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freeswitch/libs/sqlite/src/vtab.c

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/*
** 2006 June 10
**
** 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 code used to help implement virtual tables.
**
** $Id: vtab.c,v 1.39 2007/01/09 14:01:14 drh Exp $
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
#include "sqliteInt.h"
#include "os.h"
/*
** External API function used to create a new virtual-table module.
*/
int sqlite3_create_module(
sqlite3 *db, /* Database in which module is registered */
const char *zName, /* Name assigned to this module */
const sqlite3_module *pModule, /* The definition of the module */
void *pAux /* Context pointer for xCreate/xConnect */
){
int nName = strlen(zName);
Module *pMod = (Module *)sqliteMallocRaw(sizeof(Module) + nName + 1);
if( pMod ){
char *zCopy = (char *)(&pMod[1]);
strcpy(zCopy, zName);
pMod->zName = zCopy;
pMod->pModule = pModule;
pMod->pAux = pAux;
pMod = (Module *)sqlite3HashInsert(&db->aModule, zCopy, nName, (void*)pMod);
sqliteFree(pMod);
sqlite3ResetInternalSchema(db, 0);
}
return sqlite3ApiExit(db, SQLITE_OK);
}
/*
** Lock the virtual table so that it cannot be disconnected.
** Locks nest. Every lock should have a corresponding unlock.
** If an unlock is omitted, resources leaks will occur.
**
** If a disconnect is attempted while a virtual table is locked,
** the disconnect is deferred until all locks have been removed.
*/
void sqlite3VtabLock(sqlite3_vtab *pVtab){
pVtab->nRef++;
}
/*
** Unlock a virtual table. When the last lock is removed,
** disconnect the virtual table.
*/
void sqlite3VtabUnlock(sqlite3_vtab *pVtab){
pVtab->nRef--;
if( pVtab->nRef==0 ){
pVtab->pModule->xDisconnect(pVtab);
}
}
/*
** Clear any and all virtual-table information from the Table record.
** This routine is called, for example, just before deleting the Table
** record.
*/
void sqlite3VtabClear(Table *p){
sqlite3_vtab *pVtab = p->pVtab;
if( pVtab ){
assert( p->pMod && p->pMod->pModule );
sqlite3VtabUnlock(pVtab);
p->pVtab = 0;
}
if( p->azModuleArg ){
int i;
for(i=0; i<p->nModuleArg; i++){
sqliteFree(p->azModuleArg[i]);
}
sqliteFree(p->azModuleArg);
}
}
/*
** Add a new module argument to pTable->azModuleArg[].
** The string is not copied - the pointer is stored. The
** string will be freed automatically when the table is
** deleted.
*/
static void addModuleArgument(Table *pTable, char *zArg){
int i = pTable->nModuleArg++;
int nBytes = sizeof(char *)*(1+pTable->nModuleArg);
char **azModuleArg;
azModuleArg = sqliteRealloc(pTable->azModuleArg, nBytes);
if( azModuleArg==0 ){
int j;
for(j=0; j<i; j++){
sqliteFree(pTable->azModuleArg[j]);
}
sqliteFree(zArg);
sqliteFree(pTable->azModuleArg);
pTable->nModuleArg = 0;
}else{
azModuleArg[i] = zArg;
azModuleArg[i+1] = 0;
}
pTable->azModuleArg = azModuleArg;
}
/*
** The parser calls this routine when it first sees a CREATE VIRTUAL TABLE
** statement. The module name has been parsed, but the optional list
** of parameters that follow the module name are still pending.
*/
void sqlite3VtabBeginParse(
Parse *pParse, /* Parsing context */
Token *pName1, /* Name of new table, or database name */
Token *pName2, /* Name of new table or NULL */
Token *pModuleName /* Name of the module for the virtual table */
){
int iDb; /* The database the table is being created in */
Table *pTable; /* The new virtual table */
sqlite3StartTable(pParse, pName1, pName2, 0, 0, 1, 0);
pTable = pParse->pNewTable;
if( pTable==0 || pParse->nErr ) return;
assert( 0==pTable->pIndex );
iDb = sqlite3SchemaToIndex(pParse->db, pTable->pSchema);
assert( iDb>=0 );
pTable->isVirtual = 1;
pTable->nModuleArg = 0;
addModuleArgument(pTable, sqlite3NameFromToken(pModuleName));
addModuleArgument(pTable, sqlite3StrDup(pParse->db->aDb[iDb].zName));
addModuleArgument(pTable, sqlite3StrDup(pTable->zName));
pParse->sNameToken.n = pModuleName->z + pModuleName->n - pName1->z;
#ifndef SQLITE_OMIT_AUTHORIZATION
/* Creating a virtual table invokes the authorization callback twice.
