#include <string.h>
#include <assert.h>

/************************ Object Definitions ******************************/

/* Forward declaration of all object types */
typedef struct quotaGroup quotaGroup;
typedef struct quotaOpen quotaOpen;
typedef struct quotaFile quotaFile;

/*
** A "quota group" is a collection of files whose collective size we want
** to limit.  Each quota group is defined by a GLOB pattern.
**
** There is an instance of the following object for each defined quota
................................................................................
  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() */

  quotaGroup *pNext, **ppPrev;   /* Doubly linked list of all quota objects */
  quotaFile *pFile;              /* Files within this group */
};

/*
** An instance of this structure represents a single file that is part
** of a quota group.  A single file can be opened multiple times.  In
................................................................................

/*
** An instance of the following object represents each open connection
** to a file that participates in quota tracking.  This object is a 
** subclass of sqlite3_file.  The sqlite3_file object for the underlying
** VFS is appended to this structure.
*/
struct quotaOpen {
  sqlite3_file base;              /* Base class - must be first */
  quotaFile *pFile;               /* The underlying file */
  /* The underlying VFS sqlite3_file is appended to this object */
};

/************************* Global Variables **********************************/
/*
................................................................................
/* If the reference count and threshold for a quotaGroup are both
** zero, then destroy the quotaGroup.
*/
static void quotaGroupDeref(quotaGroup *p){
  if( p->pFile==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.
**
................................................................................
  }
  return *z==0;
}


/* Find a quotaGroup given the filename.
**
** Return a pointer to the quotaOpen object. Return NULL if not found.
*/
static quotaGroup *quotaGroupFind(const char *zFilename){
  quotaGroup *p;
  for(p=gQuota.pGroup; p && strglob(p->zPattern, zFilename)==0; p=p->pNext){}
  return p;
}

/* Translate an sqlite3_file* that is really a quotaOpen* into
** the sqlite3_file* for the underlying original VFS.
*/
static sqlite3_file *quotaSubOpen(sqlite3_file *pOpen){
  quotaOpen *p = (quotaOpen*)pOpen;
  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 appropriate quota group if it is a
** file that needs to be tracked.
*/
static int quotaxOpen(
  sqlite3_vfs *pVfs,          /* The quota VFS */
  const char *zName,          /* Name of file to be opened */
  sqlite3_file *pOpen,        /* Fill in this file descriptor */
  int flags,                  /* Flags to control the opening */
  int *pOutFlags              /* Flags showing results of opening */
){
  int rc;                                    /* Result code */         
  quotaOpen *pQuotaOpen;                     /* The new quota file descriptor */
  quotaFile *pFile;                          /* Corresponding quotaFile obj */
  quotaGroup *pGroup;                        /* The group file belongs to */
  sqlite3_file *pSubOpen;                    /* Real file descriptor */
  sqlite3_vfs *pOrigVfs = gQuota.pOrigVfs;   /* Real VFS */

  /* 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_WAL))==0 ){
    return pOrigVfs->xOpen(pOrigVfs, zName, pOpen, flags, pOutFlags);
  }

  /* If the name of the file does not match any quota group, then
  ** use the normal xOpen method.
  */
  quotaEnter();
  pGroup = quotaGroupFind(zName);
  if( pGroup==0 ){
    rc = pOrigVfs->xOpen(pOrigVfs, zName, pOpen, flags, pOutFlags);
  }else{
    /* If we get to this point, it means the file needs to be quota tracked.
    */
    pQuotaOpen = (quotaOpen*)pOpen;
    pSubOpen = quotaSubOpen(pOpen);
    rc = pOrigVfs->xOpen(pOrigVfs, zName, pSubOpen, flags, pOutFlags);
    if( rc==SQLITE_OK ){
      for(pFile=pGroup->pFile; pFile && strcmp(pFile->zFilename, zName);
          pFile=pFile->pNext){}
      if( pFile==0 ){
        int nName = strlen(zName);
        pFile = sqlite3_malloc( sizeof(*pFile) + nName + 1 );
................................................................................
  quotaLeave();
  return rc;
}

/************************ I/O Method Wrappers *******************************/

/* xClose requests get passed through to the original VFS.  But we
** also have to unlink the quotaOpen from the quotaGroup.

