
+ + (((sqlite3_int64)aRec[1]) << 48)
+ + (((sqlite3_int64)aRec[2]) << 40)
+ + (((sqlite3_int64)aRec[3]) << 32)
+ + (((sqlite3_int64)aRec[4]) << 24)
+ + (((sqlite3_int64)aRec[5]) << 16)
+ + (((sqlite3_int64)aRec[6]) << 8)
+ + (((sqlite3_int64)aRec[7]) << 0);
+}
+
+/*
+** Write a 64-bit big-endian integer value to the buffer aBuf[].
+*/
+static void sessionPutI64(u8 *aBuf, sqlite3_int64 i){
+ aBuf[0] = (i>>56) & 0xFF;
+ aBuf[1] = (i>>48) & 0xFF;
+ aBuf[2] = (i>>40) & 0xFF;
+ aBuf[3] = (i>>32) & 0xFF;
+ aBuf[4] = (i>>24) & 0xFF;
+ aBuf[5] = (i>>16) & 0xFF;
+ aBuf[6] = (i>> 8) & 0xFF;
+ aBuf[7] = (i>> 0) & 0xFF;
+}
+
+/*
+** This function is used to serialize the contents of value pValue (see
+** comment titled "RECORD FORMAT" above).
+**
+** If it is non-NULL, the serialized form of the value is written to
+** buffer aBuf. *pnWrite is set to the number of bytes written before
+** returning. Or, if aBuf is NULL, the only thing this function does is
+** set *pnWrite.
+**
+** If no error occurs, SQLITE_OK is returned. Or, if an OOM error occurs
+** within a call to sqlite3_value_text() (may fail if the db is utf-16))
+** SQLITE_NOMEM is returned.
+*/
+static int sessionSerializeValue(
+ u8 *aBuf, /* If non-NULL, write serialized value here */
+ sqlite3_value *pValue, /* Value to serialize */
+ int *pnWrite /* IN/OUT: Increment by bytes written */
+){
+ int nByte; /* Size of serialized value in bytes */
+
+ if( pValue ){
+ int eType; /* Value type (SQLITE_NULL, TEXT etc.) */
+
+ eType = sqlite3_value_type(pValue);
+ if( aBuf ) aBuf[0] = eType;
+
+ switch( eType ){
+ case SQLITE_NULL:
+ nByte = 1;
+ break;
+
+ case SQLITE_INTEGER:
+ case SQLITE_FLOAT:
+ if( aBuf ){
+ /* TODO: SQLite does something special to deal with mixed-endian
+ ** floating point values (e.g. ARM7). This code probably should
+ ** too. */
+ u64 i;
+ if( eType==SQLITE_INTEGER ){
+ i = (u64)sqlite3_value_int64(pValue);
+ }else{
+ double r;
+ assert( sizeof(double)==8 && sizeof(u64)==8 );
+ r = sqlite3_value_double(pValue);
+ memcpy(&i, &r, 8);
+ }
+ sessionPutI64(&aBuf[1], i);
+ }
+ nByte = 9;
+ break;
+
+ default: {
+ u8 *z;
+ int n;
+ int nVarint;
+
+ assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
+ if( eType==SQLITE_TEXT ){
+ z = (u8 *)sqlite3_value_text(pValue);
+ }else{
+ z = (u8 *)sqlite3_value_blob(pValue);
+ }
+ n = sqlite3_value_bytes(pValue);
+ if( z==0 && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
+ nVarint = sessionVarintLen(n);
+
+ if( aBuf ){
+ sessionVarintPut(&aBuf[1], n);
+ memcpy(&aBuf[nVarint + 1], eType==SQLITE_TEXT ?
+ sqlite3_value_text(pValue) : sqlite3_value_blob(pValue), n
+ );
+ }
+
+ nByte = 1 + nVarint + n;
+ break;
+ }
+ }
+ }else{
+ nByte = 1;
+ if( aBuf ) aBuf[0] = '\0';
+ }
+
+ if( pnWrite ) *pnWrite += nByte;
+ return SQLITE_OK;
+}
+
+
+/*
+** This macro is used to calculate hash key values for data structures. In
+** order to use this macro, the entire data structure must be represented
+** as a series of unsigned integers. In order to calculate a hash-key value
+** for a data structure represented as three such integers, the macro may
+** then be used as follows:
+**
+** int hash_key_value;
+** hash_key_value = HASH_APPEND(0, <value 1>);
+** hash_key_value = HASH_APPEND(hash_key_value, <value 2>);
+** hash_key_value = HASH_APPEND(hash_key_value, <value 3>);
+**
+** In practice, the data structures this macro is used for are the primary
+** key values of modified rows.
+*/
+#define HASH_APPEND(hash, add) ((hash) << 3) ^ (hash) ^ (unsigned int)(add)
+
+/*
+** Append the hash of the 64-bit integer passed as the second argument to the
+** hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendI64(unsigned int h, i64 i){
+ h = HASH_APPEND(h, i & 0xFFFFFFFF);
+ return HASH_APPEND(h, (i>>32)&0xFFFFFFFF);
+}
+
+/*
+** Append the hash of the blob passed via the second and third arguments to
+** the hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendBlob(unsigned int h, int n, const u8 *z){
+ int i;
+ for(i=0; i<n; i++) h = HASH_APPEND(h, z[i]);
+ return h;
+}
+
+/*
+** Append the hash of the data type passed as the second argument to the
+** hash-key value passed as the first. Return the new hash-key value.
+*/
+static unsigned int sessionHashAppendType(unsigned int h, int eType){
+ return HASH_APPEND(h, eType);
+}
+
+/*
+** This function may only be called from within a pre-update callback.
+** It calculates a hash based on the primary key values of the old.* or
+** new.* row currently available and, assuming no error occurs, writes it to
+** *piHash before returning. If the primary key contains one or more NULL
+** values, *pbNullPK is set to true before returning.
+**
+** If an error occurs, an SQLite error code is returned and the final values
+** of *piHash asn *pbNullPK are undefined. Otherwise, SQLITE_OK is returned
+** and the output variables are set as described above.
+*/
+static int sessionPreupdateHash(
+ sqlite3_session *pSession, /* Session object that owns pTab */
+ SessionTable *pTab, /* Session table handle */
+ int bNew, /* True to hash the new.* PK */
+ int *piHash, /* OUT: Hash value */
+ int *pbNullPK /* OUT: True if there are NULL values in PK */
+){
+ unsigned int h = 0; /* Hash value to return */
+ int i; /* Used to iterate through columns */
+
+ assert( *pbNullPK==0 );
+ assert( pTab->nCol==pSession->hook.xCount(pSession->hook.pCtx) );
+ for(i=0; i<pTab->nCol; i++){
+ if( pTab->abPK[i] ){
+ int rc;
+ int eType;
+ sqlite3_value *pVal;
+
+ if( bNew ){
+ rc = pSession->hook.xNew(pSession->hook.pCtx, i, &pVal);
+ }else{
+ rc = pSession->hook.xOld(pSession->hook.pCtx, i, &pVal);
+ }
+ if( rc!=SQLITE_OK ) return rc;
+
+ eType = sqlite3_value_type(pVal);
+ h = sessionHashAppendType(h, eType);
+ if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ i64 iVal;
+ if( eType==SQLITE_INTEGER ){
+ iVal = sqlite3_value_int64(pVal);
+ }else{
+ double rVal = sqlite3_value_double(pVal);
+ assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
+ memcpy(&iVal, &rVal, 8);
+ }
+ h = sessionHashAppendI64(h, iVal);
+ }else if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+ const u8 *z;
+ int n;
+ if( eType==SQLITE_TEXT ){
+ z = (const u8 *)sqlite3_value_text(pVal);
+ }else{
+ z = (const u8 *)sqlite3_value_blob(pVal);
+ }
+ n = sqlite3_value_bytes(pVal);
+ if( !z && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
+ h = sessionHashAppendBlob(h, n, z);
+ }else{
+ assert( eType==SQLITE_NULL );
+ *pbNullPK = 1;
+ }
+ }
+ }
+
+ *piHash = (h % pTab->nChange);
+ return SQLITE_OK;
+}
+
+/*
+** The buffer that the argument points to contains a serialized SQL value.
+** Return the number of bytes of space occupied by the value (including
+** the type byte).
+*/
+static int sessionSerialLen(u8 *a){
+ int e = *a;
+ int n;
+ if( e==0 ) return 1;
+ if( e==SQLITE_NULL ) return 1;
+ if( e==SQLITE_INTEGER || e==SQLITE_FLOAT ) return 9;
+ return sessionVarintGet(&a[1], &n) + 1 + n;
+}
+
+/*
+** Based on the primary key values stored in change aRecord, calculate a
+** hash key. Assume the has table has nBucket buckets. The hash keys
+** calculated by this function are compatible with those calculated by
+** sessionPreupdateHash().
+**
+** The bPkOnly argument is non-zero if the record at aRecord[] is from
+** a patchset DELETE. In this case the non-PK fields are omitted entirely.
+*/
+static unsigned int sessionChangeHash(
+ SessionTable *pTab, /* Table handle */
+ int bPkOnly, /* Record consists of PK fields only */
+ u8 *aRecord, /* Change record */
+ int nBucket /* Assume this many buckets in hash table */
+){
+ unsigned int h = 0; /* Value to return */
+ int i; /* Used to iterate through columns */
+ u8 *a = aRecord; /* Used to iterate through change record */
+
+ for(i=0; i<pTab->nCol; i++){
+ int eType = *a;
+ int isPK = pTab->abPK[i];
+ if( bPkOnly && isPK==0 ) continue;
+
+ /* It is not possible for eType to be SQLITE_NULL here. The session
+ ** module does not record changes for rows with NULL values stored in
+ ** primary key columns. */
+ assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT
+ || eType==SQLITE_TEXT || eType==SQLITE_BLOB
+ || eType==SQLITE_NULL || eType==0
+ );
+ assert( !isPK || (eType!=0 && eType!=SQLITE_NULL) );
+
+ if( isPK ){
+ a++;
+ h = sessionHashAppendType(h, eType);
+ if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ h = sessionHashAppendI64(h, sessionGetI64(a));
+ a += 8;
+ }else{
+ int n;
+ a += sessionVarintGet(a, &n);
+ h = sessionHashAppendBlob(h, n, a);
+ a += n;
+ }
+ }else{
+ a += sessionSerialLen(a);
+ }
+ }
+ return (h % nBucket);
+}
+
+/*
+** Arguments aLeft and aRight are pointers to change records for table pTab.
+** This function returns true if the two records apply to the same row (i.e.
+** have the same values stored in the primary key columns), or false
+** otherwise.
+*/
+static int sessionChangeEqual(
+ SessionTable *pTab, /* Table used for PK definition */
+ int bLeftPkOnly, /* True if aLeft[] contains PK fields only */
+ u8 *aLeft, /* Change record */
+ int bRightPkOnly, /* True if aRight[] contains PK fields only */
+ u8 *aRight /* Change record */
+){
+ u8 *a1 = aLeft; /* Cursor to iterate through aLeft */
+ u8 *a2 = aRight; /* Cursor to iterate through aRight */
+ int iCol; /* Used to iterate through table columns */
+
+ for(iCol=0; iCol<pTab->nCol; iCol++){
+ int n1 = sessionSerialLen(a1);
+ int n2 = sessionSerialLen(a2);
+
+ if( pTab->abPK[iCol] && (n1!=n2 || memcmp(a1, a2, n1)) ){
+ return 0;
+ }
+ if( pTab->abPK[iCol] || bLeftPkOnly==0 ) a1 += n1;
+ if( pTab->abPK[iCol] || bRightPkOnly==0 ) a2 += n2;
+ }
+
+ return 1;
+}
+
+/*
+** Arguments aLeft and aRight both point to buffers containing change
+** records with nCol columns. This function "merges" the two records into
+** a single records which is written to the buffer at *paOut. *paOut is
+** then set to point to one byte after the last byte written before
+** returning.
+**
+** The merging of records is done as follows: For each column, if the
+** aRight record contains a value for the column, copy the value from
+** their. Otherwise, if aLeft contains a value, copy it. If neither
+** record contains a value for a given column, then neither does the
+** output record.
+*/
+static void sessionMergeRecord(
+ u8 **paOut,
+ int nCol,
+ u8 *aLeft,
+ u8 *aRight
+){
+ u8 *a1 = aLeft; /* Cursor used to iterate through aLeft */
+ u8 *a2 = aRight; /* Cursor used to iterate through aRight */
+ u8 *aOut = *paOut; /* Output cursor */
+ int iCol; /* Used to iterate from 0 to nCol */
+
+ for(iCol=0; iCol<nCol; iCol++){
+ int n1 = sessionSerialLen(a1);
+ int n2 = sessionSerialLen(a2);
+ if( *a2 ){
+ memcpy(aOut, a2, n2);
+ aOut += n2;
+ }else{
+ memcpy(aOut, a1, n1);
+ aOut += n1;
+ }
+ a1 += n1;
+ a2 += n2;
+ }
+
+ *paOut = aOut;
+}
+
+/*
+** This is a helper function used by sessionMergeUpdate().
+**
+** When this function is called, both *paOne and *paTwo point to a value
+** within a change record. Before it returns, both have been advanced so
+** as to point to the next value in the record.
+**
+** If, when this function is called, *paTwo points to a valid value (i.e.
+** *paTwo[0] is not 0x00 - the "no value" placeholder), a copy of the *paTwo
+** pointer is returned and *pnVal is set to the number of bytes in the
+** serialized value. Otherwise, a copy of *paOne is returned and *pnVal
+** set to the number of bytes in the value at *paOne. If *paOne points
+** to the "no value" placeholder, *pnVal is set to 1. In other words:
+**
+** if( *paTwo is valid ) return *paTwo;
+** return *paOne;
+**
+*/
+static u8 *sessionMergeValue(
+ u8 **paOne, /* IN/OUT: Left-hand buffer pointer */
+ u8 **paTwo, /* IN/OUT: Right-hand buffer pointer */
+ int *pnVal /* OUT: Bytes in returned value */
+){
+ u8 *a1 = *paOne;
+ u8 *a2 = *paTwo;
+ u8 *pRet = 0;
+ int n1;
+
+ assert( a1 );
+ if( a2 ){
+ int n2 = sessionSerialLen(a2);
+ if( *a2 ){
+ *pnVal = n2;
+ pRet = a2;
+ }
+ *paTwo = &a2[n2];
+ }
+
+ n1 = sessionSerialLen(a1);
+ if( pRet==0 ){
+ *pnVal = n1;
+ pRet = a1;
+ }
+ *paOne = &a1[n1];
+
+ return pRet;
+}
+
+/*
+** This function is used by changeset_concat() to merge two UPDATE changes
+** on the same row.
+*/
+static int sessionMergeUpdate(
+ u8 **paOut, /* IN/OUT: Pointer to output buffer */
+ SessionTable *pTab, /* Table change pertains to */
+ int bPatchset, /* True if records are patchset records */
+ u8 *aOldRecord1, /* old.* record for first change */
+ u8 *aOldRecord2, /* old.* record for second change */
+ u8 *aNewRecord1, /* new.* record for first change */
+ u8 *aNewRecord2 /* new.* record for second change */
+){
+ u8 *aOld1 = aOldRecord1;
+ u8 *aOld2 = aOldRecord2;
+ u8 *aNew1 = aNewRecord1;
+ u8 *aNew2 = aNewRecord2;
+
+ u8 *aOut = *paOut;
+ int i;
+
+ if( bPatchset==0 ){
+ int bRequired = 0;
+
+ assert( aOldRecord1 && aNewRecord1 );
+
+ /* Write the old.* vector first. */
+ for(i=0; i<pTab->nCol; i++){
+ int nOld;
+ u8 *aOld;
+ int nNew;
+ u8 *aNew;
+
+ aOld = sessionMergeValue(&aOld1, &aOld2, &nOld);
+ aNew = sessionMergeValue(&aNew1, &aNew2, &nNew);
+ if( pTab->abPK[i] || nOld!=nNew || memcmp(aOld, aNew, nNew) ){
+ if( pTab->abPK[i]==0 ) bRequired = 1;
+ memcpy(aOut, aOld, nOld);
+ aOut += nOld;
+ }else{
+ *(aOut++) = '\0';
+ }
+ }
+
+ if( !bRequired ) return 0;
+ }
+
+ /* Write the new.* vector */
+ aOld1 = aOldRecord1;
+ aOld2 = aOldRecord2;
+ aNew1 = aNewRecord1;
+ aNew2 = aNewRecord2;
+ for(i=0; i<pTab->nCol; i++){
+ int nOld;
+ u8 *aOld;
+ int nNew;
+ u8 *aNew;
+
+ aOld = sessionMergeValue(&aOld1, &aOld2, &nOld);
+ aNew = sessionMergeValue(&aNew1, &aNew2, &nNew);
+ if( bPatchset==0
+ && (pTab->abPK[i] || (nOld==nNew && 0==memcmp(aOld, aNew, nNew)))
+ ){
+ *(aOut++) = '\0';
+ }else{
+ memcpy(aOut, aNew, nNew);
+ aOut += nNew;
+ }
+ }
+
+ *paOut = aOut;
+ return 1;
+}
+
+/*
+** This function is only called from within a pre-update-hook callback.
+** It determines if the current pre-update-hook change affects the same row
+** as the change stored in argument pChange. If so, it returns true. Otherwise
+** if the pre-update-hook does not affect the same row as pChange, it returns
+** false.
+*/
+static int sessionPreupdateEqual(
+ sqlite3_session *pSession, /* Session object that owns SessionTable */
+ SessionTable *pTab, /* Table associated with change */
+ SessionChange *pChange, /* Change to compare to */
+ int op /* Current pre-update operation */
+){
+ int iCol; /* Used to iterate through columns */
+ u8 *a = pChange->aRecord; /* Cursor used to scan change record */
+
+ assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );
+ for(iCol=0; iCol<pTab->nCol; iCol++){
+ if( !pTab->abPK[iCol] ){
+ a += sessionSerialLen(a);
+ }else{
+ sqlite3_value *pVal; /* Value returned by preupdate_new/old */
+ int rc; /* Error code from preupdate_new/old */
+ int eType = *a++; /* Type of value from change record */
+
+ /* The following calls to preupdate_new() and preupdate_old() can not
+ ** fail. This is because they cache their return values, and by the
+ ** time control flows to here they have already been called once from
+ ** within sessionPreupdateHash(). The first two asserts below verify
+ ** this (that the method has already been called). */
+ if( op==SQLITE_INSERT ){
+ /* assert( db->pPreUpdate->pNewUnpacked || db->pPreUpdate->aNew ); */
+ rc = pSession->hook.xNew(pSession->hook.pCtx, iCol, &pVal);
+ }else{
+ /* assert( db->pPreUpdate->pUnpacked ); */
+ rc = pSession->hook.xOld(pSession->hook.pCtx, iCol, &pVal);
+ }
+ assert( rc==SQLITE_OK );
+ if( sqlite3_value_type(pVal)!=eType ) return 0;
+
+ /* A SessionChange object never has a NULL value in a PK column */
+ assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT
+ || eType==SQLITE_BLOB || eType==SQLITE_TEXT
+ );
+
+ if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ i64 iVal = sessionGetI64(a);
+ a += 8;
+ if( eType==SQLITE_INTEGER ){
+ if( sqlite3_value_int64(pVal)!=iVal ) return 0;
+ }else{
+ double rVal;
+ assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
+ memcpy(&rVal, &iVal, 8);
+ if( sqlite3_value_double(pVal)!=rVal ) return 0;
+ }
+ }else{
+ int n;
+ const u8 *z;
+ a += sessionVarintGet(a, &n);
+ if( sqlite3_value_bytes(pVal)!=n ) return 0;
+ if( eType==SQLITE_TEXT ){
+ z = sqlite3_value_text(pVal);
+ }else{
+ z = sqlite3_value_blob(pVal);
+ }
+ if( memcmp(a, z, n) ) return 0;
+ a += n;
+ break;
+ }
+ }
+ }
+
+ return 1;
+}
+
+/*
+** If required, grow the hash table used to store changes on table pTab
+** (part of the session pSession). If a fatal OOM error occurs, set the
+** session object to failed and return SQLITE_ERROR. Otherwise, return
+** SQLITE_OK.