** The first invocation, to obtain permission to INSERT a row into the
** sqlite_master table, has already been made by sqlite3StartTable().
** The second call, to obtain permission to create the table, is made now.
*/
if( pTable->azModuleArg ){
sqlite3AuthCheck(pParse, SQLITE_CREATE_VTABLE, pTable->zName,
pTable->azModuleArg[0], pParse->db->aDb[iDb].zName);
}
#endif
}
/*
** This routine takes the module argument that has been accumulating
** in pParse->zArg[] and appends it to the list of arguments on the
** virtual table currently under construction in pParse->pTable.
*/
static void addArgumentToVtab(Parse *pParse){
if( pParse->sArg.z && pParse->pNewTable ){
const char *z = (const char*)pParse->sArg.z;
int n = pParse->sArg.n;
addModuleArgument(pParse->pNewTable, sqliteStrNDup(z, n));
}
}
/*
** The parser calls this routine after the CREATE VIRTUAL TABLE statement
** has been completely parsed.
*/
void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){
Table *pTab; /* The table being constructed */
sqlite3 *db; /* The database connection */
char *zModule; /* The module name of the table: USING modulename */
Module *pMod = 0;
addArgumentToVtab(pParse);
pParse->sArg.z = 0;
/* Lookup the module name. */
pTab = pParse->pNewTable;
if( pTab==0 ) return;
db = pParse->db;
if( pTab->nModuleArg<1 ) return;
zModule = pTab->azModuleArg[0];
pMod = (Module *)sqlite3HashFind(&db->aModule, zModule, strlen(zModule));
pTab->pMod = pMod;
/* If the CREATE VIRTUAL TABLE statement is being entered for the
** first time (in other words if the virtual table is actually being
** created now instead of just being read out of sqlite_master) then
** do additional initialization work and store the statement text
** in the sqlite_master table.
*/
if( !db->init.busy ){
char *zStmt;
char *zWhere;
int iDb;
Vdbe *v;
/* Compute the complete text of the CREATE VIRTUAL TABLE statement */
if( pEnd ){
pParse->sNameToken.n = pEnd->z - pParse->sNameToken.z + pEnd->n;
}
zStmt = sqlite3MPrintf("CREATE VIRTUAL TABLE %T", &pParse->sNameToken);
/* A slot for the record has already been allocated in the
** SQLITE_MASTER table. We just need to update that slot with all
** the information we've collected.
**
** The top of the stack is the rootpage allocated by sqlite3StartTable().
** This value is always 0 and is ignored, a virtual table does not have a
** rootpage. The next entry on the stack is the rowid of the record
** in the sqlite_master table.
*/
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
sqlite3NestedParse(pParse,
"UPDATE %Q.%s "
"SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q "
"WHERE rowid=#1",
db->aDb[iDb].zName, SCHEMA_TABLE(iDb),
pTab->zName,
pTab->zName,
zStmt
);
sqliteFree(zStmt);
v = sqlite3GetVdbe(pParse);
sqlite3ChangeCookie(db, v, iDb);
sqlite3VdbeAddOp(v, OP_Expire, 0, 0);
zWhere = sqlite3MPrintf("name='%q'", pTab->zName);
sqlite3VdbeOp3(v, OP_ParseSchema, iDb, 1, zWhere, P3_DYNAMIC);
sqlite3VdbeOp3(v, OP_VCreate, iDb, 0, pTab->zName, strlen(pTab->zName) + 1);
}
/* If we are rereading the sqlite_master table create the in-memory
** record of the table. If the module has already been registered,
** also call the xConnect method here.
*/
else {
Table *pOld;
Schema *pSchema = pTab->pSchema;
const char *zName = pTab->zName;
int nName = strlen(zName) + 1;
pOld = sqlite3HashInsert(&pSchema->tblHash, zName, nName, pTab);
if( pOld ){
assert( pTab==pOld ); /* Malloc must have failed inside HashInsert() */
return;
}
pParse->pNewTable = 0;
}
}
/*
** The parser calls this routine when it sees the first token
** of an argument to the module name in a CREATE VIRTUAL TABLE statement.
*/
void sqlite3VtabArgInit(Parse *pParse){
addArgumentToVtab(pParse);
pParse->sArg.z = 0;
pParse->sArg.n = 0;
