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Overview
Comment:Added SQLITE_IOERR_LOCK extended error code and support for detecting and returning errors in the os_unix lock, unlock and check reserved lock variants, also added support for populating and returning system error codes so that they can be accessed via xGetLastError, unfortunately xGetLastError can't seem to access the unixFile structure where the lastErrno is recorded. (CVS 5586)
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Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: c1af14e2b6bf5af0aff3df3adbe8cb9aabe1c4a3
User & Date: aswift 2008-08-22 00:22:35.000
Context
2008-08-22
00:25
Deferring file descriptor closing to avoid trashing locks when directly manipulating sqlite db file contents (causes errors on AFP testing) (CVS 5587) (check-in: e28a2870b4 user: aswift tags: trunk)
00:22
Added SQLITE_IOERR_LOCK extended error code and support for detecting and returning errors in the os_unix lock, unlock and check reserved lock variants, also added support for populating and returning system error codes so that they can be accessed via xGetLastError, unfortunately xGetLastError can't seem to access the unixFile structure where the lastErrno is recorded. (CVS 5586) (check-in: c1af14e2b6 user: aswift tags: trunk)
2008-08-21
20:21
Move date+time functions to start-time initialization. Additional start-time function cleanup. (CVS 5585) (check-in: 80d6a31cb3 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/os_unix.c.
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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Unix systems.
**
** $Id: os_unix.c,v 1.195 2008/07/30 17:28:04 drh Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** If SQLITE_ENABLE_LOCKING_STYLE is defined, then several different 
** locking implementations are provided:







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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to Unix systems.
**
** $Id: os_unix.c,v 1.196 2008/08/22 00:22:35 aswift Exp $
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** If SQLITE_ENABLE_LOCKING_STYLE is defined, then several different 
** locking implementations are provided:
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#endif
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  int dirfd;                /* File descriptor for the directory */
#if SQLITE_THREADSAFE
  pthread_t tid;            /* The thread that "owns" this unixFile */
#endif

};

/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"








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#endif
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  int dirfd;                /* File descriptor for the directory */
#if SQLITE_THREADSAFE
  pthread_t tid;            /* The thread that "owns" this unixFile */
#endif
  int lastErrno;            /* The unix errno from the last I/O error */
};

/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

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*/
#define LOCKING_STYLE_POSIX        1
#define LOCKING_STYLE_NONE         2
#define LOCKING_STYLE_DOTFILE      3
#define LOCKING_STYLE_FLOCK        4
#define LOCKING_STYLE_AFP          5







/*
** Helper functions to obtain and relinquish the global mutex.
*/
static void enterMutex(){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
static void leaveMutex(){







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*/
#define LOCKING_STYLE_POSIX        1
#define LOCKING_STYLE_NONE         2
#define LOCKING_STYLE_DOTFILE      3
#define LOCKING_STYLE_FLOCK        4
#define LOCKING_STYLE_AFP          5

/*
** Only set the lastErrno if the error code is a real error and not 
** a normal expected return code of SQLITE_BUSY or SQLITE_OK
*/
#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))

/*
** Helper functions to obtain and relinquish the global mutex.
*/
static void enterMutex(){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
static void leaveMutex(){
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  struct Mapping {
    const char *zFilesystem;
    int eLockingStyle;
  } aMap[] = {
    { "hfs",    LOCKING_STYLE_POSIX },
    { "ufs",    LOCKING_STYLE_POSIX },
    { "afpfs",  LOCKING_STYLE_AFP },



    { "smbfs",  LOCKING_STYLE_FLOCK },

    { "msdos",  LOCKING_STYLE_DOTFILE },
    { "webdav", LOCKING_STYLE_NONE },
    { 0, 0 }
  };
  int i;
  struct statfs fsInfo;








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  struct Mapping {
    const char *zFilesystem;
    int eLockingStyle;
  } aMap[] = {
    { "hfs",    LOCKING_STYLE_POSIX },
    { "ufs",    LOCKING_STYLE_POSIX },
    { "afpfs",  LOCKING_STYLE_AFP },
#ifdef SQLITE_ENABLE_AFP_LOCKING_SMB
    { "smbfs",  LOCKING_STYLE_AFP },
#else
    { "smbfs",  LOCKING_STYLE_FLOCK },
#endif
    { "msdos",  LOCKING_STYLE_DOTFILE },
    { "webdav", LOCKING_STYLE_NONE },
    { 0, 0 }
  };
  int i;
  struct statfs fsInfo;

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  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

/*





























































** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero.  If the file is unlocked or holds only SHARED locks, then
** return zero.