+**
+** It is possible that a non-fatal OOM error occurs in this function. In
+** that case the hash-table does not grow, but SQLITE_OK is returned anyway.
+** Growing the hash table in this case is a performance optimization only,
+** it is not required for correct operation.
+*/
+static int sessionGrowHash(int bPatchset, SessionTable *pTab){
+ if( pTab->nChange==0 || pTab->nEntry>=(pTab->nChange/2) ){
+ int i;
+ SessionChange **apNew;
+ int nNew = (pTab->nChange ? pTab->nChange : 128) * 2;
+
+ apNew = (SessionChange **)sqlite3_malloc(sizeof(SessionChange *) * nNew);
+ if( apNew==0 ){
+ if( pTab->nChange==0 ){
+ return SQLITE_ERROR;
+ }
+ return SQLITE_OK;
+ }
+ memset(apNew, 0, sizeof(SessionChange *) * nNew);
+
+ for(i=0; i<pTab->nChange; i++){
+ SessionChange *p;
+ SessionChange *pNext;
+ for(p=pTab->apChange[i]; p; p=pNext){
+ int bPkOnly = (p->op==SQLITE_DELETE && bPatchset);
+ int iHash = sessionChangeHash(pTab, bPkOnly, p->aRecord, nNew);
+ pNext = p->pNext;
+ p->pNext = apNew[iHash];
+ apNew[iHash] = p;
+ }
+ }
+
+ sqlite3_free(pTab->apChange);
+ pTab->nChange = nNew;
+ pTab->apChange = apNew;
+ }
+
+ return SQLITE_OK;
+}
+
+/*
+** This function queries the database for the names of the columns of table
+** zThis, in schema zDb. It is expected that the table has nCol columns. If
+** not, SQLITE_SCHEMA is returned and none of the output variables are
+** populated.
+**
+** Otherwise, if they are not NULL, variable *pnCol is set to the number
+** of columns in the database table and variable *pzTab is set to point to a
+** nul-terminated copy of the table name. *pazCol (if not NULL) is set to
+** point to an array of pointers to column names. And *pabPK (again, if not
+** NULL) is set to point to an array of booleans - true if the corresponding
+** column is part of the primary key.
+**
+** For example, if the table is declared as:
+**
+** CREATE TABLE tbl1(w, x, y, z, PRIMARY KEY(w, z));
+**
+** Then the four output variables are populated as follows:
+**
+** *pnCol = 4
+** *pzTab = "tbl1"
+** *pazCol = {"w", "x", "y", "z"}
+** *pabPK = {1, 0, 0, 1}
+**
+** All returned buffers are part of the same single allocation, which must
+** be freed using sqlite3_free() by the caller. If pazCol was not NULL, then
+** pointer *pazCol should be freed to release all memory. Otherwise, pointer
+** *pabPK. It is illegal for both pazCol and pabPK to be NULL.
+*/
+static int sessionTableInfo(
+ sqlite3 *db, /* Database connection */
+ const char *zDb, /* Name of attached database (e.g. "main") */
+ const char *zThis, /* Table name */
+ int *pnCol, /* OUT: number of columns */
+ const char **pzTab, /* OUT: Copy of zThis */
+ const char ***pazCol, /* OUT: Array of column names for table */
+ u8 **pabPK /* OUT: Array of booleans - true for PK col */
+){
+ char *zPragma;
+ sqlite3_stmt *pStmt;
+ int rc;
+ int nByte;
+ int nDbCol = 0;
+ int nThis;
+ int i;
+ u8 *pAlloc;
+ char **azCol = 0;
+ u8 *abPK;
+
+ assert( pazCol && pabPK );
+
+ nThis = sqlite3Strlen30(zThis);
+ zPragma = sqlite3_mprintf("PRAGMA '%q'.table_info('%q')", zDb, zThis);
+ if( !zPragma ) return SQLITE_NOMEM;
+
+ rc = sqlite3_prepare_v2(db, zPragma, -1, &pStmt, 0);
+ sqlite3_free(zPragma);
+ if( rc!=SQLITE_OK ) return rc;
+
+ nByte = nThis + 1;
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){
+ nByte += sqlite3_column_bytes(pStmt, 1);
+ nDbCol++;
+ }
+ rc = sqlite3_reset(pStmt);
+
+ if( rc==SQLITE_OK ){
+ nByte += nDbCol * (sizeof(const char *) + sizeof(u8) + 1);
+ pAlloc = sqlite3_malloc(nByte);
+ if( pAlloc==0 ){
+ rc = SQLITE_NOMEM;
+ }
+ }
+ if( rc==SQLITE_OK ){
+ azCol = (char **)pAlloc;
+ pAlloc = (u8 *)&azCol[nDbCol];
+ abPK = (u8 *)pAlloc;
+ pAlloc = &abPK[nDbCol];
+ if( pzTab ){
+ memcpy(pAlloc, zThis, nThis+1);
+ *pzTab = (char *)pAlloc;
+ pAlloc += nThis+1;
+ }
+
+ i = 0;
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){
+ int nName = sqlite3_column_bytes(pStmt, 1);
+ const unsigned char *zName = sqlite3_column_text(pStmt, 1);
+ if( zName==0 ) break;
+ memcpy(pAlloc, zName, nName+1);
+ azCol[i] = (char *)pAlloc;
+ pAlloc += nName+1;
+ abPK[i] = sqlite3_column_int(pStmt, 5);
+ i++;
+ }
+ rc = sqlite3_reset(pStmt);
+
+ }
+
+ /* If successful, populate the output variables. Otherwise, zero them and
+ ** free any allocation made. An error code will be returned in this case.
+ */
+ if( rc==SQLITE_OK ){
+ *pazCol = (const char **)azCol;
+ *pabPK = abPK;
+ *pnCol = nDbCol;
+ }else{
+ *pazCol = 0;
+ *pabPK = 0;
+ *pnCol = 0;
+ if( pzTab ) *pzTab = 0;
+ sqlite3_free(azCol);
+ }
+ sqlite3_finalize(pStmt);
+ return rc;
+}
+
+/*
+** This function is only called from within a pre-update handler for a
+** write to table pTab, part of session pSession. If this is the first
+** write to this table, set the SessionTable.nCol variable to the number
+** of columns in the table.
+**
+** Otherwise, if this is not the first time this table has been written
+** to, check that the number of columns in the table has not changed. If
+** it has not, return zero.
+**
+** If the number of columns in the table has changed since the last write
+** was recorded, set the session error-code to SQLITE_SCHEMA and return
+** non-zero. Users are not allowed to change the number of columns in a table
+** for which changes are being recorded by the session module. If they do so,
+** it is an error.
+*/
+static int sessionInitTable(sqlite3_session *pSession, SessionTable *pTab){
+ if( pTab->nCol==0 ){
+ assert( pTab->azCol==0 || pTab->abPK==0 );
+ pSession->rc = sessionTableInfo(pSession->db, pSession->zDb,
+ pTab->zName, &pTab->nCol, 0, &pTab->azCol, &pTab->abPK
+ );
+ }
+ if( pSession->rc==SQLITE_OK
+ && pTab->nCol!=pSession->hook.xCount(pSession->hook.pCtx)
+ ){
+ pSession->rc = SQLITE_SCHEMA;
+ }
+ return pSession->rc;
+}
+
+/*
+** This function is only called from with a pre-update-hook reporting a
+** change on table pTab (attached to session pSession). The type of change
+** (UPDATE, INSERT, DELETE) is specified by the first argument.
+**
+** Unless one is already present or an error occurs, an entry is added
+** to the changed-rows hash table associated with table pTab.
+*/
+static void sessionPreupdateOneChange(
+ int op, /* One of SQLITE_UPDATE, INSERT, DELETE */
+ sqlite3_session *pSession, /* Session object pTab is attached to */
+ SessionTable *pTab /* Table that change applies to */
+){
+ int iHash;
+ int bNull = 0;
+ int rc = SQLITE_OK;
+
+ if( pSession->rc ) return;
+
+ /* Load table details if required */
+ if( sessionInitTable(pSession, pTab) ) return;
+
+ /* Grow the hash table if required */
+ if( sessionGrowHash(0, pTab) ){
+ pSession->rc = SQLITE_NOMEM;
+ return;
+ }
+
+ /* Calculate the hash-key for this change. If the primary key of the row
+ ** includes a NULL value, exit early. Such changes are ignored by the
+ ** session module. */
+ rc = sessionPreupdateHash(pSession, pTab, op==SQLITE_INSERT, &iHash, &bNull);
+ if( rc!=SQLITE_OK ) goto error_out;
+
+ if( bNull==0 ){
+ /* Search the hash table for an existing record for this row. */
+ SessionChange *pC;
+ for(pC=pTab->apChange[iHash]; pC; pC=pC->pNext){
+ if( sessionPreupdateEqual(pSession, pTab, pC, op) ) break;
+ }
+
+ if( pC==0 ){
+ /* Create a new change object containing all the old values (if
+ ** this is an SQLITE_UPDATE or SQLITE_DELETE), or just the PK
+ ** values (if this is an INSERT). */
+ SessionChange *pChange; /* New change object */
+ int nByte; /* Number of bytes to allocate */
+ int i; /* Used to iterate through columns */
+
+ assert( rc==SQLITE_OK );
+ pTab->nEntry++;
+
+ /* Figure out how large an allocation is required */
+ nByte = sizeof(SessionChange);
+ for(i=0; i<pTab->nCol; i++){
+ sqlite3_value *p = 0;
+ if( op!=SQLITE_INSERT ){
+ TESTONLY(int trc = ) pSession->hook.xOld(pSession->hook.pCtx, i, &p);
+ assert( trc==SQLITE_OK );
+ }else if( pTab->abPK[i] ){
+ TESTONLY(int trc = ) pSession->hook.xNew(pSession->hook.pCtx, i, &p);
+ assert( trc==SQLITE_OK );
+ }
+
+ /* This may fail if SQLite value p contains a utf-16 string that must
+ ** be converted to utf-8 and an OOM error occurs while doing so. */
+ rc = sessionSerializeValue(0, p, &nByte);
+ if( rc!=SQLITE_OK ) goto error_out;
+ }
+
+ /* Allocate the change object */
+ pChange = (SessionChange *)sqlite3_malloc(nByte);
+ if( !pChange ){
+ rc = SQLITE_NOMEM;
+ goto error_out;
+ }else{
+ memset(pChange, 0, sizeof(SessionChange));
+ pChange->aRecord = (u8 *)&pChange[1];
+ }
+
+ /* Populate the change object. None of the preupdate_old(),
+ ** preupdate_new() or SerializeValue() calls below may fail as all
+ ** required values and encodings have already been cached in memory.
+ ** It is not possible for an OOM to occur in this block. */
+ nByte = 0;
+ for(i=0; i<pTab->nCol; i++){
+ sqlite3_value *p = 0;
+ if( op!=SQLITE_INSERT ){
+ pSession->hook.xOld(pSession->hook.pCtx, i, &p);
+ }else if( pTab->abPK[i] ){
+ pSession->hook.xNew(pSession->hook.pCtx, i, &p);
+ }
+ sessionSerializeValue(&pChange->aRecord[nByte], p, &nByte);
+ }
+
+ /* Add the change to the hash-table */
+ if( pSession->bIndirect || pSession->hook.xDepth(pSession->hook.pCtx) ){
+ pChange->bIndirect = 1;
+ }
+ pChange->nRecord = nByte;
+ pChange->op = op;
+ pChange->pNext = pTab->apChange[iHash];
+ pTab->apChange[iHash] = pChange;
+
+ }else if( pC->bIndirect ){
+ /* If the existing change is considered "indirect", but this current
+ ** change is "direct", mark the change object as direct. */
+ if( pSession->hook.xDepth(pSession->hook.pCtx)==0
+ && pSession->bIndirect==0
+ ){
+ pC->bIndirect = 0;
+ }
+ }
+ }
+
+ /* If an error has occurred, mark the session object as failed. */
+ error_out:
+ if( rc!=SQLITE_OK ){
+ pSession->rc = rc;
+ }
+}
+
+static int sessionFindTable(
+ sqlite3_session *pSession,
+ const char *zName,
+ SessionTable **ppTab
+){
+ int rc = SQLITE_OK;
+ int nName = sqlite3Strlen30(zName);
+ SessionTable *pRet;
+
+ /* Search for an existing table */
+ for(pRet=pSession->pTable; pRet; pRet=pRet->pNext){
+ if( 0==sqlite3_strnicmp(pRet->zName, zName, nName+1) ) break;
+ }
+
+ if( pRet==0 && pSession->bAutoAttach ){
+ /* If there is a table-filter configured, invoke it. If it returns 0,
+ ** do not automatically add the new table. */
+ if( pSession->xTableFilter==0
+ || pSession->xTableFilter(pSession->pFilterCtx, zName)
+ ){
+ rc = sqlite3session_attach(pSession, zName);
+ if( rc==SQLITE_OK ){
+ pRet = pSession->pTable;
+ assert( 0==sqlite3_strnicmp(pRet->zName, zName, nName+1) );
+ }
+ }
+ }
+
+ assert( rc==SQLITE_OK || pRet==0 );
+ *ppTab = pRet;
+ return rc;
+}
+
+/*
+** The 'pre-update' hook registered by this module with SQLite databases.
+*/
+static void xPreUpdate(
+ void *pCtx, /* Copy of third arg to preupdate_hook() */
+ sqlite3 *db, /* Database handle */
+ int op, /* SQLITE_UPDATE, DELETE or INSERT */
+ char const *zDb, /* Database name */
+ char const *zName, /* Table name */
+ sqlite3_int64 iKey1, /* Rowid of row about to be deleted/updated */
+ sqlite3_int64 iKey2 /* New rowid value (for a rowid UPDATE) */
+){
+ sqlite3_session *pSession;
+ int nDb = sqlite3Strlen30(zDb);
+
+ assert( sqlite3_mutex_held(db->mutex) );
+
+ for(pSession=(sqlite3_session *)pCtx; pSession; pSession=pSession->pNext){
+ SessionTable *pTab;
+
+ /* If this session is attached to a different database ("main", "temp"
+ ** etc.), or if it is not currently enabled, there is nothing to do. Skip
+ ** to the next session object attached to this database. */
+ if( pSession->bEnable==0 ) continue;
+ if( pSession->rc ) continue;
+ if( sqlite3_strnicmp(zDb, pSession->zDb, nDb+1) ) continue;
+
+ pSession->rc = sessionFindTable(pSession, zName, &pTab);
+ if( pTab ){
+ assert( pSession->rc==SQLITE_OK );
+ sessionPreupdateOneChange(op, pSession, pTab);
+ if( op==SQLITE_UPDATE ){
+ sessionPreupdateOneChange(SQLITE_INSERT, pSession, pTab);
+ }
+ }
+ }
+}
+
+/*
+** The pre-update hook implementations.
+*/
+static int sessionPreupdateOld(void *pCtx, int iVal, sqlite3_value **ppVal){
+ return sqlite3_preupdate_old((sqlite3*)pCtx, iVal, ppVal);
+}
+static int sessionPreupdateNew(void *pCtx, int iVal, sqlite3_value **ppVal){
+ return sqlite3_preupdate_new((sqlite3*)pCtx, iVal, ppVal);
+}
+static int sessionPreupdateCount(void *pCtx){
+ return sqlite3_preupdate_count((sqlite3*)pCtx);
+}
+static int sessionPreupdateDepth(void *pCtx){
+ return sqlite3_preupdate_depth((sqlite3*)pCtx);
+}
+
+/*
+** Install the pre-update hooks on the session object passed as the only
+** argument.
+*/
+static void sessionPreupdateHooks(
+ sqlite3_session *pSession
+){
+ pSession->hook.pCtx = (void*)pSession->db;
+ pSession->hook.xOld = sessionPreupdateOld;
+ pSession->hook.xNew = sessionPreupdateNew;
+ pSession->hook.xCount = sessionPreupdateCount;
+ pSession->hook.xDepth = sessionPreupdateDepth;
+}
+
+typedef struct SessionDiffCtx SessionDiffCtx;
+struct SessionDiffCtx {
+ sqlite3_stmt *pStmt;
+ int nOldOff;
+};
+
+/*
+** The diff hook implementations.
+*/
+static int sessionDiffOld(void *pCtx, int iVal, sqlite3_value **ppVal){
+ SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+ *ppVal = sqlite3_column_value(p->pStmt, iVal+p->nOldOff);
+ return SQLITE_OK;
+}
+static int sessionDiffNew(void *pCtx, int iVal, sqlite3_value **ppVal){
+ SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+ *ppVal = sqlite3_column_value(p->pStmt, iVal);
+ return SQLITE_OK;
+}
+static int sessionDiffCount(void *pCtx){
+ SessionDiffCtx *p = (SessionDiffCtx*)pCtx;
+ return p->nOldOff ? p->nOldOff : sqlite3_column_count(p->pStmt);
+}
+static int sessionDiffDepth(void *pCtx){
+ return 0;
+}
+
+/*
+** Install the diff hooks on the session object passed as the only
+** argument.
