io/openat.c

   1 /* Copyright (C) 2005-2024 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
  27 /* Open FILE with access OFLAG.  Interpret relative paths relative to
  28    the directory associated with FD.  If O_CREAT or O_TMPFILE is in OFLAG, a
  29    third argument is the file protection.  */
  30 int
  31 __openat (int fd, const char *file, int oflag, ...)
  32 {
  33   int mode;
  34
  35   if (file == NULL)
  36     {
  37       __set_errno (EINVAL);
  38       return -1;
  39     }
  40
  41   if (fd != AT_FDCWD && file[0] != '/')
  42     {
  43       /* Check FD is associated with a directory.  */
  44       struct stat64 st;
  45       if (__fstat64 (fd, &st) != 0)
  46         return -1;
  47
  48       if (!S_ISDIR (st.st_mode))
  49         {
  50           __set_errno (ENOTDIR);
  51           return -1;
  52         }
  53     }
  54
  55   if (__OPEN_NEEDS_MODE (oflag))
  56     {
  57       va_list arg;
  58       va_start (arg, oflag);
  59       mode = va_arg (arg, int);
  60       va_end (arg);
  61
  62       ignore_value (mode);
  63     }
  64
  65   __set_errno (ENOSYS);
  66   return -1;
  67 }
  68 libc_hidden_def (__openat)
  69 weak_alias (__openat, openat)
  70 stub_warning (openat)
  71
  72 /* __openat_2 is a generic wrapper that calls __openat.
  73    So give a stub warning for that symbol too.  */
  74 stub_warning (__openat_2)