*/
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){

  int r = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );
  enterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pLock->locktype>SHARED_LOCK ){
    r = 1;
  }

  /* Otherwise see if some other process holds it.
  */
  if( !r ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    fcntl(pFile->h, F_GETLK, &lock);



    if( lock.l_type!=F_UNLCK ){
      r = 1;
    }
  }
  
  leaveMutex();
  OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);

  *pResOut = r;
  return SQLITE_OK;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK









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  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

/*
** This routine translates a standard POSIX errno code into something
** useful to the clients of the sqlite3 functions.  Specifically, it is
** intended to translate a variety of "try again" errors into SQLITE_BUSY
** and a variety of "please close the file descriptor NOW" errors into 
** SQLITE_IOERR
** 
** Errors during initialization of locks, or file system support for locks,
** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
*/
static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
  switch (posixError) {
  case 0: 
    return SQLITE_OK;
    
  case EAGAIN:
  case ETIMEDOUT:
  case EBUSY:
  case EINTR:
  case ENOLCK:  
    /* random NFS retry error, unless during file system support 
     * introspection, in which it actually means what it says */
    return SQLITE_BUSY;
    
  case EACCES: 
    /* EACCES is like EAGAIN during locking operations, but not any other time*/
    if( (sqliteIOErr == SQLITE_IOERR_LOCK) || 
	(sqliteIOErr == SQLITE_IOERR_UNLOCK) || 
	(sqliteIOErr == SQLITE_IOERR_RDLOCK) ||
	(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
      return SQLITE_BUSY;
    }
    /* else fall through */
  case EPERM: 
    return SQLITE_PERM;
    
  case EDEADLK:
    return SQLITE_IOERR_BLOCKED;
    
  case EOPNOTSUPP: 
    /* something went terribly awry, unless during file system support 
     * introspection, in which it actually means what it says */
  case ENOTSUP: 
    /* invalid fd, unless during file system support introspection, in which 
     * it actually means what it says */
  case EIO:
  case EBADF:
  case EINVAL:
  case ENOTCONN:
  case ENODEV:
  case ENXIO:
  case ENOENT:
  case ESTALE:
  case ENOSYS:
    /* these should force the client to close the file and reconnect */
    
  default: 
    return sqliteIOErr;
  }
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value

** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );
  enterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pLock->locktype>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
  if( !reserved ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if (-1 == fcntl(pFile->h, F_GETLK, &lock)) {
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
      pFile->lastErrno = tErrno;
    } else if( lock.l_type!=F_UNLCK ){
      reserved = 1;
    }
  }
  
  leaveMutex();
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
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  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;




      goto end_lock;
    }
  }


  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){

    assert( pLock->cnt==0 );
    assert( pLock->locktype==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    s = fcntl(pFile->h, F_SETLK, &lock);


    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){



      rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */



      goto end_lock;
    }

    if( s==(-1) ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;



    }else{
      pFile->locktype = SHARED_LOCK;
      pFile->pOpen->nLock++;
      pLock->cnt = 1;
    }
  }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
    /* We are trying for an exclusive lock but another thread in this







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  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
    }
  }


  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    int tErrno = 0;
    assert( pLock->cnt==0 );
    assert( pLock->locktype==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    if( (s = fcntl(pFile->h, F_SETLK, &lock))==(-1) ){
      tErrno = errno;
    }
    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
      if( s != -1 ){
        /* This could happen with a network mount */
        tErrno = errno; 
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        goto end_lock;
      }
    }
    if( s==(-1) ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }else{
      pFile->locktype = SHARED_LOCK;
      pFile->pOpen->nLock++;
      pLock->cnt = 1;
    }
  }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
    /* We are trying for an exclusive lock but another thread in this
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        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;