+*/
+static void sessionDiffHooks(
+ sqlite3_session *pSession,
+ SessionDiffCtx *pDiffCtx
+){
+ pSession->hook.pCtx = (void*)pDiffCtx;
+ pSession->hook.xOld = sessionDiffOld;
+ pSession->hook.xNew = sessionDiffNew;
+ pSession->hook.xCount = sessionDiffCount;
+ pSession->hook.xDepth = sessionDiffDepth;
+}
+
+static char *sessionExprComparePK(
+ int nCol,
+ const char *zDb1, const char *zDb2,
+ const char *zTab,
+ const char **azCol, u8 *abPK
+){
+ int i;
+ const char *zSep = "";
+ char *zRet = 0;
+
+ for(i=0; i<nCol; i++){
+ if( abPK[i] ){
+ zRet = sqlite3_mprintf("%z%s\"%w\".\"%w\".\"%w\"=\"%w\".\"%w\".\"%w\"",
+ zRet, zSep, zDb1, zTab, azCol[i], zDb2, zTab, azCol[i]
+ );
+ zSep = " AND ";
+ if( zRet==0 ) break;
+ }
+ }
+
+ return zRet;
+}
+
+static char *sessionExprCompareOther(
+ int nCol,
+ const char *zDb1, const char *zDb2,
+ const char *zTab,
+ const char **azCol, u8 *abPK
+){
+ int i;
+ const char *zSep = "";
+ char *zRet = 0;
+ int bHave = 0;
+
+ for(i=0; i<nCol; i++){
+ if( abPK[i]==0 ){
+ bHave = 1;
+ zRet = sqlite3_mprintf(
+ "%z%s\"%w\".\"%w\".\"%w\" IS NOT \"%w\".\"%w\".\"%w\"",
+ zRet, zSep, zDb1, zTab, azCol[i], zDb2, zTab, azCol[i]
+ );
+ zSep = " OR ";
+ if( zRet==0 ) break;
+ }
+ }
+
+ if( bHave==0 ){
+ assert( zRet==0 );
+ zRet = sqlite3_mprintf("0");
+ }
+
+ return zRet;
+}
+
+static char *sessionSelectFindNew(
+ int nCol,
+ const char *zDb1, /* Pick rows in this db only */
+ const char *zDb2, /* But not in this one */
+ const char *zTbl, /* Table name */
+ const char *zExpr
+){
+ char *zRet = sqlite3_mprintf(
+ "SELECT * FROM \"%w\".\"%w\" WHERE NOT EXISTS ("
+ " SELECT 1 FROM \"%w\".\"%w\" WHERE %s"
+ ")",
+ zDb1, zTbl, zDb2, zTbl, zExpr
+ );
+ return zRet;
+}
+
+static int sessionDiffFindNew(
+ int op,
+ sqlite3_session *pSession,
+ SessionTable *pTab,
+ const char *zDb1,
+ const char *zDb2,
+ char *zExpr
+){
+ int rc = SQLITE_OK;
+ char *zStmt = sessionSelectFindNew(pTab->nCol, zDb1, zDb2, pTab->zName,zExpr);
+
+ if( zStmt==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ sqlite3_stmt *pStmt;
+ rc = sqlite3_prepare(pSession->db, zStmt, -1, &pStmt, 0);
+ if( rc==SQLITE_OK ){
+ SessionDiffCtx *pDiffCtx = (SessionDiffCtx*)pSession->hook.pCtx;
+ pDiffCtx->pStmt = pStmt;
+ pDiffCtx->nOldOff = 0;
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){
+ sessionPreupdateOneChange(op, pSession, pTab);
+ }
+ rc = sqlite3_finalize(pStmt);
+ }
+ sqlite3_free(zStmt);
+ }
+
+ return rc;
+}
+
+static int sessionDiffFindModified(
+ sqlite3_session *pSession,
+ SessionTable *pTab,
+ const char *zFrom,
+ const char *zExpr
+){
+ int rc = SQLITE_OK;
+
+ char *zExpr2 = sessionExprCompareOther(pTab->nCol,
+ pSession->zDb, zFrom, pTab->zName, pTab->azCol, pTab->abPK
+ );
+ if( zExpr2==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ char *zStmt = sqlite3_mprintf(
+ "SELECT * FROM \"%w\".\"%w\", \"%w\".\"%w\" WHERE %s AND (%z)",
+ pSession->zDb, pTab->zName, zFrom, pTab->zName, zExpr, zExpr2
+ );
+ if( zStmt==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ sqlite3_stmt *pStmt;
+ rc = sqlite3_prepare(pSession->db, zStmt, -1, &pStmt, 0);
+
+ if( rc==SQLITE_OK ){
+ SessionDiffCtx *pDiffCtx = (SessionDiffCtx*)pSession->hook.pCtx;
+ pDiffCtx->pStmt = pStmt;
+ pDiffCtx->nOldOff = pTab->nCol;
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){
+ sessionPreupdateOneChange(SQLITE_UPDATE, pSession, pTab);
+ }
+ rc = sqlite3_finalize(pStmt);
+ }
+ sqlite3_free(zStmt);
+ }
+ }
+
+ return rc;
+}
+
+int sqlite3session_diff(
+ sqlite3_session *pSession,
+ const char *zFrom,
+ const char *zTbl,
+ char **pzErrMsg
+){
+ const char *zDb = pSession->zDb;
+ int rc = pSession->rc;
+ SessionDiffCtx d;
+
+ memset(&d, 0, sizeof(d));
+ sessionDiffHooks(pSession, &d);
+
+ sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+ if( pzErrMsg ) *pzErrMsg = 0;
+ if( rc==SQLITE_OK ){
+ char *zExpr = 0;
+ sqlite3 *db = pSession->db;
+ SessionTable *pTo; /* Table zTbl */
+
+ /* Locate and if necessary initialize the target table object */
+ rc = sessionFindTable(pSession, zTbl, &pTo);
+ if( pTo==0 ) goto diff_out;
+ if( pTo->nCol==0 ){
+ rc = pSession->rc = sessionTableInfo(db, zDb,
+ pTo->zName, &pTo->nCol, 0, &pTo->azCol, &pTo->abPK
+ );
+ }
+
+ /* Check the table schemas match */
+ if( rc==SQLITE_OK ){
+ int bHasPk = 0;
+ int bMismatch = 0;
+ int nCol; /* Columns in zFrom.zTbl */
+ u8 *abPK;
+ const char **azCol = 0;
+ rc = sessionTableInfo(db, zFrom, zTbl, &nCol, 0, &azCol, &abPK);
+ if( rc==SQLITE_OK ){
+ if( pTo->nCol!=nCol ){
+ bMismatch = 1;
+ }else{
+ int i;
+ for(i=0; i<nCol; i++){
+ if( pTo->abPK[i]!=abPK[i] ) bMismatch = 1;
+ if( sqlite3_stricmp(azCol[i], pTo->azCol[i]) ) bMismatch = 1;
+ if( abPK[i] ) bHasPk = 1;
+ }
+ }
+
+ }
++ sqlite3_free((char*)azCol);
+ if( bMismatch ){
+ *pzErrMsg = sqlite3_mprintf("table schemas do not match");
+ rc = SQLITE_SCHEMA;
+ }
+ if( bHasPk==0 ){
+ /* Ignore tables with no primary keys */
+ goto diff_out;
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ zExpr = sessionExprComparePK(pTo->nCol,
+ zDb, zFrom, pTo->zName, pTo->azCol, pTo->abPK
+ );
+ }
+
+ /* Find new rows */
+ if( rc==SQLITE_OK ){
+ rc = sessionDiffFindNew(SQLITE_INSERT, pSession, pTo, zDb, zFrom, zExpr);
+ }
+
+ /* Find old rows */
+ if( rc==SQLITE_OK ){
+ rc = sessionDiffFindNew(SQLITE_DELETE, pSession, pTo, zFrom, zDb, zExpr);
+ }
+
+ /* Find modified rows */
+ if( rc==SQLITE_OK ){
+ rc = sessionDiffFindModified(pSession, pTo, zFrom, zExpr);
+ }
+
+ sqlite3_free(zExpr);
+ }
+
+ diff_out:
+ sessionPreupdateHooks(pSession);
+ sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+ return rc;
+}
+
+/*
+** Create a session object. This session object will record changes to
+** database zDb attached to connection db.
+*/
+int sqlite3session_create(
+ sqlite3 *db, /* Database handle */
+ const char *zDb, /* Name of db (e.g. "main") */
+ sqlite3_session **ppSession /* OUT: New session object */
+){
+ sqlite3_session *pNew; /* Newly allocated session object */
+ sqlite3_session *pOld; /* Session object already attached to db */
+ int nDb = sqlite3Strlen30(zDb); /* Length of zDb in bytes */
+
+ /* Zero the output value in case an error occurs. */
+ *ppSession = 0;
+
+ /* Allocate and populate the new session object. */
+ pNew = (sqlite3_session *)sqlite3_malloc(sizeof(sqlite3_session) + nDb + 1);
+ if( !pNew ) return SQLITE_NOMEM;
+ memset(pNew, 0, sizeof(sqlite3_session));
+ pNew->db = db;
+ pNew->zDb = (char *)&pNew[1];
+ pNew->bEnable = 1;
+ memcpy(pNew->zDb, zDb, nDb+1);
+ sessionPreupdateHooks(pNew);
+
+ /* Add the new session object to the linked list of session objects
+ ** attached to database handle $db. Do this under the cover of the db
+ ** handle mutex. */
+ sqlite3_mutex_enter(sqlite3_db_mutex(db));
+ pOld = (sqlite3_session*)sqlite3_preupdate_hook(db, xPreUpdate, (void*)pNew);
+ pNew->pNext = pOld;
+ sqlite3_mutex_leave(sqlite3_db_mutex(db));
+
+ *ppSession = pNew;
+ return SQLITE_OK;
+}
+
+/*
+** Free the list of table objects passed as the first argument. The contents
+** of the changed-rows hash tables are also deleted.
+*/
+static void sessionDeleteTable(SessionTable *pList){
+ SessionTable *pNext;
+ SessionTable *pTab;
+
+ for(pTab=pList; pTab; pTab=pNext){
+ int i;
+ pNext = pTab->pNext;
+ for(i=0; i<pTab->nChange; i++){
+ SessionChange *p;
+ SessionChange *pNext;
+ for(p=pTab->apChange[i]; p; p=pNext){
+ pNext = p->pNext;
+ sqlite3_free(p);
+ }
+ }
+ sqlite3_free((char*)pTab->azCol); /* cast works around VC++ bug */
+ sqlite3_free(pTab->apChange);
+ sqlite3_free(pTab);
+ }
+}
+
+/*
+** Delete a session object previously allocated using sqlite3session_create().
+*/
+void sqlite3session_delete(sqlite3_session *pSession){
+ sqlite3 *db = pSession->db;
+ sqlite3_session *pHead;
+ sqlite3_session **pp;
+
+ /* Unlink the session from the linked list of sessions attached to the
+ ** database handle. Hold the db mutex while doing so. */
+ sqlite3_mutex_enter(sqlite3_db_mutex(db));
+ pHead = (sqlite3_session*)sqlite3_preupdate_hook(db, 0, 0);
+ for(pp=&pHead; (*pp)!=pSession; pp=&((*pp)->pNext));
+ *pp = (*pp)->pNext;
+ if( pHead ) sqlite3_preupdate_hook(db, xPreUpdate, (void *)pHead);
+ sqlite3_mutex_leave(sqlite3_db_mutex(db));
+
+ /* Delete all attached table objects. And the contents of their
+ ** associated hash-tables. */
+ sessionDeleteTable(pSession->pTable);
+
+ /* Free the session object itself. */
+ sqlite3_free(pSession);
+}
+
+/*
+** Set a table filter on a Session Object.
+*/
+void sqlite3session_table_filter(
+ sqlite3_session *pSession,
+ int(*xFilter)(void*, const char*),
+ void *pCtx /* First argument passed to xFilter */
+){
+ pSession->bAutoAttach = 1;
+ pSession->pFilterCtx = pCtx;
+ pSession->xTableFilter = xFilter;
+}
+
+/*
+** Attach a table to a session. All subsequent changes made to the table
+** while the session object is enabled will be recorded.
+**
+** Only tables that have a PRIMARY KEY defined may be attached. It does
+** not matter if the PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias)
+** or not.
+*/
+int sqlite3session_attach(
+ sqlite3_session *pSession, /* Session object */
+ const char *zName /* Table name */
+){
+ int rc = SQLITE_OK;
+ sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+
+ if( !zName ){
+ pSession->bAutoAttach = 1;
+ }else{
+ SessionTable *pTab; /* New table object (if required) */
+ int nName; /* Number of bytes in string zName */
+
+ /* First search for an existing entry. If one is found, this call is
+ ** a no-op. Return early. */
+ nName = sqlite3Strlen30(zName);
+ for(pTab=pSession->pTable; pTab; pTab=pTab->pNext){
+ if( 0==sqlite3_strnicmp(pTab->zName, zName, nName+1) ) break;
+ }
+
+ if( !pTab ){
+ /* Allocate new SessionTable object. */
+ pTab = (SessionTable *)sqlite3_malloc(sizeof(SessionTable) + nName + 1);
+ if( !pTab ){
+ rc = SQLITE_NOMEM;
+ }else{
+ /* Populate the new SessionTable object and link it into the list. */
+ memset(pTab, 0, sizeof(SessionTable));
+ pTab->zName = (char *)&pTab[1];
+ memcpy(pTab->zName, zName, nName+1);
+ pTab->pNext = pSession->pTable;
+ pSession->pTable = pTab;
+ }
+ }
+ }
+
+ sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+ return rc;
+}
+
+/*
+** Ensure that there is room in the buffer to append nByte bytes of data.
+** If not, use sqlite3_realloc() to grow the buffer so that there is.
+**
+** If successful, return zero. Otherwise, if an OOM condition is encountered,
+** set *pRc to SQLITE_NOMEM and return non-zero.
+*/
+static int sessionBufferGrow(SessionBuffer *p, int nByte, int *pRc){
+ if( *pRc==SQLITE_OK && p->nAlloc-p->nBuf<nByte ){
+ u8 *aNew;
+ int nNew = p->nAlloc ? p->nAlloc : 128;
+ do {
+ nNew = nNew*2;
+ }while( nNew<(p->nBuf+nByte) );
+
+ aNew = (u8 *)sqlite3_realloc(p->aBuf, nNew);
+ if( 0==aNew ){
+ *pRc = SQLITE_NOMEM;
+ }else{
+ p->aBuf = aNew;
+ p->nAlloc = nNew;
+ }
+ }
+ return (*pRc!=SQLITE_OK);
+}
+
+/*
+** Append the value passed as the second argument to the buffer passed
+** as the first.
+**
+** This function is a no-op if *pRc is non-zero when it is called.
+** Otherwise, if an error occurs, *pRc is set to an SQLite error code
+** before returning.
+*/
+static void sessionAppendValue(SessionBuffer *p, sqlite3_value *pVal, int *pRc){
+ int rc = *pRc;
+ if( rc==SQLITE_OK ){
+ int nByte = 0;
+ rc = sessionSerializeValue(0, pVal, &nByte);
+ sessionBufferGrow(p, nByte, &rc);
+ if( rc==SQLITE_OK ){
+ rc = sessionSerializeValue(&p->aBuf[p->nBuf], pVal, 0);
+ p->nBuf += nByte;
+ }else{
+ *pRc = rc;
+ }
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append a single byte to the buffer.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendByte(SessionBuffer *p, u8 v, int *pRc){
+ if( 0==sessionBufferGrow(p, 1, pRc) ){
+ p->aBuf[p->nBuf++] = v;
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append a single varint to the buffer.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendVarint(SessionBuffer *p, int v, int *pRc){
+ if( 0==sessionBufferGrow(p, 9, pRc) ){
+ p->nBuf += sessionVarintPut(&p->aBuf[p->nBuf], v);
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append a blob of data to the buffer.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendBlob(
+ SessionBuffer *p,
+ const u8 *aBlob,
+ int nBlob,
+ int *pRc
+){
+ if( 0==sessionBufferGrow(p, nBlob, pRc) ){
+ memcpy(&p->aBuf[p->nBuf], aBlob, nBlob);
+ p->nBuf += nBlob;
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append a string to the buffer. All bytes in the string
+** up to (but not including) the nul-terminator are written to the buffer.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendStr(
+ SessionBuffer *p,
+ const char *zStr,
+ int *pRc
+){
+ int nStr = sqlite3Strlen30(zStr);
+ if( 0==sessionBufferGrow(p, nStr, pRc) ){
+ memcpy(&p->aBuf[p->nBuf], zStr, nStr);
+ p->nBuf += nStr;
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append the string representation of integer iVal
+** to the buffer. No nul-terminator is written.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendInteger(
+ SessionBuffer *p, /* Buffer to append to */
+ int iVal, /* Value to write the string rep. of */
+ int *pRc /* IN/OUT: Error code */
+){
+ char aBuf[24];
+ sqlite3_snprintf(sizeof(aBuf)-1, aBuf, "%d", iVal);
+ sessionAppendStr(p, aBuf, pRc);
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwise, append the string zStr enclosed in quotes (") and
+** with any embedded quote characters escaped to the buffer. No
+** nul-terminator byte is written.
+**
+** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
+** returning.
+*/
+static void sessionAppendIdent(
+ SessionBuffer *p, /* Buffer to a append to */
+ const char *zStr, /* String to quote, escape and append */
+ int *pRc /* IN/OUT: Error code */
+){
+ int nStr = sqlite3Strlen30(zStr)*2 + 2 + 1;
+ if( 0==sessionBufferGrow(p, nStr, pRc) ){
+ char *zOut = (char *)&p->aBuf[p->nBuf];
+ const char *zIn = zStr;
+ *zOut++ = '"';
+ while( *zIn ){
+ if( *zIn=='"' ) *zOut++ = '"';
+ *zOut++ = *(zIn++);
+ }
+ *zOut++ = '"';
+ p->nBuf = (int)((u8 *)zOut - p->aBuf);
+ }
+}
+
+/*
+** This function is a no-op if *pRc is other than SQLITE_OK when it is
+** called. Otherwse, it appends the serialized version of the value stored
+** in column iCol of the row that SQL statement pStmt currently points
+** to to the buffer.
+*/
+static void sessionAppendCol(
+ SessionBuffer *p, /* Buffer to append to */
+ sqlite3_stmt *pStmt, /* Handle pointing to row containing value */
+ int iCol, /* Column to read value from */
+ int *pRc /* IN/OUT: Error code */
+){
+ if( *pRc==SQLITE_OK ){
+ int eType = sqlite3_column_type(pStmt, iCol);
+ sessionAppendByte(p, (u8)eType, pRc);
+ if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ sqlite3_int64 i;
+ u8 aBuf[8];
+ if( eType==SQLITE_INTEGER ){
+ i = sqlite3_column_int64(pStmt, iCol);
+ }else{
+ double r = sqlite3_column_double(pStmt, iCol);
+ memcpy(&i, &r, 8);
+ }
+ sessionPutI64(aBuf, i);
+ sessionAppendBlob(p, aBuf, 8, pRc);
+ }
+ if( eType==SQLITE_BLOB || eType==SQLITE_TEXT ){
+ u8 *z;
+ int nByte;
+ if( eType==SQLITE_BLOB ){
+ z = (u8 *)sqlite3_column_blob(pStmt, iCol);
+ }else{
+ z = (u8 *)sqlite3_column_text(pStmt, iCol);
+ }
+ nByte = sqlite3_column_bytes(pStmt, iCol);
+ if( z || (eType==SQLITE_BLOB && nByte==0) ){
+ sessionAppendVarint(p, nByte, pRc);
+ sessionAppendBlob(p, z, nByte, pRc);
+ }else{
+ *pRc = SQLITE_NOMEM;
+ }
+ }
+ }
+}
+
+/*
+**
+** This function appends an update change to the buffer (see the comments
+** under "CHANGESET FORMAT" at the top of the file). An update change
+** consists of:
+**
+** 1 byte: SQLITE_UPDATE (0x17)
+** n bytes: old.* record (see RECORD FORMAT)
+** m bytes: new.* record (see RECORD FORMAT)
+**
+** The SessionChange object passed as the third argument contains the
+** values that were stored in the row when the session began (the old.*
+** values). The statement handle passed as the second argument points
+** at the current version of the row (the new.* values).
