/*
** 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