lib/rename.c

   1 /* rename.c -- BSD compatible directory function for System V
   2    Copyright (C) 1988, 1990 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <errno.h>
  21 #ifndef STDC_HEADERS
  22 extern int errno;
  23 #endif
  24
  25 #if !defined(S_ISDIR) && defined(S_IFDIR)
  26 #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
  27 #endif
  28
  29 /* Rename file FROM to file TO.
  30    Return 0 if successful, -1 if not. */
  31
  32 int
  33 rename (from, to)
  34      char *from;
  35      char *to;
  36 {
  37   struct stat from_stats;
  38   int pid, status;
  39
  40   if (stat (from, &from_stats))
  41     return -1;
  42
  43   if (unlink (to) && errno != ENOENT)
  44     return -1;
  45
  46   if (S_ISDIR (from_stats.st_mode))
  47     {
  48       /* Need a setuid root process to link and unlink directories. */
  49       pid = fork ();
  50       switch (pid)
  51         {
  52         case -1:                /* Error. */
  53           error (1, errno, "cannot fork");
  54
  55         case 0:                 /* Child. */
  56           execl (MVDIR, "mvdir", from, to, (char *) 0);
  57           error (255, errno, "cannot run `%s'", MVDIR);
  58
  59         default:                /* Parent. */
  60           while (wait (&status) != pid)
  61             /* Do nothing. */ ;
  62
  63           errno = 0;            /* mvdir printed the system error message. */
  64           if (status)
  65             return -1;
  66         }
  67     }
  68   else
  69     {
  70       if (link (from, to))
  71         return -1;
  72       if (unlink (from) && errno != ENOENT)
  73         {
  74           unlink (to);
  75           return -1;
  76         }
  77     }
  78   return 0;
  79 }