+**
+** If all of the old.* values are equal to their corresponding new.* value
+** (i.e. nothing has changed), then no data at all is appended to the buffer.
+**
+** Otherwise, the old.* record contains all primary key values and the
+** original values of any fields that have been modified. The new.* record
+** contains the new values of only those fields that have been modified.
+*/
+static int sessionAppendUpdate(
+ SessionBuffer *pBuf, /* Buffer to append to */
+ int bPatchset, /* True for "patchset", 0 for "changeset" */
+ sqlite3_stmt *pStmt, /* Statement handle pointing at new row */
+ SessionChange *p, /* Object containing old values */
+ u8 *abPK /* Boolean array - true for PK columns */
+){
+ int rc = SQLITE_OK;
+ SessionBuffer buf2 = {0,0,0}; /* Buffer to accumulate new.* record in */
+ int bNoop = 1; /* Set to zero if any values are modified */
+ int nRewind = pBuf->nBuf; /* Set to zero if any values are modified */
+ int i; /* Used to iterate through columns */
+ u8 *pCsr = p->aRecord; /* Used to iterate through old.* values */
+
+ sessionAppendByte(pBuf, SQLITE_UPDATE, &rc);
+ sessionAppendByte(pBuf, p->bIndirect, &rc);
+ for(i=0; i<sqlite3_column_count(pStmt); i++){
+ int bChanged = 0;
+ int nAdvance;
+ int eType = *pCsr;
+ switch( eType ){
+ case SQLITE_NULL:
+ nAdvance = 1;
+ if( sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
+ bChanged = 1;
+ }
+ break;
+
+ case SQLITE_FLOAT:
+ case SQLITE_INTEGER: {
+ nAdvance = 9;
+ if( eType==sqlite3_column_type(pStmt, i) ){
+ sqlite3_int64 iVal = sessionGetI64(&pCsr[1]);
+ if( eType==SQLITE_INTEGER ){
+ if( iVal==sqlite3_column_int64(pStmt, i) ) break;
+ }else{
+ double dVal;
+ memcpy(&dVal, &iVal, 8);
+ if( dVal==sqlite3_column_double(pStmt, i) ) break;
+ }
+ }
+ bChanged = 1;
+ break;
+ }
+
+ default: {
+ int nByte;
+ int nHdr = 1 + sessionVarintGet(&pCsr[1], &nByte);
+ assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
+ nAdvance = nHdr + nByte;
+ if( eType==sqlite3_column_type(pStmt, i)
+ && nByte==sqlite3_column_bytes(pStmt, i)
+ && 0==memcmp(&pCsr[nHdr], sqlite3_column_blob(pStmt, i), nByte)
+ ){
+ break;
+ }
+ bChanged = 1;
+ }
+ }
+
+ /* If at least one field has been modified, this is not a no-op. */
+ if( bChanged ) bNoop = 0;
+
+ /* Add a field to the old.* record. This is omitted if this modules is
+ ** currently generating a patchset. */
+ if( bPatchset==0 ){
+ if( bChanged || abPK[i] ){
+ sessionAppendBlob(pBuf, pCsr, nAdvance, &rc);
+ }else{
+ sessionAppendByte(pBuf, 0, &rc);
+ }
+ }
+
+ /* Add a field to the new.* record. Or the only record if currently
+ ** generating a patchset. */
+ if( bChanged || (bPatchset && abPK[i]) ){
+ sessionAppendCol(&buf2, pStmt, i, &rc);
+ }else{
+ sessionAppendByte(&buf2, 0, &rc);
+ }
+
+ pCsr += nAdvance;
+ }
+
+ if( bNoop ){
+ pBuf->nBuf = nRewind;
+ }else{
+ sessionAppendBlob(pBuf, buf2.aBuf, buf2.nBuf, &rc);
+ }
+ sqlite3_free(buf2.aBuf);
+
+ return rc;
+}
+
+/*
+** Append a DELETE change to the buffer passed as the first argument. Use
+** the changeset format if argument bPatchset is zero, or the patchset
+** format otherwise.
+*/
+static int sessionAppendDelete(
+ SessionBuffer *pBuf, /* Buffer to append to */
+ int bPatchset, /* True for "patchset", 0 for "changeset" */
+ SessionChange *p, /* Object containing old values */
+ int nCol, /* Number of columns in table */
+ u8 *abPK /* Boolean array - true for PK columns */
+){
+ int rc = SQLITE_OK;
+
+ sessionAppendByte(pBuf, SQLITE_DELETE, &rc);
+ sessionAppendByte(pBuf, p->bIndirect, &rc);
+
+ if( bPatchset==0 ){
+ sessionAppendBlob(pBuf, p->aRecord, p->nRecord, &rc);
+ }else{
+ int i;
+ u8 *a = p->aRecord;
+ for(i=0; i<nCol; i++){
+ u8 *pStart = a;
+ int eType = *a++;
+
+ switch( eType ){
+ case 0:
+ case SQLITE_NULL:
+ assert( abPK[i]==0 );
+ break;
+
+ case SQLITE_FLOAT:
+ case SQLITE_INTEGER:
+ a += 8;
+ break;
+
+ default: {
+ int n;
+ a += sessionVarintGet(a, &n);
+ a += n;
+ break;
+ }
+ }
+ if( abPK[i] ){
+ sessionAppendBlob(pBuf, pStart, (int)(a-pStart), &rc);
+ }
+ }
+ assert( (a - p->aRecord)==p->nRecord );
+ }
+
+ return rc;
+}
+
+/*
+** Formulate and prepare a SELECT statement to retrieve a row from table
+** zTab in database zDb based on its primary key. i.e.
+**
+** SELECT * FROM zDb.zTab WHERE pk1 = ? AND pk2 = ? AND ...
+*/
+static int sessionSelectStmt(
+ sqlite3 *db, /* Database handle */
+ const char *zDb, /* Database name */
+ const char *zTab, /* Table name */
+ int nCol, /* Number of columns in table */
+ const char **azCol, /* Names of table columns */
+ u8 *abPK, /* PRIMARY KEY array */
+ sqlite3_stmt **ppStmt /* OUT: Prepared SELECT statement */
+){
+ int rc = SQLITE_OK;
+ int i;
+ const char *zSep = "";
+ SessionBuffer buf = {0, 0, 0};
+
+ sessionAppendStr(&buf, "SELECT * FROM ", &rc);
+ sessionAppendIdent(&buf, zDb, &rc);
+ sessionAppendStr(&buf, ".", &rc);
+ sessionAppendIdent(&buf, zTab, &rc);
+ sessionAppendStr(&buf, " WHERE ", &rc);
+ for(i=0; i<nCol; i++){
+ if( abPK[i] ){
+ sessionAppendStr(&buf, zSep, &rc);
+ sessionAppendIdent(&buf, azCol[i], &rc);
+ sessionAppendStr(&buf, " = ?", &rc);
+ sessionAppendInteger(&buf, i+1, &rc);
+ zSep = " AND ";
+ }
+ }
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, ppStmt, 0);
+ }
+ sqlite3_free(buf.aBuf);
+ return rc;
+}
+
+/*
+** Bind the PRIMARY KEY values from the change passed in argument pChange
+** to the SELECT statement passed as the first argument. The SELECT statement
+** is as prepared by function sessionSelectStmt().
+**
+** Return SQLITE_OK if all PK values are successfully bound, or an SQLite
+** error code (e.g. SQLITE_NOMEM) otherwise.
+*/
+static int sessionSelectBind(
+ sqlite3_stmt *pSelect, /* SELECT from sessionSelectStmt() */
+ int nCol, /* Number of columns in table */
+ u8 *abPK, /* PRIMARY KEY array */
+ SessionChange *pChange /* Change structure */
+){
+ int i;
+ int rc = SQLITE_OK;
+ u8 *a = pChange->aRecord;
+
+ for(i=0; i<nCol && rc==SQLITE_OK; i++){
+ int eType = *a++;
+
+ switch( eType ){
+ case 0:
+ case SQLITE_NULL:
+ assert( abPK[i]==0 );
+ break;
+
+ case SQLITE_INTEGER: {
+ if( abPK[i] ){
+ i64 iVal = sessionGetI64(a);
+ rc = sqlite3_bind_int64(pSelect, i+1, iVal);
+ }
+ a += 8;
+ break;
+ }
+
+ case SQLITE_FLOAT: {
+ if( abPK[i] ){
+ double rVal;
+ i64 iVal = sessionGetI64(a);
+ memcpy(&rVal, &iVal, 8);
+ rc = sqlite3_bind_double(pSelect, i+1, rVal);
+ }
+ a += 8;
+ break;
+ }
+
+ case SQLITE_TEXT: {
+ int n;
+ a += sessionVarintGet(a, &n);
+ if( abPK[i] ){
+ rc = sqlite3_bind_text(pSelect, i+1, (char *)a, n, SQLITE_TRANSIENT);
+ }
+ a += n;
+ break;
+ }
+
+ default: {
+ int n;
+ assert( eType==SQLITE_BLOB );
+ a += sessionVarintGet(a, &n);
+ if( abPK[i] ){
+ rc = sqlite3_bind_blob(pSelect, i+1, a, n, SQLITE_TRANSIENT);
+ }
+ a += n;
+ break;
+ }
+ }
+ }
+
+ return rc;
+}
+
+/*
+** This function is a no-op if *pRc is set to other than SQLITE_OK when it
+** is called. Otherwise, append a serialized table header (part of the binary
+** changeset format) to buffer *pBuf. If an error occurs, set *pRc to an
+** SQLite error code before returning.
+*/
+static void sessionAppendTableHdr(
+ SessionBuffer *pBuf, /* Append header to this buffer */
+ int bPatchset, /* Use the patchset format if true */
+ SessionTable *pTab, /* Table object to append header for */
+ int *pRc /* IN/OUT: Error code */
+){
+ /* Write a table header */
+ sessionAppendByte(pBuf, (bPatchset ? 'P' : 'T'), pRc);
+ sessionAppendVarint(pBuf, pTab->nCol, pRc);
+ sessionAppendBlob(pBuf, pTab->abPK, pTab->nCol, pRc);
+ sessionAppendBlob(pBuf, (u8 *)pTab->zName, (int)strlen(pTab->zName)+1, pRc);
+}
+
+/*
+** Generate either a changeset (if argument bPatchset is zero) or a patchset
+** (if it is non-zero) based on the current contents of the session object
+** passed as the first argument.
+**
+** If no error occurs, SQLITE_OK is returned and the new changeset/patchset
+** stored in output variables *pnChangeset and *ppChangeset. Or, if an error
+** occurs, an SQLite error code is returned and both output variables set
+** to 0.
+*/
+static int sessionGenerateChangeset(
+ sqlite3_session *pSession, /* Session object */
+ int bPatchset, /* True for patchset, false for changeset */
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut, /* First argument for xOutput */
+ int *pnChangeset, /* OUT: Size of buffer at *ppChangeset */
+ void **ppChangeset /* OUT: Buffer containing changeset */
+){
+ sqlite3 *db = pSession->db; /* Source database handle */
+ SessionTable *pTab; /* Used to iterate through attached tables */
+ SessionBuffer buf = {0,0,0}; /* Buffer in which to accumlate changeset */
+ int rc; /* Return code */
+
+ assert( xOutput==0 || (pnChangeset==0 && ppChangeset==0 ) );
+
+ /* Zero the output variables in case an error occurs. If this session
+ ** object is already in the error state (sqlite3_session.rc != SQLITE_OK),
+ ** this call will be a no-op. */
+ if( xOutput==0 ){
+ *pnChangeset = 0;
+ *ppChangeset = 0;
+ }
+
+ if( pSession->rc ) return pSession->rc;
+ rc = sqlite3_exec(pSession->db, "SAVEPOINT changeset", 0, 0, 0);
+ if( rc!=SQLITE_OK ) return rc;
+
+ sqlite3_mutex_enter(sqlite3_db_mutex(db));
+
+ for(pTab=pSession->pTable; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
+ if( pTab->nEntry ){
+ const char *zName = pTab->zName;
+ int nCol; /* Number of columns in table */
+ u8 *abPK; /* Primary key array */
+ const char **azCol = 0; /* Table columns */
+ int i; /* Used to iterate through hash buckets */
+ sqlite3_stmt *pSel = 0; /* SELECT statement to query table pTab */
+ int nRewind = buf.nBuf; /* Initial size of write buffer */
+ int nNoop; /* Size of buffer after writing tbl header */
+
+ /* Check the table schema is still Ok. */
+ rc = sessionTableInfo(db, pSession->zDb, zName, &nCol, 0, &azCol, &abPK);
+ if( !rc && (pTab->nCol!=nCol || memcmp(abPK, pTab->abPK, nCol)) ){
+ rc = SQLITE_SCHEMA;
+ }
+
+ /* Write a table header */
+ sessionAppendTableHdr(&buf, bPatchset, pTab, &rc);
+
+ /* Build and compile a statement to execute: */
+ if( rc==SQLITE_OK ){
+ rc = sessionSelectStmt(
+ db, pSession->zDb, zName, nCol, azCol, abPK, &pSel);
+ }
+
+ nNoop = buf.nBuf;
+ for(i=0; i<pTab->nChange && rc==SQLITE_OK; i++){
+ SessionChange *p; /* Used to iterate through changes */
+
+ for(p=pTab->apChange[i]; rc==SQLITE_OK && p; p=p->pNext){
+ rc = sessionSelectBind(pSel, nCol, abPK, p);
+ if( rc!=SQLITE_OK ) continue;
+ if( sqlite3_step(pSel)==SQLITE_ROW ){
+ if( p->op==SQLITE_INSERT ){
+ int iCol;
+ sessionAppendByte(&buf, SQLITE_INSERT, &rc);
+ sessionAppendByte(&buf, p->bIndirect, &rc);
+ for(iCol=0; iCol<nCol; iCol++){
+ sessionAppendCol(&buf, pSel, iCol, &rc);
+ }
+ }else{
+ rc = sessionAppendUpdate(&buf, bPatchset, pSel, p, abPK);
+ }
+ }else if( p->op!=SQLITE_INSERT ){
+ rc = sessionAppendDelete(&buf, bPatchset, p, nCol, abPK);
+ }
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_reset(pSel);
+ }
+
+ /* If the buffer is now larger than SESSIONS_STRM_CHUNK_SIZE, pass
+ ** its contents to the xOutput() callback. */
+ if( xOutput
+ && rc==SQLITE_OK
+ && buf.nBuf>nNoop
+ && buf.nBuf>SESSIONS_STRM_CHUNK_SIZE
+ ){
+ rc = xOutput(pOut, (void*)buf.aBuf, buf.nBuf);
+ nNoop = -1;
+ buf.nBuf = 0;
+ }
+
+ }
+ }
+
+ sqlite3_finalize(pSel);
+ if( buf.nBuf==nNoop ){
+ buf.nBuf = nRewind;
+ }
+ sqlite3_free((char*)azCol); /* cast works around VC++ bug */
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ if( xOutput==0 ){
+ *pnChangeset = buf.nBuf;
+ *ppChangeset = buf.aBuf;
+ buf.aBuf = 0;
+ }else if( buf.nBuf>0 ){
+ rc = xOutput(pOut, (void*)buf.aBuf, buf.nBuf);
+ }
+ }
+
+ sqlite3_free(buf.aBuf);
+ sqlite3_exec(db, "RELEASE changeset", 0, 0, 0);
+ sqlite3_mutex_leave(sqlite3_db_mutex(db));
+ return rc;
+}
+
+/*
+** Obtain a changeset object containing all changes recorded by the
+** session object passed as the first argument.
+**
+** It is the responsibility of the caller to eventually free the buffer
+** using sqlite3_free().
+*/
+int sqlite3session_changeset(
+ sqlite3_session *pSession, /* Session object */
+ int *pnChangeset, /* OUT: Size of buffer at *ppChangeset */
+ void **ppChangeset /* OUT: Buffer containing changeset */
+){
+ return sessionGenerateChangeset(pSession, 0, 0, 0, pnChangeset, ppChangeset);
+}
+
+/*
+** Streaming version of sqlite3session_changeset().
+*/
+int sqlite3session_changeset_strm(
+ sqlite3_session *pSession,
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut
+){
+ return sessionGenerateChangeset(pSession, 0, xOutput, pOut, 0, 0);
+}
+
+/*
+** Streaming version of sqlite3session_patchset().
+*/
+int sqlite3session_patchset_strm(
+ sqlite3_session *pSession,
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut
+){
+ return sessionGenerateChangeset(pSession, 1, xOutput, pOut, 0, 0);
+}
+
+/*
+** Obtain a patchset object containing all changes recorded by the
+** session object passed as the first argument.
+**
+** It is the responsibility of the caller to eventually free the buffer
+** using sqlite3_free().
+*/
+int sqlite3session_patchset(
+ sqlite3_session *pSession, /* Session object */
+ int *pnPatchset, /* OUT: Size of buffer at *ppChangeset */
+ void **ppPatchset /* OUT: Buffer containing changeset */
+){
+ return sessionGenerateChangeset(pSession, 1, 0, 0, pnPatchset, ppPatchset);
+}
+
+/*
+** Enable or disable the session object passed as the first argument.
+*/
+int sqlite3session_enable(sqlite3_session *pSession, int bEnable){
+ int ret;
+ sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+ if( bEnable>=0 ){
+ pSession->bEnable = bEnable;
+ }
+ ret = pSession->bEnable;
+ sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+ return ret;
+}
+
+/*
+** Enable or disable the session object passed as the first argument.
+*/
+int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect){
+ int ret;
+ sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+ if( bIndirect>=0 ){
+ pSession->bIndirect = bIndirect;
+ }
+ ret = pSession->bIndirect;
+ sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+ return ret;
+}
+
+/*
+** Return true if there have been no changes to monitored tables recorded
+** by the session object passed as the only argument.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession){
+ int ret = 0;
+ SessionTable *pTab;
+
+ sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+ for(pTab=pSession->pTable; pTab && ret==0; pTab=pTab->pNext){
+ ret = (pTab->nEntry>0);
+ }
+ sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+
+ return (ret==0);
+}
+
+/*
+** Do the work for either sqlite3changeset_start() or start_strm().
+*/
+static int sessionChangesetStart(
+ sqlite3_changeset_iter **pp, /* OUT: Changeset iterator handle */
+ int (*xInput)(void *pIn, void *pData, int *pnData),
+ void *pIn,
+ int nChangeset, /* Size of buffer pChangeset in bytes */
+ void *pChangeset /* Pointer to buffer containing changeset */
+){
+ sqlite3_changeset_iter *pRet; /* Iterator to return */
+ int nByte; /* Number of bytes to allocate for iterator */
+
+ assert( xInput==0 || (pChangeset==0 && nChangeset==0) );
+
+ /* Zero the output variable in case an error occurs. */
+ *pp = 0;
+
+ /* Allocate and initialize the iterator structure. */
+ nByte = sizeof(sqlite3_changeset_iter);
+ pRet = (sqlite3_changeset_iter *)sqlite3_malloc(nByte);
+ if( !pRet ) return SQLITE_NOMEM;
+ memset(pRet, 0, sizeof(sqlite3_changeset_iter));
+ pRet->in.aData = (u8 *)pChangeset;
+ pRet->in.nData = nChangeset;
+ pRet->in.xInput = xInput;
+ pRet->in.pIn = pIn;
+ pRet->in.iNext = 0;
+ pRet->in.bEof = (xInput ? 0 : 1);
+
+ /* Populate the output variable and return success. */
+ *pp = pRet;
+ return SQLITE_OK;
+}
+
+/*
+** Create an iterator used to iterate through the contents of a changeset.
