SQLite

#  define OS_UNIX 0
# endif
#endif
#ifndef OS_WIN
# define OS_WIN 0
#endif
#if OS_UNIX
# include <unistd.h>
# include <fcntl.h>
# include <sys/stat.h>
# include <time.h>
#endif
#if OS_WIN
# include <winbase.h>
#endif

/*

  HANDLE h = CreateFile(zFilename,
     GENERIC_READ | GENERIC_WRITE,
     0,
     NULL,
     CREATE_ALWAYS,
     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
     NULL
  );
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  *pResult = h;
  return SQLITE_OK;
#endif
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *pResult and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenReadOnly(const char *zFilename, OsFile *pResult){
#if OS_UNIX
  int fd = open(zFilename, O_RDONLY);
  if( fd<0 ){
    return SQLITE_CANTOPEN;
  }
  *pResult = fd;
  return SQLITE_OK;
#endif
#if OS_WIN
  HANDLE h = CreateFile(zFilename,
     GENERIC_READ,
     0,
     NULL,
     OPEN_EXISTING,
     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
     NULL
  );
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  *pResult = h;
  return SQLITE_OK;
#endif

/*
** Get a read or write lock on a file.
*/
int sqliteOsLock(OsFile id, int wrlock){
#if OS_UNIX
  int rc;
  struct flock lock;

  lock.l_type = wrlock ? F_WRLCK : F_RDLCK;
  lock.l_whence = SEEK_SET;
  lock.l_start = lock.l_len = 0L;


  rc = fcntl(id, F_SETLK, &lock);


  return rc==0 ? SQLITE_OK : SQLITE_BUSY;
#endif
#if OS_WIN
  if( !LockFile(id, 0, 0, 1024, 0) ){
    return SQLITE_BUSY;
  }
  return SQLITE_OK;
#endif
}

/*
** Release the read or write lock from a file.
*/
int sqliteOsUnlock(OsFile id){
#if OS_UNIX
  int rc;
  struct flock lock;
  lock.l_type = F_UNLCK;
  lock.l_whence = SEEK_SET;
  lock.l_start = lock.l_len = 0L;


  rc = fcntl(id, F_SETLK, &lock);
  return rc==0 ? SQLITE_OK : SQLITE_IOERR;
#endif
#if OS_WIN
  return UnlockFile(id, 0, 0, 1024, 0) ? SQLITE_OK : SQLITE_IOERR;
#endif
}

# deifne SQLITE_MIN_SLEEP_MS 1
#endif

int sqliteOsDelete(const char*);
int sqliteOsFileExists(const char*);
int sqliteOsOpenReadWrite(const char*, OsFile*, int*);
int sqliteOsOpenExclusive(const char*, OsFile*);
int sqliteOsOpenReadOnly(const char*, OsFile*);
int sqliteOsTempFileName(char*);
int sqliteOsClose(OsFile);
int sqliteOsRead(OsFile, void*, int amt);
int sqliteOsWrite(OsFile, const void*, int amt);
int sqliteOsSeek(OsFile, int offset);
int sqliteOsSync(OsFile);
int sqliteOsTruncate(OsFile, int size);

** 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 1.23 2001/09/19 13:58:44 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "os.h"
#include <assert.h>
#include <string.h>

      return SQLITE_BUSY;
    }
    pPager->state = SQLITE_READLOCK;

    /* If a journal file exists, try to play it back.
    */
    if( sqliteOsFileExists(pPager->zJournal) ){
       int rc;

       /* Open the journal for exclusive access.  Return SQLITE_BUSY if
       ** we cannot get exclusive access to the journal file
       */
       rc = sqliteOsOpenReadOnly(pPager->zJournal, &pPager->jfd);
       if( rc==SQLITE_OK ){
         pPager->journalOpen = 1;
       }
       if( rc!=SQLITE_OK || sqliteOsLock(pPager->jfd, 1)!=SQLITE_OK ){
         if( pPager->journalOpen ){
           sqliteOsClose(pPager->jfd);
           pPager->journalOpen = 0;