--- /dev/null
+/*
+** 2010 September 31
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains a VFS "shim" - a layer that sits in between the
+** pager and the real VFS.
+**
+** This particular shim enforces a quota system on files. One or more
+** database files are in a "quota group" that is defined by a GLOB
+** pattern. A quota is set for the combined size of all files in the
+** the group. A quota of zero means "no limit". If the total size
+** of all files in the quota group is met or exceeded, then new
+** write requests that attempt to enlarge a file fail with SQLITE_FULL.
+**
+** However, before returning SQLITE_FULL, the write requests invoke
+** a callback function that is configurable for each quota group.
+** This callback has the opportunity to enlarge the quota. If the
+** callback does enlarge the quota such that the total size of all
+** files within the group is less than the new quota, then the write
+** continues as if nothing had happened.
+*/
+#include "sqlite3.h"
+
+/************************ Object Definitions ******************************/
+
+/*
+** This module contains a table of filename patterns that have size
+** quotas. The quota applies to the sum of the sizes of all open
+** database files whose names match the GLOB pattern.
+**
+** Each quota is an instance of the following object. Quotas must
+** be established (using sqlite3_quota_set()) prior to opening any
+** of the database connections that access files governed by the
+** quota.
+**
+** Each entry in the quota table is an instance of the following object.
+*/
+typedef struct quotaGroup quotaGroup;
+struct quotaGroup {
+ const char *zPattern; /* Filename pattern to be quotaed */
+ sqlite3_int64 iLimit; /* Upper bound on total file size */
+ sqlite3_int64 iSize; /* Current size of all files */
+ void (*xCallback)( /* Callback invoked when going over quota */
+ const char *zFilename, /* Name of file whose size increases */
+ sqlite3_int64 *piLimit, /* IN/OUT: The current limit */
+ sqlite3_int64 iSize, /* Total size of all files in the group */
+ void *pArg /* Client data */
+ );
+ void *pArg; /* Third argument to the xCallback() */
+ int nRef; /* Number of files in the group references. */
+ quotaGroup *pNext, **ppPrev; /* Doubly linked list of all quota objects */
+};
+
+/*
+** An instance of the following object represents each file that
+** participates in quota tracking. The sqlite3_file object for the
+** underlying VFS is appended to this structure.
+*/
+typedef struct quotaFile quotaFile;
+struct quotaFile {
+ sqlite3_file base; /* Base class - must be first */
+ const char *zFilename; /* Name of this file */
+ quotaGroup *pGroup; /* Upper bound on file size */
+ /* The underlying VFS sqlite3_file is appended to this object */
+};
+
+/************************* Global Variables **********************************/
+/*
+** All global variables used by this file are containing within the following
+** gQuota structure.
+*/
+static struct {
+ /* The pOrigVfs is a pointer to the real underlying VFS implementation.
+ ** Most operations pass-through to the real VFS. This value is read-only
+ ** during operation. It is only modified at start-time and thus does not
+ ** require a mutex.
+ */
+ sqlite3_vfs *pOrigVfs;
+
+ /* The sThisVfs is the VFS structure used by this shim. It is initialized
+ ** at start-time and thus does not require a mutex
+ */
+ sqlite3_vfs sThisVfs;
+
+ /* The sIoMethods defines the methods used by sqlite3_file objects
+ ** associated with this shim. It is initialized at start-time and does
+ ** not require a mutex.
+ **
+ ** When the underlying VFS is called to open a file, it might return
+ ** either a version 1 or a version 2 sqlite3_file object. This shim
+ ** has to create a wrapper sqlite3_file of the same version. Hence
+ ** there are two I/O method structures, one for version 1 and the other
+ ** for version 2.
+ */
+ sqlite3_io_methods sIoMethodsV1;
+ sqlite3_io_methods sIoMethodsV2;
+
+ /* True when this shim as been initialized.