*/
static int quotaClose(sqlite3_file *pOpen){
  quotaOpen *p = (quotaOpen*)pOpen;
  quotaFile *pFile = p->pFile;
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  int rc;
  rc = pSubOpen->pMethods->xClose(pSubOpen);
  quotaEnter();
  pFile->nRef--;
  if( pFile->nRef==0 ){
    quotaGroup *pGroup = pFile->pGroup;
    pGroup->iSize -= pFile->iSize;
................................................................................
  return rc;
}

/* Pass xRead requests directory thru to the original VFS without
** further processing.
*/
static int quotaRead(
  sqlite3_file *pOpen,
  void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xRead(pSubOpen, 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 *pOpen,
  const void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){
  quotaOpen *p = (quotaOpen*)pOpen;
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  sqlite3_int64 iEnd = iOfst+iAmt;
  quotaGroup *pGroup;
  quotaFile *pFile = p->pFile;
  sqlite3_int64 szNew;

  if( pFile->iSize<iEnd ){
    pGroup = pFile->pGroup;
................................................................................
  }
  return pSubOpen->pMethods->xWrite(pSubOpen, pBuf, iAmt, iOfst);
}

/* Pass xTruncate requests thru to the original VFS.  If the
** success, update the file size.
*/
static int quotaTruncate(sqlite3_file *pOpen, sqlite3_int64 size){
  quotaOpen *p = (quotaOpen*)pOpen;
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  int rc = pSubOpen->pMethods->xTruncate(pSubOpen, size);
  quotaFile *pFile = p->pFile;
  quotaGroup *pGroup;
  if( rc==SQLITE_OK ){
    quotaEnter();
    pGroup = pFile->pGroup;
    pGroup->iSize -= pFile->iSize;
................................................................................
    quotaLeave();
  }
  return rc;
}

/* Pass xSync requests through to the original VFS without change
*/
static int quotaSync(sqlite3_file *pOpen, int flags){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xSync(pSubOpen, 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 *pOpen, sqlite3_int64 *pSize){
  quotaOpen *p = (quotaOpen*)pOpen;
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  quotaFile *pFile = p->pFile;
  quotaGroup *pGroup;
  sqlite3_int64 sz;
  int rc;

  rc = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
  if( rc==SQLITE_OK ){
................................................................................
    *pSize = sz;
  }
  return rc;
}

/* Pass xLock requests through to the original VFS unchanged.
*/
static int quotaLock(sqlite3_file *pOpen, int lock){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xLock(pSubOpen, lock);
}

/* Pass xUnlock requests through to the original VFS unchanged.
*/
static int quotaUnlock(sqlite3_file *pOpen, int lock){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xUnlock(pSubOpen, lock);
}

/* Pass xCheckReservedLock requests through to the original VFS unchanged.
*/
static int quotaCheckReservedLock(sqlite3_file *pOpen, int *pResOut){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xCheckReservedLock(pSubOpen, pResOut);
}

/* Pass xFileControl requests through to the original VFS unchanged.
*/
static int quotaOpenControl(sqlite3_file *pOpen, int op, void *pArg){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xFileControl(pSubOpen, op, pArg);
}

/* Pass xSectorSize requests through to the original VFS unchanged.
*/
static int quotaSectorSize(sqlite3_file *pOpen){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xSectorSize(pSubOpen);
}

/* Pass xDeviceCharacteristics requests through to the original VFS unchanged.
*/
static int quotaDeviceCharacteristics(sqlite3_file *pOpen){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xDeviceCharacteristics(pSubOpen);
}

/* Pass xShmMap requests through to the original VFS unchanged.
*/
static int quotaShmMap(
  sqlite3_file *pOpen,            /* 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 *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xShmMap(pSubOpen, iRegion, szRegion, bExtend, pp);
}

/* Pass xShmLock requests through to the original VFS unchanged.
*/
static int quotaShmLock(
  sqlite3_file *pOpen,       /* 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 *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xShmLock(pSubOpen, ofst, n, flags);
}

