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Overview
Comment:Store application-defined function names as lower-case to avoid the need for case conversions before calling xFindFunction on virtual tables. Avoid using lookaside to store the destructors for application defined functions, as lookaside should be reserved for transient allocations.
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Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 777189ce88799f93f393fd14fd716111c85bcdcb23690fd561f78ea2bd2ce5da
User & Date: drh 2018-05-26 16:00:26
Context
2018-05-28
18:25
When compiling with SQLITE_DEBUG, add run-time checks to ensure that no statement aborts unless either there have been no writes or else there is a statement journal. check-in: ce99c772 user: drh tags: trunk
17:31
When compiling with SQLITE_DEBUG, add run-time checks to ensure that no statement aborts unless either there have been no writes or else there is a statement journal. check-in: 5a4542db user: drh tags: stmt-journal-testing
2018-05-26
18:03
Experimental change that allows overloaded functions to be analyzed by the xBestIndex method and used by the xFilter method of a virtual table. Leaf check-in: a353b1d7 user: drh tags: vtab-func-constraint
16:00
Store application-defined function names as lower-case to avoid the need for case conversions before calling xFindFunction on virtual tables. Avoid using lookaside to store the destructors for application defined functions, as lookaside should be reserved for transient allocations. check-in: 777189ce user: drh tags: trunk
13:55
Add a single sentence of documentation about the virtual table scan flags. No changes to code. check-in: 27b4fa5d user: drh tags: trunk
Changes
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Changes to src/callback.c.

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  /* If the createFlag parameter is true and the search did not reveal an
  ** exact match for the name, number of arguments and encoding, then add a
  ** new entry to the hash table and return it.
  */
  if( createFlag && bestScore<FUNC_PERFECT_MATCH && 
      (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
    FuncDef *pOther;

    pBest->zName = (const char*)&pBest[1];
    pBest->nArg = (u16)nArg;
    pBest->funcFlags = enc;
    memcpy((char*)&pBest[1], zName, nName+1);

    pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);
    if( pOther==pBest ){
      sqlite3DbFree(db, pBest);
      sqlite3OomFault(db);
      return 0;
    }else{
      pBest->pNext = pOther;







>




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  /* If the createFlag parameter is true and the search did not reveal an
  ** exact match for the name, number of arguments and encoding, then add a
  ** new entry to the hash table and return it.
  */
  if( createFlag && bestScore<FUNC_PERFECT_MATCH && 
      (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
    FuncDef *pOther;
    u8 *z;
    pBest->zName = (const char*)&pBest[1];
    pBest->nArg = (u16)nArg;
    pBest->funcFlags = enc;
    memcpy((char*)&pBest[1], zName, nName+1);
    for(z=(u8*)pBest->zName; *z; z++) *z = sqlite3UpperToLower[*z];
    pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);
    if( pOther==pBest ){
      sqlite3DbFree(db, pBest);
      sqlite3OomFault(db);
      return 0;
    }else{
      pBest->pNext = pOther;

Changes to src/main.c.

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#ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) ){
    return SQLITE_MISUSE_BKPT;
  }
#endif
  sqlite3_mutex_enter(db->mutex);
  if( xDestroy ){
    pArg = (FuncDestructor *)sqlite3DbMallocZero(db, sizeof(FuncDestructor));
    if( !pArg ){

      xDestroy(p);
      goto out;
    }

    pArg->xDestroy = xDestroy;
    pArg->pUserData = p;
  }
  rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, xSFunc, xStep, xFinal, pArg);
  if( pArg && pArg->nRef==0 ){
    assert( rc!=SQLITE_OK );
    xDestroy(p);
    sqlite3DbFree(db, pArg);
  }

 out:
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
................................................................................
  sqlite3DbFree(db, zFunc8);
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
#endif
























/*
** Declare that a function has been overloaded by a virtual table.
**
** If the function already exists as a regular global function, then
** this routine is a no-op.  If the function does not exist, then create
** a new one that always throws a run-time error.  
................................................................................
** properly.
*/
int sqlite3_overload_function(
  sqlite3 *db,
  const char *zName,
  int nArg
){
  int rc = SQLITE_OK;


#ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
    return SQLITE_MISUSE_BKPT;
  }
#endif
  sqlite3_mutex_enter(db->mutex);
  if( sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)==0 ){
    rc = sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
                           0, sqlite3InvalidFunction, 0, 0, 0);
  }
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#ifndef SQLITE_OMIT_TRACE
/*
** Register a trace function.  The pArg from the previously registered trace
** is returned.  
**







