lib/faccessat.c

   1 /* Check the access rights of a file relative to an open directory.
   2    Copyright (C) 2009-2017 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 3 of the License, or
   7    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* written by Eric Blake */
  18
  19 #include <config.h>
  20
  21 #include <unistd.h>
  22 #include <fcntl.h>
  23
  24 #ifndef HAVE_ACCESS
  25 /* Mingw lacks access, but it also lacks real vs. effective ids, so
  26    the gnulib euidaccess module is good enough.  */
  27 # undef access
  28 # define access euidaccess
  29 #endif
  30
  31 /* Invoke access or euidaccess on file, FILE, using mode MODE, in the directory
  32    open on descriptor FD.  If possible, do it without changing the
  33    working directory.  Otherwise, resort to using save_cwd/fchdir, then
  34    (access|euidaccess)/restore_cwd.  If either the save_cwd or the
  35    restore_cwd fails, then give a diagnostic and exit nonzero.
  36    Note that this implementation only supports AT_EACCESS, although some
  37    native versions also support AT_SYMLINK_NOFOLLOW.  */
  38
  39 #define AT_FUNC_NAME faccessat
  40 #define AT_FUNC_F1 euidaccess
  41 #define AT_FUNC_F2 access
  42 #define AT_FUNC_USE_F1_COND AT_EACCESS
  43 #define AT_FUNC_POST_FILE_PARAM_DECLS , int mode, int flag
  44 #define AT_FUNC_POST_FILE_ARGS        , mode
  45 #include "at-func.c"