+ */
+ int isInitialized;
+
+ /* For run-time access any of the other global data structures in this
+ ** shim, the following mutex must be held.
+ */
+ sqlite3_mutex *pMutex;
+
+ /* List of quotaGroup objects.
+ */
+ quotaGroup *pGroup;
+
+} gQuota;
+
+/************************* Utility Routines *********************************/
+/*
+** Acquire and release the mutex used to serialize access to the
+** list of quotaGroups.
+*/
+static void quotaEnter(void){ sqlite3_mutex_enter(gQuota.pMutex); }
+static void quotaLeave(void){ sqlite3_mutex_leave(gQuota.pMutex); }
+
+
+/* If the reference count and threshold for a quotaGroup are both
+** zero, then destroy the quotaGroup.
+*/
+static void quotaGroupDeref(quotaFile *p){
+ if( p->nRef==0 && p->iLimit==0 ){
+ if( p->pNext ) p->pNext->ppPrev = p->ppPrev;
+ if( p->ppPrev ) *p->ppPrev = p->pNext;
+ sqlite3_free(p);
+ }
+}
+
+/*
+** Return TRUE if string z matches glob pattern zGlob.
+**
+** Globbing rules:
+**
+** '*' Matches any sequence of zero or more characters.
+**
+** '?' Matches exactly one character.
+**
+** [...] Matches one character from the enclosed list of
+** characters.
+**
+** [^...] Matches one character not in the enclosed list.
+**
+*/
+static int strglob(const char *zGlob, const char *z){
+ int c, c2;
+ int invert;
+ int seen;
+
+ while( (c = (*(zGlob++)))!=0 ){
+ if( c=='*' ){
+ while( (c=(*(zGlob++))) == '*' || c=='?' ){
+ if( c=='?' && (*(z++))==0 ) return 0;
+ }
+ if( c==0 ){
+ return 1;
+ }else if( c=='[' ){
+ while( *z && th3strglob(zGlob-1,z)==0 ){
+ z++;
+ }
+ return (*z)!=0;
+ }
+ while( (c2 = (*(z++)))!=0 ){
+ while( c2!=c ){
+ c2 = *(z++);
+ if( c2==0 ) return 0;
+ }
+ if( th3strglob(zGlob,z) ) return 1;
+ }
+ return 0;
+ }else if( c=='?' ){
+ if( (*(z++))==0 ) return 0;
+ }else if( c=='[' ){
+ int prior_c = 0;
+ seen = 0;
+ invert = 0;
+ c = *(z++);
+ if( c==0 ) return 0;
+ c2 = *(zGlob++);
+ if( c2=='^' ){
+ invert = 1;
+ c2 = *(zGlob++);
+ }
+ if( c2==']' ){
+ if( c==']' ) seen = 1;
+ c2 = *(zGlob++);
+ }
+ while( c2 && c2!=']' ){
+ if( c2=='-' && zGlob[0]!=']' && zGlob[0]!=0 && prior_c>0 ){
+ c2 = *(zGlob++);
+ if( c>=prior_c && c<=c2 ) seen = 1;
+ prior_c = 0;
+ }else{
+ if( c==c2 ){
+ seen = 1;
+ }
+ prior_c = c2;
+ }
+ c2 = *(zGlob++);
+ }
+ if( c2==0 || (seen ^ invert)==0 ) return 0;
+ }else{
+ if( c!=(*(z++)) ) return 0;
+ }
+ }
+ return *z==0;
+}
+
+
+/* Find a quotaGroup given the filename.
+** Return a pointer to the quotaFile object. return NULL if not found.
+*/
+static quotaGroup *quotaGroupFind(const char *zFilename){
+ quotaGroup *p;
+ for(p=pGroup; p && strglob(p->zPattern, zFilename)==0; p=p->pNext){}
+ return p;
+}
+
+/* Translate an sqlite3_file* that is really a quotaFile* into
+** an sqlite3_file* for the underlying original VFS.
