/*

** 2005 May 25

**

** 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 the implementation of the sqlite3_prepare()

** interface, and routines that contribute to loading the database schema

** from disk.

**

** $Id: prepare.c,v 1.97 2008/09/08 09:06:19 danielk1977 Exp $

*/

#include "sqliteInt.h"

#include <ctype.h>

/*

** Fill the InitData structure with an error message that indicates

** that the database is corrupt.

*/

static void corruptSchema(

  InitData *pData,     /* Initialization context */

  const char *zObj,    /* Object being parsed at the point of error */

  const char *zExtra   /* Error information */

){

  sqlite3 *db = pData->db;

  if( !db->mallocFailed && (db->flags & SQLITE_RecoveryMode)==0 ){

    if( zObj==0 ) zObj = "?";

    sqlite3SetString(pData->pzErrMsg, pData->db,

       "malformed database schema (%s)", zObj);

    if( zExtra && zExtra[0] ){

      *pData->pzErrMsg = sqlite3MAppendf(pData->db, *pData->pzErrMsg, "%s - %s",

                                  *pData->pzErrMsg, zExtra);

    }

  }

  pData->rc = SQLITE_CORRUPT;

}

/*

** This is the callback routine for the code that initializes the

** database.  See sqlite3Init() below for additional information.

** This routine is also called from the OP_ParseSchema opcode of the VDBE.

**

** Each callback contains the following information:

**

**     argv[0] = name of thing being created

**     argv[1] = root page number for table or index. 0 for trigger or view.

**     argv[2] = SQL text for the CREATE statement.

**

*/

int sqlite3InitCallback(void *pInit, int argc, char **argv, char **azColName){

  InitData *pData = (InitData*)pInit;

  sqlite3 *db = pData->db;

  int iDb = pData->iDb;

  assert( sqlite3_mutex_held(db->mutex) );

  DbClearProperty(db, iDb, DB_Empty);

  if( db->mallocFailed ){

    corruptSchema(pData, argv[0], 0);

    return SQLITE_NOMEM;

  }

  assert( argc==3 );

  assert( iDb>=0 && iDb<db->nDb );

  if( argv==0 ) return 0;   /* Might happen if EMPTY_RESULT_CALLBACKS are on */

  if( argv[1]==0 ){

    corruptSchema(pData, argv[0], 0);

  }else if( argv[2] && argv[2][0] ){

    /* Call the parser to process a CREATE TABLE, INDEX or VIEW.

    ** But because db->init.busy is set to 1, no VDBE code is generated

    ** or executed.  All the parser does is build the internal data

    ** structures that describe the table, index, or view.

    */

    char *zErr;

    int rc;

    u8 lookasideEnabled;

    assert( db->init.busy );

    db->init.iDb = iDb;

    db->init.newTnum = atoi(argv[1]);

    lookasideEnabled = db->lookaside.bEnabled;

    db->lookaside.bEnabled = 0;

    rc = sqlite3_exec(db, argv[2], 0, 0, &zErr);

    db->init.iDb = 0;

    db->lookaside.bEnabled = lookasideEnabled;

    assert( rc!=SQLITE_OK || zErr==0 );

    if( SQLITE_OK!=rc ){

      pData->rc = rc;

      if( rc==SQLITE_NOMEM ){

        db->mallocFailed = 1;

      }else if( rc!=SQLITE_INTERRUPT ){

        corruptSchema(pData, argv[0], zErr);

      }

      sqlite3DbFree(db, zErr);

    }

  }else if( argv[0]==0 ){

    corruptSchema(pData, 0, 0);

  }else{

    /* If the SQL column is blank it means this is an index that

    ** was created to be the PRIMARY KEY or to fulfill a UNIQUE

    ** constraint for a CREATE TABLE.  The index should have already

    ** been created when we processed the CREATE TABLE.  All we have

    ** to do here is record the root page number for that index.

    */

    Index *pIndex;

    pIndex = sqlite3FindIndex(db, argv[0], db->aDb[iDb].zName);

    if( pIndex==0 || pIndex->tnum!=0 ){

      /* This can occur if there exists an index on a TEMP table which

      ** has the same name as another index on a permanent index.  Since

      ** the permanent table is hidden by the TEMP table, we can also

      ** safely ignore the index on the permanent table.

      */

      /* Do Nothing */;

    }else{

      pIndex->tnum = atoi(argv[1]);

    }

  }

  return 0;

