SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.267 2006/05/03 23:34:06 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

  PgHdr *pNextStmt, *pPrevStmt;  /* List of pages in the statement journal */
  u8 inJournal;                  /* TRUE if has been written to journal */
  u8 inStmt;                     /* TRUE if in the statement subjournal */
  u8 dirty;                      /* TRUE if we need to write back changes */
  u8 needSync;                   /* Sync journal before writing this page */
  u8 alwaysRollback;             /* Disable dont_rollback() for this page */
  short int nRef;                /* Number of users of this page */
  PgHdr *pDirty, *pPrevDirty;    /* Dirty pages sorted by PgHdr.pgno */
  u32 notUsed;                   /* Buffer space */
#ifdef SQLITE_CHECK_PAGES
  u32 pageHash;
#endif
  /* pPager->pageSize bytes of page data follow this header */
  /* Pager.nExtra bytes of local data follow the page data */
};

  OsFile *fd, *jfd;           /* File descriptors for database and journal */
  OsFile *stfd;               /* File descriptor for the statement subjournal*/
  BusyHandler *pBusyHandler;  /* Pointer to sqlite.busyHandler */
  PgHdr *pFirst, *pLast;      /* List of free pages */
  PgHdr *pFirstSynced;        /* First free page with PgHdr.needSync==0 */
  PgHdr *pAll;                /* List of all pages */
  PgHdr *pStmt;               /* List of pages in the statement subjournal */
  PgHdr *pDirty;              /* List of all dirty pages */
  i64 journalOff;             /* Current byte offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  i64 stmtHdrOff;             /* First journal header written this statement */
  i64 stmtCksum;              /* cksumInit when statement was started */
  i64 stmtJSize;              /* Size of journal at stmt_begin() */
  int sectorSize;             /* Assumed sector size during rollback */
#ifdef SQLITE_TEST

      pPg->inJournal = 0;
      pPg->dirty = 0;
      pPg->needSync = 0;
#ifdef SQLITE_CHECK_PAGES
      pPg->pageHash = pager_pagehash(pPg);
#endif
    }
    pPager->pDirty = 0;
    pPager->dirtyCache = 0;
    pPager->nRec = 0;
  }else{
    assert( pPager->aInJournal==0 );
    assert( pPager->dirtyCache==0 || pPager->useJournal==0 );
  }
  rc = sqlite3OsUnlock(pPager->fd, SHARED_LOCK);

  while( i>0 ){
    cksum += aData[i];
    i -= 200;
  }
  return cksum;
}

/* Forward declaration */
static void makeClean(PgHdr*);

/*
** Read a single page from the journal file opened on file descriptor
** jfd.  Playback this one page.
**
** If useCksum==0 it means this journal does not use checksums.  Checksums
** are not used in statement journals because statement journals do not
** need to survive power failures.

  assert( pPager->state>=PAGER_EXCLUSIVE || pPg!=0 );
  TRACE3("PLAYBACK %d page %d\n", PAGERID(pPager), pgno);
  if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
    rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
    if( rc==SQLITE_OK ){
      rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize);
    }
    if( pPg ){
      makeClean(pPg);
    }
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
    ** database active. However such a page may be rolled back as a result
    ** of an internal error resulting in an automatic call to
    ** sqlite3pager_rollback().

    }
    pPg->needSync = 0;
    pPg->dirty = 0;
#ifdef SQLITE_CHECK_PAGES
    pPg->pageHash = pager_pagehash(pPg);
#endif
  }
  pPager->pDirty = 0;
  return rc;
}

/*
** Truncate the main file of the given pager to the number of pages
** indicated.
*/

      ppPg = &pPg->pNextAll;
    }else if( pPg->nRef>0 ){
      memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
      ppPg = &pPg->pNextAll;
    }else{
      *ppPg = pPg->pNextAll;
      unlinkPage(pPg);
      makeClean(pPg);
      sqliteFree(pPg);
      pPager->nPage--;
    }
  }
}
#else
#define memoryTruncate(p)

/*
** Collect every dirty page into a dirty list and
** return a pointer to the head of that list.  All pages are
** collected even if they are still in use.
*/
static PgHdr *pager_get_all_dirty_pages(Pager *pPager){








  return pPager->pDirty;
}

/*
** Return TRUE if there is a hot journal on the given pager.
** A hot journal is one that needs to be played back.
**
** If the current size of the database file is 0 but a journal file

  assert( pPg->nRef==0 );

