sysdeps/mach/hurd/symlinkat.c

   1 /* Create a symbolic link named relative to an open directory.  Hurd version.
   2    Copyright (C) 1991-2016 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 (const char *from, int fd, const char *to)
  32 {
  33   error_t err;
  34   file_t dir, node;
  35   char *name;
  36   const size_t len = strlen (from) + 1;
  37   char buf[sizeof (_HURD_SYMLINK) + len];
  38
  39   /* A symlink is a file whose translator is "/hurd/symlink\0target\0".  */
  40
  41   memcpy (buf, _HURD_SYMLINK, sizeof (_HURD_SYMLINK));
  42   memcpy (&buf[sizeof (_HURD_SYMLINK)], from, len);
  43
  44   dir = __file_name_split_at (fd, to, &name);
  45   if (dir == MACH_PORT_NULL)
  46     return -1;
  47
  48   /* Create a new, unlinked node in the target directory.  */
  49   err = __dir_mkfile (dir, O_WRITE, 0777 & ~_hurd_umask, &node);
  50
  51   if (! err)
  52     {
  53       /* Set the node's translator to make it a symlink.  */
  54       err = __file_set_translator (node,
  55                                    FS_TRANS_EXCL|FS_TRANS_SET,
  56                                    FS_TRANS_EXCL|FS_TRANS_SET, 0,
  57                                    buf, sizeof (_HURD_SYMLINK) + len,
  58                                    MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND);
  59
  60       if (! err)
  61         /* Link the node, now a valid symlink, into the target directory.  */
  62         err = __dir_link (dir, node, name, 1);
  63
  64       __mach_port_deallocate (__mach_task_self (), node);
  65     }
  66
  67   __mach_port_deallocate (__mach_task_self (), dir);
  68
  69   if (err)
  70     return __hurd_fail (err);
  71   return 0;
  72 }