sysdeps/mach/hurd/readlink.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 97 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <unistd.h>
  20 #include <hurd.h>
  21 #include <hurd/paths.h>
  22 #include <fcntl.h>
  23 #include <string.h>
  24
  25 /* Read the contents of the symbolic link FILE_NAME into no more than
  26    LEN bytes of BUF.  The contents are not null-terminated.
  27    Returns the number of characters read, or -1 for errors.  */
  28 ssize_t
  29 __readlink (file_name, buf, len)
  30      const char *file_name;
  31      char *buf;
  32      size_t len;
  33 {
  34   error_t err;
  35   file_t file;
  36   struct stat st;
  37
  38   file = __file_name_lookup (file_name, O_READ | O_NOLINK, 0);
  39   if (file == MACH_PORT_NULL)
  40     return -1;
  41
  42   err = __io_stat (file, &st);
  43   if (! err)
  44     if (S_ISLNK (st.st_mode))
  45       {
  46         char *rbuf = buf;
  47
  48         err = __io_read (file, &rbuf, &len, 0, len);
  49         if (!err && rbuf != buf)
  50           {
  51             memcpy (buf, rbuf, len);
  52             __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len);
  53           }
  54       }
  55     else
  56       err = EINVAL;
  57
  58   __mach_port_deallocate (__mach_task_self (), file);
  59
  60   if (err)
  61     return __hurd_fail (err);
  62   else
  63     return len;
  64 }
  65 weak_alias (__readlink, readlink)