}

/*

** Attempt to read the database schema and initialize internal

** data structures for a single database file.  The index of the

** database file is given by iDb.  iDb==0 is used for the main

** database.  iDb==1 should never be used.  iDb>=2 is used for

** auxiliary databases.  Return one of the SQLITE_ error codes to

** indicate success or failure.

*/

static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){

  int rc;

  BtCursor *curMain;

  int size;

  Table *pTab;

  Db *pDb;

  char const *azArg[4];

  int meta[10];

  InitData initData;

  char const *zMasterSchema;

  char const *zMasterName = SCHEMA_TABLE(iDb);

  /*

  ** The master database table has a structure like this

  */

  static const char master_schema[] = 

     "CREATE TABLE sqlite_master(\n"

     "  type text,\n"

     "  name text,\n"

     "  tbl_name text,\n"

     "  rootpage integer,\n"

     "  sql text\n"

     ")"

  ;

#ifndef SQLITE_OMIT_TEMPDB

  static const char temp_master_schema[] = 

     "CREATE TEMP TABLE sqlite_temp_master(\n"

     "  type text,\n"

     "  name text,\n"

     "  tbl_name text,\n"

     "  rootpage integer,\n"

     "  sql text\n"

     ")"

  ;

#else

  #define temp_master_schema 0

#endif

  assert( iDb>=0 && iDb<db->nDb );

  assert( db->aDb[iDb].pSchema );

  assert( sqlite3_mutex_held(db->mutex) );

  assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

  /* zMasterSchema and zInitScript are set to point at the master schema

  ** and initialisation script appropriate for the database being

  ** initialised. zMasterName is the name of the master table.

  */

  if( !OMIT_TEMPDB && iDb==1 ){

    zMasterSchema = temp_master_schema;

  }else{

    zMasterSchema = master_schema;

  }

  zMasterName = SCHEMA_TABLE(iDb);

  /* Construct the schema tables.  */

  azArg[0] = zMasterName;

  azArg[1] = "1";

  azArg[2] = zMasterSchema;

  azArg[3] = 0;

  initData.db = db;

  initData.iDb = iDb;

  initData.rc = SQLITE_OK;

  initData.pzErrMsg = pzErrMsg;

  (void)sqlite3SafetyOff(db);

  sqlite3InitCallback(&initData, 3, (char **)azArg, 0);

  (void)sqlite3SafetyOn(db);

  if( initData.rc ){

    rc = initData.rc;

    goto error_out;

  }

  pTab = sqlite3FindTable(db, zMasterName, db->aDb[iDb].zName);

  if( pTab ){

    pTab->tabFlags |= TF_Readonly;

  }

  /* Create a cursor to hold the database open

  */

  pDb = &db->aDb[iDb];

  if( pDb->pBt==0 ){

    if( !OMIT_TEMPDB && iDb==1 ){

      DbSetProperty(db, 1, DB_SchemaLoaded);

    }

    return SQLITE_OK;

  }

  curMain = sqlite3MallocZero(sqlite3BtreeCursorSize());

  if( !curMain ){

    rc = SQLITE_NOMEM;

    goto error_out;

  }

  sqlite3BtreeEnter(pDb->pBt);

  rc = sqlite3BtreeCursor(pDb->pBt, MASTER_ROOT, 0, 0, curMain);

  if( rc!=SQLITE_OK && rc!=SQLITE_EMPTY ){

    sqlite3SetString(pzErrMsg, db, "%s", sqlite3ErrStr(rc));

    goto initone_error_out;

  }

  /* Get the database meta information.

  **

  ** Meta values are as follows:

  **    meta[0]   Schema cookie.  Changes with each schema change.

  **    meta[1]   File format of schema layer.

  **    meta[2]   Size of the page cache.

  **    meta[3]   Use freelist if 0.  Autovacuum if greater than zero.

  **    meta[4]   Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE

  **    meta[5]   The user cookie. Used by the application.

  **    meta[6]   Incremental-vacuum flag.

  **    meta[7]

  **    meta[8]

  **    meta[9]

  **

  ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to

  ** the possible values of meta[4].

  */

  if( rc==SQLITE_OK ){

    int i;

    for(i=0; i<sizeof(meta)/sizeof(meta[0]); i++){

      rc = sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]);

      if( rc ){

        sqlite3SetString(pzErrMsg, db, "%s", sqlite3ErrStr(rc));

        goto initone_error_out;

      }

    }

  }else{

    memset(meta, 0, sizeof(meta));

  }

  pDb->pSchema->schema_cookie = meta[0];