    }
  }
  
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){







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        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
  }
  
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
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    SimulateIOErrorBenign(0);
    if( locktype==SHARED_LOCK ){
      lock.l_type = F_RDLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      if( fcntl(h, F_SETLK, &lock)==(-1) ){

        rc = SQLITE_IOERR_RDLOCK;




      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(h, F_SETLK, &lock)!=(-1) ){
      pLock->locktype = SHARED_LOCK;
    }else{

      rc = SQLITE_IOERR_UNLOCK;




    }
  }
  if( locktype==NO_LOCK ){
    struct openCnt *pOpen;

    /* Decrement the shared lock counter.  Release the lock using an
    ** OS call only when all threads in this same process have released
    ** the lock.
    */
    pLock->cnt--;
    if( pLock->cnt==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( fcntl(h, F_SETLK, &lock)!=(-1) ){
        pLock->locktype = NO_LOCK;
      }else{

        rc = SQLITE_IOERR_UNLOCK;



        pLock->cnt = 1;

      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */







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    SimulateIOErrorBenign(0);
    if( locktype==SHARED_LOCK ){
      lock.l_type = F_RDLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      if( fcntl(h, F_SETLK, &lock)==(-1) ){
        int tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
				goto end_unlock;
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(h, F_SETLK, &lock)!=(-1) ){
      pLock->locktype = SHARED_LOCK;
    }else{
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
			goto end_unlock;
    }
  }
  if( locktype==NO_LOCK ){
    struct openCnt *pOpen;

    /* Decrement the shared lock counter.  Release the lock using an
    ** OS call only when all threads in this same process have released
    ** the lock.
    */
    pLock->cnt--;
    if( pLock->cnt==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( fcntl(h, F_SETLK, &lock)!=(-1) ){
        pLock->locktype = NO_LOCK;
      }else{
        int tErrno = errno;
				rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        pLock->cnt = 1;
				goto end_unlock;
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
1474
1475
1476
1477
1478
1479
1480


1481
1482
1483
1484
1485
1486
1487
        }
        sqlite3_free(pOpen->aPending);
        pOpen->nPending = 0;
        pOpen->aPending = 0;
      }
    }
  }


  leaveMutex();
  if( rc==SQLITE_OK ) pFile->locktype = locktype;
  return rc;
}

/*
** This function performs the parts of the "close file" operation 







>
>







1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
        }
        sqlite3_free(pOpen->aPending);
        pOpen->nPending = 0;
        pOpen->aPending = 0;
      }
    }
  }
	
end_unlock:
  leaveMutex();
  if( rc==SQLITE_OK ) pFile->locktype = locktype;
  return rc;
}

/*
** This function performs the parts of the "close file" operation 
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575

1576
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1589
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1591


1592


1593

1594
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1600
1601
1602
1603
1604
1605
1606

1607
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1609


1610
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1614
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1617
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1619
1620
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1623
1624
1625
1626
1627
1628
1629



1630


1631


1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
  unsigned char startEndFlag;       /* 1=rel to end of fork, 0=rel to start */
  int fd;                           /* file desc to assoc this lock with */
};

#define afpfsByteRangeLock2FSCTL        _IOWR('z', 23, struct ByteRangeLockPB2)

/* 
** Return 0 on success, 1 on failure.  To match the behavior of the 
** normal posix file locking (used in unixLock for example), we should 
** provide 'richer' return codes - specifically to differentiate between
** 'file busy' and 'file system error' results.
*/
static int _AFPFSSetLock(
  const char *path, 
  int fd, 

  unsigned long long offset, 
  unsigned long long length, 
  int setLockFlag
){
  struct ByteRangeLockPB2       pb;
  int                     err;
  
  pb.unLockFlag = setLockFlag ? 0 : 1;
  pb.startEndFlag = 0;
  pb.offset = offset;
  pb.length = length; 
  pb.fd = fd;
  OSTRACE5("AFPLOCK setting lock %s for %d in range %llx:%llx\n", 
    (setLockFlag?"ON":"OFF"), fd, offset, length);
  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
  if ( err==-1 ) {


