main.c

sqlite数据库管理系统开放源码

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.164.2.2 2004/06/26 14:40:05 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information
** from sqliteInit into the sqliteInitCallback.
*/
typedef struct {
  sqlite *db;         /* The database being initialized */
  char **pzErrMsg;    /* Error message stored here */
} InitData;

/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
static void corruptSchema(InitData *pData, const char *zExtra){
  sqliteSetString(pData->pzErrMsg, "malformed database schema",
     zExtra!=0 && zExtra[0]!=0 ? " - " : (char*)0, zExtra, (char*)0);
}

/*
** This is the callback routine for the code that initializes the
** database.  See sqliteInit() below for additional information.
**
** Each callback contains the following information:
**
**     argv[0] = "file-format" or "schema-cookie" or "table" or "index"
**     argv[1] = table or index name or meta statement type.
**     argv[2] = root page number for table or index.  NULL for meta.
**     argv[3] = SQL text for a CREATE TABLE or CREATE INDEX statement.
**     argv[4] = "1" for temporary files, "0" for main database, "2" or more
**               for auxiliary database files.
**
*/
static
int sqliteInitCallback(void *pInit, int argc, char **argv, char **azColName){
  InitData *pData = (InitData*)pInit;
  int nErr = 0;

  assert( argc==5 );
  if( argv==0 ) return 0;   /* Might happen if EMPTY_RESULT_CALLBACKS are on */
  if( argv[0]==0 ){
    corruptSchema(pData, 0);
    return 1;
  }
  switch( argv[0][0] ){
    case 'v':
    case 'i':
    case 't': {  /* CREATE TABLE, CREATE INDEX, or CREATE VIEW statements */
      sqlite *db = pData->db;
      if( argv[2]==0 || argv[4]==0 ){
        corruptSchema(pData, 0);
        return 1;
      }
      if( argv[3] && argv[3][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;
        assert( db->init.busy );
        db->init.iDb = atoi(argv[4]);
        assert( db->init.iDb>=0 && db->init.iDb<db->nDb );
        db->init.newTnum = atoi(argv[2]);
        if( sqlite_exec(db, argv[3], 0, 0, &zErr) ){
          corruptSchema(pData, zErr);
          sqlite_freemem(zErr);
        }
        db->init.iDb = 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.
        */
        int iDb;
        Index *pIndex;

        iDb = atoi(argv[4]);
        assert( iDb>=0 && iDb<db->nDb );
        pIndex = sqliteFindIndex(db, argv[1], 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[2]);
        }
      }
      break;
    }
    default: {
      /* This can not happen! */
      nErr = 1;
      assert( nErr==0 );
    }
  }
  return nErr;
}

/*
** This is a callback procedure used to reconstruct a table.  The
** name of the table to be reconstructed is passed in as argv[0].
**
** This routine is used to automatically upgrade a database from
** format version 1 or 2 to version 3.  The correct operation of
** this routine relys on the fact that no indices are used when
** copying a table out to a temporary file.
**
** The change from version 2 to version 3 occurred between SQLite
** version 2.5.6 and 2.6.0 on 2002-July-18.  
*/
static
int upgrade_3_callback(void *pInit, int argc, char **argv, char **NotUsed){
  InitData *pData = (InitData*)pInit;
  int rc;
  Table *pTab;
  Trigger *pTrig;
  char *zErr = 0;

  pTab = sqliteFindTable(pData->db, argv[0], 0);
  assert( pTab!=0 );
  assert( sqliteStrICmp(pTab->zName, argv[0])==0 );
  if( pTab ){
    pTrig = pTab->pTrigger;
    pTab->pTrigger = 0;  /* Disable all triggers before rebuilding the table */
  }
  rc = sqlite_exec_printf(pData->db,
    "CREATE TEMP TABLE sqlite_x AS SELECT * FROM '%q'; "
    "DELETE FROM '%q'; "
    "INSERT INTO '%q' SELECT * FROM sqlite_x; "
    "DROP TABLE sqlite_x;",
    0, 0, &zErr, argv[0], argv[0], argv[0]);
  if( zErr ){
    if( *pData->pzErrMsg ) sqlite_freemem(*pData->pzErrMsg);
    *pData->pzErrMsg = zErr;
  }