+*/
+int sqlite3changeset_start(
+ sqlite3_changeset_iter **pp, /* OUT: Changeset iterator handle */
+ int nChangeset, /* Size of buffer pChangeset in bytes */
+ void *pChangeset /* Pointer to buffer containing changeset */
+){
+ return sessionChangesetStart(pp, 0, 0, nChangeset, pChangeset);
+}
+
+/*
+** Streaming version of sqlite3changeset_start().
+*/
+int sqlite3changeset_start_strm(
+ sqlite3_changeset_iter **pp, /* OUT: Changeset iterator handle */
+ int (*xInput)(void *pIn, void *pData, int *pnData),
+ void *pIn
+){
+ return sessionChangesetStart(pp, xInput, pIn, 0, 0);
+}
+
+/*
+** Ensure that there are at least nByte bytes available in the buffer. Or,
+** if there are not nByte bytes remaining in the input, that all available
+** data is in the buffer.
+**
+** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
+*/
+static int sessionInputBuffer(SessionInput *pIn, int nByte){
+ int rc = SQLITE_OK;
+ if( pIn->xInput ){
+ while( !pIn->bEof && (pIn->iNext+nByte)>=pIn->nData && rc==SQLITE_OK ){
+ int nNew = SESSIONS_STRM_CHUNK_SIZE;
+
+ if( pIn->iNext>=SESSIONS_STRM_CHUNK_SIZE ){
+ int nMove = pIn->buf.nBuf - pIn->iNext;
+ memmove(pIn->buf.aBuf, &pIn->buf.aBuf[pIn->iNext], nMove);
+ pIn->buf.nBuf -= pIn->iNext;
+ pIn->iNext = 0;
+ }
+
+ if( SQLITE_OK==sessionBufferGrow(&pIn->buf, nNew, &rc) ){
+ rc = pIn->xInput(pIn->pIn, &pIn->buf.aBuf[pIn->buf.nBuf], &nNew);
+ if( nNew==0 ){
+ pIn->bEof = 1;
+ }else{
+ pIn->buf.nBuf += nNew;
+ }
+ }
+
+ pIn->aData = pIn->buf.aBuf;
+ pIn->nData = pIn->buf.nBuf;
+ }
+ }
+ return rc;
+}
+
+/*
+** When this function is called, *ppRec points to the start of a record
+** that contains nCol values. This function advances the pointer *ppRec
+** until it points to the byte immediately following that record.
+*/
+static void sessionSkipRecord(
+ u8 **ppRec, /* IN/OUT: Record pointer */
+ int nCol /* Number of values in record */
+){
+ u8 *aRec = *ppRec;
+ int i;
+ for(i=0; i<nCol; i++){
+ int eType = *aRec++;
+ if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+ int nByte;
+ aRec += sessionVarintGet((u8*)aRec, &nByte);
+ aRec += nByte;
+ }else if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ aRec += 8;
+ }
+ }
+
+ *ppRec = aRec;
+}
+
+/*
+** This function sets the value of the sqlite3_value object passed as the
+** first argument to a copy of the string or blob held in the aData[]
+** buffer. SQLITE_OK is returned if successful, or SQLITE_NOMEM if an OOM
+** error occurs.
+*/
+static int sessionValueSetStr(
+ sqlite3_value *pVal, /* Set the value of this object */
+ u8 *aData, /* Buffer containing string or blob data */
+ int nData, /* Size of buffer aData[] in bytes */
+ u8 enc /* String encoding (0 for blobs) */
+){
+ /* In theory this code could just pass SQLITE_TRANSIENT as the final
+ ** argument to sqlite3ValueSetStr() and have the copy created
+ ** automatically. But doing so makes it difficult to detect any OOM
+ ** error. Hence the code to create the copy externally. */
+ u8 *aCopy = sqlite3_malloc(nData+1);
+ if( aCopy==0 ) return SQLITE_NOMEM;
+ memcpy(aCopy, aData, nData);
+ sqlite3ValueSetStr(pVal, nData, (char*)aCopy, enc, sqlite3_free);
+ return SQLITE_OK;
+}
+
+/*
+** Deserialize a single record from a buffer in memory. See "RECORD FORMAT"
+** for details.
+**
+** When this function is called, *paChange points to the start of the record
+** to deserialize. Assuming no error occurs, *paChange is set to point to
+** one byte after the end of the same record before this function returns.
+** If the argument abPK is NULL, then the record contains nCol values. Or,
+** if abPK is other than NULL, then the record contains only the PK fields
+** (in other words, it is a patchset DELETE record).
+**
+** If successful, each element of the apOut[] array (allocated by the caller)
+** is set to point to an sqlite3_value object containing the value read
+** from the corresponding position in the record. If that value is not
+** included in the record (i.e. because the record is part of an UPDATE change
+** and the field was not modified), the corresponding element of apOut[] is
+** set to NULL.
+**
+** It is the responsibility of the caller to free all sqlite_value structures
+** using sqlite3_free().
+**
+** If an error occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
+** The apOut[] array may have been partially populated in this case.
+*/
+static int sessionReadRecord(
+ SessionInput *pIn, /* Input data */
+ int nCol, /* Number of values in record */
+ u8 *abPK, /* Array of primary key flags, or NULL */
+ sqlite3_value **apOut /* Write values to this array */
+){
+ int i; /* Used to iterate through columns */
+ int rc = SQLITE_OK;
+
+ for(i=0; i<nCol && rc==SQLITE_OK; i++){
+ int eType = 0; /* Type of value (SQLITE_NULL, TEXT etc.) */
+ if( abPK && abPK[i]==0 ) continue;
+ rc = sessionInputBuffer(pIn, 9);
+ if( rc==SQLITE_OK ){
+ eType = pIn->aData[pIn->iNext++];
+ }
+
+ assert( apOut[i]==0 );
+ if( eType ){
+ apOut[i] = sqlite3ValueNew(0);
+ if( !apOut[i] ) rc = SQLITE_NOMEM;
+ }
+
+ if( rc==SQLITE_OK ){
+ u8 *aVal = &pIn->aData[pIn->iNext];
+ if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+ int nByte;
+ pIn->iNext += sessionVarintGet(aVal, &nByte);
+ rc = sessionInputBuffer(pIn, nByte);
+ if( rc==SQLITE_OK ){
+ u8 enc = (eType==SQLITE_TEXT ? SQLITE_UTF8 : 0);
+ rc = sessionValueSetStr(apOut[i],&pIn->aData[pIn->iNext],nByte,enc);
+ }
+ pIn->iNext += nByte;
+ }
+ if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ sqlite3_int64 v = sessionGetI64(aVal);
+ if( eType==SQLITE_INTEGER ){
+ sqlite3VdbeMemSetInt64(apOut[i], v);
+ }else{
+ double d;
+ memcpy(&d, &v, 8);
+ sqlite3VdbeMemSetDouble(apOut[i], d);
+ }
+ pIn->iNext += 8;
+ }
+ }
+ }
+
+ return rc;
+}
+
+/*
+** The input pointer currently points to the second byte of a table-header.
+** Specifically, to the following:
+**
+** + number of columns in table (varint)
+** + array of PK flags (1 byte per column),
+** + table name (nul terminated).
+**
+** This function ensures that all of the above is present in the input
+** buffer (i.e. that it can be accessed without any calls to xInput()).
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
+** The input pointer is not moved.
+*/
+static int sessionChangesetBufferTblhdr(SessionInput *pIn, int *pnByte){
+ int rc = SQLITE_OK;
+ int nCol = 0;
+ int nRead = 0;
+
+ rc = sessionInputBuffer(pIn, 9);
+ if( rc==SQLITE_OK ){
+ nRead += sessionVarintGet(&pIn->aData[pIn->iNext + nRead], &nCol);
+ rc = sessionInputBuffer(pIn, nRead+nCol+100);
+ nRead += nCol;
+ }
+
+ while( rc==SQLITE_OK ){
+ while( (pIn->iNext + nRead)<pIn->nData && pIn->aData[pIn->iNext + nRead] ){
+ nRead++;
+ }
+ if( (pIn->iNext + nRead)<pIn->nData ) break;
+ rc = sessionInputBuffer(pIn, nRead + 100);
+ }
+ *pnByte = nRead+1;
+ return rc;
+}
+
+/*
+** The input pointer currently points to the first byte of the first field
+** of a record consisting of nCol columns. This function ensures the entire
+** record is buffered. It does not move the input pointer.
+**
+** If successful, SQLITE_OK is returned and *pnByte is set to the size of
+** the record in bytes. Otherwise, an SQLite error code is returned. The
+** final value of *pnByte is undefined in this case.
+*/
+static int sessionChangesetBufferRecord(
+ SessionInput *pIn, /* Input data */
+ int nCol, /* Number of columns in record */
+ int *pnByte /* OUT: Size of record in bytes */
+){
+ int rc = SQLITE_OK;
+ int nByte = 0;
+ int i;
+ for(i=0; rc==SQLITE_OK && i<nCol; i++){
+ int eType;
+ rc = sessionInputBuffer(pIn, nByte + 10);
+ if( rc==SQLITE_OK ){
+ eType = pIn->aData[pIn->iNext + nByte++];
+ if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+ int n;
+ nByte += sessionVarintGet(&pIn->aData[pIn->iNext+nByte], &n);
+ nByte += n;
+ rc = sessionInputBuffer(pIn, nByte);
+ }else if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+ nByte += 8;
+ }
+ }
+ }
+ *pnByte = nByte;
+ return rc;
+}
+
+/*
+** The input pointer currently points to the second byte of a table-header.
+** Specifically, to the following:
+**
+** + number of columns in table (varint)
+** + array of PK flags (1 byte per column),
+** + table name (nul terminated).
+**
+** This function decodes the table-header and populates the p->nCol,
+** p->zTab and p->abPK[] variables accordingly. The p->apValue[] array is
+** also allocated or resized according to the new value of p->nCol. The
+** input pointer is left pointing to the byte following the table header.
+**
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code
+** is returned and the final values of the various fields enumerated above
+** are undefined.
+*/
+static int sessionChangesetReadTblhdr(sqlite3_changeset_iter *p){
+ int rc;
+ int nCopy;
+ assert( p->rc==SQLITE_OK );
+
+ rc = sessionChangesetBufferTblhdr(&p->in, &nCopy);
+ if( rc==SQLITE_OK ){
+ int nByte;
+ int nVarint;
+ nVarint = sessionVarintGet(&p->in.aData[p->in.iNext], &p->nCol);
+ nCopy -= nVarint;
+ p->in.iNext += nVarint;
+ nByte = p->nCol * sizeof(sqlite3_value*) * 2 + nCopy;
+ p->tblhdr.nBuf = 0;
+ sessionBufferGrow(&p->tblhdr, nByte, &rc);
+ }
+
+ if( rc==SQLITE_OK ){
+ int iPK = sizeof(sqlite3_value*)*p->nCol*2;
+ memset(p->tblhdr.aBuf, 0, iPK);
+ memcpy(&p->tblhdr.aBuf[iPK], &p->in.aData[p->in.iNext], nCopy);
+ p->in.iNext += nCopy;
+ }
+
+ p->apValue = (sqlite3_value**)p->tblhdr.aBuf;
+ p->abPK = (u8*)&p->apValue[p->nCol*2];
+ p->zTab = (char*)&p->abPK[p->nCol];
+ return (p->rc = rc);
+}
+
+/*
+** Advance the changeset iterator to the next change.
+**
+** If both paRec and pnRec are NULL, then this function works like the public
+** API sqlite3changeset_next(). If SQLITE_ROW is returned, then the
+** sqlite3changeset_new() and old() APIs may be used to query for values.
+**
+** Otherwise, if paRec and pnRec are not NULL, then a pointer to the change
+** record is written to *paRec before returning and the number of bytes in
+** the record to *pnRec.
+**
+** Either way, this function returns SQLITE_ROW if the iterator is
+** successfully advanced to the next change in the changeset, an SQLite
+** error code if an error occurs, or SQLITE_DONE if there are no further
+** changes in the changeset.
+*/
+static int sessionChangesetNext(
+ sqlite3_changeset_iter *p, /* Changeset iterator */
+ u8 **paRec, /* If non-NULL, store record pointer here */
+ int *pnRec /* If non-NULL, store size of record here */
+){
+ int i;
+ u8 op;
+
+ assert( (paRec==0 && pnRec==0) || (paRec && pnRec) );
+
+ /* If the iterator is in the error-state, return immediately. */
+ if( p->rc!=SQLITE_OK ) return p->rc;
+
+ /* Free the current contents of p->apValue[], if any. */
+ if( p->apValue ){
+ for(i=0; i<p->nCol*2; i++){
+ sqlite3ValueFree(p->apValue[i]);
+ }
+ memset(p->apValue, 0, sizeof(sqlite3_value*)*p->nCol*2);
+ }
+
+ /* Make sure the buffer contains at least 10 bytes of input data, or all
+ ** remaining data if there are less than 10 bytes available. This is
+ ** sufficient either for the 'T' or 'P' byte and the varint that follows
+ ** it, or for the two single byte values otherwise. */
+ p->rc = sessionInputBuffer(&p->in, 2);
+ if( p->rc!=SQLITE_OK ) return p->rc;
+
+ /* If the iterator is already at the end of the changeset, return DONE. */
+ if( p->in.iNext>=p->in.nData ){
+ return SQLITE_DONE;
+ }
+
+ op = p->in.aData[p->in.iNext++];
+ if( op=='T' || op=='P' ){
+ p->bPatchset = (op=='P');
+ if( sessionChangesetReadTblhdr(p) ) return p->rc;
+ if( (p->rc = sessionInputBuffer(&p->in, 2)) ) return p->rc;
+ op = p->in.aData[p->in.iNext++];
+ }
+
+ p->op = op;
+ p->bIndirect = p->in.aData[p->in.iNext++];
+ if( p->op!=SQLITE_UPDATE && p->op!=SQLITE_DELETE && p->op!=SQLITE_INSERT ){
+ return (p->rc = SQLITE_CORRUPT_BKPT);
+ }
+
+ if( paRec ){
+ int nVal; /* Number of values to buffer */
+ if( p->bPatchset==0 && op==SQLITE_UPDATE ){
+ nVal = p->nCol * 2;
+ }else if( p->bPatchset && op==SQLITE_DELETE ){
+ nVal = 0;
+ for(i=0; i<p->nCol; i++) if( p->abPK[i] ) nVal++;
+ }else{
+ nVal = p->nCol;
+ }
+ p->rc = sessionChangesetBufferRecord(&p->in, nVal, pnRec);
+ if( p->rc!=SQLITE_OK ) return p->rc;
+ *paRec = &p->in.aData[p->in.iNext];
+ p->in.iNext += *pnRec;
+ }else{
+
+ /* If this is an UPDATE or DELETE, read the old.* record. */
+ if( p->op!=SQLITE_INSERT && (p->bPatchset==0 || p->op==SQLITE_DELETE) ){
+ u8 *abPK = p->bPatchset ? p->abPK : 0;
+ p->rc = sessionReadRecord(&p->in, p->nCol, abPK, p->apValue);
+ if( p->rc!=SQLITE_OK ) return p->rc;
+ }
+
+ /* If this is an INSERT or UPDATE, read the new.* record. */
+ if( p->op!=SQLITE_DELETE ){
+ p->rc = sessionReadRecord(&p->in, p->nCol, 0, &p->apValue[p->nCol]);
+ if( p->rc!=SQLITE_OK ) return p->rc;
+ }
+
+ if( p->bPatchset && p->op==SQLITE_UPDATE ){
+ /* If this is an UPDATE that is part of a patchset, then all PK and
+ ** modified fields are present in the new.* record. The old.* record
+ ** is currently completely empty. This block shifts the PK fields from
+ ** new.* to old.*, to accommodate the code that reads these arrays. */
+ int i;
+ for(i=0; i<p->nCol; i++){
+ assert( p->apValue[i]==0 );
+ assert( p->abPK[i]==0 || p->apValue[i+p->nCol] );
+ if( p->abPK[i] ){
+ p->apValue[i] = p->apValue[i+p->nCol];
+ p->apValue[i+p->nCol] = 0;
+ }
+ }
+ }
+ }
+
+ return SQLITE_ROW;
+}
+
+/*
+** Advance an iterator created by sqlite3changeset_start() to the next
+** change in the changeset. This function may return SQLITE_ROW, SQLITE_DONE
+** or SQLITE_CORRUPT.
+**
+** This function may not be called on iterators passed to a conflict handler
+** callback by changeset_apply().
+*/
+int sqlite3changeset_next(sqlite3_changeset_iter *p){
+ return sessionChangesetNext(p, 0, 0);
+}
+
+/*
+** The following function extracts information on the current change
+** from a changeset iterator. It may only be called after changeset_next()
+** has returned SQLITE_ROW.
+*/
+int sqlite3changeset_op(
+ sqlite3_changeset_iter *pIter, /* Iterator handle */
+ const char **pzTab, /* OUT: Pointer to table name */
+ int *pnCol, /* OUT: Number of columns in table */
+ int *pOp, /* OUT: SQLITE_INSERT, DELETE or UPDATE */
+ int *pbIndirect /* OUT: True if change is indirect */
+){
+ *pOp = pIter->op;
+ *pnCol = pIter->nCol;
+ *pzTab = pIter->zTab;
+ if( pbIndirect ) *pbIndirect = pIter->bIndirect;
+ return SQLITE_OK;
+}
+
+/*
+** Return information regarding the PRIMARY KEY and number of columns in
+** the database table affected by the change that pIter currently points
+** to. This function may only be called after changeset_next() returns
+** SQLITE_ROW.
+*/
+int sqlite3changeset_pk(
+ sqlite3_changeset_iter *pIter, /* Iterator object */
+ unsigned char **pabPK, /* OUT: Array of boolean - true for PK cols */
+ int *pnCol /* OUT: Number of entries in output array */
+){
+ *pabPK = pIter->abPK;
+ if( pnCol ) *pnCol = pIter->nCol;
+ return SQLITE_OK;
+}
+
+/*
+** This function may only be called while the iterator is pointing to an
+** SQLITE_UPDATE or SQLITE_DELETE change (see sqlite3changeset_op()).
+** Otherwise, SQLITE_MISUSE is returned.
+**
+** It sets *ppValue to point to an sqlite3_value structure containing the
+** iVal'th value in the old.* record. Or, if that particular value is not
+** included in the record (because the change is an UPDATE and the field
+** was not modified and is not a PK column), set *ppValue to NULL.
+**
+** If value iVal is out-of-range, SQLITE_RANGE is returned and *ppValue is
+** not modified. Otherwise, SQLITE_OK.