+*/
+static sqlite3_file *quotaSubFile(sqlite3_file *pFile){
+ quotaFile *p = (quotaFile*)pFile;
+ return (sqlite3_file*)&p[1];
+}
+
+/************************* VFS Method Wrappers *****************************/
+/*
+** This is the xOpen method used for the "quota" VFS.
+**
+** Most of the work is done by the underlying original VFS. This method
+** simply links the new file into the quota group if it is a file that
+** needs to be tracked.
+*/
+static int quotaOpen(
+ sqlite3_vfs *pVfs,
+ const char *zName,
+ sqlite3_file *pFile,
+ int flags,
+ int *pOutFlags
+){
+ int rc;
+ quotaFile *pQuotaFile;
+ sqlite3_file *pSubFile;
+
+ /* If the file is not a main database file or a WAL, then use the
+ ** normal xOpen method.
+ */
+ if( (flags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_MAIN_WAL))==0 ){
+ return gQuota.pOrigVfs->xOpen(gQuota.pOrigVfs, zName,
+ pFile, flags, pOutFlags);
+ }
+
+ /* If the name of the file does not match any quota group, then
+ ** use the normal xOpen method.
+ */
+ quotaEnter();
+ pGroup = quotaFindGroup(zName);
+ if( pGroup==0 ){
+ return gQuota.pOrigVfs->xOpen(gQuota.pOrigVfs, zName,
+ pFile, flags, pOutFlags);
+ }
+
+ /* If we get to this point, it means the file needs
+ ** to be quota tracked.
+ */
+ pQuotaFile = (quotaFile*)pFile;
+ pSubFile = quotaSubFile(pFile);
+ rc = gQuota.pOrigVfs->xOpen(gQuota.pOrigVfs, zName,
+ pSubFile, flags, pOutFlags);
+ if( rc==SQLITE_OK ){
+ pQuotaFile->iSize = 0;
+ pQuotaFile->pGroup = pGroup;
+ pGroup->nRef++;
+ quotaLeave();
+ pQuotaFile->zFilename = zName;
+ if( pSubFile->pMethods.iVersion==1 ){
+ pQuotaFile->base.pMethods = &gQuota.sIoMethodsV1;
+ }else{
+ pQuotaFile->base.pMethods = &gQuota.sIoMethodsV2;
+ }
+ }
+ return rc;
+}
+
+/************************ I/O Method Wrappers *******************************/
+
+/* xClose requests get passed through to the original VFS. But we
+** also have to unlink the quotaFile from the quotaGroup.
+*/
+static int quotaClose(sqlite3_file *pFile){
+ quotaFile *p = (quotaFile*)pFile;
+ quotaGroup *pGroup = p->pGroup;
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ int rc;
+ rc = pSubFile->pMethods.xClose(pSubFile);
+ quotaEnter();
+ pGroup->nRef--;
+ pGroup->iSize -= p->iSize;
+ quotaGroupDeref(pGroup);
+ quotaLeave();
+ return rc;
+}
+
+/* Pass xRead requests directory thru to the original VFS without
+** further processing.
+*/
+static int quotaRead(
+ sqlite3_file *pFile,
+ void *pBuf,
+ int iAmt,
+ sqlite3_int64 iOfst
+){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xRead(pSubFile, pBuf, iAmt, iOfst);
+}
+
+/* Check xWrite requests to see if they expand the file. If they do,
+** the perform a quota check before passing them through to the
+** original VFS.