  /* Write the page to the database file if it is dirty.
  */
  if( pPg->dirty ){
    int rc;
    assert( pPg->needSync==0 );
    makeClean(pPg);
    pPg->dirty = 1;
    pPg->pDirty = 0;
    rc = pager_write_pagelist( pPg );
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  assert( pPg->dirty==0 );

    }
    if( pPager->aInStmt && (int)pgno<=pPager->stmtSize
             && (pPager->aInStmt[pgno/8] & (1<<(pgno&7)))!=0 ){
      page_add_to_stmt_list(pPg);
    }else{
      page_remove_from_stmt_list(pPg);
    }
    makeClean(pPg);
    pPg->nRef = 1;
    REFINFO(pPg);

    pPager->nRef++;
    if( pPager->nExtra>0 ){
      memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra);
    }

      if( pPager->useJournal && !pPager->tempFile ){
        rc = pager_open_journal(pPager);
      }
    }
  }
  return rc;
}

/*
** Make a page dirty.  Set its dirty flag and add it to the dirty
** page list.
*/
static void makeDirty(PgHdr *pPg){
  if( pPg->dirty==0 ){
    Pager *pPager = pPg->pPager;
    pPg->dirty = 1;
    pPg->pDirty = pPager->pDirty;
    if( pPager->pDirty ){
      pPager->pDirty->pPrevDirty = pPg;
    }
    pPg->pPrevDirty = 0;
    pPager->pDirty = pPg;
  }
}

/*
** Make a page clean.  Clear its dirty bit and remove it from the
** dirty page list.
*/
static void makeClean(PgHdr *pPg){
  if( pPg->dirty ){
    pPg->dirty = 0;
    if( pPg->pDirty ){
      pPg->pDirty->pPrevDirty = pPg->pPrevDirty;
    }
    if( pPg->pPrevDirty ){
      pPg->pPrevDirty->pDirty = pPg->pDirty;
    }else{
      pPg->pPager->pDirty = pPg->pDirty;
    }
  }
}


/*
** Mark a data page as writeable.  The page is written into the journal 
** if it is not there already.  This routine must be called before making
** changes to a page.
**
** The first time this routine is called, the pager creates a new

  assert( !pPager->setMaster );

  CHECK_PAGE(pPg);

  /* Mark the page as dirty.  If the page has already been written
  ** to the journal then we can return right away.
  */
  makeDirty(pPg);
  if( pPg->inJournal && (pPg->inStmt || pPager->stmtInUse==0) ){
    pPager->dirtyCache = 1;
  }else{

    /* If we get this far, it means that the page needs to be
    ** written to the transaction journal or the ckeckpoint journal
    ** or both.

      ** gets written at least once so that the disk file will be the correct
      ** size. If you do not write this page and the size of the file
      ** on the disk ends up being too small, that can lead to database
      ** corruption during the next transaction.
      */
    }else{
      TRACE3("DONT_WRITE page %d of %d\n", pgno, PAGERID(pPager));
      makeClean(pPg);
#ifdef SQLITE_CHECK_PAGES
      pPg->pageHash = pager_pagehash(pPg);
#endif
    }
  }
}

      pPg->dirty = 0;
      pPg->inJournal = 0;
      pPg->inStmt = 0;
      pPg->needSync = 0;
      pPg->pPrevStmt = pPg->pNextStmt = 0;
      pPg = pPg->pDirty;
    }
    pPager->pDirty = 0;
#ifndef NDEBUG
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
      assert( !pPg->alwaysRollback );
      assert( !pHist->pOrig );
      assert( !pHist->pStmt );
    }

        TRACE3("PAGE %d is clean on %d\n", p->pgno, PAGERID(pPager));
      }
      clearHistory(pHist);
      p->dirty = 0;
      p->inJournal = 0;
      p->inStmt = 0;
      p->pPrevStmt = p->pNextStmt = 0;

      if( pPager->xReiniter ){
        pPager->xReiniter(PGHDR_TO_DATA(p), pPager->pageSize);
      }
    }

    pPager->pDirty = 0;
    pPager->pStmt = 0;
    pPager->dbSize = pPager->origDbSize;
    memoryTruncate(pPager);
    pPager->stmtInUse = 0;
    pPager->state = PAGER_SHARED;
    return SQLITE_OK;
  }