+*/
+int sqlite3changeset_old(
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ int iVal, /* Index of old.* value to retrieve */
+ sqlite3_value **ppValue /* OUT: Old value (or NULL pointer) */
+){
+ if( pIter->op!=SQLITE_UPDATE && pIter->op!=SQLITE_DELETE ){
+ return SQLITE_MISUSE;
+ }
+ if( iVal<0 || iVal>=pIter->nCol ){
+ return SQLITE_RANGE;
+ }
+ *ppValue = pIter->apValue[iVal];
+ return SQLITE_OK;
+}
+
+/*
+** This function may only be called while the iterator is pointing to an
+** SQLITE_UPDATE or SQLITE_INSERT change (see sqlite3changeset_op()).
+** Otherwise, SQLITE_MISUSE is returned.
+**
+** It sets *ppValue to point to an sqlite3_value structure containing the
+** iVal'th value in the new.* record. Or, if that particular value is not
+** included in the record (because the change is an UPDATE and the field
+** was not modified), set *ppValue to NULL.
+**
+** If value iVal is out-of-range, SQLITE_RANGE is returned and *ppValue is
+** not modified. Otherwise, SQLITE_OK.
+*/
+int sqlite3changeset_new(
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ int iVal, /* Index of new.* value to retrieve */
+ sqlite3_value **ppValue /* OUT: New value (or NULL pointer) */
+){
+ if( pIter->op!=SQLITE_UPDATE && pIter->op!=SQLITE_INSERT ){
+ return SQLITE_MISUSE;
+ }
+ if( iVal<0 || iVal>=pIter->nCol ){
+ return SQLITE_RANGE;
+ }
+ *ppValue = pIter->apValue[pIter->nCol+iVal];
+ return SQLITE_OK;
+}
+
+/*
+** The following two macros are used internally. They are similar to the
+** sqlite3changeset_new() and sqlite3changeset_old() functions, except that
+** they omit all error checking and return a pointer to the requested value.
+*/
+#define sessionChangesetNew(pIter, iVal) (pIter)->apValue[(pIter)->nCol+(iVal)]
+#define sessionChangesetOld(pIter, iVal) (pIter)->apValue[(iVal)]
+
+/*
+** This function may only be called with a changeset iterator that has been
+** passed to an SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT
+** conflict-handler function. Otherwise, SQLITE_MISUSE is returned.
+**
+** If successful, *ppValue is set to point to an sqlite3_value structure
+** containing the iVal'th value of the conflicting record.
+**
+** If value iVal is out-of-range or some other error occurs, an SQLite error
+** code is returned. Otherwise, SQLITE_OK.
+*/
+int sqlite3changeset_conflict(
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ int iVal, /* Index of conflict record value to fetch */
+ sqlite3_value **ppValue /* OUT: Value from conflicting row */
+){
+ if( !pIter->pConflict ){
+ return SQLITE_MISUSE;
+ }
+ if( iVal<0 || iVal>=sqlite3_column_count(pIter->pConflict) ){
+ return SQLITE_RANGE;
+ }
+ *ppValue = sqlite3_column_value(pIter->pConflict, iVal);
+ return SQLITE_OK;
+}
+
+/*
+** This function may only be called with an iterator passed to an
+** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
+** it sets the output variable to the total number of known foreign key
+** violations in the destination database and returns SQLITE_OK.
+**
+** In all other cases this function returns SQLITE_MISUSE.
+*/
+int sqlite3changeset_fk_conflicts(
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ int *pnOut /* OUT: Number of FK violations */
+){
+ if( pIter->pConflict || pIter->apValue ){
+ return SQLITE_MISUSE;
+ }
+ *pnOut = pIter->nCol;
+ return SQLITE_OK;
+}
+
+
+/*
+** Finalize an iterator allocated with sqlite3changeset_start().
+**
+** This function may not be called on iterators passed to a conflict handler
+** callback by changeset_apply().
+*/
+int sqlite3changeset_finalize(sqlite3_changeset_iter *p){
+ int rc = SQLITE_OK;
+ if( p ){
+ int i; /* Used to iterate through p->apValue[] */
+ rc = p->rc;
+ if( p->apValue ){
+ for(i=0; i<p->nCol*2; i++) sqlite3ValueFree(p->apValue[i]);
+ }
+ sqlite3_free(p->tblhdr.aBuf);
+ sqlite3_free(p->in.buf.aBuf);
+ sqlite3_free(p);
+ }
+ return rc;
+}
+
+static int sessionChangesetInvert(
+ SessionInput *pInput, /* Input changeset */
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut,
+ int *pnInverted, /* OUT: Number of bytes in output changeset */
+ void **ppInverted /* OUT: Inverse of pChangeset */
+){
+ int rc = SQLITE_OK; /* Return value */
+ SessionBuffer sOut; /* Output buffer */
+ int nCol = 0; /* Number of cols in current table */
+ u8 *abPK = 0; /* PK array for current table */
+ sqlite3_value **apVal = 0; /* Space for values for UPDATE inversion */
+ SessionBuffer sPK = {0, 0, 0}; /* PK array for current table */
+
+ /* Initialize the output buffer */
+ memset(&sOut, 0, sizeof(SessionBuffer));
+
+ /* Zero the output variables in case an error occurs. */
+ if( ppInverted ){
+ *ppInverted = 0;
+ *pnInverted = 0;
+ }
+
+ while( 1 ){
+ u8 eType;
+
+ /* Test for EOF. */
+ if( (rc = sessionInputBuffer(pInput, 2)) ) goto finished_invert;
+ if( pInput->iNext>=pInput->nData ) break;
+ eType = pInput->aData[pInput->iNext];
+
+ switch( eType ){
+ case 'T': {
+ /* A 'table' record consists of:
+ **
+ ** * A constant 'T' character,
+ ** * Number of columns in said table (a varint),
+ ** * An array of nCol bytes (sPK),
+ ** * A nul-terminated table name.
+ */
+ int nByte;
+ int nVar;
+ pInput->iNext++;
+ if( (rc = sessionChangesetBufferTblhdr(pInput, &nByte)) ){
+ goto finished_invert;
+ }
+ nVar = sessionVarintGet(&pInput->aData[pInput->iNext], &nCol);
+ sPK.nBuf = 0;
+ sessionAppendBlob(&sPK, &pInput->aData[pInput->iNext+nVar], nCol, &rc);
+ sessionAppendByte(&sOut, eType, &rc);
+ sessionAppendBlob(&sOut, &pInput->aData[pInput->iNext], nByte, &rc);
+ if( rc ) goto finished_invert;
+
+ pInput->iNext += nByte;
+ sqlite3_free(apVal);
+ apVal = 0;
+ abPK = sPK.aBuf;
+ break;
+ }
+
+ case SQLITE_INSERT:
+ case SQLITE_DELETE: {
+ int nByte;
+ int bIndirect = pInput->aData[pInput->iNext+1];
+ int eType2 = (eType==SQLITE_DELETE ? SQLITE_INSERT : SQLITE_DELETE);
+ pInput->iNext += 2;
+ assert( rc==SQLITE_OK );
+ rc = sessionChangesetBufferRecord(pInput, nCol, &nByte);
+ sessionAppendByte(&sOut, eType2, &rc);
+ sessionAppendByte(&sOut, bIndirect, &rc);
+ sessionAppendBlob(&sOut, &pInput->aData[pInput->iNext], nByte, &rc);
+ pInput->iNext += nByte;
+ if( rc ) goto finished_invert;
+ break;
+ }
+
+ case SQLITE_UPDATE: {
+ int iCol;
+
+ if( 0==apVal ){
+ apVal = (sqlite3_value **)sqlite3_malloc(sizeof(apVal[0])*nCol*2);
+ if( 0==apVal ){
+ rc = SQLITE_NOMEM;
+ goto finished_invert;
+ }
+ memset(apVal, 0, sizeof(apVal[0])*nCol*2);
+ }
+
+ /* Write the header for the new UPDATE change. Same as the original. */
+ sessionAppendByte(&sOut, eType, &rc);
+ sessionAppendByte(&sOut, pInput->aData[pInput->iNext+1], &rc);
+
+ /* Read the old.* and new.* records for the update change. */
+ pInput->iNext += 2;
+ rc = sessionReadRecord(pInput, nCol, 0, &apVal[0]);
+ if( rc==SQLITE_OK ){
+ rc = sessionReadRecord(pInput, nCol, 0, &apVal[nCol]);
+ }
+
+ /* Write the new old.* record. Consists of the PK columns from the
+ ** original old.* record, and the other values from the original
+ ** new.* record. */
+ for(iCol=0; iCol<nCol; iCol++){
+ sqlite3_value *pVal = apVal[iCol + (abPK[iCol] ? 0 : nCol)];
+ sessionAppendValue(&sOut, pVal, &rc);
+ }
+
+ /* Write the new new.* record. Consists of a copy of all values
+ ** from the original old.* record, except for the PK columns, which
+ ** are set to "undefined". */
+ for(iCol=0; iCol<nCol; iCol++){
+ sqlite3_value *pVal = (abPK[iCol] ? 0 : apVal[iCol]);
+ sessionAppendValue(&sOut, pVal, &rc);
+ }
+
+ for(iCol=0; iCol<nCol*2; iCol++){
+ sqlite3ValueFree(apVal[iCol]);
+ }
+ memset(apVal, 0, sizeof(apVal[0])*nCol*2);
+ if( rc!=SQLITE_OK ){
+ goto finished_invert;
+ }
+
+ break;
+ }
+
+ default:
+ rc = SQLITE_CORRUPT_BKPT;
+ goto finished_invert;
+ }
+
+ assert( rc==SQLITE_OK );
+ if( xOutput && sOut.nBuf>=SESSIONS_STRM_CHUNK_SIZE ){
+ rc = xOutput(pOut, sOut.aBuf, sOut.nBuf);
+ sOut.nBuf = 0;
+ if( rc!=SQLITE_OK ) goto finished_invert;
+ }
+ }
+
+ assert( rc==SQLITE_OK );
+ if( pnInverted ){
+ *pnInverted = sOut.nBuf;
+ *ppInverted = sOut.aBuf;
+ sOut.aBuf = 0;
+ }else if( sOut.nBuf>0 ){
+ rc = xOutput(pOut, sOut.aBuf, sOut.nBuf);
+ }
+
+ finished_invert:
+ sqlite3_free(sOut.aBuf);
+ sqlite3_free(apVal);
+ sqlite3_free(sPK.aBuf);
+ return rc;
+}
+
+
+/*
+** Invert a changeset object.
+*/
+int sqlite3changeset_invert(
+ int nChangeset, /* Number of bytes in input */
+ const void *pChangeset, /* Input changeset */
+ int *pnInverted, /* OUT: Number of bytes in output changeset */
+ void **ppInverted /* OUT: Inverse of pChangeset */
+){
+ SessionInput sInput;
+
+ /* Set up the input stream */
+ memset(&sInput, 0, sizeof(SessionInput));
+ sInput.nData = nChangeset;
+ sInput.aData = (u8*)pChangeset;
+
+ return sessionChangesetInvert(&sInput, 0, 0, pnInverted, ppInverted);
+}
+
+/*
+** Streaming version of sqlite3changeset_invert().
+*/
+int sqlite3changeset_invert_strm(
+ int (*xInput)(void *pIn, void *pData, int *pnData),
+ void *pIn,
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut
+){
+ SessionInput sInput;
+ int rc;
+
+ /* Set up the input stream */
+ memset(&sInput, 0, sizeof(SessionInput));
+ sInput.xInput = xInput;
+ sInput.pIn = pIn;
+
+ rc = sessionChangesetInvert(&sInput, xOutput, pOut, 0, 0);
+ sqlite3_free(sInput.buf.aBuf);
+ return rc;
+}
+
+typedef struct SessionApplyCtx SessionApplyCtx;
+struct SessionApplyCtx {
+ sqlite3 *db;
+ sqlite3_stmt *pDelete; /* DELETE statement */
+ sqlite3_stmt *pUpdate; /* UPDATE statement */
+ sqlite3_stmt *pInsert; /* INSERT statement */
+ sqlite3_stmt *pSelect; /* SELECT statement */
+ int nCol; /* Size of azCol[] and abPK[] arrays */
+ const char **azCol; /* Array of column names */
+ u8 *abPK; /* Boolean array - true if column is in PK */
+};
+
+/*
+** Formulate a statement to DELETE a row from database db. Assuming a table
+** structure like this:
+**
+** CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The DELETE statement looks like this:
+**
+** DELETE FROM x WHERE a = :1 AND c = :3 AND (:5 OR b IS :2 AND d IS :4)
+**
+** Variable :5 (nCol+1) is a boolean. It should be set to 0 if we require
+** matching b and d values, or 1 otherwise. The second case comes up if the
+** conflict handler is invoked with NOTFOUND and returns CHANGESET_REPLACE.
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pDelete is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionDeleteRow(
+ sqlite3 *db, /* Database handle */
+ const char *zTab, /* Table name */
+ SessionApplyCtx *p /* Session changeset-apply context */
+){
+ int i;
+ const char *zSep = "";
+ int rc = SQLITE_OK;
+ SessionBuffer buf = {0, 0, 0};
+ int nPk = 0;
+
+ sessionAppendStr(&buf, "DELETE FROM ", &rc);
+ sessionAppendIdent(&buf, zTab, &rc);
+ sessionAppendStr(&buf, " WHERE ", &rc);
+
+ for(i=0; i<p->nCol; i++){
+ if( p->abPK[i] ){
+ nPk++;
+ sessionAppendStr(&buf, zSep, &rc);
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " = ?", &rc);
+ sessionAppendInteger(&buf, i+1, &rc);
+ zSep = " AND ";
+ }
+ }
+
+ if( nPk<p->nCol ){
+ sessionAppendStr(&buf, " AND (?", &rc);
+ sessionAppendInteger(&buf, p->nCol+1, &rc);
+ sessionAppendStr(&buf, " OR ", &rc);
+
+ zSep = "";
+ for(i=0; i<p->nCol; i++){
+ if( !p->abPK[i] ){
+ sessionAppendStr(&buf, zSep, &rc);
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " IS ?", &rc);
+ sessionAppendInteger(&buf, i+1, &rc);
+ zSep = "AND ";
+ }
+ }
+ sessionAppendStr(&buf, ")", &rc);
+ }
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pDelete, 0);
+ }
+ sqlite3_free(buf.aBuf);
+
+ return rc;
+}
+
+/*
+** Formulate and prepare a statement to UPDATE a row from database db.
+** Assuming a table structure like this:
+**
+** CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The UPDATE statement looks like this:
+**
+** UPDATE x SET
+** a = CASE WHEN ?2 THEN ?3 ELSE a END,
+** b = CASE WHEN ?5 THEN ?6 ELSE b END,
+** c = CASE WHEN ?8 THEN ?9 ELSE c END,
+** d = CASE WHEN ?11 THEN ?12 ELSE d END
+** WHERE a = ?1 AND c = ?7 AND (?13 OR
+** (?5==0 OR b IS ?4) AND (?11==0 OR d IS ?10) AND
+** )
+**
+** For each column in the table, there are three variables to bind:
+**
+** ?(i*3+1) The old.* value of the column, if any.
+** ?(i*3+2) A boolean flag indicating that the value is being modified.
+** ?(i*3+3) The new.* value of the column, if any.
+**
+** Also, a boolean flag that, if set to true, causes the statement to update
+** a row even if the non-PK values do not match. This is required if the
+** conflict-handler is invoked with CHANGESET_DATA and returns
+** CHANGESET_REPLACE. This is variable "?(nCol*3+1)".
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pUpdate is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionUpdateRow(
+ sqlite3 *db, /* Database handle */
+ const char *zTab, /* Table name */
+ SessionApplyCtx *p /* Session changeset-apply context */
+){
+ int rc = SQLITE_OK;
+ int i;
+ const char *zSep = "";
+ SessionBuffer buf = {0, 0, 0};
+
+ /* Append "UPDATE tbl SET " */
+ sessionAppendStr(&buf, "UPDATE ", &rc);
+ sessionAppendIdent(&buf, zTab, &rc);
+ sessionAppendStr(&buf, " SET ", &rc);
+
+ /* Append the assignments */
+ for(i=0; i<p->nCol; i++){
+ sessionAppendStr(&buf, zSep, &rc);
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " = CASE WHEN ?", &rc);
+ sessionAppendInteger(&buf, i*3+2, &rc);
+ sessionAppendStr(&buf, " THEN ?", &rc);
+ sessionAppendInteger(&buf, i*3+3, &rc);
+ sessionAppendStr(&buf, " ELSE ", &rc);
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " END", &rc);
+ zSep = ", ";
+ }
+
+ /* Append the PK part of the WHERE clause */
+ sessionAppendStr(&buf, " WHERE ", &rc);
+ for(i=0; i<p->nCol; i++){
+ if( p->abPK[i] ){
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " = ?", &rc);
+ sessionAppendInteger(&buf, i*3+1, &rc);
+ sessionAppendStr(&buf, " AND ", &rc);
+ }
+ }
+
+ /* Append the non-PK part of the WHERE clause */
+ sessionAppendStr(&buf, " (?", &rc);
+ sessionAppendInteger(&buf, p->nCol*3+1, &rc);
+ sessionAppendStr(&buf, " OR 1", &rc);
+ for(i=0; i<p->nCol; i++){
+ if( !p->abPK[i] ){
+ sessionAppendStr(&buf, " AND (?", &rc);
+ sessionAppendInteger(&buf, i*3+2, &rc);
+ sessionAppendStr(&buf, "=0 OR ", &rc);
+ sessionAppendIdent(&buf, p->azCol[i], &rc);
+ sessionAppendStr(&buf, " IS ?", &rc);
+ sessionAppendInteger(&buf, i*3+1, &rc);
+ sessionAppendStr(&buf, ")", &rc);
+ }
+ }
+ sessionAppendStr(&buf, ")", &rc);
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pUpdate, 0);
+ }
+ sqlite3_free(buf.aBuf);
+
+ return rc;
+}
+
+/*
+** Formulate and prepare an SQL statement to query table zTab by primary
+** key. Assuming the following table structure:
+**
+** CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
+**
+** The SELECT statement looks like this:
+**
+** SELECT * FROM x WHERE a = ?1 AND c = ?3
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pSelect is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionSelectRow(
+ sqlite3 *db, /* Database handle */
+ const char *zTab, /* Table name */
+ SessionApplyCtx *p /* Session changeset-apply context */
+){
+ return sessionSelectStmt(
+ db, "main", zTab, p->nCol, p->azCol, p->abPK, &p->pSelect);
+}
+
+/*
+** Formulate and prepare an INSERT statement to add a record to table zTab.
+** For example:
+**
+** INSERT INTO main."zTab" VALUES(?1, ?2, ?3 ...);
+**
+** If successful, SQLITE_OK is returned and SessionApplyCtx.pInsert is left
+** pointing to the prepared version of the SQL statement.