+*/
+static int quotaWrite(
+ sqlite3_file *pFile,
+ void *pBuf,
+ int iAmt,
+ sqlite3_int64 iOfst
+){
+ quotaFile *p = (quotaFile*)pFile;
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ sqlite3_int64 iEnd = iOfst+iAmt;
+ quotaGroup *pGroup;
+ sqlite3_int64 szNew;
+
+ if( p->iSize<iEnd ){
+ pGroup = p->pGroup;
+ quotaEnter();
+ szNew = pGroup->iSize - p->iSize + iEnd;
+ if( szNew >= pGroup->iLimit && pGroup->iLimit > 0 ){
+ if( pGroup->xCallback ){
+ pGroup->xCallback(p->zFilename, &pGroup->iLimit, szNew,
+ pGroup->pArg);
+ }
+ if( szNew >= pGroup->iLimit && pGroup->iLimit > 0 ){
+ quotaLeave();
+ return SQLITE_FULL;
+ }
+ }
+ pGroup->iSize = szNew;
+ quotaLeave();
+ }
+ return pSubFile->pMethods.xWrite(pSubFile, pBuf, iAmt, iOfst);
+}
+
+/* Pass xTruncate requests thru to the original VFS. If the
+** success, update the file size.
+*/
+static int quotaTruncate(sqlite3_file *pFile, sqlite3_int64 size){
+ quotaFile *p = (quotaFile*)pFile);
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ int rc = pSubFile->pMethods.xTruncate(pSubFile, size);
+ quotaGroup *pGroup = p->pGroup;
+ if( rc==SQLITE_OK ){
+ quotaEnter();
+ pGroup->iSize -= p->iSize;
+ p->iSize = size;
+ pGroup->iSize += size;
+ quotaLeave();
+ }
+ return rc;
+}
+
+/* Pass xSync requests through to the original VFS without change
+*/
+static int quotaSync(sqlite3_file *pFile, int flags){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xSync(pSubFile, flags);
+}
+
+/* Pass xFileSize requests through to the original VFS but then
+** update the quotaGroup with the new size before returning.
+*/
+static int quotaFileSize(sqlite3_file *pFile, sqlite3_int64 *pSize){
+ quotaFile *p = (quotaFile*)pFile;
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ quotaGroup *pGroup;
+ sqlite3_int64 sz;
+ int rc;
+
+ rc = pSubFile->pMethods.xFileSize(pSubFile, &sz);
+ if( rc==SQLITE_OK ){
+ pGroup = p->pGroup;
+ quotaEnter();
+ pGroup->iSize -= p->iSize;
+ p->iSize = sz;
+ pGroup->iSize += sz;
+ quotaLeave();
+ *pSize = sz;
+ }
+ return rc;
+}
+
+/* Pass xLock requests through to the original VFS unchanged.
+*/
+static int quotaLock(sqlite3_file *pFile, int lock){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xLock(pSubFile, lock);
+}
+
+/* Pass xUnlock requests through to the original VFS unchanged.
+*/
+static int quotaUnlock(sqlite3_file *pFile, int lock){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xUnlock(pSubFile, lock);
+}
+
+/* Pass xCheckReservedLock requests through to the original VFS unchanged.
+*/
+static int quotaCheckReservedLock(sqlite3_file *pFile, int *pResOut){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xCheckReservedLock(pSubFile, pResOut);
+}
+
+/* Pass xFileControl requests through to the original VFS unchanged.
+*/
+static int quotaFileControl(sqlite3_file *pFile, int op, void *pArg){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xFileControl(pSubFile, op, pArg);
+}
+
+/* Pass xSectorSize requests through to the original VFS unchanged.
+*/
+static int quotaSectorSize(sqlite3_file *pFile){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xSectorSize(pSubFile);
+}
+
+/* Pass xDeviceCharacteristics requests through to the original VFS unchanged.
+*/
+static int quotaDeviceCharacteristics(sqlite3_file *pFile){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xDeviceCharacteristics(pSubFile);
+}
+
+/* Pass xShmMap requests through to the original VFS unchanged.
+*/
+static int quotaShmMap(
+ sqlite3_file *pFile, /* Handle open on database file */
+ int iRegion, /* Region to retrieve */
+ int szRegion, /* Size of regions */
+ int bExtend, /* True to extend file if necessary */
+ void volatile **pp /* OUT: Mapped memory */
+){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xShmMap(pSubFile, iRegion, szRegion, bExtend, pp);
+}
+
+/* Pass xShmLock requests through to the original VFS unchanged.