    OSTRACE4("AFPLOCK failed to fsctl() '%s' %d %s\n", path, errno, 


      strerror(errno));

    return 1; /* error */
  } else {
    return 0;
  }
}

/*
 ** This routine checks if there is a RESERVED lock held on the specified
 ** file by this or any other process. If such a lock is held, return
 ** non-zero.  If the file is unlocked or holds only SHARED locks, then
 ** return zero.
 */
static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){

  int r = 0;
  unixFile *pFile = (unixFile*)id;
  


  assert( pFile ); 
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
  
  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    r = 1;
  }
  
  /* Otherwise see if some other process holds it.
   */
  if ( !r ) {
    /* lock the byte */
    int failed = _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1,1);  
    if (failed) {
      /* if we failed to get the lock then someone else must have it */
      r = 1;
    } else {
      /* if we succeeded in taking the reserved lock, unlock it to restore
      ** the original state */
      _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1, 0);



    }


  }


  OSTRACE3("TEST WR-LOCK %d %d\n", pFile->h, r);
  
  *pResOut = r;
  return SQLITE_OK;
}

/* AFP-style locking following the behavior of unixLock, see the unixLock 
** function comments for details of lock management. */
static int afpLock(sqlite3_file *id, int locktype){
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;







|
<
<
<
|


<
>











|

|


>
>
|
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>
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|

|



|
|
<
<
<
<

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|


>
>
|




|




|
|
|
|
<
<
<


|
>
>
>

>
>
|
>
>
|

|
|







1674
1675
1676
1677
1678
1679
1680
1681



1682
1683
1684

1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716




1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737



1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
  unsigned char startEndFlag;       /* 1=rel to end of fork, 0=rel to start */
  int fd;                           /* file desc to assoc this lock with */
};

#define afpfsByteRangeLock2FSCTL        _IOWR('z', 23, struct ByteRangeLockPB2)

/* 
 ** Return SQLITE_OK on success, SQLITE_BUSY on failure.



 */
static int _AFPFSSetLock(
  const char *path, 

  unixFile *pFile, 
  unsigned long long offset, 
  unsigned long long length, 
  int setLockFlag
){
  struct ByteRangeLockPB2       pb;
  int                     err;
  
  pb.unLockFlag = setLockFlag ? 0 : 1;
  pb.startEndFlag = 0;
  pb.offset = offset;
  pb.length = length; 
  pb.fd = pFile->h;
  OSTRACE5("AFPLOCK setting lock %s for %d in range %llx:%llx\n", 
    (setLockFlag?"ON":"OFF"), pFile->h, offset, length);
  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
  if ( err==-1 ) {
    int rc;
    int tErrno = errno;
    OSTRACE4("AFPLOCK failed to fsctl() '%s' %d %s\n", path, tErrno, strerror(tErrno));
    rc = sqliteErrorFromPosixError(tErrno, setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK); /* error */
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc;
  } else {
    return SQLITE_OK;
  }
}

/* AFP-style reserved lock checking following the behavior of 
** unixCheckReservedLock, see the unixCheckReservedLock function comments */




static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;
  
  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
  
  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it.
   */
  if( !reserved ){
    /* lock the RESERVED byte */
    int lrc = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1,1);  
    if( SQLITE_OK==lrc ){



      /* if we succeeded in taking the reserved lock, unlock it to restore
      ** the original state */
      lrc = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1, 0);
    } else {
      /* if we failed to get the lock then someone else must have it */
      reserved = 1;
    }
    if( IS_LOCK_ERROR(lrc) ){
      rc=lrc;
    }
  }
  
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);
  
