vtab.c

sqlite的最新源码 This ZIP archive contains preprocessed C code for the SQLite library as individual sour

        for(j=i; (j+nDel)<=nType; j++){
          zType[j] = zType[j+nDel];
        }
        if( zType[i]=='\0' && i>0 ){
          assert(zType[i-1]==' ');
          zType[i-1] = '\0';
        }
        pTab->aCol[iCol].isHidden = 1;
      }
    }
  }
  return rc;
}

/*
** This function is invoked by the parser to call the xConnect() method
** of the virtual table pTab. If an error occurs, an error code is returned 
** and an error left in pParse.
**
** This call is a no-op if table pTab is not a virtual table.
*/
int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){
  Module *pMod;
  int rc = SQLITE_OK;

  if( !pTab || (pTab->tabFlags & TF_Virtual)==0 || pTab->pVtab ){
    return SQLITE_OK;
  }

  pMod = pTab->pMod;
  if( !pMod ){
    const char *zModule = pTab->azModuleArg[0];
    sqlite3ErrorMsg(pParse, "no such module: %s", zModule);
    rc = SQLITE_ERROR;
  } else {
    char *zErr = 0;
    sqlite3 *db = pParse->db;
    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xConnect, &zErr);
    if( rc!=SQLITE_OK ){
      sqlite3ErrorMsg(pParse, "%s", zErr);
    }
    sqlite3DbFree(db, zErr);
  }

  return rc;
}

/*
** Add the virtual table pVtab to the array sqlite3.aVTrans[].
*/
static int addToVTrans(sqlite3 *db, sqlite3_vtab *pVtab){
  const int ARRAY_INCR = 5;

  /* Grow the sqlite3.aVTrans array if required */
  if( (db->nVTrans%ARRAY_INCR)==0 ){
    sqlite3_vtab **aVTrans;
    int nBytes = sizeof(sqlite3_vtab *) * (db->nVTrans + ARRAY_INCR);
    aVTrans = sqlite3DbRealloc(db, (void *)db->aVTrans, nBytes);
    if( !aVTrans ){
      return SQLITE_NOMEM;
    }
    memset(&aVTrans[db->nVTrans], 0, sizeof(sqlite3_vtab *)*ARRAY_INCR);
    db->aVTrans = aVTrans;
  }

  /* Add pVtab to the end of sqlite3.aVTrans */
  db->aVTrans[db->nVTrans++] = pVtab;
  sqlite3VtabLock(pVtab);
  return SQLITE_OK;
}

/*
** This function is invoked by the vdbe to call the xCreate method
** of the virtual table named zTab in database iDb. 
**
** If an error occurs, *pzErr is set to point an an English language
** description of the error and an SQLITE_XXX error code is returned.
** In this case the caller must call sqlite3DbFree(db, ) on *pzErr.
*/
int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){
  int rc = SQLITE_OK;
  Table *pTab;
  Module *pMod;
  const char *zModule;

  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zName);
  assert(pTab && (pTab->tabFlags & TF_Virtual)!=0 && !pTab->pVtab);
  pMod = pTab->pMod;
  zModule = pTab->azModuleArg[0];

  /* If the module has been registered and includes a Create method, 
  ** invoke it now. If the module has not been registered, return an 
  ** error. Otherwise, do nothing.
  */
  if( !pMod ){
    *pzErr = sqlite3MPrintf(db, "no such module: %s", zModule);
    rc = SQLITE_ERROR;
  }else{
    rc = vtabCallConstructor(db, pTab, pMod, pMod->pModule->xCreate, pzErr);
  }

  if( rc==SQLITE_OK && pTab->pVtab ){
      rc = addToVTrans(db, pTab->pVtab);
  }

  return rc;
}

/*
** This function is used to set the schema of a virtual table.  It is only
** valid to call this function from within the xCreate() or xConnect() of a
** virtual table module.
*/
int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable){
  Parse sParse;

  int rc = SQLITE_OK;
  Table *pTab;
  char *zErr = 0;

  sqlite3_mutex_enter(db->mutex);
  pTab = db->pVTab;
  if( !pTab ){
    sqlite3Error(db, SQLITE_MISUSE, 0);
    sqlite3_mutex_leave(db->mutex);
    return SQLITE_MISUSE;
  }
  assert((pTab->tabFlags & TF_Virtual)!=0 && pTab->nCol==0 && pTab->aCol==0);

  memset(&sParse, 0, sizeof(Parse));
  sParse.declareVtab = 1;
  sParse.db = db;