  /* If an error occurred in the SQL above, then the transaction will
  ** rollback which will delete the internal symbol tables.  This will
  ** cause the structure that pTab points to be deleted.  In case that
  ** happened, we need to refetch pTab.
  */
  pTab = sqliteFindTable(pData->db, argv[0], 0);
  if( pTab ){
    assert( sqliteStrICmp(pTab->zName, argv[0])==0 );
    pTab->pTrigger = pTrig;  /* Re-enable triggers */
  }
  return rc!=SQLITE_OK;
}



/*
** 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 sqliteInitOne(sqlite *db, int iDb, char **pzErrMsg){
  int rc;
  BtCursor *curMain;
  int size;
  Table *pTab;
  char const *azArg[6];
  char zDbNum[30];
  int meta[SQLITE_N_BTREE_META];
  InitData initData;
  char const *zMasterSchema;
  char const *zMasterName;
  char *zSql = 0;

  /*
  ** The master database table has a structure like this
  */
  static char master_schema[] = 
     "CREATE TABLE sqlite_master(\n"
     "  type text,\n"
     "  name text,\n"
     "  tbl_name text,\n"
     "  rootpage integer,\n"
     "  sql text\n"
     ")"
  ;
  static 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"
     ")"
  ;

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

  /* 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( iDb==1 ){
    zMasterSchema = temp_master_schema;
    zMasterName = TEMP_MASTER_NAME;
  }else{
    zMasterSchema = master_schema;
    zMasterName = MASTER_NAME;
  }

  /* Construct the schema table.
  */
  sqliteSafetyOff(db);
  azArg[0] = "table";
  azArg[1] = zMasterName;
  azArg[2] = "2";
  azArg[3] = zMasterSchema;
  sprintf(zDbNum, "%d", iDb);
  azArg[4] = zDbNum;
  azArg[5] = 0;
  initData.db = db;
  initData.pzErrMsg = pzErrMsg;
  sqliteInitCallback(&initData, 5, (char **)azArg, 0);
  pTab = sqliteFindTable(db, zMasterName, db->aDb[iDb].zName);
  if( pTab ){
    pTab->readOnly = 1;
  }else{
    return SQLITE_NOMEM;
  }
  sqliteSafetyOn(db);

  /* Create a cursor to hold the database open
  */
  if( db->aDb[iDb].pBt==0 ) return SQLITE_OK;
  rc = sqliteBtreeCursor(db->aDb[iDb].pBt, 2, 0, &curMain);
  if( rc ){
    sqliteSetString(pzErrMsg, sqlite_error_string(rc), (char*)0);
    return rc;
  }

  /* Get the database meta information
  */
  rc = sqliteBtreeGetMeta(db->aDb[iDb].pBt, meta);
  if( rc ){
    sqliteSetString(pzErrMsg, sqlite_error_string(rc), (char*)0);
    sqliteBtreeCloseCursor(curMain);
    return rc;
  }
  db->aDb[iDb].schema_cookie = meta[1];
  if( iDb==0 ){
    db->next_cookie = meta[1];
    db->file_format = meta[2];
    size = meta[3];
    if( size==0 ){ size = MAX_PAGES; }
    db->cache_size = size;
    db->safety_level = meta[4];
    if( meta[6]>0 && meta[6]<=2 && db->temp_store==0 ){
      db->temp_store = meta[6];
    }
    if( db->safety_level==0 ) db->safety_level = 2;