+*/
+static int quotaShmLock(
+ sqlite3_file *pFile, /* Database file holding the shared memory */
+ int ofst, /* First lock to acquire or release */
+ int n, /* Number of locks to acquire or release */
+ int flags /* What to do with the lock */
+){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xShmLock(pSubFile, ofst, n, flags);
+}
+
+/* Pass xShmBarrier requests through to the original VFS unchanged.
+*/
+static int quotaShmBarrier(sqlite3_file *pFile){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xShmBarrier(pSubFile);
+}
+
+/* Pass xShmUnmap requests through to the original VFS unchanged.
+*/
+static int quotaShmUnmap(sqlite3_file *pFile, int deleteFlag){
+ sqlite3_file *pSubFile = quotaSubFile(pFile);
+ return pSubFile->pMethods.xShmUnmap(pSubFile, deleteFlag);
+}
+
+/************************** Public Interfaces *****************************/
+/*
+** Initialize the quota VFS shim. Use the VFS named zOrigVfsName
+** as the VFS that does the actual work. Use the default if
+** zOrigVfsName==NULL.
+**
+** The quota VFS shim is named "quota". It will become the default
+** VFS if makeDefault is non-zero.
+**
+** THIS ROUTINE IS NOT THREADSAFE. Call this routine exactly once
+** during start-up.
+*/
+int sqlite3_quota_initialize(const char *zOrigVfsName, int makeDefault){
+ sqlite3_vfs *pOrigVfs;
+ if( gQuota.isInitialize ) return SQLITE_MISUSE;
+ gQuota.isInitialized = 1;
+ pOrigVfs = sqlite3_vfs_find(zOrigVfsName);
+ if( pOrigVfs==0 ) return SQLITE_ERROR;
+ gQuota.pOrigVfs = pOrigVfs;
+ gQuota.sThisVfs = *pOrigVfs;
+ gQuota.sThisVfs.xOpen = quotaOpen;
+ gQuota.sThisVfs.szOsFile += sizeof(quotaFile);
+ gQuota.sThisVfs.zName = "quota";
+ gQuota.sIoMethodsV1.iVersion = 1;
+ gQuota.sIoMethodsV1.xClose = quotaClose;
+ gQuota.sIoMethodsV1.xRead = quotaRead;
+ gQuota.sIoMethodsV1.xWrite = quotaWrite;
+ gQuota.sIoMethodsV1.xTruncate = quotaTruncate;
+ gQuota.sIoMethodsV1.xSync = quotaSync;
+ gQuota.sIoMethodsV1.xFileSize = quotaFileSize;
+ gQuota.sIoMethodsV1.xLock = quotaLock;
+ gQuota.sIoMethodsV1.xUnlock = quotaUnlock;
+ gQuota.sIoMethodsV1.xCheckReservedLock = quotaCheckReservedLock;
+ gQuota.sIoMethodsV1.xFileControl = quotaFileControl;
+ gQuota.sIoMethodsV1.xSectorSize = quotaSectoSize;
+ gQuota.sIoMethodsV1.xDeviceCharacteristics = quotaDeviceCharacteristics;
+ gQuota.sIoMethodsV2 = gQuota.sIoMethodsV1;
+ gQuota.sIoMethodsV2.iVersion = 2;
+ gQuota.sIoMethodsV2.xShmMap = quotaShmMap;
+ gQuota.sIoMethodsV2.xShmLock = quotaShmLock;
+ gQuota.sIoMethodsV2.xShmBarrier = quotaShmBarrier;
+ gQuota.sIoMethodsV2.xShmUnmap = quotaShmUnmap;
+ gQuota.pMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+}
+
+/*
+** Shutdown the quota system.
