stdio/FreeBSD/_flock_stub.c

   1 /*
   2  * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 /*
  31  * POSIX stdio FILE locking functions. These assume that the locking
  32  * is only required at FILE structure level, not at file descriptor
  33  * level too.
  34  *
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.16 2008/04/17 22:17:53 jhb Exp $");
  39
  40 #include "namespace.h"
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <pthread.h>
  46 #include "un-namespace.h"
  47
  48 #include "local.h"
  49
  50 /*
  51  * Weak symbols for externally visible functions in this file:
  52  */
  53 __weak_reference(_flockfile, flockfile);
  54 __weak_reference(_flockfile_debug_stub, _flockfile_debug);
  55 __weak_reference(_ftrylockfile, ftrylockfile);
  56 __weak_reference(_funlockfile, funlockfile);
  57
  58 void
  59 _flockfile(FILE *fp)
  60 {
  61         // <rdar://problem/21533199> - preserve errno.
  62         int save_errno = errno;
  63         _pthread_mutex_lock(&fp->_fl_mutex);
  64         errno = save_errno;
  65 }
  66
  67 /*
  68  * This can be overriden by the threads library if it is linked in.
  69  */
  70 void
  71 _flockfile_debug_stub(FILE *fp, char *fname, int lineno)
  72 {
  73         _flockfile(fp);
  74 }
  75
  76 int
  77 _ftrylockfile(FILE *fp)
  78 {
  79         int     ret = 0;
  80
  81         // <rdar://problem/21533199> - preserve errno.
  82         int save_errno = errno;
  83         if (_pthread_mutex_trylock(&fp->_fl_mutex) != 0)
  84                 ret = -1;
  85         errno = save_errno;
  86
  87         return (ret);
  88 }
  89
  90 void
  91 _funlockfile(FILE *fp)
  92 {
  93         // <rdar://problem/21533199> - preserve errno.
  94         int save_errno = errno;
  95         _pthread_mutex_unlock(&fp->_fl_mutex);
  96         errno = save_errno;
  97 }