external/gpl2/xcvs/dist/lib/openat.c

   1 /* provide a replacement openat function
   2    Copyright (C) 2004, 2005 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include "openat.h"
  25
  26 #include <stdlib.h>
  27 #include <stdarg.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30 #include <fcntl.h>
  31
  32 #include "error.h"
  33 #include "exitfail.h"
  34 #include "save-cwd.h"
  35
  36 #include "gettext.h"
  37 #define _(msgid) gettext (msgid)
  38
  39 /* Replacement for Solaris' openat function.
  40    <http://www.google.com/search?q=openat+site:docs.sun.com>
  41    Simulate it by doing save_cwd/fchdir/open/restore_cwd.
  42    If either the save_cwd or the restore_cwd fails (relatively unlikely,
  43    and usually indicative of a problem that deserves close attention),
  44    then give a diagnostic and exit nonzero.
  45    Otherwise, upon failure, set errno and return -1, as openat does.
  46    Upon successful completion, return a file descriptor.  */
  47 int
  48 rpl_openat (int fd, char const *file, int flags, ...)
  49 {
  50   struct saved_cwd saved_cwd;
  51   int saved_errno;
  52   int new_fd;
  53   mode_t mode = 0;
  54
  55   if (flags & O_CREAT)
  56     {
  57       va_list arg;
  58       va_start (arg, flags);
  59
  60       /* Assume that mode_t is passed compatibly with mode_t's type
  61          after argument promotion.  */
  62       mode = va_arg (arg, mode_t);
  63
  64       va_end (arg);
  65     }
  66
  67   if (fd == AT_FDCWD || *file == '/')
  68     return open (file, flags, mode);
  69
  70   if (save_cwd (&saved_cwd) != 0)
  71     error (exit_failure, errno,
  72            _("openat: unable to record current working directory"));
  73
  74   if (fchdir (fd) != 0)
  75     {
  76       saved_errno = errno;
  77       free_cwd (&saved_cwd);
  78       errno = saved_errno;
  79       return -1;
  80     }
  81
  82   new_fd = open (file, flags, mode);
  83   saved_errno = errno;
  84
  85   if (restore_cwd (&saved_cwd) != 0)
  86     error (exit_failure, errno,
  87            _("openat: unable to restore working directory"));
  88
  89   free_cwd (&saved_cwd);
  90
  91   errno = saved_errno;
  92   return new_fd;
  93 }
  94
  95 /* Replacement for Solaris' function by the same name.
  96    <http://www.google.com/search?q=fdopendir+site:docs.sun.com>
  97    Simulate it by doing save_cwd/fchdir/opendir(".")/restore_cwd.
  98    If either the save_cwd or the restore_cwd fails (relatively unlikely,
  99    and usually indicative of a problem that deserves close attention),
 100    then give a diagnostic and exit nonzero.
 101    Otherwise, this function works just like Solaris' fdopendir.  */
 102 DIR *
 103 fdopendir (int fd)
 104 {
 105   struct saved_cwd saved_cwd;
 106   int saved_errno;
 107   DIR *dir;
 108
 109   if (fd == AT_FDCWD)
 110     return opendir (".");
 111
 112   if (save_cwd (&saved_cwd) != 0)
 113     error (exit_failure, errno,
 114            _("fdopendir: unable to record current working directory"));
 115
 116   if (fchdir (fd) != 0)
 117     {
 118       saved_errno = errno;
 119       free_cwd (&saved_cwd);
 120       errno = saved_errno;
 121       return NULL;
 122     }
 123
 124   dir = opendir (".");
 125   saved_errno = errno;
 126
 127   if (restore_cwd (&saved_cwd) != 0)
 128     error (exit_failure, errno,
 129            _("fdopendir: unable to restore working directory"));
 130
 131   free_cwd (&saved_cwd);
 132
 133   errno = saved_errno;
 134   return dir;
 135 }
 136
 137 /* Replacement for Solaris' function by the same name.
 138    <http://www.google.com/search?q=fstatat+site:docs.sun.com>
 139    Simulate it by doing save_cwd/fchdir/(stat|lstat)/restore_cwd.
 140    If either the save_cwd or the restore_cwd fails (relatively unlikely,
 141    and usually indicative of a problem that deserves close attention),
 142    then give a diagnostic and exit nonzero.
 143    Otherwise, this function works just like Solaris' fstatat.  */
 144 int
 145 fstatat (int fd, char const *file, struct stat *st, int flag)
 146 {
 147   struct saved_cwd saved_cwd;
 148   int saved_errno;
 149   int err;
 150
 151   if (fd == AT_FDCWD)
 152     return (flag == AT_SYMLINK_NOFOLLOW
 153             ? lstat (file, st)
 154             : stat (file, st));
 155
 156   if (save_cwd (&saved_cwd) != 0)
 157     error (exit_failure, errno,
 158            _("fstatat: unable to record current working directory"));
 159
 160   if (fchdir (fd) != 0)
 161     {
 162       saved_errno = errno;
 163       free_cwd (&saved_cwd);
 164       errno = saved_errno;
 165       return -1;
 166     }
 167
 168   err = (flag == AT_SYMLINK_NOFOLLOW
 169          ? lstat (file, st)
 170          : stat (file, st));
 171   saved_errno = errno;
 172
 173   if (restore_cwd (&saved_cwd) != 0)
 174     error (exit_failure, errno,
 175            _("fstatat: unable to restore working directory"));
 176
 177   free_cwd (&saved_cwd);
 178
 179   errno = saved_errno;
 180   return err;
 181 }