  if( 
      SQLITE_OK == sqlite3RunParser(&sParse, zCreateTable, &zErr) && 
      sParse.pNewTable && 
      !sParse.pNewTable->pSelect && 
      (sParse.pNewTable->tabFlags & TF_Virtual)==0
  ){
    pTab->aCol = sParse.pNewTable->aCol;
    pTab->nCol = sParse.pNewTable->nCol;
    sParse.pNewTable->nCol = 0;
    sParse.pNewTable->aCol = 0;
    db->pVTab = 0;
  } else {
    sqlite3Error(db, SQLITE_ERROR, zErr);
    sqlite3DbFree(db, zErr);
    rc = SQLITE_ERROR;
  }
  sParse.declareVtab = 0;

  sqlite3_finalize((sqlite3_stmt*)sParse.pVdbe);
  sqlite3DeleteTable(sParse.pNewTable);
  sParse.pNewTable = 0;

  assert( (rc&0xff)==rc );
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

/*
** This function is invoked by the vdbe to call the xDestroy method
** of the virtual table named zTab in database iDb. This occurs
** when a DROP TABLE is mentioned.
**
** This call is a no-op if zTab is not a virtual table.
*/
int sqlite3VtabCallDestroy(sqlite3 *db, int iDb, const char *zTab)
{
  int rc = SQLITE_OK;
  Table *pTab;

  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zName);
  assert(pTab);
  if( pTab->pVtab ){
    int (*xDestroy)(sqlite3_vtab *pVTab) = pTab->pMod->pModule->xDestroy;
    rc = sqlite3SafetyOff(db);
    assert( rc==SQLITE_OK );
    if( xDestroy ){
      rc = xDestroy(pTab->pVtab);
    }
    (void)sqlite3SafetyOn(db);
    if( rc==SQLITE_OK ){
      int i;
      for(i=0; i<db->nVTrans; i++){
        if( db->aVTrans[i]==pTab->pVtab ){
          db->aVTrans[i] = db->aVTrans[--db->nVTrans];
          break;
        }
      }
      pTab->pVtab = 0;
    }
  }

  return rc;
}

/*
** This function invokes either the xRollback or xCommit method
** of each of the virtual tables in the sqlite3.aVTrans array. The method
** called is identified by the second argument, "offset", which is
** the offset of the method to call in the sqlite3_module structure.
**
** The array is cleared after invoking the callbacks. 
*/
static void callFinaliser(sqlite3 *db, int offset){
  int i;
  if( db->aVTrans ){
    for(i=0; i<db->nVTrans && db->aVTrans[i]; i++){
      sqlite3_vtab *pVtab = db->aVTrans[i];
      int (*x)(sqlite3_vtab *);
      x = *(int (**)(sqlite3_vtab *))((char *)pVtab->pModule + offset);
      if( x ) x(pVtab);
      sqlite3VtabUnlock(db, pVtab);
    }
    sqlite3DbFree(db, db->aVTrans);
    db->nVTrans = 0;
    db->aVTrans = 0;
  }
}

/*
** Invoke the xSync method of all virtual tables in the sqlite3.aVTrans
** array. Return the error code for the first error that occurs, or
** SQLITE_OK if all xSync operations are successful.
**
** Set *pzErrmsg to point to a buffer that should be released using 
** sqlite3DbFree() containing an error message, if one is available.
*/
int sqlite3VtabSync(sqlite3 *db, char **pzErrmsg){
  int i;
  int rc = SQLITE_OK;
  int rcsafety;
  sqlite3_vtab **aVTrans = db->aVTrans;

  rc = sqlite3SafetyOff(db);
  db->aVTrans = 0;
  for(i=0; rc==SQLITE_OK && i<db->nVTrans && aVTrans[i]; i++){
    sqlite3_vtab *pVtab = aVTrans[i];
    int (*x)(sqlite3_vtab *);
    x = pVtab->pModule->xSync;
    if( x ){
      rc = x(pVtab);
      sqlite3DbFree(db, *pzErrmsg);
      *pzErrmsg = pVtab->zErrMsg;
      pVtab->zErrMsg = 0;
    }
  }
  db->aVTrans = aVTrans;
  rcsafety = sqlite3SafetyOn(db);

  if( rc==SQLITE_OK ){
    rc = rcsafety;
  }
  return rc;
}

/*
** Invoke the xRollback method of all virtual tables in the 
** sqlite3.aVTrans array. Then clear the array itself.
*/
int sqlite3VtabRollback(sqlite3 *db){
  callFinaliser(db, offsetof(sqlite3_module,xRollback));
  return SQLITE_OK;
}

/*
** Invoke the xCommit method of all virtual tables in the 
** sqlite3.aVTrans array. Then clear the array itself.
*/
int sqlite3VtabCommit(sqlite3 *db){
  callFinaliser(db, offsetof(sqlite3_module,xCommit));
  return SQLITE_OK;
}