/* Pass xShmBarrier requests through to the original VFS unchanged.
*/
static void quotaShmBarrier(sqlite3_file *pOpen){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  pSubOpen->pMethods->xShmBarrier(pSubOpen);
}

/* Pass xShmUnmap requests through to the original VFS unchanged.
*/
static int quotaShmUnmap(sqlite3_file *pOpen, int deleteFlag){
  sqlite3_file *pSubOpen = quotaSubOpen(pOpen);
  return pSubOpen->pMethods->xShmUnmap(pSubOpen, 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
................................................................................
  gQuota.pMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
  if( !gQuota.pMutex ){
    return SQLITE_NOMEM;
  }
  gQuota.isInitialized = 1;
  gQuota.pOrigVfs = pOrigVfs;
  gQuota.sThisVfs = *pOrigVfs;
  gQuota.sThisVfs.xOpen = quotaxOpen;
  gQuota.sThisVfs.szOsFile += sizeof(quotaOpen);
  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 = quotaOpenControl;
  gQuota.sIoMethodsV1.xSectorSize = quotaSectorSize;
  gQuota.sIoMethodsV1.xDeviceCharacteristics = quotaDeviceCharacteristics;
  gQuota.sIoMethodsV2 = gQuota.sIoMethodsV1;
  gQuota.sIoMethodsV2.iVersion = 2;
  gQuota.sIoMethodsV2.xShmMap = quotaShmMap;
  gQuota.sIoMethodsV2.xShmLock = quotaShmLock;
  gQuota.sIoMethodsV2.xShmBarrier = quotaShmBarrier;
................................................................................
  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( gQuota.pGroup ) gQuota.pGroup->ppPrev = &pGroup->pNext;
    pGroup->pNext = gQuota.pGroup;
    pGroup->ppPrev = &gQuota.pGroup;
    gQuota.pGroup = pGroup;
  }
  pGroup->iLimit = iLimit;
  pGroup->xCallback = xCallback;



  pGroup->pArg = pArg;

  quotaGroupDeref(pGroup);
  quotaLeave();
  return SQLITE_OK;
}

  
/***************************** Test Code ***********************************/
#ifdef SQLITE_TEST
#include <tcl.h>




typedef struct TclQuotaCallback TclQuotaCallback;
struct TclQuotaCallback {
  Tcl_Interp *interp;
  Tcl_Obj *pScript;
  TclQuotaCallback *pNext;
};
static TclQuotaCallback *pQuotaCallbackList = 0;

extern const char *sqlite3TestErrorName(int);





static void tclQuotaCallback(
  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 */
){
  TclQuotaCallback *p;            /* Callback script object */
................................................................................
    Tcl_UnsetVar(p->interp, Tcl_GetString(pVarname), 0);
  }

  Tcl_DecrRefCount(pEval);
  Tcl_DecrRefCount(pVarname);
  if( rc!=TCL_OK ) Tcl_BackgroundError(p->interp);
}












/*
** tclcmd: sqlite3_quota_initialize NAME MAKEDEFAULT
*/
static int test_quota_initialize(
  void * clientData,
  Tcl_Interp *interp,
................................................................................
    return TCL_ERROR;
  }

  /* Call sqlite3_quota_shutdown() */
  rc = sqlite3_quota_shutdown();
  Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);

  /* If the quota system was successfully shut down, delete all the quota
  ** callback script objects in the global linked list.
  */
  if( rc==SQLITE_OK ){
    TclQuotaCallback *p, *pNext;
    for(p=pQuotaCallbackList; p; p=pNext){
      pNext = p->pNext;
      Tcl_DecrRefCount(p->pScript);
      ckfree((char *)p);
    }
    pQuotaCallbackList = 0;
  }

  return TCL_OK;
}

/*
** tclcmd: sqlite3_quota_set PATTERN LIMIT SCRIPT
*/
static int test_quota_set(
................................................................................
  Tcl_Obj *CONST objv[]
){
  const char *zPattern;           /* File pattern to configure */
  sqlite3_int64 iLimit;           /* Initial quota in bytes */
  Tcl_Obj *pScript;               /* Tcl script to invoke to increase quota */
  int rc;                         /* Value returned by quota_set() */
  TclQuotaCallback *p;            /* Callback object */


