/*

** 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 1.74 2008/08/02 03:50:39 drh Exp $

*/

#ifndef SQLITE_OMIT_VIRTUALTABLE

#include "sqliteInt.h"

static int createModule(

  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 */

  void (*xDestroy)(void *)        /* Module destructor function */

) {

  int rc, nName;

  Module *pMod;

  sqlite3_mutex_enter(db->mutex);

  nName = strlen(zName);

  pMod = (Module *)sqlite3DbMallocRaw(db, sizeof(Module) + nName + 1);

  if( pMod ){

    Module *pDel;

    char *zCopy = (char *)(&pMod[1]);

    memcpy(zCopy, zName, nName+1);

    pMod->zName = zCopy;

    pMod->pModule = pModule;

    pMod->pAux = pAux;

    pMod->xDestroy = xDestroy;

    pDel = (Module *)sqlite3HashInsert(&db->aModule, zCopy, nName, (void*)pMod);

    if( pDel && pDel->xDestroy ){

      pDel->xDestroy(pDel->pAux);

    }

    sqlite3DbFree(db, pDel);

    if( pDel==pMod ){

      db->mallocFailed = 1;

    }

    sqlite3ResetInternalSchema(db, 0);

  }

  rc = sqlite3ApiExit(db, SQLITE_OK);

  sqlite3_mutex_leave(db->mutex);

  return rc;

}

/*

** 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 */

){

  return createModule(db, zName, pModule, pAux, 0);

}

/*

** External API function used to create a new virtual-table module.

*/

int sqlite3_create_module_v2(

  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 */

  void (*xDestroy)(void *)        /* Module destructor function */

){

  return createModule(db, zName, pModule, pAux, xDestroy);

}

/*

** 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 *db, sqlite3_vtab *pVtab){

  pVtab->nRef--;

  assert(db);

  assert( sqlite3SafetyCheckOk(db) );

  if( pVtab->nRef==0 ){

    if( db->magic==SQLITE_MAGIC_BUSY ){

      (void)sqlite3SafetyOff(db);

      pVtab->pModule->xDisconnect(pVtab);

      (void)sqlite3SafetyOn(db);

    } else {

      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;

  sqlite3 *db = p->db;

  if( pVtab ){

    assert( p->pMod && p->pMod->pModule );

    sqlite3VtabUnlock(db, pVtab);

    p->pVtab = 0;

  }

  if( p->azModuleArg ){

    int i;

    for(i=0; i<p->nModuleArg; i++){

      sqlite3DbFree(db, p->azModuleArg[i]);

    }

    sqlite3DbFree(db, 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(sqlite3 *db, Table *pTable, char *zArg){

  int i = pTable->nModuleArg++;

  int nBytes = sizeof(char *)*(1+pTable->nModuleArg);

  char **azModuleArg;

  azModuleArg = sqlite3DbRealloc(db, pTable->azModuleArg, nBytes);

  if( azModuleArg==0 ){

    int j;

    for(j=0; j<i; j++){

      sqlite3DbFree(db, pTable->azModuleArg[j]);

    }

    sqlite3DbFree(db, zArg);

    sqlite3DbFree(db, 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 */

  sqlite3 *db;          /* Database connection */

  if( pParse->db->flags & SQLITE_SharedCache ){

    sqlite3ErrorMsg(pParse, "Cannot use virtual tables in shared-cache mode");

    return;

  }

  sqlite3StartTable(pParse, pName1, pName2, 0, 0, 1, 0);

  pTable = pParse->pNewTable;

  if( pTable==0 || pParse->nErr ) return;

  assert( 0==pTable->pIndex );

  db = pParse->db;

  iDb = sqlite3SchemaToIndex(db, pTable->pSchema);

  assert( iDb>=0 );

  pTable->isVirtual = 1;

  pTable->nModuleArg = 0;

  addModuleArgument(db, pTable, sqlite3NameFromToken(db, pModuleName));

  addModuleArgument(db, pTable, sqlite3DbStrDup(db, db->aDb[iDb].zName));

  addModuleArgument(db, pTable, sqlite3DbStrDup(db, 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;

    sqlite3 *db = pParse->db;

    addModuleArgument(db, pParse->pNewTable, sqlite3DbStrNDup(db, 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(db, "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 VM register number pParse->regRowid holds the rowid of an

