******************************************************************************
**
** This file contains code for a VFS layer that acts as a wrapper around
-** an existing VFS. The code in this file attempts to detect a specific
-** bug in SQLite - writing data to a database file page when:
+** an existing VFS. The code in this file attempts to verify that SQLite
+** correctly populates and syncs a journal file before writing to a
+** corresponding database file.
**
-** a) the original page data is not stored in a synced portion of the
-** journal file, and
-** b) the page was not a free-list leaf page when the transaction was
-** first opened.
-**
-** $Id: test_journal.c,v 1.7 2009/01/07 18:08:49 danielk1977 Exp $
+** $Id: test_journal.c,v 1.8 2009/01/08 12:05:56 danielk1977 Exp $
*/
#if SQLITE_TEST /* This file is used for testing only */
#include "sqlite3.h"
#include "sqliteInt.h"
+/*
+** INTERFACE
+**
+** The public interface to this wrapper VFS is two functions:
+**
+** jt_register()
+** jt_unregister()
+**
+** See header comments associated with those two functions below for
+** details.
+**
+** LIMITATIONS
+**
+** This wrapper will not work if "PRAGMA synchronous = off" is used.
+**
+** OPERATION
+**
+** Starting a Transaction:
+**
+** When a write-transaction is started, the contents of the database is
+** inspected and the following data stored as part of the database file
+** handle (type struct jt_file):
+**
+** a) The page-size of the database file.
+** b) The number of pages that are in the database file.
+** c) The set of page numbers corresponding to free-list leaf pages.
+** d) A check-sum for every page in the database file.
+**
+** The start of a write-transaction is deemed to have occured when a
+** 28-byte journal header is written to byte offset 0 of the journal
+** file.
+**
+** Syncing the Journal File:
+**
+** Whenever the xSync method is invoked to sync a journal-file, the
+** contents of the journal file are read. For each page written to
+** the journal file, a check-sum is calculated and compared to the
+** check-sum calculated for the corresponding database page when the
+** write-transaction was initialized. The success of the comparison
+** is assert()ed. So if SQLite has written something other than the
+** original content to the database file, an assert() will fail.
+**
+** Additionally, the set of page numbers for which records exist in
+** the journal file is added to (unioned with) the set of page numbers
+** corresponding to free-list leaf pages collected when the
+** write-transaction was initialized. This set comprises the page-numbers
+** corresponding to those pages that SQLite may now safely modify.
+**
+** Writing to the Database File:
+**
+** When a block of data is written to a database file, the following
+** invariants are asserted:
+**
+** a) That the block of data is an aligned block of page-size bytes.
+**
+** b) That if the page being written did not exist when the
+** transaction was started (i.e. the database file is growing), then
+** the journal-file must have been synced at least once since
+** the start of the transaction.
+**
+** c) That if the page being written did exist when the transaction
+** was started, then the page must have either been a free-list
+** leaf page at the start of the transaction, or else must have
+** been stored in the journal file prior to the most recent sync.
+**
+** Closing a Transaction:
+**
+** When a transaction is closed, all data collected at the start of
+** the transaction, or following an xSync of a journal-file, is
+** discarded. The end of a transaction is recognized when any one
+** of the following occur:
+**
+** a) A block of zeroes (or anything else that is not a valid
+** journal-header) is written to the start of the journal file.
+**
+** b) A journal file is truncated to zero bytes in size using xTruncate.
+**
+** c) The journal file is deleted using xDelete.
+*/
+
/*
** Maximum pathname length supported by the jt backend.
*/
u32 nPagesize; /* Page size when transaction started */
Bitvec *pWritable; /* Bitvec of pages that may be written to the file */
u32 *aCksum; /* Checksum for first nPage pages */
+ int nSync; /* Number of times journal file has been synced */
/* Only used by journal file-handles */
sqlite3_int64 iMaxOff; /* Maximum offset written to this transaction */
static int jtDelete(sqlite3_vfs*, const char *zName, int syncDir);
static int jtAccess(sqlite3_vfs*, const char *zName, int flags, int *);
static int jtFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
-#ifndef SQLITE_OMIT_LOAD_EXTENSION
static void *jtDlOpen(sqlite3_vfs*, const char *zFilename);
static void jtDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
static void (*jtDlSym(sqlite3_vfs*,void*, const char *zSymbol))(void);
static void jtDlClose(sqlite3_vfs*, void*);
-#endif /* SQLITE_OMIT_LOAD_EXTENSION */
static int jtRandomness(sqlite3_vfs*, int nByte, char *zOut);
static int jtSleep(sqlite3_vfs*, int microseconds);
static int jtCurrentTime(sqlite3_vfs*, double*);
jtDelete, /* xDelete */
jtAccess, /* xAccess */
jtFullPathname, /* xFullPathname */
-#ifndef SQLITE_OMIT_LOAD_EXTENSION
jtDlOpen, /* xDlOpen */
jtDlError, /* xDlError */
jtDlSym, /* xDlSym */
jtDlClose, /* xDlClose */
-#else
- 0, /* xDlOpen */
- 0, /* xDlError */
- 0, /* xDlSym */
- 0, /* xDlClose */
-#endif /* SQLITE_OMIT_LOAD_EXTENSION */
jtRandomness, /* xRandomness */
jtSleep, /* xSleep */
jtCurrentTime /* xCurrentTime */
};
struct JtGlobal {
- sqlite3_vfs *pVfs;
- jt_file *pList;
+ sqlite3_vfs *pVfs; /* Parent VFS */
+ jt_file *pList; /* List of all open files */
};
static struct JtGlobal g = {0, 0};
+/*
+** The jt_file pointed to by the argument may or may not be a file-handle
+** open on a main database file. If it is, and a transaction is currently
+** opened on the file, then discard all transaction related data.