+*/
+static int sessionInsertRow(
+ sqlite3 *db, /* Database handle */
+ const char *zTab, /* Table name */
+ SessionApplyCtx *p /* Session changeset-apply context */
+){
+ int rc = SQLITE_OK;
+ int i;
+ SessionBuffer buf = {0, 0, 0};
+
+ sessionAppendStr(&buf, "INSERT INTO main.", &rc);
+ sessionAppendIdent(&buf, zTab, &rc);
+ sessionAppendStr(&buf, " VALUES(?", &rc);
+ for(i=1; i<p->nCol; i++){
+ sessionAppendStr(&buf, ", ?", &rc);
+ }
+ sessionAppendStr(&buf, ")", &rc);
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pInsert, 0);
+ }
+ sqlite3_free(buf.aBuf);
+ return rc;
+}
+
+/*
+** A wrapper around sqlite3_bind_value() that detects an extra problem.
+** See comments in the body of this function for details.
+*/
+static int sessionBindValue(
+ sqlite3_stmt *pStmt, /* Statement to bind value to */
+ int i, /* Parameter number to bind to */
+ sqlite3_value *pVal /* Value to bind */
+){
+ int eType = sqlite3_value_type(pVal);
+ /* COVERAGE: The (pVal->z==0) branch is never true using current versions
+ ** of SQLite. If a malloc fails in an sqlite3_value_xxx() function, either
+ ** the (pVal->z) variable remains as it was or the type of the value is
+ ** set to SQLITE_NULL. */
+ if( (eType==SQLITE_TEXT || eType==SQLITE_BLOB) && pVal->z==0 ){
+ /* This condition occurs when an earlier OOM in a call to
+ ** sqlite3_value_text() or sqlite3_value_blob() (perhaps from within
+ ** a conflict-handler) has zeroed the pVal->z pointer. Return NOMEM. */
+ return SQLITE_NOMEM;
+ }
+ return sqlite3_bind_value(pStmt, i, pVal);
+}
+
+/*
+** Iterator pIter must point to an SQLITE_INSERT entry. This function
+** transfers new.* values from the current iterator entry to statement
+** pStmt. The table being inserted into has nCol columns.
+**
+** New.* value $i 0 from the iterator is bound to variable ($i+1) of
+** statement pStmt. If parameter abPK is NULL, all values from 0 to (nCol-1)
+** are transfered to the statement. Otherwise, if abPK is not NULL, it points
+** to an array nCol elements in size. In this case only those values for
+** which abPK[$i] is true are read from the iterator and bound to the
+** statement.
+**
+** An SQLite error code is returned if an error occurs. Otherwise, SQLITE_OK.
+*/
+static int sessionBindRow(
+ sqlite3_changeset_iter *pIter, /* Iterator to read values from */
+ int(*xValue)(sqlite3_changeset_iter *, int, sqlite3_value **),
+ int nCol, /* Number of columns */
+ u8 *abPK, /* If not NULL, bind only if true */
+ sqlite3_stmt *pStmt /* Bind values to this statement */
+){
+ int i;
+ int rc = SQLITE_OK;
+
+ /* Neither sqlite3changeset_old or sqlite3changeset_new can fail if the
+ ** argument iterator points to a suitable entry. Make sure that xValue
+ ** is one of these to guarantee that it is safe to ignore the return
+ ** in the code below. */
+ assert( xValue==sqlite3changeset_old || xValue==sqlite3changeset_new );
+
+ for(i=0; rc==SQLITE_OK && i<nCol; i++){
+ if( !abPK || abPK[i] ){
+ sqlite3_value *pVal;
+ (void)xValue(pIter, i, &pVal);
+ rc = sessionBindValue(pStmt, i+1, pVal);
+ }
+ }
+ return rc;
+}
+
+/*
+** SQL statement pSelect is as generated by the sessionSelectRow() function.
+** This function binds the primary key values from the change that changeset
+** iterator pIter points to to the SELECT and attempts to seek to the table
+** entry. If a row is found, the SELECT statement left pointing at the row
+** and SQLITE_ROW is returned. Otherwise, if no row is found and no error
+** has occured, the statement is reset and SQLITE_OK is returned. If an
+** error occurs, the statement is reset and an SQLite error code is returned.
+**
+** If this function returns SQLITE_ROW, the caller must eventually reset()
+** statement pSelect. If any other value is returned, the statement does
+** not require a reset().
+**
+** If the iterator currently points to an INSERT record, bind values from the
+** new.* record to the SELECT statement. Or, if it points to a DELETE or
+** UPDATE, bind values from the old.* record.
+*/
+static int sessionSeekToRow(
+ sqlite3 *db, /* Database handle */
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ u8 *abPK, /* Primary key flags array */
+ sqlite3_stmt *pSelect /* SELECT statement from sessionSelectRow() */
+){
+ int rc; /* Return code */
+ int nCol; /* Number of columns in table */
+ int op; /* Changset operation (SQLITE_UPDATE etc.) */
+ const char *zDummy; /* Unused */
+
+ sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+ rc = sessionBindRow(pIter,
+ op==SQLITE_INSERT ? sqlite3changeset_new : sqlite3changeset_old,
+ nCol, abPK, pSelect
+ );
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_step(pSelect);
+ if( rc!=SQLITE_ROW ) rc = sqlite3_reset(pSelect);
+ }
+
+ return rc;
+}
+
+/*
+** Invoke the conflict handler for the change that the changeset iterator
+** currently points to.
+**
+** Argument eType must be either CHANGESET_DATA or CHANGESET_CONFLICT.
+** If argument pbReplace is NULL, then the type of conflict handler invoked
+** depends solely on eType, as follows:
+**
+** eType value Value passed to xConflict
+** -------------------------------------------------
+** CHANGESET_DATA CHANGESET_NOTFOUND
+** CHANGESET_CONFLICT CHANGESET_CONSTRAINT
+**
+** Or, if pbReplace is not NULL, then an attempt is made to find an existing
+** record with the same primary key as the record about to be deleted, updated
+** or inserted. If such a record can be found, it is available to the conflict
+** handler as the "conflicting" record. In this case the type of conflict
+** handler invoked is as follows:
+**
+** eType value PK Record found? Value passed to xConflict
+** ----------------------------------------------------------------
+** CHANGESET_DATA Yes CHANGESET_DATA
+** CHANGESET_DATA No CHANGESET_NOTFOUND
+** CHANGESET_CONFLICT Yes CHANGESET_CONFLICT
+** CHANGESET_CONFLICT No CHANGESET_CONSTRAINT
+**
+** If pbReplace is not NULL, and a record with a matching PK is found, and
+** the conflict handler function returns SQLITE_CHANGESET_REPLACE, *pbReplace
+** is set to non-zero before returning SQLITE_OK.
+**
+** If the conflict handler returns SQLITE_CHANGESET_ABORT, SQLITE_ABORT is
+** returned. Or, if the conflict handler returns an invalid value,
+** SQLITE_MISUSE. If the conflict handler returns SQLITE_CHANGESET_OMIT,
+** this function returns SQLITE_OK.
+*/
+static int sessionConflictHandler(
+ int eType, /* Either CHANGESET_DATA or CONFLICT */
+ SessionApplyCtx *p, /* changeset_apply() context */
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ int(*xConflict)(void *, int, sqlite3_changeset_iter*),
+ void *pCtx, /* First argument for conflict handler */
+ int *pbReplace /* OUT: Set to true if PK row is found */
+){
+ int res; /* Value returned by conflict handler */
+ int rc;
+ int nCol;
+ int op;
+ const char *zDummy;
+
+ sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+
+ assert( eType==SQLITE_CHANGESET_CONFLICT || eType==SQLITE_CHANGESET_DATA );
+ assert( SQLITE_CHANGESET_CONFLICT+1==SQLITE_CHANGESET_CONSTRAINT );
+ assert( SQLITE_CHANGESET_DATA+1==SQLITE_CHANGESET_NOTFOUND );
+
+ /* Bind the new.* PRIMARY KEY values to the SELECT statement. */
+ if( pbReplace ){
+ rc = sessionSeekToRow(p->db, pIter, p->abPK, p->pSelect);
+ }else{
+ rc = SQLITE_OK;
+ }
+
+ if( rc==SQLITE_ROW ){
+ /* There exists another row with the new.* primary key. */
+ pIter->pConflict = p->pSelect;
+ res = xConflict(pCtx, eType, pIter);
+ pIter->pConflict = 0;
+ rc = sqlite3_reset(p->pSelect);
+ }else if( rc==SQLITE_OK ){
+ /* No other row with the new.* primary key. */
+ res = xConflict(pCtx, eType+1, pIter);
+ if( res==SQLITE_CHANGESET_REPLACE ) rc = SQLITE_MISUSE;
+ }
+
+ if( rc==SQLITE_OK ){
+ switch( res ){
+ case SQLITE_CHANGESET_REPLACE:
+ assert( pbReplace );
+ *pbReplace = 1;
+ break;
+
+ case SQLITE_CHANGESET_OMIT:
+ break;
+
+ case SQLITE_CHANGESET_ABORT:
+ rc = SQLITE_ABORT;
+ break;
+
+ default:
+ rc = SQLITE_MISUSE;
+ break;
+ }
+ }
+
+ return rc;
+}
+
+/*
+** Attempt to apply the change that the iterator passed as the first argument
+** currently points to to the database. If a conflict is encountered, invoke
+** the conflict handler callback.
+**
+** If argument pbRetry is NULL, then ignore any CHANGESET_DATA conflict. If
+** one is encountered, update or delete the row with the matching primary key
+** instead. Or, if pbRetry is not NULL and a CHANGESET_DATA conflict occurs,
+** invoke the conflict handler. If it returns CHANGESET_REPLACE, set *pbRetry
+** to true before returning. In this case the caller will invoke this function
+** again, this time with pbRetry set to NULL.
+**
+** If argument pbReplace is NULL and a CHANGESET_CONFLICT conflict is
+** encountered invoke the conflict handler with CHANGESET_CONSTRAINT instead.
+** Or, if pbReplace is not NULL, invoke it with CHANGESET_CONFLICT. If such
+** an invocation returns SQLITE_CHANGESET_REPLACE, set *pbReplace to true
+** before retrying. In this case the caller attempts to remove the conflicting
+** row before invoking this function again, this time with pbReplace set
+** to NULL.
+**
+** If any conflict handler returns SQLITE_CHANGESET_ABORT, this function
+** returns SQLITE_ABORT. Otherwise, if no error occurs, SQLITE_OK is
+** returned.
+*/
+static int sessionApplyOneOp(
+ sqlite3_changeset_iter *pIter, /* Changeset iterator */
+ SessionApplyCtx *p, /* changeset_apply() context */
+ int(*xConflict)(void *, int, sqlite3_changeset_iter *),
+ void *pCtx, /* First argument for the conflict handler */
+ int *pbReplace, /* OUT: True to remove PK row and retry */
+ int *pbRetry /* OUT: True to retry. */
+){
+ const char *zDummy;
+ int op;
+ int nCol;
+ int rc = SQLITE_OK;
+
+ assert( p->pDelete && p->pUpdate && p->pInsert && p->pSelect );
+ assert( p->azCol && p->abPK );
+ assert( !pbReplace || *pbReplace==0 );
+
+ sqlite3changeset_op(pIter, &zDummy, &nCol, &op, 0);
+
+ if( op==SQLITE_DELETE ){
+
+ /* Bind values to the DELETE statement. If conflict handling is required,
+ ** bind values for all columns and set bound variable (nCol+1) to true.
+ ** Or, if conflict handling is not required, bind just the PK column
+ ** values and, if it exists, set (nCol+1) to false. Conflict handling
+ ** is not required if:
+ **
+ ** * this is a patchset, or
+ ** * (pbRetry==0), or
+ ** * all columns of the table are PK columns (in this case there is
+ ** no (nCol+1) variable to bind to).
+ */
+ u8 *abPK = (pIter->bPatchset ? p->abPK : 0);
+ rc = sessionBindRow(pIter, sqlite3changeset_old, nCol, abPK, p->pDelete);
+ if( rc==SQLITE_OK && sqlite3_bind_parameter_count(p->pDelete)>nCol ){
+ rc = sqlite3_bind_int(p->pDelete, nCol+1, (pbRetry==0 || abPK));
+ }
+ if( rc!=SQLITE_OK ) return rc;
+
+ sqlite3_step(p->pDelete);
+ rc = sqlite3_reset(p->pDelete);
+ if( rc==SQLITE_OK && sqlite3_changes(p->db)==0 ){
+ rc = sessionConflictHandler(
+ SQLITE_CHANGESET_DATA, p, pIter, xConflict, pCtx, pbRetry
+ );
+ }else if( (rc&0xff)==SQLITE_CONSTRAINT ){
+ rc = sessionConflictHandler(
+ SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
+ );
+ }
+
+ }else if( op==SQLITE_UPDATE ){
+ int i;
+
+ /* Bind values to the UPDATE statement. */
+ for(i=0; rc==SQLITE_OK && i<nCol; i++){
+ sqlite3_value *pOld = sessionChangesetOld(pIter, i);
+ sqlite3_value *pNew = sessionChangesetNew(pIter, i);
+
+ sqlite3_bind_int(p->pUpdate, i*3+2, !!pNew);
+ if( pOld ){
+ rc = sessionBindValue(p->pUpdate, i*3+1, pOld);
+ }
+ if( rc==SQLITE_OK && pNew ){
+ rc = sessionBindValue(p->pUpdate, i*3+3, pNew);
+ }
+ }
+ if( rc==SQLITE_OK ){
+ sqlite3_bind_int(p->pUpdate, nCol*3+1, pbRetry==0 || pIter->bPatchset);
+ }
+ if( rc!=SQLITE_OK ) return rc;
+
+ /* Attempt the UPDATE. In the case of a NOTFOUND or DATA conflict,
+ ** the result will be SQLITE_OK with 0 rows modified. */
+ sqlite3_step(p->pUpdate);
+ rc = sqlite3_reset(p->pUpdate);
+
+ if( rc==SQLITE_OK && sqlite3_changes(p->db)==0 ){
+ /* A NOTFOUND or DATA error. Search the table to see if it contains
+ ** a row with a matching primary key. If so, this is a DATA conflict.
+ ** Otherwise, if there is no primary key match, it is a NOTFOUND. */
+
+ rc = sessionConflictHandler(
+ SQLITE_CHANGESET_DATA, p, pIter, xConflict, pCtx, pbRetry
+ );
+
+ }else if( (rc&0xff)==SQLITE_CONSTRAINT ){
+ /* This is always a CONSTRAINT conflict. */
+ rc = sessionConflictHandler(
+ SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
+ );
+ }
+
+ }else{
+ assert( op==SQLITE_INSERT );
+ rc = sessionBindRow(pIter, sqlite3changeset_new, nCol, 0, p->pInsert);
+ if( rc!=SQLITE_OK ) return rc;
+
+ sqlite3_step(p->pInsert);
+ rc = sqlite3_reset(p->pInsert);
+ if( (rc&0xff)==SQLITE_CONSTRAINT ){
+ rc = sessionConflictHandler(
+ SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, pbReplace
+ );
+ }
+ }
+
+ return rc;
+}
+
+/*
+** Argument pIter is a changeset iterator that has been initialized, but
+** not yet passed to sqlite3changeset_next(). This function applies the
+** changeset to the main database attached to handle "db". The supplied
+** conflict handler callback is invoked to resolve any conflicts encountered
+** while applying the change.
+*/
+static int sessionChangesetApply(
+ sqlite3 *db, /* Apply change to "main" db of this handle */
+ sqlite3_changeset_iter *pIter, /* Changeset to apply */
+ int(*xFilter)(
+ void *pCtx, /* Copy of sixth arg to _apply() */
+ const char *zTab /* Table name */
+ ),
+ int(*xConflict)(
+ void *pCtx, /* Copy of fifth arg to _apply() */
+ int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */
+ sqlite3_changeset_iter *p /* Handle describing change and conflict */
+ ),
+ void *pCtx /* First argument passed to xConflict */
+){
+ int schemaMismatch = 0;
+ int rc; /* Return code */
+ const char *zTab = 0; /* Name of current table */
+ int nTab = 0; /* Result of sqlite3Strlen30(zTab) */
+ SessionApplyCtx sApply; /* changeset_apply() context object */
+
+ assert( xConflict!=0 );
+
+ memset(&sApply, 0, sizeof(sApply));
+ sqlite3_mutex_enter(sqlite3_db_mutex(db));
+ rc = sqlite3_exec(db, "SAVEPOINT changeset_apply", 0, 0, 0);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_exec(db, "PRAGMA defer_foreign_keys = 1", 0, 0, 0);
+ }
+ while( rc==SQLITE_OK && SQLITE_ROW==sqlite3changeset_next(pIter) ){
+ int nCol;
+ int op;
+ int bReplace = 0;
+ int bRetry = 0;
+ const char *zNew;
+
+ sqlite3changeset_op(pIter, &zNew, &nCol, &op, 0);
+
+ if( zTab==0 || sqlite3_strnicmp(zNew, zTab, nTab+1) ){
+ u8 *abPK;
+
+ sqlite3_free((char*)sApply.azCol); /* cast works around VC++ bug */
+ sqlite3_finalize(sApply.pDelete);
+ sqlite3_finalize(sApply.pUpdate);
+ sqlite3_finalize(sApply.pInsert);
+ sqlite3_finalize(sApply.pSelect);
+ memset(&sApply, 0, sizeof(sApply));
+ sApply.db = db;
+
+ /* If an xFilter() callback was specified, invoke it now. If the
+ ** xFilter callback returns zero, skip this table. If it returns
+ ** non-zero, proceed. */
+ schemaMismatch = (xFilter && (0==xFilter(pCtx, zNew)));
+ if( schemaMismatch ){
+ zTab = sqlite3_mprintf("%s", zNew);
+ if( zTab==0 ){
+ rc = SQLITE_NOMEM;
+ break;
+ }
+ nTab = (int)strlen(zTab);
+ sApply.azCol = (const char **)zTab;
+ }else{
+ sqlite3changeset_pk(pIter, &abPK, 0);
+ rc = sessionTableInfo(
+ db, "main", zNew, &sApply.nCol, &zTab, &sApply.azCol, &sApply.abPK
+ );
+ if( rc!=SQLITE_OK ) break;
+
+ if( sApply.nCol==0 ){
+ schemaMismatch = 1;
+ sqlite3_log(SQLITE_SCHEMA,
+ "sqlite3changeset_apply(): no such table: %s", zTab
+ );
+ }
+ else if( sApply.nCol!=nCol ){
+ schemaMismatch = 1;
+ sqlite3_log(SQLITE_SCHEMA,
+ "sqlite3changeset_apply(): table %s has %d columns, expected %d",
+ zTab, sApply.nCol, nCol
+ );
+ }
+ else if( memcmp(sApply.abPK, abPK, nCol)!=0 ){
+ schemaMismatch = 1;
+ sqlite3_log(SQLITE_SCHEMA, "sqlite3changeset_apply(): "
+ "primary key mismatch for table %s", zTab
+ );
+ }
+ else if(
+ (rc = sessionSelectRow(db, zTab, &sApply))
+ || (rc = sessionUpdateRow(db, zTab, &sApply))
+ || (rc = sessionDeleteRow(db, zTab, &sApply))
+ || (rc = sessionInsertRow(db, zTab, &sApply))
+ ){
+ break;
+ }
+ nTab = sqlite3Strlen30(zTab);
+ }
+ }
+
+ /* If there is a schema mismatch on the current table, proceed to the
+ ** next change. A log message has already been issued. */
+ if( schemaMismatch ) continue;
+
+ rc = sessionApplyOneOp(pIter, &sApply, xConflict, pCtx, &bReplace, &bRetry);
+
+ if( rc==SQLITE_OK && bRetry ){
+ rc = sessionApplyOneOp(pIter, &sApply, xConflict, pCtx, &bReplace, 0);
+ }
+
+ if( bReplace ){
+ assert( pIter->op==SQLITE_INSERT );
+ rc = sqlite3_exec(db, "SAVEPOINT replace_op", 0, 0, 0);
+ if( rc==SQLITE_OK ){
+ rc = sessionBindRow(pIter,
+ sqlite3changeset_new, sApply.nCol, sApply.abPK, sApply.pDelete);
+ sqlite3_bind_int(sApply.pDelete, sApply.nCol+1, 1);
+ }
+ if( rc==SQLITE_OK ){
+ sqlite3_step(sApply.pDelete);
+ rc = sqlite3_reset(sApply.pDelete);
+ }
+ if( rc==SQLITE_OK ){
+ rc = sessionApplyOneOp(pIter, &sApply, xConflict, pCtx, 0, 0);
+ }
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_exec(db, "RELEASE replace_op", 0, 0, 0);
+ }
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3changeset_finalize(pIter);
+ }else{
+ sqlite3changeset_finalize(pIter);
+ }
+
+ if( rc==SQLITE_OK ){
+ int nFk, notUsed;
+ sqlite3_db_status(db, SQLITE_DBSTATUS_DEFERRED_FKS, &nFk, ¬Used, 0);
+ if( nFk!=0 ){
+ int res = SQLITE_CHANGESET_ABORT;
+ sqlite3_changeset_iter sIter;
+ memset(&sIter, 0, sizeof(sIter));
+ sIter.nCol = nFk;
+ res = xConflict(pCtx, SQLITE_CHANGESET_FOREIGN_KEY, &sIter);
+ if( res!=SQLITE_CHANGESET_OMIT ){
+ rc = SQLITE_CONSTRAINT;
+ }
+ }
+ }
+ sqlite3_exec(db, "PRAGMA defer_foreign_keys = 0", 0, 0, 0);
+
+ if( rc==SQLITE_OK ){
+ rc = sqlite3_exec(db, "RELEASE changeset_apply", 0, 0, 0);
+ }else{
+ sqlite3_exec(db, "ROLLBACK TO changeset_apply", 0, 0, 0);
+ sqlite3_exec(db, "RELEASE changeset_apply", 0, 0, 0);
+ }
+
+ sqlite3_finalize(sApply.pInsert);
+ sqlite3_finalize(sApply.pDelete);
+ sqlite3_finalize(sApply.pUpdate);
+ sqlite3_finalize(sApply.pSelect);
+ sqlite3_free((char*)sApply.azCol); /* cast works around VC++ bug */
+ sqlite3_mutex_leave(sqlite3_db_mutex(db));
+ return rc;
+}
+
+/*
+** Apply the changeset passed via pChangeset/nChangeset to the main database
+** attached to handle "db". Invoke the supplied conflict handler callback
+** to resolve any conflicts encountered while applying the change.