    /*
    **  file_format==1    Version 2.1.0.
    **  file_format==2    Version 2.2.0. Add support for INTEGER PRIMARY KEY.
    **  file_format==3    Version 2.6.0. Fix empty-string index bug.
    **  file_format==4    Version 2.7.0. Add support for separate numeric and
    **                    text datatypes.
    */
    if( db->file_format==0 ){
      /* This happens if the database was initially empty */
      db->file_format = 4;
    }else if( db->file_format>4 ){
      sqliteBtreeCloseCursor(curMain);
      sqliteSetString(pzErrMsg, "unsupported file format", (char*)0);
      return SQLITE_ERROR;
    }
  }else if( iDb!=1 && (db->file_format!=meta[2] || db->file_format<4) ){
    assert( db->file_format>=4 );
    if( meta[2]==0 ){
      sqliteSetString(pzErrMsg, "cannot attach empty database: ",
         db->aDb[iDb].zName, (char*)0);
    }else{
      sqliteSetString(pzErrMsg, "incompatible file format in auxiliary "
         "database: ", db->aDb[iDb].zName, (char*)0);
    }
    sqliteBtreeClose(db->aDb[iDb].pBt);
    db->aDb[iDb].pBt = 0;
    return SQLITE_FORMAT;
  }
  sqliteBtreeSetCacheSize(db->aDb[iDb].pBt, db->cache_size);
  sqliteBtreeSetSafetyLevel(db->aDb[iDb].pBt, meta[4]==0 ? 2 : meta[4]);

  /* Read the schema information out of the schema tables
  */
  assert( db->init.busy );
  sqliteSafetyOff(db);

  /* The following SQL will read the schema from the master tables.
  ** The first version works with SQLite file formats 2 or greater.
  ** The second version is for format 1 files.
  **
  ** Beginning with file format 2, the rowid for new table entries
  ** (including entries in sqlite_master) is an increasing integer.
  ** So for file format 2 and later, we can play back sqlite_master
  ** and all the CREATE statements will appear in the right order.
  ** But with file format 1, table entries were random and so we
  ** have to make sure the CREATE TABLEs occur before their corresponding
  ** CREATE INDEXs.  (We don't have to deal with CREATE VIEW or
  ** CREATE TRIGGER in file format 1 because those constructs did
  ** not exist then.) 
  */
  if( db->file_format>=2 ){
    sqliteSetString(&zSql, 
        "SELECT type, name, rootpage, sql, ", zDbNum, " FROM \"",
       db->aDb[iDb].zName, "\".", zMasterName, (char*)0);
  }else{
    sqliteSetString(&zSql, 
        "SELECT type, name, rootpage, sql, ", zDbNum, " FROM \"",
       db->aDb[iDb].zName, "\".", zMasterName, 
       " WHERE type IN ('table', 'index')"
       " ORDER BY CASE type WHEN 'table' THEN 0 ELSE 1 END", (char*)0);
  }
  rc = sqlite_exec(db, zSql, sqliteInitCallback, &initData, 0);

  sqliteFree(zSql);
  sqliteSafetyOn(db);
  sqliteBtreeCloseCursor(curMain);
  if( sqlite_malloc_failed ){
    sqliteSetString(pzErrMsg, "out of memory", (char*)0);
    rc = SQLITE_NOMEM;
    sqliteResetInternalSchema(db, 0);
  }
  if( rc==SQLITE_OK ){
    DbSetProperty(db, iDb, DB_SchemaLoaded);
  }else{
    sqliteResetInternalSchema(db, iDb);
  }
  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 the database is initialized, the SQLITE_Initialized
** bit is set in the flags field of the sqlite structure.  An
** attempt is made to initialize the database as soon as it
** is opened.  If that fails (perhaps because another process
** has the sqlite_master table locked) than another attempt
** is made the first time the database is accessed.
*/
int sqliteInit(sqlite *db, char **pzErrMsg){
  int i, rc;
  
  if( db->init.busy ) return SQLITE_OK;