/*

** 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: legacy.c,v 1.29 2008/08/02 03:50:39 drh Exp $

*/

#include "sqliteInt.h"

#include <ctype.h>

/*

** Execute SQL code.  Return one of the SQLITE_ success/failure

** codes.  Also write an error message into memory obtained from

** malloc() and make *pzErrMsg point to that message.

**

** If the SQL is a query, then for each row in the query result

** the xCallback() function is called.  pArg becomes the first

** argument to xCallback().  If xCallback=NULL then no callback

** is invoked, even for queries.

*/

int sqlite3_exec(

  sqlite3 *db,                /* The database on which the SQL executes */

  const char *zSql,           /* The SQL to be executed */

  sqlite3_callback xCallback, /* Invoke this callback routine */

  void *pArg,                 /* First argument to xCallback() */

  char **pzErrMsg             /* Write error messages here */

){

  int rc = SQLITE_OK;

  const char *zLeftover;

  sqlite3_stmt *pStmt = 0;

  char **azCols = 0;

  int nRetry = 0;

  int nCallback;

  if( zSql==0 ) zSql = "";

  sqlite3_mutex_enter(db->mutex);

  sqlite3Error(db, SQLITE_OK, 0);

  while( (rc==SQLITE_OK || (rc==SQLITE_SCHEMA && (++nRetry)<2)) && zSql[0] ){

    int nCol;

    char **azVals = 0;

    pStmt = 0;

    rc = sqlite3_prepare(db, zSql, -1, &pStmt, &zLeftover);

    assert( rc==SQLITE_OK || pStmt==0 );

    if( rc!=SQLITE_OK ){

      continue;

    }

    if( !pStmt ){

      /* this happens for a comment or white-space */

      zSql = zLeftover;

      continue;

    }

    nCallback = 0;

    nCol = sqlite3_column_count(pStmt);

    while( 1 ){

      int i;

      rc = sqlite3_step(pStmt);

      /* Invoke the callback function if required */

      if( xCallback && (SQLITE_ROW==rc || 

          (SQLITE_DONE==rc && !nCallback && db->flags&SQLITE_NullCallback)) ){

        if( 0==nCallback ){

          if( azCols==0 ){

            azCols = sqlite3DbMallocZero(db, 2*nCol*sizeof(const char*) + 1);

            if( azCols==0 ){

              goto exec_out;

            }

          }

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

            azCols[i] = (char *)sqlite3_column_name(pStmt, i);

            /* sqlite3VdbeSetColName() installs column names as UTF8

            ** strings so there is no way for sqlite3_column_name() to fail. */

            assert( azCols[i]!=0 );

          }

          nCallback++;

        }

        if( rc==SQLITE_ROW ){

          azVals = &azCols[nCol];

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

            azVals[i] = (char *)sqlite3_column_text(pStmt, i);

            if( !azVals[i] && sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){

              db->mallocFailed = 1;

              goto exec_out;

            }

          }

        }

        if( xCallback(pArg, nCol, azVals, azCols) ){

          rc = SQLITE_ABORT;

          sqlite3_finalize(pStmt);

          pStmt = 0;

          sqlite3Error(db, SQLITE_ABORT, 0);

          goto exec_out;

        }

      }

      if( rc!=SQLITE_ROW ){

        rc = sqlite3_finalize(pStmt);

        pStmt = 0;

        if( rc!=SQLITE_SCHEMA ){

          nRetry = 0;

          zSql = zLeftover;

          while( isspace((unsigned char)zSql[0]) ) zSql++;

        }

        break;

      }

    }

    sqlite3DbFree(db, azCols);

    azCols = 0;

  }

exec_out:

  if( pStmt ) sqlite3_finalize(pStmt);

  sqlite3DbFree(db, azCols);

  rc = sqlite3ApiExit(db, rc);

  if( rc!=SQLITE_OK && rc==sqlite3_errcode(db) && pzErrMsg ){

    int nErrMsg = 1 + strlen(sqlite3_errmsg(db));

    *pzErrMsg = sqlite3Malloc(nErrMsg);

    if( *pzErrMsg ){

      memcpy(*pzErrMsg, sqlite3_errmsg(db), nErrMsg);

    }

  }else if( pzErrMsg ){

    *pzErrMsg = 0;

  }

  assert( (rc&db->errMask)==rc );

  sqlite3_mutex_leave(db->mutex);

  return rc;

}