  *pResOut = reserved;
  return rc;
}

/* AFP-style locking following the behavior of unixLock, see the unixLock 
** function comments for details of lock management. */
static int afpLock(sqlite3_file *id, int locktype){
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703


1704
1705
1706
1707



1708
1709
1710


1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    int failed;
    failed = _AFPFSSetLock(context->filePath, pFile->h, PENDING_BYTE, 1, 1);
    if (failed) {
      rc = SQLITE_BUSY;
      goto afp_end_lock;
    }
  }
  
  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    int lk, failed;
    
    /* Now get the read-lock */
    /* note that the quality of the randomness doesn't matter that much */
    lk = random(); 
    context->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
    failed = _AFPFSSetLock(context->filePath, pFile->h, 
      SHARED_FIRST+context->sharedLockByte, 1, 1);


    
    /* Drop the temporary PENDING lock */
    if (_AFPFSSetLock(context->filePath, pFile->h, PENDING_BYTE, 1, 0)) {
      rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */



      goto afp_end_lock;
    }
    


    if( failed ){
      rc = SQLITE_BUSY;
    } else {
      pFile->locktype = SHARED_LOCK;
    }
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    int failed = 0;
    assert( 0!=pFile->locktype );
    if (locktype >= RESERVED_LOCK && pFile->locktype < RESERVED_LOCK) {
        /* Acquire a RESERVED lock */
        failed = _AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1,1);
    }
    if (!failed && locktype == EXCLUSIVE_LOCK) {
      /* Acquire an EXCLUSIVE lock */
        
      /* Remove the shared lock before trying the range.  we'll need to 
      ** reestablish the shared lock if we can't get the  afpUnlock
      */
      if (!_AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST +
                         context->sharedLockByte, 1, 0)) {
        /* now attemmpt to get the exclusive lock range */
        failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST, 
                               SHARED_SIZE, 1);
        if (failed && _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST +
                                    context->sharedLockByte, 1, 1)) {
          rc = SQLITE_IOERR_RDLOCK; /* this should never happen */
        }
      } else {
        /* */
        rc = SQLITE_IOERR_UNLOCK; /* this should never happen */
      }
    }
    if( failed && rc == SQLITE_OK){
      rc = SQLITE_BUSY;
    }
  }
  
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;







|

|








|

|



|
|
>
>
|

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|
>
>
>

<
|
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|












|







|
|

|

|
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|


<
|


|
|







1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831

1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
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1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866

1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  if( locktype==SHARED_LOCK 
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    int failed;
    failed = _AFPFSSetLock(context->filePath, pFile, PENDING_BYTE, 1, 1);
    if (failed) {
      rc = failed;
      goto afp_end_lock;
    }
  }
  
  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    int lk, lrc1, lrc2, lrc1Errno;
    
    /* Now get the read-lock SHARED_LOCK */
    /* note that the quality of the randomness doesn't matter that much */
    lk = random(); 
    context->sharedLockByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
    lrc1 = _AFPFSSetLock(context->filePath, pFile, 
          SHARED_FIRST+context->sharedLockByte, 1, 1);
    if( IS_LOCK_ERROR(lrc1) ){
      lrc1Errno = pFile->lastErrno;
    }
    /* Drop the temporary PENDING lock */
    lrc2 = _AFPFSSetLock(context->filePath, pFile, PENDING_BYTE, 1, 0);
    
    if( IS_LOCK_ERROR(lrc1) ) {
      pFile->lastErrno = lrc1Errno;
      rc = lrc1;
      goto afp_end_lock;

    } else if( IS_LOCK_ERROR(lrc2) ){
      rc = lrc2;
      goto afp_end_lock;
    } else if( lrc1 != SQLITE_OK ) {
      rc = lrc1;
    } else {
      pFile->locktype = SHARED_LOCK;
    }
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    int failed = 0;
    assert( 0!=pFile->locktype );
    if (locktype >= RESERVED_LOCK && pFile->locktype < RESERVED_LOCK) {
        /* Acquire a RESERVED lock */
        failed = _AFPFSSetLock(context->filePath, pFile, RESERVED_BYTE, 1,1);
    }
    if (!failed && locktype == EXCLUSIVE_LOCK) {
      /* Acquire an EXCLUSIVE lock */
        