  /* Process arguments */
  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "PATTERN LIMIT SCRIPT");
    return TCL_ERROR;
  }
  zPattern = Tcl_GetString(objv[1]);
  if( Tcl_GetWideIntFromObj(interp, objv[2], &iLimit) ) return TCL_ERROR;
  pScript = objv[3];



  /* Allocate a TclQuotaCallback object */
  p = (TclQuotaCallback *)ckalloc(sizeof(TclQuotaCallback));
  memset(p, 0, sizeof(TclQuotaCallback));






  /* Invoke sqlite3_quota_set() */
  rc = sqlite3_quota_set(zPattern, iLimit, tclQuotaCallback, (void *)p);
  if( rc!=SQLITE_OK ){
    ckfree((char *)p);
  }else{
    Tcl_IncrRefCount(pScript);
    p->interp = interp;
    p->pScript = pScript;
    p->pNext = pQuotaCallbackList;
    pQuotaCallbackList = p;
  }

  Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
  return TCL_OK;
}











































/*
** 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){
................................................................................
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
  } aCmd[] = {
    { "sqlite3_quota_initialize", test_quota_initialize },
    { "sqlite3_quota_shutdown", test_quota_shutdown },
    { "sqlite3_quota_set", test_quota_set },

  };
  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){
    Tcl_CreateObjCommand(interp, aCmd[i].zName, aCmd[i].xProc, 0, 0);
  }

  return TCL_OK;
}
#endif

#include <string.h>
#include <assert.h>

/************************ Object Definitions ******************************/

/* Forward declaration of all object types */
typedef struct quotaGroup quotaGroup;
typedef struct quotaConn quotaConn;
typedef struct quotaFile quotaFile;

/*
** A "quota group" is a collection of files whose collective size we want
** to limit.  Each quota group is defined by a GLOB pattern.
**
** There is an instance of the following object for each defined quota
................................................................................
  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() */
  void (*xDestroy)(void*);       /* Optional destructor for pArg */
  quotaGroup *pNext, **ppPrev;   /* Doubly linked list of all quota objects */
  quotaFile *pFile;              /* Files within this group */
};

/*
** An instance of this structure represents a single file that is part
** of a quota group.  A single file can be opened multiple times.  In
................................................................................

/*
** An instance of the following object represents each open connection
** to a file that participates in quota tracking.  This object is a 
** subclass of sqlite3_file.  The sqlite3_file object for the underlying
** VFS is appended to this structure.
*/
struct quotaConn {
  sqlite3_file base;              /* Base class - must be first */
  quotaFile *pFile;               /* The underlying file */
  /* The underlying VFS sqlite3_file is appended to this object */
};

/************************* Global Variables **********************************/
/*
................................................................................
/* If the reference count and threshold for a quotaGroup are both
** zero, then destroy the quotaGroup.
*/
static void quotaGroupDeref(quotaGroup *p){
  if( p->pFile==0 && p->iLimit==0 ){
    if( p->pNext ) p->pNext->ppPrev = p->ppPrev;
    if( p->ppPrev ) *p->ppPrev = p->pNext;
    if( p->xDestroy ) p->xDestroy(p->pArg);
    sqlite3_free(p);
  }
}

/*
** Return TRUE if string z matches glob pattern zGlob.
**
................................................................................
  }
  return *z==0;
}


/* Find a quotaGroup given the filename.
**
** Return a pointer to the quotaGroup object. Return NULL if not found.
*/
static quotaGroup *quotaGroupFind(const char *zFilename){
  quotaGroup *p;
  for(p=gQuota.pGroup; p && strglob(p->zPattern, zFilename)==0; p=p->pNext){}
  return p;
}