  /* If opening a non-empty database, check the text encoding. For the

  ** main database, set sqlite3.enc to the encoding of the main database.

  ** For an attached db, it is an error if the encoding is not the same

  ** as sqlite3.enc.

  */

  if( meta[4] ){  /* text encoding */

    if( iDb==0 ){

      /* If opening the main database, set ENC(db). */

      ENC(db) = (u8)meta[4];

      db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, "BINARY", 6, 0);

    }else{

      /* If opening an attached database, the encoding much match ENC(db) */

      if( meta[4]!=ENC(db) ){

        sqlite3SetString(pzErrMsg, db, "attached databases must use the same"

            " text encoding as main database");

        rc = SQLITE_ERROR;

        goto initone_error_out;

      }

    }

  }else{

    DbSetProperty(db, iDb, DB_Empty);

  }

  pDb->pSchema->enc = ENC(db);

  if( pDb->pSchema->cache_size==0 ){

    size = meta[2];

    if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }

    if( size<0 ) size = -size;

    pDb->pSchema->cache_size = size;

    sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);

  }

  /*

  ** file_format==1    Version 3.0.0.

  ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN

  ** file_format==3    Version 3.1.4.  // ditto but with non-NULL defaults

  ** file_format==4    Version 3.3.0.  // DESC indices.  Boolean constants

  */

  pDb->pSchema->file_format = meta[1];

  if( pDb->pSchema->file_format==0 ){

    pDb->pSchema->file_format = 1;

  }

  if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){

    sqlite3SetString(pzErrMsg, db, "unsupported file format");

    rc = SQLITE_ERROR;

    goto initone_error_out;

  }

  /* Ticket #2804:  When we open a database in the newer file format,

  ** clear the legacy_file_format pragma flag so that a VACUUM will

  ** not downgrade the database and thus invalidate any descending

  ** indices that the user might have created.

  */

  if( iDb==0 && meta[1]>=4 ){

    db->flags &= ~SQLITE_LegacyFileFmt;

  }

  /* Read the schema information out of the schema tables

  */

  assert( db->init.busy );

  if( rc==SQLITE_EMPTY ){

    /* For an empty database, there is nothing to read */

    rc = SQLITE_OK;

  }else{

    char *zSql;

    zSql = sqlite3MPrintf(db, 

        "SELECT name, rootpage, sql FROM '%q'.%s",

        db->aDb[iDb].zName, zMasterName);

    (void)sqlite3SafetyOff(db);

#ifndef SQLITE_OMIT_AUTHORIZATION

    {

      int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);

      xAuth = db->xAuth;

      db->xAuth = 0;

#endif

      rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);

#ifndef SQLITE_OMIT_AUTHORIZATION

      db->xAuth = xAuth;

    }

#endif

    if( rc==SQLITE_OK ) rc = initData.rc;

    (void)sqlite3SafetyOn(db);

    sqlite3DbFree(db, zSql);

#ifndef SQLITE_OMIT_ANALYZE

    if( rc==SQLITE_OK ){

      sqlite3AnalysisLoad(db, iDb);

    }

#endif

  }

  if( db->mallocFailed ){

    rc = SQLITE_NOMEM;

    sqlite3ResetInternalSchema(db, 0);

  }

  if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){

    /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider

    ** the schema loaded, even if errors occured. In this situation the 

    ** current sqlite3_prepare() operation will fail, but the following one

    ** will attempt to compile the supplied statement against whatever subset

    ** of the schema was loaded before the error occured. The primary

    ** purpose of this is to allow access to the sqlite_master table

    ** even when its contents have been corrupted.

    */

    DbSetProperty(db, iDb, DB_SchemaLoaded);

    rc = SQLITE_OK;

  }

  /* Jump here for an error that occurs after successfully allocating

  ** curMain and calling sqlite3BtreeEnter(). For an error that occurs

  ** before that point, jump to error_out.

  */

initone_error_out:

  sqlite3BtreeCloseCursor(curMain);

  sqlite3_free(curMain);

  sqlite3BtreeLeave(pDb->pBt);

error_out:

  if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){

    db->mallocFailed = 1;

  }

  return rc;

}

/*

** Initialize all database files - the main database file, the file

** used to store temporary tables, and any additional database files

** created using ATTACH statements.  Return a success code.  If an

** error occurs, write an error message into *pzErrMsg.

**

** After a database is initialized, the DB_SchemaLoaded bit is set

** bit is set in the flags field of the Db structure. If the database

** file was of zero-length, then the DB_Empty flag is also set.

*/

int sqlite3Init(sqlite3 *db, char **pzErrMsg){

  int i, rc;

  int commit_internal = !(db->flags&SQLITE_InternChanges);

  assert( sqlite3_mutex_held(db->mutex) );

  if( db->init.busy ) return SQLITE_OK;

  rc = SQLITE_OK;

  db->init.busy = 1;