      /* Remove the shared lock before trying the range.  we'll need to 
      ** reestablish the shared lock if we can't get the  afpUnlock
      */
      if (!(failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST +
                         context->sharedLockByte, 1, 0))) {
        /* now attemmpt to get the exclusive lock range */
        failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST, 
                               SHARED_SIZE, 1);
        if (failed && (failed = _AFPFSSetLock(context->filePath, pFile, 
                       SHARED_FIRST + context->sharedLockByte, 1, 1))) {
          rc = failed;
        }
      } else {

        rc = failed; 
      }
    }
    if( failed ){
      rc = failed;
    }
  }
  
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
1773
1774
1775
1776
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1778
1779
1780
1781
1782
1783
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1786
1787
1788

1789
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1812
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1818
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1828
1829
1830
1831
1832
1833
1834
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
         pFile->locktype, getpid());
  
  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  enterMutex();

  if( pFile->locktype>SHARED_LOCK ){
    if( locktype==SHARED_LOCK ){
      int failed = 0;

      /* unlock the exclusive range - then re-establish the shared lock */
      if (pFile->locktype==EXCLUSIVE_LOCK) {
        failed = _AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST, 
                                 SHARED_SIZE, 0);
        if (!failed) {
          /* successfully removed the exclusive lock */
          if (_AFPFSSetLock(context->filePath, pFile->h, SHARED_FIRST+
                            context->sharedLockByte, 1, 1)) {
            /* failed to re-establish our shared lock */
            rc = SQLITE_IOERR_RDLOCK; /* This should never happen */
          }
        } else {
          /* This should never happen - failed to unlock the exclusive range */
          rc = SQLITE_IOERR_UNLOCK;
        } 
      }
    }
    if (rc == SQLITE_OK && pFile->locktype>=PENDING_LOCK) {
      if (_AFPFSSetLock(context->filePath, pFile->h, PENDING_BYTE, 1, 0)){

        /* failed to release the pending lock */
        rc = SQLITE_IOERR_UNLOCK; /* This should never happen */
      }
    } 
    if (rc == SQLITE_OK && pFile->locktype>=RESERVED_LOCK) {
      if (_AFPFSSetLock(context->filePath, pFile->h, RESERVED_BYTE, 1, 0)) {

        /* failed to release the reserved lock */
        rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */
      }
    } 
  }
  if( locktype==NO_LOCK ){
    int failed = _AFPFSSetLock(context->filePath, pFile->h, 
                               SHARED_FIRST + context->sharedLockByte, 1, 0);
    if (failed) {
      rc = SQLITE_IOERR_UNLOCK;  /* This should never happen */
    }
  }
  if (rc == SQLITE_OK)
    pFile->locktype = locktype;
  leaveMutex();
  return rc;
}







|








>


<



|



|
|

|


<
|




|
>

|



|
>

|




|


|







1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
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1907
1908
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1910
1911
1912
1913
1914

1915
1916
1917
1918
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1920
1921
1922
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1928
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1950
1951
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1953
1954
1955
1956
1957
1958
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
         pFile->locktype, getpid());

  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE;
  }
  enterMutex();
  int failed = SQLITE_OK;
  if( pFile->locktype>SHARED_LOCK ){
    if( locktype==SHARED_LOCK ){