/* Translate an sqlite3_file* that is really a quotaConn* into
** the sqlite3_file* for the underlying original VFS.
*/
static sqlite3_file *quotaSubOpen(sqlite3_file *pConn){
  quotaConn *p = (quotaConn*)pConn;
  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 appropriate quota group if it is a
** file that needs to be tracked.
*/
static int quotaOpen(
  sqlite3_vfs *pVfs,          /* The quota VFS */
  const char *zName,          /* Name of file to be opened */
  sqlite3_file *pConn,        /* Fill in this file descriptor */
  int flags,                  /* Flags to control the opening */
  int *pOutFlags              /* Flags showing results of opening */
){
  int rc;                                    /* Result code */         
  quotaConn *pQuotaOpen;                     /* The new quota file descriptor */
  quotaFile *pFile;                          /* Corresponding quotaFile obj */
  quotaGroup *pGroup;                        /* The group file belongs to */
  sqlite3_file *pSubOpen;                    /* Real file descriptor */
  sqlite3_vfs *pOrigVfs = gQuota.pOrigVfs;   /* Real VFS */

  /* 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_WAL))==0 ){
    return pOrigVfs->xOpen(pOrigVfs, zName, pConn, flags, pOutFlags);
  }

  /* If the name of the file does not match any quota group, then
  ** use the normal xOpen method.
  */
  quotaEnter();
  pGroup = quotaGroupFind(zName);
  if( pGroup==0 ){
    rc = pOrigVfs->xOpen(pOrigVfs, zName, pConn, flags, pOutFlags);
  }else{
    /* If we get to this point, it means the file needs to be quota tracked.
    */
    pQuotaOpen = (quotaConn*)pConn;
    pSubOpen = quotaSubOpen(pConn);
    rc = pOrigVfs->xOpen(pOrigVfs, zName, pSubOpen, flags, pOutFlags);
    if( rc==SQLITE_OK ){
      for(pFile=pGroup->pFile; pFile && strcmp(pFile->zFilename, zName);
          pFile=pFile->pNext){}
      if( pFile==0 ){
        int nName = strlen(zName);
        pFile = sqlite3_malloc( sizeof(*pFile) + nName + 1 );
................................................................................
  quotaLeave();
  return rc;
}

/************************ I/O Method Wrappers *******************************/

/* xClose requests get passed through to the original VFS.  But we
** also have to unlink the quotaConn from the quotaFile and quotaGroup.
** The quotaFile and/or quotaGroup are freed if they are no longer in use.
*/
static int quotaClose(sqlite3_file *pConn){
  quotaConn *p = (quotaConn*)pConn;
  quotaFile *pFile = p->pFile;
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  int rc;
  rc = pSubOpen->pMethods->xClose(pSubOpen);
  quotaEnter();
  pFile->nRef--;
  if( pFile->nRef==0 ){
    quotaGroup *pGroup = pFile->pGroup;
    pGroup->iSize -= pFile->iSize;
................................................................................
  return rc;
}

/* Pass xRead requests directory thru to the original VFS without
** further processing.
*/
static int quotaRead(
  sqlite3_file *pConn,
  void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xRead(pSubOpen, 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 *pConn,
  const void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){
  quotaConn *p = (quotaConn*)pConn;
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  sqlite3_int64 iEnd = iOfst+iAmt;
  quotaGroup *pGroup;
  quotaFile *pFile = p->pFile;
  sqlite3_int64 szNew;

  if( pFile->iSize<iEnd ){
    pGroup = pFile->pGroup;
................................................................................
  }
  return pSubOpen->pMethods->xWrite(pSubOpen, pBuf, iAmt, iOfst);
}

/* Pass xTruncate requests thru to the original VFS.  If the
** success, update the file size.
*/
static int quotaTruncate(sqlite3_file *pConn, sqlite3_int64 size){
  quotaConn *p = (quotaConn*)pConn;
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  int rc = pSubOpen->pMethods->xTruncate(pSubOpen, size);
  quotaFile *pFile = p->pFile;
  quotaGroup *pGroup;
  if( rc==SQLITE_OK ){
    quotaEnter();
    pGroup = pFile->pGroup;
    pGroup->iSize -= pFile->iSize;
................................................................................
    quotaLeave();
  }
  return rc;
}

