annotate lib/same.c @ 5135:46d5c1c09035

(same_name): Return bool, not int. (errno): Don't declare; we assume C89 or better now.
author Paul Eggert <eggert@cs.ucla.edu>
date Fri, 06 Aug 2004 06:19:08 +0000
parents de285d9e7c4d
children b3d5c90efc81
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1 /* Determine whether two file names refer to the same file.
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2
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3 Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004 Free
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4 Software Foundation, Inc.
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5
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6 This program is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2, or (at your option)
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9 any later version.
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10
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11 This program is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with this program; if not, write to the Free Software Foundation,
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18 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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19
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20 /* written by Jim Meyering */
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21
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22 #if HAVE_CONFIG_H
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23 # include <config.h>
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24 #endif
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25
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26 #include <stdbool.h>
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27 #include <stdio.h>
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28 #ifdef HAVE_UNISTD_H
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29 # include <unistd.h>
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30 #endif
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31 #include <stdlib.h>
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32 #include <sys/types.h>
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33 #include <sys/stat.h>
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34 #include <ctype.h>
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35 #include <errno.h>
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36
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37 #include <string.h>
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38
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39 #include <limits.h>
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40 #ifndef _POSIX_NAME_MAX
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41 # define _POSIX_NAME_MAX 14
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42 #endif
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43
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44 #include "same.h"
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45 #include "dirname.h"
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46 #include "error.h"
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47 #include "xalloc.h"
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48
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49 #define MIN(a, b) ((a) < (b) ? (a) : (b))
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50
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51 #define SAME_INODE(Stat_buf_1, Stat_buf_2) \
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52 ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \
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53 && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev)
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54
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55 /* Return nonzero if SOURCE and DEST point to the same name in the same
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56 directory. */
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57
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58 bool
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59 same_name (const char *source, const char *dest)
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60 {
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61 /* Compare the basenames. */
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62 char const *source_basename = base_name (source);
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63 char const *dest_basename = base_name (dest);
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64 size_t source_baselen = base_len (source_basename);
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65 size_t dest_baselen = base_len (dest_basename);
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66 bool identical_basenames =
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67 (source_baselen == dest_baselen
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68 && memcmp (source_basename, dest_basename, dest_baselen) == 0);
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69 bool compare_dirs = identical_basenames;
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70 bool same = false;
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71
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72 #if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
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73 /* This implementation silently truncates pathname components. If
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74 the base names might be truncated, check whether the truncated
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75 base names are the same, while checking the directories. */
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76 size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;
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77 size_t min_baselen = MIN (source_baselen, dest_baselen);
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78 if (slen_max <= min_baselen
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79 && memcmp (source_basename, dest_basename, slen_max) == 0)
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80 compare_dirs = true;
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81 #endif
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82
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83 if (compare_dirs)
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84 {
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85 struct stat source_dir_stats;
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86 struct stat dest_dir_stats;
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87 char *source_dirname, *dest_dirname;
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88
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89 /* Compare the parent directories (via the device and inode numbers). */
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90 source_dirname = dir_name (source);
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91 dest_dirname = dir_name (dest);
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92
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93 if (stat (source_dirname, &source_dir_stats))
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94 {
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95 /* Shouldn't happen. */
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96 error (1, errno, "%s", source_dirname);
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97 }
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98
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99 if (stat (dest_dirname, &dest_dir_stats))
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100 {
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101 /* Shouldn't happen. */
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102 error (1, errno, "%s", dest_dirname);
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103 }
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104
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105 same = SAME_INODE (source_dir_stats, dest_dir_stats);
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106
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107 #if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
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108 if (same && ! identical_basenames)
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109 {
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110 long name_max = (errno = 0, pathconf (dest_dirname, _PC_NAME_MAX));
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111 if (name_max < 0)
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112 {
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113 if (errno)
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114 {
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115 /* Shouldn't happen. */
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116 error (1, errno, "%s", dest_dirname);
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117 }
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118 same = false;
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119 }
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120 else
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121 same = (name_max <= min_baselen
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122 && memcmp (source_basename, dest_basename, name_max) == 0);
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123 }
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124 #endif
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125
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126 free (source_dirname);
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127 free (dest_dirname);
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128 }
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129
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130 return same;
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131 }