sysdeps/mach/hurd/symlinkat.c

   1 /* Create a symbolic link named relative to an open directory.  Hurd version.
   2    Copyright (C) 1991,1992,1993,1994,1995,1996,1997,2006
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stddef.h>
  23 #include <unistd.h>
  24 #include <hurd.h>
  25 #include <hurd/paths.h>
  26 #include <hurd/fd.h>
  27 #include <string.h>
  28
  29
  30 /* Make a link to FROM called TO relative to FD.  */
  31 int
  32 symlinkat (from, fd, to)
  33      const char *from;
  34      int fd;
  35      const char *to;
  36 {
  37   error_t err;
  38   file_t dir, node;
  39   char *name;
  40   const size_t len = strlen (from) + 1;
  41   char buf[sizeof (_HURD_SYMLINK) + len];
  42
  43   /* A symlink is a file whose translator is "/hurd/symlink\0target\0".  */
  44
  45   memcpy (buf, _HURD_SYMLINK, sizeof (_HURD_SYMLINK));
  46   memcpy (&buf[sizeof (_HURD_SYMLINK)], from, len);
  47
  48   dir = __file_name_split_at (fd, to, &name);
  49   if (dir == MACH_PORT_NULL)
  50     return -1;
  51
  52   /* Create a new, unlinked node in the target directory.  */
  53   err = __dir_mkfile (dir, O_WRITE, 0777 & ~_hurd_umask, &node);
  54
  55   if (! err)
  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 (), dir);
  68   __mach_port_deallocate (__mach_task_self (), node);
  69
  70   if (err)
  71     return __hurd_fail (err);
  72   return 0;
  73 }