/* Pass xSync requests through to the original VFS without change
*/
static int quotaSync(sqlite3_file *pConn, int flags){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xSync(pSubOpen, 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 *pConn, sqlite3_int64 *pSize){
  quotaConn *p = (quotaConn*)pConn;
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  quotaFile *pFile = p->pFile;
  quotaGroup *pGroup;
  sqlite3_int64 sz;
  int rc;

  rc = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
  if( rc==SQLITE_OK ){
................................................................................
    *pSize = sz;
  }
  return rc;
}

/* Pass xLock requests through to the original VFS unchanged.
*/
static int quotaLock(sqlite3_file *pConn, int lock){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xLock(pSubOpen, lock);
}

/* Pass xUnlock requests through to the original VFS unchanged.
*/
static int quotaUnlock(sqlite3_file *pConn, int lock){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xUnlock(pSubOpen, lock);
}

/* Pass xCheckReservedLock requests through to the original VFS unchanged.
*/
static int quotaCheckReservedLock(sqlite3_file *pConn, int *pResOut){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xCheckReservedLock(pSubOpen, pResOut);
}

/* Pass xFileControl requests through to the original VFS unchanged.
*/
static int quotaFileControl(sqlite3_file *pConn, int op, void *pArg){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xFileControl(pSubOpen, op, pArg);
}

/* Pass xSectorSize requests through to the original VFS unchanged.
*/
static int quotaSectorSize(sqlite3_file *pConn){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xSectorSize(pSubOpen);
}

/* Pass xDeviceCharacteristics requests through to the original VFS unchanged.
*/
static int quotaDeviceCharacteristics(sqlite3_file *pConn){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xDeviceCharacteristics(pSubOpen);
}

/* Pass xShmMap requests through to the original VFS unchanged.
*/
static int quotaShmMap(
  sqlite3_file *pConn,            /* 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 *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xShmMap(pSubOpen, iRegion, szRegion, bExtend, pp);
}

/* Pass xShmLock requests through to the original VFS unchanged.
*/
static int quotaShmLock(
  sqlite3_file *pConn,       /* 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 *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xShmLock(pSubOpen, ofst, n, flags);
}

/* Pass xShmBarrier requests through to the original VFS unchanged.
*/
static void quotaShmBarrier(sqlite3_file *pConn){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  pSubOpen->pMethods->xShmBarrier(pSubOpen);
}

/* Pass xShmUnmap requests through to the original VFS unchanged.
*/
static int quotaShmUnmap(sqlite3_file *pConn, int deleteFlag){
  sqlite3_file *pSubOpen = quotaSubOpen(pConn);
  return pSubOpen->pMethods->xShmUnmap(pSubOpen, 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
................................................................................
  gQuota.pMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
  if( !gQuota.pMutex ){
    return SQLITE_NOMEM;
  }
  gQuota.isInitialized = 1;
  gQuota.pOrigVfs = pOrigVfs;
  gQuota.sThisVfs = *pOrigVfs;
  gQuota.sThisVfs.xOpen = quotaOpen;
  gQuota.sThisVfs.szOsFile += sizeof(quotaConn);
  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 = quotaSectorSize;
  gQuota.sIoMethodsV1.xDeviceCharacteristics = quotaDeviceCharacteristics;
  gQuota.sIoMethodsV2 = gQuota.sIoMethodsV1;
  gQuota.sIoMethodsV2.iVersion = 2;
  gQuota.sIoMethodsV2.xShmMap = quotaShmMap;
  gQuota.sIoMethodsV2.xShmLock = quotaShmLock;
  gQuota.sIoMethodsV2.xShmBarrier = quotaShmBarrier;
................................................................................
  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 */
  void (*xDestroy)(void*)         /* Optional destructor for pArg */
){
  quotaGroup *pGroup;
  quotaEnter();
  pGroup = gQuota.pGroup;
  while( pGroup && strcmp(pGroup->zPattern, zPattern)!=0 ){
    pGroup = pGroup->pNext;
  }
................................................................................
    if( gQuota.pGroup ) gQuota.pGroup->ppPrev = &pGroup->pNext;
    pGroup->pNext = gQuota.pGroup;
    pGroup->ppPrev = &gQuota.pGroup;
    gQuota.pGroup = pGroup;
  }
  pGroup->iLimit = iLimit;
  pGroup->xCallback = xCallback;
  if( pGroup->xDestroy && pGroup->pArg!=pArg ){
    pGroup->xDestroy(pGroup->pArg);
  }
  pGroup->pArg = pArg;
  pGroup->xDestroy = xDestroy;
  quotaGroupDeref(pGroup);
  quotaLeave();
  return SQLITE_OK;
}