+*/
static void closeTransaction(jt_file *p){
sqlite3BitvecDestroy(p->pWritable);
sqlite3_free(p->aCksum);
p->pWritable = 0;
p->aCksum = 0;
+ p->nSync = 0;
}
/*
}
+/*
+** Parameter zJournal is the name of a journal file that is currently
+** open. This function locates and returns the handle opened on the
+** corresponding database file by the pager that currently has the
+** journal file opened. This file-handle is identified by the
+** following properties:
+**
+** a) SQLITE_OPEN_MAIN_DB was specified when the file was opened.
+**
+** b) The file-name specified when the file was opened matches
+** all but the final 8 characters of the journal file name.
+**
+** c) There is currently a reserved lock on the file.
+**/
static jt_file *locateDatabaseHandle(const char *zJournal){
- jt_file *pMain;
+ jt_file *pMain = 0;
for(pMain=g.pList; pMain; pMain=pMain->pNext){
int nName = strlen(zJournal) - strlen("-journal");
if( (pMain->flags&SQLITE_OPEN_MAIN_DB)
return pMain;
}
-
+/*
+** Parameter z points to a buffer of 4 bytes in size containing a
+** unsigned 32-bit integer stored in big-endian format. Decode the
+** integer and return its value.
+*/
static u32 decodeUint32(const unsigned char *z){
return (z[0]<<24) + (z[1]<<16) + (z[2]<<8) + z[3];
}
-static int calculateCksums(jt_file *pMain){
- int rc = SQLITE_OK;
- int ii, jj;
- unsigned char *aData = sqlite3_malloc(pMain->nPagesize);
- if( !aData ){
- return SQLITE_IOERR_NOMEM;
- }
-
- for(ii=0; rc==SQLITE_OK && ii<pMain->nPage; ii++){
- u32 cksum = 0;
- sqlite_int64 iOff = (sqlite3_int64)(pMain->nPagesize) * (sqlite3_int64)ii;
- rc = sqlite3OsRead(pMain->pReal, aData, pMain->nPagesize, iOff);
- for(jj=0; jj<pMain->nPagesize; jj++){
- cksum = cksum + aData[jj] + (cksum<<3);
- }
- pMain->aCksum[ii] = cksum;
- }
- sqlite3_free(aData);
-
- return rc;
-}
-
-static int readFreelist(jt_file *pMain){
- int rc;
- sqlite3_file *p = pMain->pReal;
- sqlite3_int64 iSize;
-
- rc = sqlite3OsFileSize(p, &iSize);
- if( rc==SQLITE_OK && iSize>=pMain->nPagesize ){
- unsigned char *zBuf = (unsigned char *)malloc(pMain->nPagesize);
- u32 iTrunk;
-
- rc = sqlite3OsRead(p, zBuf, pMain->nPagesize, 0);
- iTrunk = decodeUint32(&zBuf[32]);
- while( rc==SQLITE_OK && iTrunk>0 ){
- u32 nLeaf;
- u32 iLeaf;
- sqlite3_int64 iOff = (iTrunk-1)*pMain->nPagesize;
- rc = sqlite3OsRead(p, zBuf, pMain->nPagesize, iOff);
- nLeaf = decodeUint32(&zBuf[4]);
- for(iLeaf=0; rc==SQLITE_OK && iLeaf<nLeaf; iLeaf++){
- u32 pgno = decodeUint32(&zBuf[8+4*iLeaf]);
- sqlite3BitvecSet(pMain->pWritable, pgno);
- }
- iTrunk = decodeUint32(zBuf);
- }
-
- free(zBuf);
+/*
+** Calculate a checksum from the buffer of length n bytes pointed to
+** by parameter z.