      /* unlock the exclusive range - then re-establish the shared lock */
      if (pFile->locktype==EXCLUSIVE_LOCK) {
        failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST, 
                                 SHARED_SIZE, 0);
        if (!failed) {
          /* successfully removed the exclusive lock */
          if ((failed = _AFPFSSetLock(context->filePath, pFile, SHARED_FIRST+
                            context->sharedLockByte, 1, 1))) {
            /* failed to re-establish our shared lock */
            rc = failed;
          }
        } else {

          rc = failed;
        } 
      }
    }
    if (rc == SQLITE_OK && pFile->locktype>=PENDING_LOCK) {
      if ((failed = _AFPFSSetLock(context->filePath, pFile, 
                                  PENDING_BYTE, 1, 0))){
        /* failed to release the pending lock */
        rc = failed; 
      }
    } 
    if (rc == SQLITE_OK && pFile->locktype>=RESERVED_LOCK) {
      if ((failed = _AFPFSSetLock(context->filePath, pFile, 
                                  RESERVED_BYTE, 1, 0))) {
        /* failed to release the reserved lock */
        rc = failed;  
      }
    } 
  }
  if( locktype==NO_LOCK ){
    int failed = _AFPFSSetLock(context->filePath, pFile, 
                               SHARED_FIRST + context->sharedLockByte, 1, 0);
    if (failed) {
      rc = failed;  
    }
  }
  if (rc == SQLITE_OK)
    pFile->locktype = locktype;
  leaveMutex();
  return rc;
}
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#pragma mark flock() style locking

/*
** The flockLockingContext is not used
*/
typedef void flockLockingContext;



static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){

  int r = 1;
  unixFile *pFile = (unixFile*)id;
  





  if (pFile->locktype != RESERVED_LOCK) {





    /* attempt to get the lock */
    int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
    if (!rc) {
      /* got the lock, unlock it */
      flock(pFile->h, LOCK_UN);











      r = 0;  /* no one has it reserved */





    }
  }



  *pResOut = r;
  return SQLITE_OK;
}

static int flockLock(sqlite3_file *id, int locktype) {


  unixFile *pFile = (unixFile*)id;
  


  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */

  int rc = flock(pFile->h, LOCK_EX | LOCK_NB);
  if (rc) {

    /* didn't get, must be busy */
    return SQLITE_BUSY;



  } else {
    /* got it, set the type and return ok */
    pFile->locktype = locktype;
    return SQLITE_OK;
  }



}

static int flockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  



  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  int rc = flock(pFile->h, LOCK_UN);
  if (rc)





    return SQLITE_IOERR_UNLOCK;
  else {
    pFile->locktype = NO_LOCK;
    return SQLITE_OK;
  }
}

/*
** Close a file.
*/
static int flockClose(sqlite3_file *id) {
  if( id ){
    flockUnlock(id, NO_LOCK);
  }
  return closeUnixFile(id);
}

#pragma mark Old-School .lock file based locking



static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {

  int r = 1;
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;





  if (pFile->locktype != RESERVED_LOCK) {






    struct stat statBuf;

    if (lstat(zLockFile, &statBuf) != 0){



      /* file does not exist, we could have it if we want it */
      r = 0;



    }
  }



  *pResOut = r;
  return SQLITE_OK;
}

static int dotlockLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  char *zLockFile = (char *)pFile->lockingContext;


  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
    return SQLITE_OK;

  }
  
  /* check to see if lock file already exists */
  struct stat statBuf;
  if (lstat(zLockFile,&statBuf) == 0){
    return SQLITE_BUSY; /* it does, busy */

  }
  
  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */


    return SQLITE_BUSY; 




  }



  close(fd);
  
  /* got it, set the type and return ok */
  pFile->locktype = locktype;


  return SQLITE_OK;
}

static int dotlockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;




  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  unlink(zLockFile);









  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
 ** Close a file.
 */







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#pragma mark flock() style locking

/*
** The flockLockingContext is not used
*/
typedef void flockLockingContext;

/* flock-style reserved lock checking following the behavior of 
 ** unixCheckReservedLock, see the unixCheckReservedLock function comments */
static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;
  
  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );
  
