lib/same.c

   1 /* Determine whether two file names refer to the same file.
   2    Copyright (C) 1997-2000, 2002-2003 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 Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #ifdef HAVE_UNISTD_H
  26 # include <unistd.h>
  27 #endif
  28 #if HAVE_STDLIB_H
  29 # include <stdlib.h>
  30 #endif
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <ctype.h>
  34 #include <errno.h>
  35 #ifndef errno
  36 extern int errno;
  37 #endif
  38
  39 #if HAVE_STRING_H
  40 # include <string.h>
  41 #else
  42 # include <strings.h>
  43 #endif
  44
  45 #include "same.h"
  46 #include "dirname.h"
  47 #include "error.h"
  48 #include "xalloc.h"
  49
  50 #ifndef HAVE_DECL_FREE
  51 "this configure-time declaration test was not run"
  52 #endif
  53 #if !HAVE_DECL_FREE
  54 void free ();
  55 #endif
  56
  57 #define SAME_INODE(Stat_buf_1, Stat_buf_2) \
  58   ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \
  59    && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev)
  60
  61 /* Return nonzero if SOURCE and DEST point to the same name in the same
  62    directory.  */
  63
  64 int
  65 same_name (const char *source, const char *dest)
  66 {
  67   /* Compare the basenames.  */
  68   char const *source_basename = base_name (source);
  69   char const *dest_basename = base_name (dest);
  70   size_t source_baselen = base_len (source_basename);
  71   size_t dest_baselen = base_len (dest_basename);
  72
  73   if (source_baselen == dest_baselen
  74       && memcmp (source_basename, dest_basename, dest_baselen) == 0)
  75     {
  76       struct stat source_dir_stats;
  77       struct stat dest_dir_stats;
  78       char *source_dirname, *dest_dirname;
  79
  80       /* Compare the parent directories (via the device and inode numbers).  */
  81       source_dirname = dir_name (source);
  82       dest_dirname = dir_name (dest);
  83
  84       if (stat (source_dirname, &source_dir_stats))
  85         {
  86           /* Shouldn't happen.  */
  87           error (1, errno, "%s", source_dirname);
  88         }
  89
  90       if (stat (dest_dirname, &dest_dir_stats))
  91         {
  92           /* Shouldn't happen.  */
  93           error (1, errno, "%s", dest_dirname);
  94         }
  95
  96       free (source_dirname);
  97       free (dest_dirname);
  98
  99       if (SAME_INODE (source_dir_stats, dest_dir_stats))
 100         return 1;
 101     }
 102
 103   return 0;
 104 }