/*
** If the virtual table pVtab supports the transaction interface
** (xBegin/xRollback/xCommit and optionally xSync) and a transaction is
** not currently open, invoke the xBegin method now.
**
** If the xBegin call is successful, place the sqlite3_vtab pointer
** in the sqlite3.aVTrans array.
*/
int sqlite3VtabBegin(sqlite3 *db, sqlite3_vtab *pVtab){
  int rc = SQLITE_OK;
  const sqlite3_module *pModule;

  /* Special case: If db->aVTrans is NULL and db->nVTrans is greater
  ** than zero, then this function is being called from within a
  ** virtual module xSync() callback. It is illegal to write to 
  ** virtual module tables in this case, so return SQLITE_LOCKED.
  */
  if( sqlite3VtabInSync(db) ){
    return SQLITE_LOCKED;
  }
  if( !pVtab ){
    return SQLITE_OK;
  } 
  pModule = pVtab->pModule;

  if( pModule->xBegin ){
    int i;


    /* If pVtab is already in the aVTrans array, return early */
    for(i=0; (i<db->nVTrans) && 0!=db->aVTrans[i]; i++){
      if( db->aVTrans[i]==pVtab ){
        return SQLITE_OK;
      }
    }

    /* Invoke the xBegin method */
    rc = pModule->xBegin(pVtab);
    if( rc==SQLITE_OK ){
      rc = addToVTrans(db, pVtab);
    }
  }
  return rc;
}

/*
** The first parameter (pDef) is a function implementation.  The
** second parameter (pExpr) is the first argument to this function.
** If pExpr is a column in a virtual table, then let the virtual
** table implementation have an opportunity to overload the function.
**
** This routine is used to allow virtual table implementations to
** overload MATCH, LIKE, GLOB, and REGEXP operators.
**
** Return either the pDef argument (indicating no change) or a 
** new FuncDef structure that is marked as ephemeral using the
** SQLITE_FUNC_EPHEM flag.
*/
FuncDef *sqlite3VtabOverloadFunction(
  sqlite3 *db,    /* Database connection for reporting malloc problems */
  FuncDef *pDef,  /* Function to possibly overload */
  int nArg,       /* Number of arguments to the function */
  Expr *pExpr     /* First argument to the function */
){
  Table *pTab;
  sqlite3_vtab *pVtab;
  sqlite3_module *pMod;
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  void *pArg;
  FuncDef *pNew;
  int rc = 0;
  char *zLowerName;
  unsigned char *z;


  /* Check to see the left operand is a column in a virtual table */
  if( pExpr==0 ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;
  pTab = pExpr->pTab;
  if( pTab==0 ) return pDef;
  if( (pTab->tabFlags & TF_Virtual)==0 ) return pDef;
  pVtab = 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, &xFunc, &pArg);
    sqlite3DbFree(db, zLowerName);
    if( pVtab->zErrMsg ){
      sqlite3Error(db, rc, "%s", pVtab->zErrMsg);
      sqlite3DbFree(db, pVtab->zErrMsg);
      pVtab->zErrMsg = 0;
    }
  }
  if( rc==0 ){
    return pDef;
  }

  /* Create a new ephemeral function definition for the overloaded
  ** function */
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) + strlen(pDef->zName) );
  if( pNew==0 ){
    return pDef;
  }
  *pNew = *pDef;
  pNew->zName = (char *)&pNew[1];
  memcpy(pNew->zName, pDef->zName, strlen(pDef->zName)+1);
  pNew->xFunc = xFunc;
  pNew->pUserData = pArg;
  pNew->flags |= SQLITE_FUNC_EPHEM;
  return pNew;
}

/*
** Make sure virtual table pTab is contained in the pParse->apVirtualLock[]
** array so that an OP_VBegin will get generated for it.  Add pTab to the
** array if it is missing.  If pTab is already in the array, this routine
** is a no-op.
*/
void sqlite3VtabMakeWritable(Parse *pParse, Table *pTab){
  int i, n;
  assert( IsVirtual(pTab) );
  for(i=0; i<pParse->nVtabLock; i++){
    if( pTab==pParse->apVtabLock[i] ) return;
  }
  n = (pParse->nVtabLock+1)*sizeof(pParse->apVtabLock[0]);
  pParse->apVtabLock = sqlite3_realloc(pParse->apVtabLock, n);
  if( pParse->apVtabLock ){
    pParse->apVtabLock[pParse->nVtabLock++] = pTab;
  }else{
    pParse->db->mallocFailed = 1;
  }
}

#endif /* SQLITE_OMIT_VIRTUALTABLE */