  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){

    if( DbHasProperty(db, i, DB_SchemaLoaded) || i==1 ) continue;

    rc = sqlite3InitOne(db, i, pzErrMsg);

    if( rc ){

      sqlite3ResetInternalSchema(db, i);

    }

  }

  /* Once all the other databases have been initialised, load the schema

  ** for the TEMP database. This is loaded last, as the TEMP database

  ** schema may contain references to objects in other databases.

  */

#ifndef SQLITE_OMIT_TEMPDB

  if( rc==SQLITE_OK && db->nDb>1 && !DbHasProperty(db, 1, DB_SchemaLoaded) ){

    rc = sqlite3InitOne(db, 1, pzErrMsg);

    if( rc ){

      sqlite3ResetInternalSchema(db, 1);

    }

  }

#endif

  db->init.busy = 0;

  if( rc==SQLITE_OK && commit_internal ){

    sqlite3CommitInternalChanges(db);

  }

  return rc; 

}

/*

** This routine is a no-op if the database schema is already initialised.

** Otherwise, the schema is loaded. An error code is returned.

*/

int sqlite3ReadSchema(Parse *pParse){

  int rc = SQLITE_OK;

  sqlite3 *db = pParse->db;

  assert( sqlite3_mutex_held(db->mutex) );

  if( !db->init.busy ){

    rc = sqlite3Init(db, &pParse->zErrMsg);

  }

  if( rc!=SQLITE_OK ){

    pParse->rc = rc;

    pParse->nErr++;

  }

  return rc;

}

/*

** Check schema cookies in all databases.  If any cookie is out

** of date, return 0.  If all schema cookies are current, return 1.

*/

static int schemaIsValid(sqlite3 *db){

  int iDb;

  int rc;

  BtCursor *curTemp;

  int cookie;

  int allOk = 1;

  curTemp = (BtCursor *)sqlite3Malloc(sqlite3BtreeCursorSize());

  if( curTemp ){

    assert( sqlite3_mutex_held(db->mutex) );

    for(iDb=0; allOk && iDb<db->nDb; iDb++){

      Btree *pBt;

      pBt = db->aDb[iDb].pBt;

      if( pBt==0 ) continue;

      memset(curTemp, 0, sqlite3BtreeCursorSize());

      rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 0, curTemp);

      if( rc==SQLITE_OK ){

        rc = sqlite3BtreeGetMeta(pBt, 1, (u32 *)&cookie);

        if( rc==SQLITE_OK && cookie!=db->aDb[iDb].pSchema->schema_cookie ){

          allOk = 0;

        }

        sqlite3BtreeCloseCursor(curTemp);

      }

      if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){

        db->mallocFailed = 1;

      }

    }

    sqlite3_free(curTemp);

  }else{

    allOk = 0;

    db->mallocFailed = 1;

  }

  return allOk;

}

/*

** Convert a schema pointer into the iDb index that indicates

** which database file in db->aDb[] the schema refers to.

**

** If the same database is attached more than once, the first

** attached database is returned.

*/

int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){

  int i = -1000000;

  /* If pSchema is NULL, then return -1000000. This happens when code in 

  ** expr.c is trying to resolve a reference to a transient table (i.e. one

  ** created by a sub-select). In this case the return value of this 

  ** function should never be used.

  **

  ** We return -1000000 instead of the more usual -1 simply because using

  ** -1000000 as incorrectly using -1000000 index into db->aDb[] is much 

  ** more likely to cause a segfault than -1 (of course there are assert()

  ** statements too, but it never hurts to play the odds).

  */

  assert( sqlite3_mutex_held(db->mutex) );

  if( pSchema ){

    for(i=0; i<db->nDb; i++){

      if( db->aDb[i].pSchema==pSchema ){

        break;

      }

    }

    assert( i>=0 &&i>=0 &&  i<db->nDb );

  }

  return i;

}

/*

** Compile the UTF-8 encoded SQL statement zSql into a statement handle.

*/

static int sqlite3Prepare(

  sqlite3 *db,              /* Database handle. */

  const char *zSql,         /* UTF-8 encoded SQL statement. */

  int nBytes,               /* Length of zSql in bytes. */

  int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */

  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

  const char **pzTail       /* OUT: End of parsed string */

){