  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    /* attempt to get the lock */
    int lrc = flock(pFile->h, LOCK_EX | LOCK_NB);
    if( !lrc ){
      /* got the lock, unlock it */
      lrc = flock(pFile->h, LOCK_UN);
      if ( lrc ) {
        int tErrno = errno;
        /* unlock failed with an error */
        lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(lrc) ){
          pFile->lastErrno = tErrno;
          rc = lrc;
        }
      }
    } else {
      int tErrno = errno;
      reserved = 1;
      /* someone else might have it reserved */
      lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); 
      if( IS_LOCK_ERROR(lrc) ){
        pFile->lastErrno = tErrno;
        rc = lrc;
      }
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

static int flockLock(sqlite3_file *id, int locktype) {
  int rc = SQLITE_OK;
  int lrc;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  
  if (flock(pFile->h, LOCK_EX | LOCK_NB)) {

    int tErrno = errno;
    /* didn't get, must be busy */
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
  } else {
    /* got it, set the type and return ok */
    pFile->locktype = locktype;

  }
  OSTRACE4("LOCK    %d %s %s\n", pFile->h, locktypeName(locktype), 
           rc==SQLITE_OK ? "ok" : "failed");
  return rc;
}

static int flockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  
  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
           pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  int rc = flock(pFile->h, LOCK_UN);
  if (rc) {
    int r, tErrno = errno;
    r = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    if( IS_LOCK_ERROR(r) ){
      pFile->lastErrno = tErrno;
    }
    return r;
  } else {
    pFile->locktype = NO_LOCK;
    return SQLITE_OK;
  }
}

/*
** Close a file.
*/
static int flockClose(sqlite3_file *id) {
  if( id ){
    flockUnlock(id, NO_LOCK);
  }
  return closeUnixFile(id);
}

#pragma mark Old-School .lock file based locking

/* Dotlock-style reserved lock checking following the behavior of 
** unixCheckReservedLock, see the unixCheckReservedLock function comments */
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  
  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    char *zLockFile = (char *)pFile->lockingContext;
    struct stat statBuf;
    
    if( lstat(zLockFile, &statBuf)==0 ){
      /* file exists, someone else has the lock */
      reserved = 1;
    }else{
      /* file does not exist, we could have it if we want it */
			int tErrno = errno;
      if( ENOENT != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;
      }
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

static int dotlockLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  char *zLockFile = (char *)pFile->lockingContext;
  int rc=SQLITE_OK;

  /* if we already have a lock, it is exclusive.  
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
    rc = SQLITE_OK;
    goto dotlock_end_lock;
  }
  
  /* check to see if lock file already exists */
  struct stat statBuf;
  if (lstat(zLockFile,&statBuf) == 0){
    rc = SQLITE_BUSY; /* it does, busy */
    goto dotlock_end_lock;
  }
  
  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
    if( EEXIST == tErrno ){
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
	pFile->lastErrno = tErrno;
      }
    }
    goto dotlock_end_lock;
  } 
  close(fd);
  
  /* got it, set the type and return ok */
  pFile->locktype = locktype;

 dotlock_end_lock:
  return rc;
}

static int dotlockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );
  
  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }
  
  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  if (unlink(zLockFile) ) {
    int rc, tErrno = errno;
    if( ENOENT != tErrno ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc; 
  }
  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
 ** Close a file.
 */
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    }

    case LOCKING_STYLE_FLOCK: 
    case LOCKING_STYLE_NONE: 
      break;
#endif
  }


  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd);
    close(h);
  }else{
    pNew->pMethod = &aIoMethod[eLockingStyle-1];
    OpenCounter(+1);
  }







|
>







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2434
    }

    case LOCKING_STYLE_FLOCK: 
    case LOCKING_STYLE_NONE: 
      break;
#endif
  }
  
  pNew->lastErrno = 0;
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd);
    close(h);
  }else{
    pNew->pMethod = &aIoMethod[eLockingStyle-1];
    OpenCounter(+1);
  }
Changes to src/sqlite.h.in.
26
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31
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38
39
40
** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.392 2008/08/12 14:51:30 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.







|







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** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.393 2008/08/22 00:22:35 aswift Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
512
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519
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525
#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))


/*
** CAPI3REF: Flags For File Open Operations {H10230} <H11120> <H12700>
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the xOpen method of the







>







512
513
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#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))

/*
** CAPI3REF: Flags For File Open Operations {H10230} <H11120> <H12700>
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the xOpen method of the