    ** entry in the sqlite_master table tht was created for this vtab

    ** by sqlite3StartTable().

    */

    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);

    sqlite3NestedParse(pParse,

      "UPDATE %Q.%s "

         "SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q "

       "WHERE rowid=#%d",

      db->aDb[iDb].zName, SCHEMA_TABLE(iDb),

      pTab->zName,

      pTab->zName,

      zStmt,

      pParse->regRowid

    );

    sqlite3DbFree(db, zStmt);

    v = sqlite3GetVdbe(pParse);

    sqlite3ChangeCookie(pParse, iDb);

    sqlite3VdbeAddOp2(v, OP_Expire, 0, 0);

    zWhere = sqlite3MPrintf(db, "name='%q'", pTab->zName);

    sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 1, 0, zWhere, P4_DYNAMIC);

    sqlite3VdbeAddOp4(v, OP_VCreate, iDb, 0, 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 ){

      db->mallocFailed = 1;

      assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */

      return;

    }

    pSchema->db = pParse->db;

    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 = 0;

  const char *const*azArg = (const char *const*)pTab->azModuleArg;

  int nArg = pTab->nModuleArg;

  char *zErr = 0;

  char *zModuleName = sqlite3MPrintf(db, "%s", pTab->zName);

  if( !zModuleName ){

    return SQLITE_NOMEM;

  }

  assert( !db->pVTab );

  assert( xConstruct );

  db->pVTab = pTab;

  rc = sqlite3SafetyOff(db);

  assert( rc==SQLITE_OK );

  rc = xConstruct(db, pMod->pAux, nArg, azArg, &pVtab, &zErr);

  rc2 = sqlite3SafetyOn(db);

  if( rc==SQLITE_OK && pVtab ){

    pVtab->pModule = pMod->pModule;

    pVtab->nRef = 1;

    pTab->pVtab = pVtab;

  }

  if( SQLITE_OK!=rc ){

    if( zErr==0 ){

      *pzErr = sqlite3MPrintf(db, "vtable constructor failed: %s", zModuleName);

    }else {

      *pzErr = sqlite3MPrintf(db, "%s", zErr);

      sqlite3DbFree(db, zErr);

    }

  }else if( db->pVTab ){

    const char *zFormat = "vtable constructor did not declare schema: %s";

    *pzErr = sqlite3MPrintf(db, zFormat, pTab->zName);

    rc = SQLITE_ERROR;

  } 

  if( rc==SQLITE_OK ){

    rc = rc2;

  }

  db->pVTab = 0;

  sqlite3DbFree(db, zModuleName);

  /* If everything went according to plan, loop through the columns

  ** of the table to see if any of them contain the token "hidden".

  ** If so, set the Column.isHidden flag and remove the token from

  ** the type string.

  */

  if( rc==SQLITE_OK ){

    int iCol;

    for(iCol=0; iCol<pTab->nCol; iCol++){

      char *zType = pTab->aCol[iCol].zType;

      int nType;

      int i = 0;

      if( !zType ) continue;

      nType = strlen(zType);

      if( sqlite3StrNICmp("hidden", zType, 6) || (zType[6] && zType[6]!=' ') ){

        for(i=0; i<nType; i++){

          if( (0==sqlite3StrNICmp(" hidden", &zType[i], 7))

           && (zType[i+7]=='\0' || zType[i+7]==' ')

          ){

            i++;

            break;

          }

        }

      }

      if( i<nType ){

        int j;

        int nDel = 6 + (zType[i+6] ? 1 : 0);

        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->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);

    }

    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->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(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;

}

/*