io/openat.c

   1 /* Copyright (C) 2005-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <stdarg.h>
  21 #include <stddef.h>
  22 #include <stdio.h>
  23 #include <sys/stat.h>
  24 #include <kernel-features.h>
  25
  26 /* Some mostly-generic code (e.g. sysdeps/posix/getcwd.c) uses this variable
  27    if __ASSUME_ATFCTS is not defined.  */
  28 #ifndef __ASSUME_ATFCTS
  29 int __have_atfcts;
  30 #endif
  31
  32 /* Open FILE with access OFLAG.  Interpret relative paths relative to
  33    the directory associated with FD.  If O_CREAT or O_TMPFILE is in OFLAG, a
  34    third argument is the file protection.  */
  35 int
  36 __openat (int fd, const char *file, int oflag, ...)
  37 {
  38   int mode;
  39
  40   if (file == NULL)
  41     {
  42       __set_errno (EINVAL);
  43       return -1;
  44     }
  45
  46   if (fd != AT_FDCWD && file[0] != '/')
  47     {
  48       /* Check FD is associated with a directory.  */
  49       struct stat64 st;
  50       if (__fxstat64 (_STAT_VER, fd, &st) != 0)
  51         return -1;
  52
  53       if (!S_ISDIR (st.st_mode))
  54         {
  55           __set_errno (ENOTDIR);
  56           return -1;
  57         }
  58     }
  59
  60   if (__OPEN_NEEDS_MODE (oflag))
  61     {
  62       va_list arg;
  63       va_start (arg, oflag);
  64       mode = va_arg (arg, int);
  65       va_end (arg);
  66
  67       ignore_value (mode);
  68     }
  69
  70   __set_errno (ENOSYS);
  71   return -1;
  72 }
  73 libc_hidden_def (__openat)
  74 weak_alias (__openat, openat)
  75 stub_warning (openat)
  76
  77 /* __openat_2 is a generic wrapper that calls __openat.
  78    So give a stub warning for that symbol too.  */
  79 stub_warning (__openat_2)