+*/
+int sqlite3changeset_apply(
+ sqlite3 *db, /* Apply change to "main" db of this handle */
+ int nChangeset, /* Size of changeset in bytes */
+ void *pChangeset, /* Changeset blob */
+ int(*xFilter)(
+ void *pCtx, /* Copy of sixth arg to _apply() */
+ const char *zTab /* Table name */
+ ),
+ int(*xConflict)(
+ void *pCtx, /* Copy of fifth arg to _apply() */
+ int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */
+ sqlite3_changeset_iter *p /* Handle describing change and conflict */
+ ),
+ void *pCtx /* First argument passed to xConflict */
+){
+ sqlite3_changeset_iter *pIter; /* Iterator to skip through changeset */
+ int rc = sqlite3changeset_start(&pIter, nChangeset, pChangeset);
+ if( rc==SQLITE_OK ){
+ rc = sessionChangesetApply(db, pIter, xFilter, xConflict, pCtx);
+ }
+ return rc;
+}
+
+/*
+** Apply the changeset passed via xInput/pIn to the main database
+** attached to handle "db". Invoke the supplied conflict handler callback
+** to resolve any conflicts encountered while applying the change.
+*/
+int sqlite3changeset_apply_strm(
+ sqlite3 *db, /* Apply change to "main" db of this handle */
+ int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
+ void *pIn, /* First arg for xInput */
+ int(*xFilter)(
+ void *pCtx, /* Copy of sixth arg to _apply() */
+ const char *zTab /* Table name */
+ ),
+ int(*xConflict)(
+ void *pCtx, /* Copy of sixth arg to _apply() */
+ int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */
+ sqlite3_changeset_iter *p /* Handle describing change and conflict */
+ ),
+ void *pCtx /* First argument passed to xConflict */
+){
+ sqlite3_changeset_iter *pIter; /* Iterator to skip through changeset */
+ int rc = sqlite3changeset_start_strm(&pIter, xInput, pIn);
+ if( rc==SQLITE_OK ){
+ rc = sessionChangesetApply(db, pIter, xFilter, xConflict, pCtx);
+ }
+ return rc;
+}
+
+/*
+** This function is called to merge two changes to the same row together as
+** part of an sqlite3changeset_concat() operation. A new change object is
+** allocated and a pointer to it stored in *ppNew.
+*/
+static int sessionChangeMerge(
+ SessionTable *pTab, /* Table structure */
+ int bPatchset, /* True for patchsets */
+ SessionChange *pExist, /* Existing change */
+ int op2, /* Second change operation */
+ int bIndirect, /* True if second change is indirect */
+ u8 *aRec, /* Second change record */
+ int nRec, /* Number of bytes in aRec */
+ SessionChange **ppNew /* OUT: Merged change */
+){
+ SessionChange *pNew = 0;
+
+ if( !pExist ){
+ pNew = (SessionChange *)sqlite3_malloc(sizeof(SessionChange) + nRec);
+ if( !pNew ){
+ return SQLITE_NOMEM;
+ }
+ memset(pNew, 0, sizeof(SessionChange));
+ pNew->op = op2;
+ pNew->bIndirect = bIndirect;
+ pNew->nRecord = nRec;
+ pNew->aRecord = (u8*)&pNew[1];
+ memcpy(pNew->aRecord, aRec, nRec);
+ }else{
+ int op1 = pExist->op;
+
+ /*
+ ** op1=INSERT, op2=INSERT -> Unsupported. Discard op2.
+ ** op1=INSERT, op2=UPDATE -> INSERT.
+ ** op1=INSERT, op2=DELETE -> (none)
+ **
+ ** op1=UPDATE, op2=INSERT -> Unsupported. Discard op2.
+ ** op1=UPDATE, op2=UPDATE -> UPDATE.
+ ** op1=UPDATE, op2=DELETE -> DELETE.
+ **
+ ** op1=DELETE, op2=INSERT -> UPDATE.
+ ** op1=DELETE, op2=UPDATE -> Unsupported. Discard op2.
+ ** op1=DELETE, op2=DELETE -> Unsupported. Discard op2.
+ */
+ if( (op1==SQLITE_INSERT && op2==SQLITE_INSERT)
+ || (op1==SQLITE_UPDATE && op2==SQLITE_INSERT)
+ || (op1==SQLITE_DELETE && op2==SQLITE_UPDATE)
+ || (op1==SQLITE_DELETE && op2==SQLITE_DELETE)
+ ){
+ pNew = pExist;
+ }else if( op1==SQLITE_INSERT && op2==SQLITE_DELETE ){
+ sqlite3_free(pExist);
+ assert( pNew==0 );
+ }else{
+ u8 *aExist = pExist->aRecord;
+ int nByte;
+ u8 *aCsr;
+
+ /* Allocate a new SessionChange object. Ensure that the aRecord[]
+ ** buffer of the new object is large enough to hold any record that
+ ** may be generated by combining the input records. */
+ nByte = sizeof(SessionChange) + pExist->nRecord + nRec;
+ pNew = (SessionChange *)sqlite3_malloc(nByte);
+ if( !pNew ){
+ sqlite3_free(pExist);
+ return SQLITE_NOMEM;
+ }
+ memset(pNew, 0, sizeof(SessionChange));
+ pNew->bIndirect = (bIndirect && pExist->bIndirect);
+ aCsr = pNew->aRecord = (u8 *)&pNew[1];
+
+ if( op1==SQLITE_INSERT ){ /* INSERT + UPDATE */
+ u8 *a1 = aRec;
+ assert( op2==SQLITE_UPDATE );
+ pNew->op = SQLITE_INSERT;
+ if( bPatchset==0 ) sessionSkipRecord(&a1, pTab->nCol);
+ sessionMergeRecord(&aCsr, pTab->nCol, aExist, a1);
+ }else if( op1==SQLITE_DELETE ){ /* DELETE + INSERT */
+ assert( op2==SQLITE_INSERT );
+ pNew->op = SQLITE_UPDATE;
+ if( bPatchset ){
+ memcpy(aCsr, aRec, nRec);
+ aCsr += nRec;
+ }else{
+ if( 0==sessionMergeUpdate(&aCsr, pTab, bPatchset, aExist, 0,aRec,0) ){
+ sqlite3_free(pNew);
+ pNew = 0;
+ }
+ }
+ }else if( op2==SQLITE_UPDATE ){ /* UPDATE + UPDATE */
+ u8 *a1 = aExist;
+ u8 *a2 = aRec;
+ assert( op1==SQLITE_UPDATE );
+ if( bPatchset==0 ){
+ sessionSkipRecord(&a1, pTab->nCol);
+ sessionSkipRecord(&a2, pTab->nCol);
+ }
+ pNew->op = SQLITE_UPDATE;
+ if( 0==sessionMergeUpdate(&aCsr, pTab, bPatchset, aRec, aExist,a1,a2) ){
+ sqlite3_free(pNew);
+ pNew = 0;
+ }
+ }else{ /* UPDATE + DELETE */
+ assert( op1==SQLITE_UPDATE && op2==SQLITE_DELETE );
+ pNew->op = SQLITE_DELETE;
+ if( bPatchset ){
+ memcpy(aCsr, aRec, nRec);
+ aCsr += nRec;
+ }else{
+ sessionMergeRecord(&aCsr, pTab->nCol, aRec, aExist);
+ }
+ }
+
+ if( pNew ){
+ pNew->nRecord = (int)(aCsr - pNew->aRecord);
+ }
+ sqlite3_free(pExist);
+ }
+ }
+
+ *ppNew = pNew;
+ return SQLITE_OK;
+}
+
+/*
+** Add all changes in the changeset passed via the first two arguments to
+** hash tables.
+*/
+static int sessionChangesetToHash(
+ sqlite3_changeset_iter *pIter, /* Iterator to read from */
+ SessionTable **ppTabList /* IN/OUT: List of table objects */
+){
+ u8 *aRec;
+ int nRec;
+ int rc = SQLITE_OK;
+ SessionTable *pTab = 0;
+
+ while( SQLITE_ROW==sessionChangesetNext(pIter, &aRec, &nRec) ){
+ const char *zNew;
+ int nCol;
+ int op;
+ int iHash;
+ int bIndirect;
+ SessionChange *pChange;
+ SessionChange *pExist = 0;
+ SessionChange **pp;
+
+ sqlite3changeset_op(pIter, &zNew, &nCol, &op, &bIndirect);
+ if( !pTab || sqlite3_stricmp(zNew, pTab->zName) ){
+ /* Search the list for a matching table */
+ int nNew = (int)strlen(zNew);
+ u8 *abPK;
+
+ sqlite3changeset_pk(pIter, &abPK, 0);
+ for(pTab = *ppTabList; pTab; pTab=pTab->pNext){
+ if( 0==sqlite3_strnicmp(pTab->zName, zNew, nNew+1) ) break;
+ }
+ if( !pTab ){
+ pTab = sqlite3_malloc(sizeof(SessionTable) + nCol + nNew+1);
+ if( !pTab ){
+ rc = SQLITE_NOMEM;
+ break;
+ }
+ memset(pTab, 0, sizeof(SessionTable));
+ pTab->pNext = *ppTabList;
+ pTab->nCol = nCol;
+ pTab->abPK = (u8*)&pTab[1];
+ memcpy(pTab->abPK, abPK, nCol);
+ pTab->zName = (char*)&pTab->abPK[nCol];
+ memcpy(pTab->zName, zNew, nNew+1);
+ *ppTabList = pTab;
+ }else if( pTab->nCol!=nCol || memcmp(pTab->abPK, abPK, nCol) ){
+ rc = SQLITE_SCHEMA;
+ break;
+ }
+ }
+
+ if( sessionGrowHash(pIter->bPatchset, pTab) ){
+ rc = SQLITE_NOMEM;
+ break;
+ }
+ iHash = sessionChangeHash(
+ pTab, (pIter->bPatchset && op==SQLITE_DELETE), aRec, pTab->nChange
+ );
+
+ /* Search for existing entry. If found, remove it from the hash table.
+ ** Code below may link it back in.
+ */
+ for(pp=&pTab->apChange[iHash]; *pp; pp=&(*pp)->pNext){
+ int bPkOnly1 = 0;
+ int bPkOnly2 = 0;
+ if( pIter->bPatchset ){
+ bPkOnly1 = (*pp)->op==SQLITE_DELETE;
+ bPkOnly2 = op==SQLITE_DELETE;
+ }
+ if( sessionChangeEqual(pTab, bPkOnly1, (*pp)->aRecord, bPkOnly2, aRec) ){
+ pExist = *pp;
+ *pp = (*pp)->pNext;
+ pTab->nEntry--;
+ break;
+ }
+ }
+
+ rc = sessionChangeMerge(pTab,
+ pIter->bPatchset, pExist, op, bIndirect, aRec, nRec, &pChange
+ );
+ if( rc ) break;
+ if( pChange ){
+ pChange->pNext = pTab->apChange[iHash];
+ pTab->apChange[iHash] = pChange;
+ pTab->nEntry++;
+ }
+ }
+
+ if( rc==SQLITE_OK ) rc = pIter->rc;
+ return rc;
+}
+
+/*
+** 1. Iterate through the left-hand changeset. Add an entry to a table
+** specific hash table for each change in the changeset. The hash table
+** key is the PK of the row affected by the change.
+**
+** 2. Then interate through the right-hand changeset. Attempt to add an
+** entry to a hash table for each component change. If a change already
+** exists with the same PK values, combine the two into a single change.
+**
+** 3. Write an output changeset based on the contents of the hash table.
+*/
+static int sessionChangesetConcat(
+ sqlite3_changeset_iter *pLeft,
+ sqlite3_changeset_iter *pRight,
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut,
+ int *pnOut,
+ void **ppOut
+){
+ SessionTable *pList = 0; /* List of SessionTable objects */
+ int rc; /* Return code */
+ int bPatch; /* True for a patchset */
+ SessionTable *pTab;
+ SessionBuffer buf = {0, 0, 0};
+
+ assert( xOutput==0 || (ppOut==0 && pnOut==0) );
+
+ assert( pLeft->zTab==0 && pRight->zTab==0 );
+ rc = sessionChangesetToHash(pLeft, &pList);
+ assert( pLeft->zTab || pList==0 );
+ if( rc==SQLITE_OK ){
+ rc = sessionChangesetToHash(pRight, &pList);
+ }
+ bPatch = pLeft->bPatchset || pRight->bPatchset;
+
+ if( pLeft->zTab && pRight->zTab && pLeft->bPatchset!=pRight->bPatchset ){
+ rc = SQLITE_ERROR;
+ }
+
+ /* Create the serialized output changeset based on the contents of the
+ ** hash tables attached to the SessionTable objects in list pList.
+ */
+ for(pTab=pList; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
+ int i;
+ if( pTab->nEntry==0 ) continue;
+
+ sessionAppendTableHdr(&buf, bPatch, pTab, &rc);
+ for(i=0; i<pTab->nChange; i++){
+ SessionChange *p;
+ for(p=pTab->apChange[i]; p; p=p->pNext){
+ sessionAppendByte(&buf, p->op, &rc);
+ sessionAppendByte(&buf, p->bIndirect, &rc);
+ sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
+ }
+ }
+
+ if( rc==SQLITE_OK && xOutput && buf.nBuf>=SESSIONS_STRM_CHUNK_SIZE ){
+ rc = xOutput(pOut, buf.aBuf, buf.nBuf);
+ buf.nBuf = 0;
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ if( xOutput ){
+ if( buf.nBuf>0 ) rc = xOutput(pOut, buf.aBuf, buf.nBuf);
+ }else{
+ *ppOut = buf.aBuf;
+ *pnOut = buf.nBuf;
+ buf.aBuf = 0;
+ }
+ }
+ sqlite3_free(buf.aBuf);
+
+ sessionDeleteTable(pList);
+ return rc;
+}
+
+/*
+** Combine two changesets together.
+*/
+int sqlite3changeset_concat(
+ int nLeft, /* Number of bytes in lhs input */
+ void *pLeft, /* Lhs input changeset */
+ int nRight /* Number of bytes in rhs input */,
+ void *pRight, /* Rhs input changeset */
+ int *pnOut, /* OUT: Number of bytes in output changeset */
+ void **ppOut /* OUT: changeset (left <concat> right) */
+){
+ sqlite3_changeset_iter *pIter1 = 0;
+ sqlite3_changeset_iter *pIter2 = 0;
+ int rc;
+
+ *pnOut = 0;
+ *ppOut = 0;
+ rc = sqlite3changeset_start(&pIter1, nLeft, pLeft);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3changeset_start(&pIter2, nRight, pRight);
+ }
+ if( rc==SQLITE_OK ){
+ rc = sessionChangesetConcat(pIter1, pIter2, 0, 0, pnOut, ppOut);
+ }
+
+ sqlite3changeset_finalize(pIter1);
+ sqlite3changeset_finalize(pIter2);
+ return rc;
+}
+
+/*
+** Streaming version of sqlite3changeset_concat().
+*/
+int sqlite3changeset_concat_strm(
+ int (*xInputA)(void *pIn, void *pData, int *pnData),
+ void *pInA,
+ int (*xInputB)(void *pIn, void *pData, int *pnData),
+ void *pInB,
+ int (*xOutput)(void *pOut, const void *pData, int nData),
+ void *pOut
+){
+ sqlite3_changeset_iter *pIter1 = 0;
+ sqlite3_changeset_iter *pIter2 = 0;
+ int rc;
+
+ rc = sqlite3changeset_start_strm(&pIter1, xInputA, pInA);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3changeset_start_strm(&pIter2, xInputB, pInB);
+ }
+ if( rc==SQLITE_OK ){
+ rc = sessionChangesetConcat(pIter1, pIter2, xOutput, pOut, 0, 0);
+ }
+
+ sqlite3changeset_finalize(pIter1);
+ sqlite3changeset_finalize(pIter2);
+ return rc;
+}
+
+#endif /* SQLITE_ENABLE_SESSION && SQLITE_ENABLE_PREUPDATE_HOOK */
projects / thirdparty / sqlite.git / commitdiff