  ** page pgno before the 'move' operation, it needs to be retained 
  ** for the page moved there.
  */
  pPgOld = pager_lookup(pPager, pgno);
  if( pPgOld ){
    assert( pPgOld->nRef==0 );
    unlinkHashChain(pPager, pPgOld);
    makeClean(pPgOld);
    if( pPgOld->needSync ){
      assert( pPgOld->inJournal );
      pPg->inJournal = 1;
      pPg->needSync = 1;
      assert( pPager->needSync );
    }
  }

  /* Change the page number for pPg and insert it into the new hash-chain. */
  pPg->pgno = pgno;
  h = pager_hash(pgno);
  if( pPager->aHash[h] ){
    assert( pPager->aHash[h]->pPrevHash==0 );
    pPager->aHash[h]->pPrevHash = pPg;
  }
  pPg->pNextHash = pPager->aHash[h];
  pPager->aHash[h] = pPg;
  pPg->pPrevHash = 0;

  makeDirty(pPg);
  pPager->dirtyCache = 1;

  if( needSyncPgno ){
    /* If needSyncPgno is non-zero, then the journal file needs to be 
    ** sync()ed before any data is written to database file page needSyncPgno.
    ** Currently, no such page exists in the page-cache and the 
    ** Pager.aInJournal bit has been set. This needs to be remedied by loading
    ** the page into the pager-cache and setting the PgHdr.needSync flag.
    **
    ** The sqlite3pager_get() call may cause the journal to sync. So make
    ** sure the Pager.needSync flag is set too.
    */
    int rc;
    void *pNeedSync;
    assert( pPager->needSync );
    rc = sqlite3pager_get(pPager, needSyncPgno, &pNeedSync);
    if( rc!=SQLITE_OK ) return rc;
    pPager->needSync = 1;
    DATA_TO_PGHDR(pNeedSync)->needSync = 1;
    DATA_TO_PGHDR(pNeedSync)->inJournal = 1;
    makeDirty(DATA_TO_PGHDR(pNeedSync));
    sqlite3pager_unref(pNeedSync);
  }

  return SQLITE_OK;
}
#endif

#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for calling sqlite3_result_error()
# from within an aggregate function implementation.
#
# $Id: aggerror.test,v 1.3 2006/05/03 23:34:06 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl


# Add the x_count aggregate function to the database handle.
# x_count will error out if its input is 40 or 41 or if its
# final results is 42.  Make sure that such errors are handled
# appropriately.
#
do_test aggerror-1.1 {
  set DB [sqlite3_connection_pointer db]
  sqlite3_create_aggregate $DB
  execsql {
    CREATE TABLE t1(a);
    INSERT INTO t1 VALUES(1);
    INSERT INTO t1 VALUES(2);
    INSERT INTO t1 SELECT a+2 FROM t1;
    INSERT INTO t1 SELECT a+4 FROM t1;
    INSERT INTO t1 SELECT a+8 FROM t1;
    INSERT INTO t1 SELECT a+16 FROM t1;
    INSERT INTO t1 SELECT a+32 FROM t1 ORDER BY a LIMIT 7;
    SELECT x_count(*) FROM t1;
  }
} {39}
do_test aggerror-1.2 {
  execsql {
    INSERT INTO t1 VALUES(40);
    SELECT x_count(*) FROM t1;
  }
} {40}
do_test aggerror-1.3 {
  catchsql {
    SELECT x_count(a) FROM t1;
  }
} {1 {value of 40 handed to x_count}}
ifcapable utf16 {
  do_test aggerror-1.4 {
    execsql {
      UPDATE t1 SET a=41 WHERE a=40
    }
    catchsql {
      SELECT x_count(a) FROM t1;
    }
  } {1 abc}
}
do_test aggerror-1.5 {
  execsql {
    SELECT x_count(*) FROM t1
  }
} 40
do_test aggerror-1.6 {
  execsql {
    INSERT INTO t1 VALUES(40);
    INSERT INTO t1 VALUES(42);
  }
  catchsql {
    SELECT x_count(*) FROM t1;
  }
} {1 {x_count totals to 42}}

finish_test