+**
+** All SQLite database connections must be closed before calling this
+** routine.
+**
+** THIS ROUTINE IS NOT THREADSAFE. Call this routine exactly one while
+** shutting down in order to free all remaining quota groups.
+*/
+int sqlite3_quota_shutdown(void){
+ if( gQuota.isInitialized==0 ) return SQLITE_MISUSE;
+ gQuota.isInitialized = 0;
+ sqlite3_mutex_free(gQuota.pMutex);
+ while( gQuota.pGroup ){
+ quotaGroup *p = gQuota.pGroup;
+ gQuota.pGroup = p->pNext;
+ if( p->nRef ) return SQLITE_MISUSE;
+ sqlite3_free(p);
+ }
+ memset(&gQuota, 0, sizeof(gQuota));
+}
+
+/*
+** Create or destroy a quota group.
+**
+** The quota group is defined by the zPattern. When calling this routine
+** with a zPattern for a quota group that already exists, this routine
+** merely updates the iLimit, xCallback, and pArg values for that quota
+** group. If zPattern is new, then a new quota group is created.
+**
+** If the iLimit for a quota group is set to zero, then the quota group
+** is disabled and will be deleted when the last database connection using
+** the quota group is closed.
+**
+** Calling this routine on a zPattern that does not exist and with a
+** zero iLimit is a no-op.
+**
+** A quota group must exist with a non-zero iLimit prior to opening
+** database connections if those connections are to participate in the
+** quota group. Creating a quota group does not effect database connections
+** that are already open.
+*/
+int sqlite3_quota_set(
+ const char *zPattern, /* The filename pattern */
+ sqlite3_int64 iLimit, /* New quota to set for this quota group */
+ void (*xCallback)( /* Callback invoked when going over quota */
+ const char *zFilename, /* Name of file whose size increases */
+ sqlite3_int64 *piLimit, /* IN/OUT: The current limit */
+ sqlite3_int64 iSize, /* Total size of all files in the group */
+ void *pArg /* Client data */
+ );
+ void *pArg /* client data passed thru to callback */
+){
+ quotaGroup *pGroup;
+ quotaEnter();
+ pGroup = gQuota.pGroup;
+ while( pGroup && strcmp(pGroup->zPattern, zPattern)!=0 ){
+ pGroup = pGroup->pNext;
+ }
+ if( pGroup==0 && iLimit>0 ){
+ int nPattern = strlen(zPattern);
+ pGroup = sqlite3_malloc( sizeof(*pGroup) + nPattern + 1 );
+ if( pGroup==0 ){
+ quotaLeave();
+ return SQLITE_NOMEM;
+ }
+ memset(pGroup, 0, sizeof(*pGroup));
+ pGroup->zPattern = (char*)&pGroup[1];
+ memcpy(pGroup->zPattern, zPattern, nPattern+1);
+ pGroup->pNext = gQuota.pGroup;
+ if( gQuota.pGroup ) gQuota.pGroup->ppPrev = &pGroup->pNext;
+ pGroup->ppPrev = &gQuota.pNext;
+ }
+ pGroup->iLimit = iLimit;
+ pGroup->xCallback = xCallback;
+ pGroup->pArg = pArg;
+ quotaGroupDeref(pGroup);
+ quotaLeave();
+ return SQLITE_OK;
+}
+
+
+/***************************** Test Code ***********************************/
+#ifdef SQLITE_TEST
+#include <tcl.h>
+/*
+** This routine registers the custom TCL commands defined in this
+** module. This should be the only procedure visible from outside
+** of this module.
+*/
+int Sqlitequota_Init(Tcl_Interp *interp){
+#ifdef SQLITE_ENABLE_ASYNCIO
+#endif /* SQLITE_ENABLE_ASYNCIO */
+ return TCL_OK;
+}
+#endif
projects / thirdparty / sqlite.git / commitdiff
