external/bsd/tmux/dist/compat/openat.c

   1 /* Id */
   2
   3 /*
   4  * Copyright (c) 2013 Nicholas Marriott <nicm@users.sourceforge.net>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
  15  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  16  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdarg.h>
  22 #include <unistd.h>
  23
  24 #include "tmux.h"
  25
  26 int
  27 openat(int fd, const char *path, int flags, ...)
  28 {
  29         mode_t  mode;
  30         va_list ap;
  31         int     dotfd, retval, saved_errno;
  32
  33         if (flags & O_CREAT) {
  34                 va_start(ap, flags);
  35                 mode = va_arg(ap, mode_t);
  36                 va_end(ap);
  37         } else
  38                 mode = 0;
  39
  40         dotfd = -1;
  41         if (fd != AT_FDCWD) {
  42                 dotfd = open(".", O_RDONLY);
  43                 if (dotfd == -1)
  44                         return (-1);
  45                 if (fchdir(fd) != 0)
  46                         return (-1);
  47         }
  48
  49         retval = open(path, flags, mode);
  50
  51         if (dotfd != -1) {
  52                 if (fchdir(dotfd) != 0) {
  53                         saved_errno = errno;
  54                         close(retval);
  55                         close(dotfd);
  56                         errno = saved_errno;
  57                         return (-1);
  58                 }
  59                 close(dotfd);
  60         }
  61
  62         return (retval);
  63 }