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#ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) ){
    return SQLITE_MISUSE_BKPT;
  }
#endif
  sqlite3_mutex_enter(db->mutex);
  if( xDestroy ){
    pArg = (FuncDestructor *)sqlite3Malloc(sizeof(FuncDestructor));
    if( !pArg ){
      sqlite3OomFault(db);
      xDestroy(p);
      goto out;
    }
    pArg->nRef = 0;
    pArg->xDestroy = xDestroy;
    pArg->pUserData = p;
  }
  rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, xSFunc, xStep, xFinal, pArg);
  if( pArg && pArg->nRef==0 ){
    assert( rc!=SQLITE_OK );
    xDestroy(p);
    sqlite3_free(pArg);
  }

 out:
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
................................................................................
  sqlite3DbFree(db, zFunc8);
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
#endif


/*
** The following is the implementation of an SQL function that always
** fails with an error message stating that the function is used in the
** wrong context.  The sqlite3_overload_function() API might construct
** SQL function that use this routine so that the functions will exist
** for name resolution but are actually overloaded by the xFindFunction
** method of virtual tables.
*/
static void sqlite3InvalidFunction(
  sqlite3_context *context,  /* The function calling context */
  int NotUsed,               /* Number of arguments to the function */
  sqlite3_value **NotUsed2   /* Value of each argument */
){
  const char *zName = (const char*)sqlite3_user_data(context);
  char *zErr;
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  zErr = sqlite3_mprintf(
      "unable to use function %s in the requested context", zName);
  sqlite3_result_error(context, zErr, -1);
  sqlite3_free(zErr);
}

/*
** Declare that a function has been overloaded by a virtual table.
**
** If the function already exists as a regular global function, then
** this routine is a no-op.  If the function does not exist, then create
** a new one that always throws a run-time error.  
................................................................................
** properly.
*/
int sqlite3_overload_function(
  sqlite3 *db,
  const char *zName,
  int nArg
){
  int rc;
  char *zCopy;

#ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) || zName==0 || nArg<-2 ){
    return SQLITE_MISUSE_BKPT;
  }
#endif
  sqlite3_mutex_enter(db->mutex);
  rc = sqlite3FindFunction(db, zName, nArg, SQLITE_UTF8, 0)!=0;
  sqlite3_mutex_leave(db->mutex);
  if( rc ) return SQLITE_OK;
  zCopy = sqlite3_mprintf(zName);
  if( zCopy==0 ) return SQLITE_NOMEM;
  return sqlite3_create_function_v2(db, zName, nArg, SQLITE_UTF8,
                           zCopy, sqlite3InvalidFunction, 0, 0, sqlite3_free);
}

#ifndef SQLITE_OMIT_TRACE
/*
** Register a trace function.  The pArg from the previously registered trace
** is returned.  
**

Changes to src/sqliteInt.h.

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int sqlite3KeyInfoIsWriteable(KeyInfo*);
#endif
int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
  void (*)(sqlite3_context*,int,sqlite3_value **),
  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
  FuncDestructor *pDestructor
);

void sqlite3OomFault(sqlite3*);
void sqlite3OomClear(sqlite3*);
int sqlite3ApiExit(sqlite3 *db, int);
int sqlite3OpenTempDatabase(Parse *);

void sqlite3StrAccumInit(StrAccum*, sqlite3*, char*, int, int);
char *sqlite3StrAccumFinish(StrAccum*);
................................................................................
void sqlite3VtabArgInit(Parse*);
void sqlite3VtabArgExtend(Parse*, Token*);
int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
int sqlite3VtabCallConnect(Parse*, Table*);
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, VTable *);
FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
void sqlite3ParserReset(Parse*);
int sqlite3Reprepare(Vdbe*);
void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);







>







 







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int sqlite3KeyInfoIsWriteable(KeyInfo*);
#endif
int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
  void (*)(sqlite3_context*,int,sqlite3_value **),
  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
  FuncDestructor *pDestructor
);
void sqlite3NoopDestructor(void*);
void sqlite3OomFault(sqlite3*);
void sqlite3OomClear(sqlite3*);
int sqlite3ApiExit(sqlite3 *db, int);
int sqlite3OpenTempDatabase(Parse *);

void sqlite3StrAccumInit(StrAccum*, sqlite3*, char*, int, int);
char *sqlite3StrAccumFinish(StrAccum*);
................................................................................
void sqlite3VtabArgInit(Parse*);
void sqlite3VtabArgExtend(Parse*, Token*);
int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
int sqlite3VtabCallConnect(Parse*, Table*);
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, VTable *);
FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);

sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
void sqlite3ParserReset(Parse*);
int sqlite3Reprepare(Vdbe*);
void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);

Changes to src/vdbeapi.c.