+*/
+static u32 genCksum(const unsigned char *z, int n){
+ int i;
+ u32 cksum = 0;
+ for(i=0; i<n; i++){
+ cksum = cksum + z[i] + (cksum<<3);
}
-
- return rc;
+ return cksum;
}
/*
** serialized journal header. This function deserializes four of the
** integer fields contained in the journal header and writes their
** values to the output variables.
+**
+** SQLITE_OK is returned if the journal-header is successfully
+** decoded. Otherwise, SQLITE_ERROR.
*/
static int decodeJournalHdr(
const unsigned char *zBuf, /* Input: 28 byte journal header */
u32 *pnPagesize /* Out: Page size in bytes */
){
unsigned char aMagic[] = { 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7 };
- if( memcmp(aMagic, zBuf, 8) ) return 1;
+ if( memcmp(aMagic, zBuf, 8) ) return SQLITE_ERROR;
if( pnRec ) *pnRec = decodeUint32(&zBuf[8]);
if( pnPage ) *pnPage = decodeUint32(&zBuf[16]);
if( pnSector ) *pnSector = decodeUint32(&zBuf[20]);
if( pnPagesize ) *pnPagesize = decodeUint32(&zBuf[24]);
- return 0;
+ return SQLITE_OK;
+}
+
+/*
+** This function is called when a new transaction is opened, just after
+** the first journal-header is written to the journal file.
+*/
+static int openTransaction(jt_file *pMain, jt_file *pJournal){
+ unsigned char *aData;
+ sqlite3_file *p = pMain->pReal;
+ int rc = SQLITE_OK;
+
+ aData = sqlite3_malloc(pMain->nPagesize);
+ pMain->pWritable = sqlite3BitvecCreate(pMain->nPage);
+ pMain->aCksum = sqlite3_malloc(sizeof(u32) * (pMain->nPage + 1));
+ pJournal->iMaxOff = 0;
+
+ if( !pMain->pWritable || !pMain->aCksum || !aData ){
+ rc = SQLITE_IOERR_NOMEM;
+ }else if( pMain->nPage>0 ){
+ u32 iTrunk;
+
+ /* Read the database free-list. Add the page-number for each free-list
+ ** leaf to the jt_file.pWritable bitvec.
+ */
+ rc = sqlite3OsRead(p, aData, pMain->nPagesize, 0);
+ iTrunk = decodeUint32(&aData[32]);
+ while( rc==SQLITE_OK && iTrunk>0 ){
+ u32 nLeaf;
+ u32 iLeaf;
+ sqlite3_int64 iOff = (iTrunk-1)*pMain->nPagesize;
+ rc = sqlite3OsRead(p, aData, pMain->nPagesize, iOff);
+ nLeaf = decodeUint32(&aData[4]);
+ for(iLeaf=0; rc==SQLITE_OK && iLeaf<nLeaf; iLeaf++){
+ u32 pgno = decodeUint32(&aData[8+4*iLeaf]);
+ sqlite3BitvecSet(pMain->pWritable, pgno);
+ }
+ iTrunk = decodeUint32(aData);
+ }
+
+ /* Calculate and store a checksum for each page in the database file. */
+ if( rc==SQLITE_OK ){
+ int ii;
+ for(ii=0; rc==SQLITE_OK && ii<pMain->nPage; ii++){
+ i64 iOff = (i64)(pMain->nPagesize) * (i64)ii;
+ rc = sqlite3OsRead(pMain->pReal, aData, pMain->nPagesize, iOff);
+ pMain->aCksum[ii] = genCksum(aData, pMain->nPagesize);
+ }
+ }
+ }
+
+ sqlite3_free(aData);
+ return rc;
}
/*
/* Writing the first journal header to a journal file. This happens
** when a transaction is first started. */
int rc;
- pMain->pWritable = sqlite3BitvecCreate(pMain->nPage);
- pMain->aCksum = sqlite3_malloc(sizeof(u32) * (pMain->nPage + 1));
- p->iMaxOff = 0;
- if( !pMain->pWritable || !pMain->aCksum ){
- return SQLITE_IOERR_NOMEM;
- }
- rc = readFreelist(pMain);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = calculateCksums(pMain);
- if( rc!=SQLITE_OK ){
+ if( SQLITE_OK!=(rc=openTransaction(pMain, p)) ){
return rc;
}
}
}
}
- if( p->flags&SQLITE_OPEN_MAIN_DB && p->pWritable && iAmt==p->nPagesize ){
+ if( p->flags&SQLITE_OPEN_MAIN_DB && p->pWritable ){
u32 pgno = iOfst/p->nPagesize + 1;
+
+ assert( iAmt==p->nPagesize && (iOfst%p->nPagesize)==0 );
+ assert( pgno<=p->nPage || p->nSync>0 );
assert( pgno>p->nPage || sqlite3BitvecTest(p->pWritable, pgno) );
}
unsigned char zBuf[28];
sqlite3_file *pReal = p->pReal;
