/*

** 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 1.31 2006/09/02 20:57:52 drh Exp $

*/

#ifndef SQLITE_OMIT_VIRTUALTABLE

#include "sqliteInt.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, 0, 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, char **, sqlite3_vtab **),

  char **pzErr

){

  int rc;

  int rc2;

  char **azArg = pTab->azModuleArg;

  int nArg = pTab->nModuleArg;

  char *zErr = sqlite3MPrintf("vtable constructor failed: %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);

  rc2 = sqlite3SafetyOn(db);

  if( rc==SQLITE_OK && pTab->pVtab ){

    pTab->pVtab->pModule = pMod->pModule;

    pTab->pVtab->nRef = 1;

  }

  if( SQLITE_OK!=rc ){

    *pzErr = zErr;

    zErr = 0;

  } 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(zErr);

  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;

  const char *zModule;

  int rc = SQLITE_OK;

  if( !pTab || !pTab->isVirtual || pTab->pVtab ){

    return SQLITE_OK;

  }

  pMod = pTab->pMod;

  zModule = pTab->azModuleArg[0];

  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;

  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){