summaryrefslogtreecommitdiff
path: root/lib/same.c
blob: ecbc58fdbeb69b1c47ade0dc980602189df32310 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/* Determine whether two file names refer to the same file.

   Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004 Free
   Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* written by Jim Meyering */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdbool.h>
#include <stdio.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>
#include <errno.h>

#include <string.h>

#include <limits.h>
#ifndef _POSIX_NAME_MAX
# define _POSIX_NAME_MAX 14
#endif

#include "same.h"
#include "dirname.h"
#include "error.h"
#include "xalloc.h"

#ifndef MIN
# define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif

#define SAME_INODE(Stat_buf_1, Stat_buf_2) \
  ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \
   && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev)

/* Return nonzero if SOURCE and DEST point to the same name in the same
   directory.  */

bool
same_name (const char *source, const char *dest)
{
  /* Compare the basenames.  */
  char const *source_basename = base_name (source);
  char const *dest_basename = base_name (dest);
  size_t source_baselen = base_len (source_basename);
  size_t dest_baselen = base_len (dest_basename);
  bool identical_basenames =
    (source_baselen == dest_baselen
     && memcmp (source_basename, dest_basename, dest_baselen) == 0);
  bool compare_dirs = identical_basenames;
  bool same = false;

#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
  /* This implementation silently truncates pathname components.  If
     the base names might be truncated, check whether the truncated
     base names are the same, while checking the directories.  */
  size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;
  size_t min_baselen = MIN (source_baselen, dest_baselen);
  if (slen_max <= min_baselen
      && memcmp (source_basename, dest_basename, slen_max) == 0)
    compare_dirs = true;
#endif

  if (compare_dirs)
    {
      struct stat source_dir_stats;
      struct stat dest_dir_stats;
      char *source_dirname, *dest_dirname;

      /* Compare the parent directories (via the device and inode numbers).  */
      source_dirname = dir_name (source);
      dest_dirname = dir_name (dest);

      if (stat (source_dirname, &source_dir_stats))
	{
	  /* Shouldn't happen.  */
	  error (1, errno, "%s", source_dirname);
	}

      if (stat (dest_dirname, &dest_dir_stats))
	{
	  /* Shouldn't happen.  */
	  error (1, errno, "%s", dest_dirname);
	}

      same = SAME_INODE (source_dir_stats, dest_dir_stats);

#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
      if (same && ! identical_basenames)
	{
	  long name_max = (errno = 0, pathconf (dest_dirname, _PC_NAME_MAX));
	  if (name_max < 0)
	    {
	      if (errno)
		{
		  /* Shouldn't happen.  */
		  error (1, errno, "%s", dest_dirname);
		}
	      same = false;
	    }
	  else
	    same = (name_max <= min_baselen
		    && memcmp (source_basename, dest_basename, name_max) == 0);
	}
#endif

      free (source_dirname);
      free (dest_dirname);
    }

  return same;
}