  
/***************************** Test Code ***********************************/
#ifdef SQLITE_TEST
#include <tcl.h>

/*
** Argument passed to a TCL quota-over-limit callback.
*/
typedef struct TclQuotaCallback TclQuotaCallback;
struct TclQuotaCallback {
  Tcl_Interp *interp;    /* Interpreter in which to run the script */
  Tcl_Obj *pScript;      /* Script to be run */

};


extern const char *sqlite3TestErrorName(int);


/*
** This is the callback from a quota-over-limit.
*/
static void tclQuotaCallback(
  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 */
){
  TclQuotaCallback *p;            /* Callback script object */
................................................................................
    Tcl_UnsetVar(p->interp, Tcl_GetString(pVarname), 0);
  }

  Tcl_DecrRefCount(pEval);
  Tcl_DecrRefCount(pVarname);
  if( rc!=TCL_OK ) Tcl_BackgroundError(p->interp);
}

/*
** Destructor for a TCL quota-over-limit callback.
*/
static void tclCallbackDestructor(void *pObj){
  TclQuotaCallback *p = (TclQuotaCallback*)pObj;
  if( p ){
    Tcl_DecrRefCount(p->pScript);
    ckfree((char *)p);
  }
}

/*
** tclcmd: sqlite3_quota_initialize NAME MAKEDEFAULT
*/
static int test_quota_initialize(
  void * clientData,
  Tcl_Interp *interp,
................................................................................
    return TCL_ERROR;
  }

  /* Call sqlite3_quota_shutdown() */
  rc = sqlite3_quota_shutdown();
  Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);














  return TCL_OK;
}

/*
** tclcmd: sqlite3_quota_set PATTERN LIMIT SCRIPT
*/
static int test_quota_set(
................................................................................
  Tcl_Obj *CONST objv[]
){
  const char *zPattern;           /* File pattern to configure */
  sqlite3_int64 iLimit;           /* Initial quota in bytes */
  Tcl_Obj *pScript;               /* Tcl script to invoke to increase quota */
  int rc;                         /* Value returned by quota_set() */
  TclQuotaCallback *p;            /* Callback object */
  int nScript;                    /* Length of callback script */

  /* Process arguments */
  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "PATTERN LIMIT SCRIPT");
    return TCL_ERROR;
  }
  zPattern = Tcl_GetString(objv[1]);
  if( Tcl_GetWideIntFromObj(interp, objv[2], &iLimit) ) return TCL_ERROR;
  pScript = objv[3];
  Tcl_GetStringFromObj(pScript, &nScript);

  if( nScript>0 ){
    /* Allocate a TclQuotaCallback object */
    p = (TclQuotaCallback *)ckalloc(sizeof(TclQuotaCallback));
    memset(p, 0, sizeof(TclQuotaCallback));
    p->interp = interp;
    Tcl_IncrRefCount(pScript);
    p->pScript = pScript;
  }else{
    p = 0;
  }
  /* Invoke sqlite3_quota_set() */
  rc = sqlite3_quota_set(zPattern, iLimit, tclQuotaCallback,







                         (void*)p, tclCallbackDestructor);


  Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
  return TCL_OK;
}

/*
** tclcmd:  sqlite3_quota_dump
*/
static int test_quota_dump(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  Tcl_Obj *pResult;
  Tcl_Obj *pGroupTerm;
  Tcl_Obj *pFileTerm;
  quotaGroup *pGroup;
  quotaFile *pFile;

