prepare.c

一个小型嵌入式数据库SQLite的源码,C语言

    sqlite3SafetyOff(db);
    rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);
    if( rc==SQLITE_ABORT ) rc = initData.rc;
    sqlite3SafetyOn(db);
    sqliteFree(zSql);
#ifndef SQLITE_OMIT_ANALYZE
    if( rc==SQLITE_OK ){
      sqlite3AnalysisLoad(db, iDb);
    }
#endif
    sqlite3BtreeCloseCursor(curMain);
  }
  if( sqlite3MallocFailed() ){
    /* sqlite3SetString(pzErrMsg, "out of memory", (char*)0); */
    rc = SQLITE_NOMEM;
    sqlite3ResetInternalSchema(db, 0);
  }
  if( rc==SQLITE_OK ){
    DbSetProperty(db, iDb, DB_SchemaLoaded);
  }else{
    sqlite3ResetInternalSchema(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 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 called_initone = 0;
  
  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);
    }
    called_initone = 1;
  }

  /* 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);
    }
    called_initone = 1;
  }
#endif

  db->init.busy = 0;
  if( rc==SQLITE_OK && called_initone ){
    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;
  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;

  for(iDb=0; allOk && iDb<db->nDb; iDb++){
    Btree *pBt;
    pBt = db->aDb[iDb].pBt;
    if( pBt==0 ) continue;
    rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 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);
    }
  }
  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).
  */
  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.
*/
int sqlite3_prepare(
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */
  int nBytes,               /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  const char** pzTail       /* OUT: End of parsed string */
){
  Parse sParse;
  char *zErrMsg = 0;
  int rc = SQLITE_OK;
  int i;

  /* Assert that malloc() has not failed */
  assert( !sqlite3MallocFailed() );

  assert( ppStmt );
  *ppStmt = 0;
  if( sqlite3SafetyOn(db) ){
    return SQLITE_MISUSE;
  }

  /* If any attached database schemas are locked, do not proceed with
  ** compilation. Instead return SQLITE_LOCKED immediately.
  */
  for(i=0; i<db->nDb; i++) {
    Btree *pBt = db->aDb[i].pBt;
    if( pBt && sqlite3BtreeSchemaLocked(pBt) ){
      const char *zDb = db->aDb[i].zName;
      sqlite3Error(db, SQLITE_LOCKED, "database schema is locked: %s", zDb);
      sqlite3SafetyOff(db);
      return SQLITE_LOCKED;
    }
  }
  
  memset(&sParse, 0, sizeof(sParse));
  sParse.db = db;
  if( nBytes>=0 && zSql[nBytes]!=0 ){
    char *zSqlCopy = sqlite3StrNDup(zSql, nBytes);
    sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);
    sParse.zTail += zSql - zSqlCopy;
    sqliteFree(zSqlCopy);
  }else{
    sqlite3RunParser(&sParse, zSql, &zErrMsg);
  }

  if( sqlite3MallocFailed() ){
    sParse.rc = SQLITE_NOMEM;
  }
  if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
  if( sParse.checkSchema && !schemaIsValid(db) ){
    sParse.rc = SQLITE_SCHEMA;
  }
  if( sParse.rc==SQLITE_SCHEMA ){
    sqlite3ResetInternalSchema(db, 0);
  }
  if( sqlite3MallocFailed() ){
    sParse.rc = SQLITE_NOMEM;
  }
  if( pzTail ) *pzTail = sParse.zTail;
  rc = sParse.rc;

#ifndef SQLITE_OMIT_EXPLAIN
  if( rc==SQLITE_OK && sParse.pVdbe && sParse.explain ){
    if( sParse.explain==2 ){
      sqlite3VdbeSetNumCols(sParse.pVdbe, 3);
      sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "order", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "from", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "detail", P3_STATIC);
    }else{
      sqlite3VdbeSetNumCols(sParse.pVdbe, 5);
      sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "addr", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "opcode", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "p1", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 3, COLNAME_NAME, "p2", P3_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 4, COLNAME_NAME, "p3", P3_STATIC);
    }
  } 
#endif

  if( sqlite3SafetyOff(db) ){
    rc = SQLITE_MISUSE;
  }
  if( rc==SQLITE_OK ){
    *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
  }else if( sParse.pVdbe ){
    sqlite3_finalize((sqlite3_stmt*)sParse.pVdbe);
  }

  if( zErrMsg ){
    sqlite3Error(db, rc, "%s", zErrMsg);
    sqliteFree(zErrMsg);
  }else{
    sqlite3Error(db, rc, 0);
  }

  rc = sqlite3ApiExit(db, rc);
  sqlite3ReleaseThreadData();
  assert( (rc&db->errMask)==rc );
  return rc;
}

#ifndef SQLITE_OMIT_UTF16
/*
** Compile the UTF-16 encoded SQL statement zSql into a statement handle.
*/
int sqlite3_prepare16(
  sqlite3 *db,              /* Database handle. */ 
  const void *zSql,         /* UTF-8 encoded SQL statement. */
  int nBytes,               /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  const void **pzTail       /* OUT: End of parsed string */
){
  /* This function currently works by first transforming the UTF-16
  ** encoded string to UTF-8, then invoking sqlite3_prepare(). The
  ** tricky bit is figuring out the pointer to return in *pzTail.
  */
  char *zSql8;
  const char *zTail8 = 0;
  int rc = SQLITE_OK;

  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }
  zSql8 = sqlite3utf16to8(zSql, nBytes);
  if( zSql8 ){
    rc = sqlite3_prepare(db, zSql8, -1, ppStmt, &zTail8);
  }

  if( zTail8 && pzTail ){
    /* If sqlite3_prepare returns a tail pointer, we calculate the
    ** equivalent pointer into the UTF-16 string by counting the unicode
    ** characters between zSql8 and zTail8, and then returning a pointer
    ** the same number of characters into the UTF-16 string.
    */
    int chars_parsed = sqlite3utf8CharLen(zSql8, zTail8-zSql8);
    *pzTail = (u8 *)zSql + sqlite3utf16ByteLen(zSql, chars_parsed);
  }
  sqliteFree(zSql8); 
  return sqlite3ApiExit(db, rc);
}
#endif /* SQLITE_OMIT_UTF16 */