sysdeps/mach/hurd/symlinkat.c

   1 /* Create a symbolic link named relative to an open directory.  Hurd version.
   2    Copyright (C) 1991-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stddef.h>
  22 #include <unistd.h>
  23 #include <hurd.h>
  24 #include <hurd/paths.h>
  25 #include <hurd/fd.h>
  26 #include <string.h>
  27
  28
  29 /* Make a link to FROM called TO relative to FD.  */
  30 int
  31 symlinkat (from, fd, to)
  32      const char *from;
  33      int fd;
  34      const char *to;
  35 {
  36   error_t err;
  37   file_t dir, node;
  38   char *name;
  39   const size_t len = strlen (from) + 1;
  40   char buf[sizeof (_HURD_SYMLINK) + len];
  41
  42   /* A symlink is a file whose translator is "/hurd/symlink\0target\0".  */
  43
  44   memcpy (buf, _HURD_SYMLINK, sizeof (_HURD_SYMLINK));
  45   memcpy (&buf[sizeof (_HURD_SYMLINK)], from, len);
  46
  47   dir = __file_name_split_at (fd, to, &name);
  48   if (dir == MACH_PORT_NULL)
  49     return -1;
  50
  51   /* Create a new, unlinked node in the target directory.  */
  52   err = __dir_mkfile (dir, O_WRITE, 0777 & ~_hurd_umask, &node);
  53
  54   if (! err)
  55     {
  56       /* Set the node's translator to make it a symlink.  */
  57       err = __file_set_translator (node,
  58                                    FS_TRANS_EXCL|FS_TRANS_SET,
  59                                    FS_TRANS_EXCL|FS_TRANS_SET, 0,
  60                                    buf, sizeof (_HURD_SYMLINK) + len,
  61                                    MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND);
  62
  63       if (! err)
  64         /* Link the node, now a valid symlink, into the target directory.  */
  65         err = __dir_link (dir, node, name, 1);
  66
  67       __mach_port_deallocate (__mach_task_self (), node);
  68     }
  69
  70   __mach_port_deallocate (__mach_task_self (), dir);
  71
  72   if (err)
  73     return __hurd_fail (err);
  74   return 0;
  75 }