  pResult = Tcl_NewObj();
  quotaEnter();
  for(pGroup=gQuota.pGroup; pGroup; pGroup=pGroup->pNext){
    pGroupTerm = Tcl_NewObj();
    Tcl_ListObjAppendElement(interp, pGroupTerm,
          Tcl_NewStringObj(pGroup->zPattern, -1));
    Tcl_ListObjAppendElement(interp, pGroupTerm,
          Tcl_NewWideIntObj(pGroup->iLimit));
    Tcl_ListObjAppendElement(interp, pGroupTerm,
          Tcl_NewWideIntObj(pGroup->iSize));
    for(pFile=pGroup->pFile; pFile; pFile=pFile->pNext){
      pFileTerm = Tcl_NewObj();
      Tcl_ListObjAppendElement(interp, pFileTerm,
            Tcl_NewStringObj(pFile->zFilename, -1));
      Tcl_ListObjAppendElement(interp, pFileTerm,
            Tcl_NewWideIntObj(pFile->iSize));
      Tcl_ListObjAppendElement(interp, pFileTerm,
            Tcl_NewWideIntObj(pFile->nRef));
      Tcl_ListObjAppendElement(interp, pGroupTerm, pFileTerm);
    }
    Tcl_ListObjAppendElement(interp, pResult, pGroupTerm);
  }
  quotaLeave();
  Tcl_SetObjResult(interp, pResult);
  return TCL_OK;
}

/*
** 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){
................................................................................
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
  } aCmd[] = {
    { "sqlite3_quota_initialize", test_quota_initialize },
    { "sqlite3_quota_shutdown", test_quota_shutdown },
    { "sqlite3_quota_set", test_quota_set },
    { "sqlite3_quota_dump", test_quota_dump },
  };
  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){
    Tcl_CreateObjCommand(interp, aCmd[i].zName, aCmd[i].xProc, 0, 0);
  }

  return TCL_OK;
}
#endif

} {SQLITE_MISUSE}
set ::quota [list]
do_test quota-2.4.2 {
  catchsql { INSERT INTO t1 VALUES(3, randomblob(1100)) }
} {1 {database or disk is full}}
do_test quota-2.4.3 { set ::quota } {5120 6144}
do_test quota-2.4.4 { file size test.db } {5120}
do_test quota-2.4.5 {
  db close
  sqlite3_quota_shutdown
} {SQLITE_OK}

#-------------------------------------------------------------------------
# Try some tests with more than one connection to a database file. Still
# in rollback mode.
................................................................................
} {3072}
do_test quota-3.1.3 {
  sqlite3 db2 test.db
  set ::quota [list]
  execsql { CREATE TABLE t2(a, b) } db2
  set ::quota
} {}


do_test quota-3.X {
  catch { db close }
  catch { db2 close }
















  sqlite3_quota_shutdown 

} {SQLITE_OK}



finish_test

} {SQLITE_MISUSE}
set ::quota [list]
do_test quota-2.4.2 {
  catchsql { INSERT INTO t1 VALUES(3, randomblob(1100)) }
} {1 {database or disk is full}}
do_test quota-2.4.3 { set ::quota } {5120 6144}
do_test quota-2.4.4 { file size test.db } {5120}
do_test quota-2.4.99 {
  db close
  sqlite3_quota_shutdown
} {SQLITE_OK}

#-------------------------------------------------------------------------
# Try some tests with more than one connection to a database file. Still
# in rollback mode.
................................................................................
} {3072}
do_test quota-3.1.3 {
  sqlite3 db2 test.db
  set ::quota [list]
  execsql { CREATE TABLE t2(a, b) } db2
  set ::quota
} {}
puts "quotas: [sqlite3_quota_dump]"

do_test quota-3.X {
  catch { db close }
  catch { db2 close }
} {0}

#-------------------------------------------------------------------------
# Quotas are deleted when unused and when there limit is set to zero
#

# Return a list of all currently defined quotas.  Each quota is identified
# by its pattern.
proc quota_list {} {
  set allq {}
  foreach q [sqlite3_quota_dump] {
    lappend allq [lindex $q 0]
  }
  return [lsort $allq]
}
do_test quota-4.1 {
  sqlite3_quota_set *test.db 0 {}
  quota_list
} {}
do_test quota-4.2 {
  sqlite3_quota_set *test.db 4096 {}
  quota_list
} {*test.db}


sqlite3_quota_shutdown 
finish_test