}
/*
** The parser calls this routine for each token after the first token
** in an argument to the module name in a CREATE VIRTUAL TABLE statement.
*/
void sqlite3VtabArgExtend(Parse *pParse, Token *p){
Token *pArg = &pParse->sArg;
if( pArg->z==0 ){
pArg->z = p->z;
pArg->n = p->n;
}else{
assert(pArg->z < p->z);
pArg->n = (p->z + p->n - pArg->z);
}
}
/*
** Invoke a virtual table constructor (either xCreate or xConnect). The
** pointer to the function to invoke is passed as the fourth parameter
** to this procedure.
*/
static int vtabCallConstructor(
sqlite3 *db,
Table *pTab,
Module *pMod,
int (*xConstruct)(sqlite3*,void*,int,const char*const*,sqlite3_vtab**,char**),
char **pzErr
){
int rc;
int rc2;
sqlite3_vtab *pVtab;
const char *const*azArg = (const char *const*)pTab->azModuleArg;
int nArg = pTab->nModuleArg;
char *zErr = 0;
char *zModuleName = sqlite3MPrintf("%s", pTab->zName);
assert( !db->pVTab );
assert( xConstruct );
db->pVTab = pTab;
rc = sqlite3SafetyOff(db);
assert( rc==SQLITE_OK );
rc = xConstruct(db, pMod->pAux, nArg, azArg, &pTab->pVtab, &zErr);
rc2 = sqlite3SafetyOn(db);
pVtab = pTab->pVtab;
if( rc==SQLITE_OK && pVtab ){
pVtab->pModule = pMod->pModule;
pVtab->nRef = 1;
}
if( SQLITE_OK!=rc ){
if( zErr==0 ){
*pzErr = sqlite3MPrintf("vtable constructor failed: %s", zModuleName);
}else {
*pzErr = sqlite3MPrintf("%s", zErr);
sqlite3_free(zErr);
}
}else if( db->pVTab ){
const char *zFormat = "vtable constructor did not declare schema: %s";
*pzErr = sqlite3MPrintf(zFormat, pTab->zName);
rc = SQLITE_ERROR;
}
if( rc==SQLITE_OK ){
rc = rc2;
}
db->pVTab = 0;
sqliteFree(zModuleName);
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->isVirtual || 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);
}
sqliteFree(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 = sqliteRealloc((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 sqliteFree() 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->isVirtual && !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("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 = db->pVTab;
char *zErr = 0;
if( !pTab ){
sqlite3Error(db, SQLITE_MISUSE, 0);
return SQLITE_MISUSE;
}
assert(pTab->isVirtual && 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->isVirtual
){
pTab->aCol = sParse.pNewTable->aCol;
pTab->nCol = sParse.pNewTable->nCol;
sParse.pNewTable->nCol = 0;
sParse.pNewTable->aCol = 0;
} else {
sqlite3Error(db, SQLITE_ERROR, zErr);
sqliteFree(zErr);
rc = SQLITE_ERROR;
}
sParse.declareVtab = 0;
sqlite3_finalize((sqlite3_stmt*)sParse.pVdbe);
sqlite3DeleteTable(0, sParse.pNewTable);
sParse.pNewTable = 0;
db->pVTab = 0;
assert( (rc&0xff)==rc );
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);
}
sqlite3SafetyOn(db);
if( rc==SQLITE_OK ){
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;
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(pVtab);
}
sqliteFree(db->aVTrans);
db->nVTrans = 0;
db->aVTrans = 0;
}
/*
** If argument rc2 is not SQLITE_OK, then return it and do nothing.
** Otherwise, 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.
*/
int sqlite3VtabSync(sqlite3 *db, int rc2){
int i;
int rc = SQLITE_OK;
int rcsafety;
sqlite3_vtab **aVTrans = db->aVTrans;
if( rc2!=SQLITE_OK ) return rc2;
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);
}
}
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, (int)(intptr_t)(&((sqlite3_module *)0)->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, (int)(intptr_t)(&((sqlite3_module *)0)->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( 0==db->aVTrans && db->nVTrans>0 ){
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 ){
return rc;
}
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(
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;
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->isVirtual ) 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 xFuncFunction method on the virtual table implementation
** to see if the implementation wants to overload this function
*/
zLowerName = sqlite3StrDup(pDef->zName);
for(z=(unsigned char*)zLowerName; *z; z++){
*z = sqlite3UpperToLower[*z];
}
rc = pMod->xFindFunction(pVtab, nArg, zLowerName, &xFunc, &pArg);
sqliteFree(zLowerName);
if( rc==0 ){
return pDef;
}
/* Create a new ephemeral function definition for the overloaded
** function */
pNew = sqliteMalloc( sizeof(*pNew) + strlen(pDef->zName) );
if( pNew==0 ){
return pDef;
}
*pNew = *pDef;
strcpy(pNew->zName, pDef->zName);
pNew->xFunc = xFunc;
pNew->pUserData = pArg;
pNew->flags |= SQLITE_FUNC_EPHEM;
return pNew;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
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