sqlite3_int64 iOff = 0;
- sqlite3_int64 iSize = 0;
+ sqlite3_int64 iSize = p->iMaxOff;
unsigned char *aPage;
aPage = sqlite3_malloc(pMain->nPagesize);
if( !aPage ){
return SQLITE_IOERR_NOMEM;
}
- /* rc = sqlite3OsFileSize(p->pReal, &iSize); */
- iSize = p->iMaxOff;
+
while( rc==SQLITE_OK && iOff<iSize ){
u32 nRec, nPage, nSector, nPagesize;
u32 ii;
+
+ /* Read and decode the next journal-header from the journal file. */
rc = sqlite3OsRead(pReal, zBuf, 28, iOff);
if( rc!=SQLITE_OK
|| decodeJournalHdr(zBuf, &nRec, &nPage, &nSector, &nPagesize)
goto finish_rjf;
}
iOff += nSector;
+
if( nRec==0 ){
/* A trick. There might be another journal-header immediately
** following this one. In this case, 0 records means 0 records,
if( iSize>=(iOff+nSector) ){
rc = sqlite3OsRead(pReal, zBuf, 28, iOff);
if( rc!=SQLITE_OK || 0==decodeJournalHdr(zBuf, 0, 0, 0, 0) ){
-assert(rc!=SQLITE_OK);
continue;
}
}
nRec = (iSize-iOff) / (pMain->nPagesize+8);
}
+
+ /* Read all the records that follow the journal-header just read. */
for(ii=0; rc==SQLITE_OK && ii<nRec && iOff<iSize; ii++){
u32 pgno;
rc = sqlite3OsRead(pReal, zBuf, 4, iOff);
if( 0==sqlite3BitvecTest(pMain->pWritable, pgno) ){
rc = sqlite3OsRead(pReal, aPage, pMain->nPagesize, iOff+4);
if( rc==SQLITE_OK ){
- int jj;
- u32 cksum = 0;
- for(jj=0; jj<pMain->nPagesize; jj++){
- cksum = cksum + aPage[jj] + (cksum<<3);
- }
+ u32 cksum = genCksum(aPage, pMain->nPagesize);
assert( cksum==pMain->aCksum[pgno-1] );
}
}
/* Set the bitvec values */
if( pMain->pWritable ){
+ pMain->nSync++;
rc = readJournalFile(p, pMain);
if( rc!=SQLITE_OK ){
return rc;
return sqlite3OsFullPathname(g.pVfs, zPath, nOut, zOut);
}
-#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Open the dynamic library located at zPath and return a handle.
*/
static void *jtDlOpen(sqlite3_vfs *pVfs, const char *zPath){
- return sqlite3OsDlOpen(g.pVfs, zPath);
+ return g.pVfs->xDlOpen(g.pVfs, zPath);
}
/*
** with dynamic libraries.
*/
static void jtDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
- sqlite3OsDlError(g.pVfs, nByte, zErrMsg);
+ g.pVfs->xDlError(g.pVfs, nByte, zErrMsg);
}
/*
** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
*/
static void (*jtDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){
- return sqlite3OsDlSym(g.pVfs, p, zSym);
+ return g.pVfs->xDlSym(g.pVfs, p, zSym);
}
/*
** Close the dynamic library handle pHandle.
*/
static void jtDlClose(sqlite3_vfs *pVfs, void *pHandle){
- sqlite3OsDlClose(g.pVfs, pHandle);
+ g.pVfs->xDlClose(g.pVfs, pHandle);
}
-#endif /* SQLITE_OMIT_LOAD_EXTENSION */
/*
** Populate the buffer pointed to by zBufOut with nByte bytes of
return sqlite3OsCurrentTime(g.pVfs, pTimeOut);
}
+/**************************************************************************
+** Start of public API.
+*/
+
+/*
+** Configure the jt VFS as a wrapper around the VFS named by parameter
+** zWrap. If the isDefault parameter is true, then the jt VFS is installed
+** as the new default VFS for SQLite connections. If isDefault is not
+** true, then the jt VFS is installed as non-default. In this case it
+** is available via its name, "jt".
+*/
int jt_register(char *zWrap, int isDefault){
g.pVfs = sqlite3_vfs_find(zWrap);
if( g.pVfs==0 ){
return SQLITE_ERROR;
}
- jt_vfs.szOsFile += g.pVfs->szOsFile;
+ jt_vfs.szOsFile = sizeof(jt_file) + g.pVfs->szOsFile;
sqlite3_vfs_register(&jt_vfs, isDefault);
return SQLITE_OK;
}
+/*
+** Uninstall the jt VFS, if it is installed.
+*/
void jt_unregister(){
sqlite3_vfs_unregister(&jt_vfs);
}
projects / thirdparty / sqlite.git / commitdiff