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  if( *piTime==0 ){
    rc = sqlite3OsCurrentTimeInt64(p->pOut->db->pVfs, piTime);
    if( rc ) *piTime = 0;
  }
  return *piTime;
}

/*
** The following is the implementation of an SQL function that always
** fails with an error message stating that the function is used in the
** wrong context.  The sqlite3_overload_function() API might construct
** SQL function that use this routine so that the functions will exist
** for name resolution but are actually overloaded by the xFindFunction
** method of virtual tables.
*/
void sqlite3InvalidFunction(
  sqlite3_context *context,  /* The function calling context */
  int NotUsed,               /* Number of arguments to the function */
  sqlite3_value **NotUsed2   /* Value of each argument */
){
  const char *zName = context->pFunc->zName;
  char *zErr;
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  zErr = sqlite3_mprintf(
      "unable to use function %s in the requested context", zName);
  sqlite3_result_error(context, zErr, -1);
  sqlite3_free(zErr);
}

/*
** Create a new aggregate context for p and return a pointer to
** its pMem->z element.
*/
static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
  Mem *pMem = p->pMem;
  assert( (pMem->flags & MEM_Agg)==0 );







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  if( *piTime==0 ){
    rc = sqlite3OsCurrentTimeInt64(p->pOut->db->pVfs, piTime);
    if( rc ) *piTime = 0;
  }
  return *piTime;
}























/*
** Create a new aggregate context for p and return a pointer to
** its pMem->z element.
*/
static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
  Mem *pMem = p->pMem;
  assert( (pMem->flags & MEM_Agg)==0 );

Changes to src/vdbemem.c.

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  }else{
    pMem->u.i = val;
    pMem->flags = MEM_Int;
  }
}

/* A no-op destructor */
static void sqlite3NoopDestructor(void *p){ UNUSED_PARAMETER(p); }

/*
** Set the value stored in *pMem should already be a NULL.
** Also store a pointer to go with it.
*/
void sqlite3VdbeMemSetPointer(
  Mem *pMem,







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  }else{
    pMem->u.i = val;
    pMem->flags = MEM_Int;
  }
}

/* A no-op destructor */
void sqlite3NoopDestructor(void *p){ UNUSED_PARAMETER(p); }

/*
** Set the value stored in *pMem should already be a NULL.
** Also store a pointer to go with it.
*/
void sqlite3VdbeMemSetPointer(
  Mem *pMem,

Changes to src/vtab.c.

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  Table *pTab;
  sqlite3_vtab *pVtab;
  sqlite3_module *pMod;
  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**) = 0;
  void *pArg = 0;
  FuncDef *pNew;
  int rc = 0;
  char *zLowerName;
  unsigned char *z;


  /* Check to see the left operand is a column in a virtual table */
  if( NEVER(pExpr==0) ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;
  pTab = pExpr->pTab;
  if( pTab==0 ) return pDef;
  if( !IsVirtual(pTab) ) return pDef;
................................................................................
  pVtab = sqlite3GetVTable(db, pTab)->pVtab;
  assert( pVtab!=0 );
  assert( pVtab->pModule!=0 );
  pMod = (sqlite3_module *)pVtab->pModule;
  if( pMod->xFindFunction==0 ) return pDef;
 
  /* Call the xFindFunction method on the virtual table implementation
  ** to see if the implementation wants to overload this function 




  */
  zLowerName = sqlite3DbStrDup(db, pDef->zName);
  if( zLowerName ){
    for(z=(unsigned char*)zLowerName; *z; z++){





      *z = sqlite3UpperToLower[*z];
    }
    rc = pMod->xFindFunction(pVtab, nArg, zLowerName, &xSFunc, &pArg);
    sqlite3DbFree(db, zLowerName);
  }


  if( rc==0 ){
    return pDef;
  }

  /* Create a new ephemeral function definition for the overloaded
  ** function */
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew)







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  Table *pTab;
  sqlite3_vtab *pVtab;
  sqlite3_module *pMod;
  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**) = 0;
  void *pArg = 0;
  FuncDef *pNew;
  int rc = 0;




  /* Check to see the left operand is a column in a virtual table */
  if( NEVER(pExpr==0) ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;
  pTab = pExpr->pTab;
  if( pTab==0 ) return pDef;
  if( !IsVirtual(pTab) ) return pDef;
................................................................................
  pVtab = sqlite3GetVTable(db, pTab)->pVtab;
  assert( pVtab!=0 );
  assert( pVtab->pModule!=0 );
  pMod = (sqlite3_module *)pVtab->pModule;
  if( pMod->xFindFunction==0 ) return pDef;
 
  /* Call the xFindFunction method on the virtual table implementation
  ** to see if the implementation wants to overload this function.
  **
  ** Though undocumented, we have historically always invoked xFindFunction
  ** with an all lower-case function name.  Continue in this tradition to
  ** avoid any chance of an incompatibility.
  */



#ifdef SQLITE_DEBUG
  {
    int i;
    for(i=0; pDef->zName[i]; i++){
      unsigned char x = (unsigned char)pDef->zName[i];
      assert( x==sqlite3UpperToLower[x] );
    }


  }
#endif
  rc = pMod->xFindFunction(pVtab, nArg, pDef->zName, &xSFunc, &pArg);
  if( rc==0 ){
    return pDef;
  }

  /* Create a new ephemeral function definition for the overloaded
  ** function */
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew)