io/readlinkat.c

   1 /* Copyright (C) 2005-2022 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 <unistd.h>
  21
  22 /* Read the contents of the symbolic link PATH relative to FD into no
  23    more than LEN bytes of BUF.  The contents are not null-terminated.
  24    Returns the number of characters read, or -1 for errors.  */
  25 ssize_t
  26 readlinkat (int fd, const char *path, char *buf, size_t len)
  27 {
  28   if (path == NULL)
  29     {
  30       __set_errno (EINVAL);
  31       return -1;
  32     }
  33
  34   if (fd != AT_FDCWD && fd < 0 && *path != '/')
  35     {
  36       __set_errno (EBADF);
  37       return -1;
  38     }
  39
  40   __set_errno (ENOSYS);
  41   return -1;
  42 }
  43 stub_warning (readlinkat)
  44 libc_hidden_def (readlinkat)