1/* Determine whether two file names refer to the same file. 2 3 Copyright (C) 1997-2000, 2002-2006, 2009-2010 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18/* written by Jim Meyering */ 19 20#include <config.h> 21 22#include <stdbool.h> 23#include <stdio.h> 24#include <unistd.h> 25#include <stdlib.h> 26#include <sys/types.h> 27#include <sys/stat.h> 28#include <ctype.h> 29#include <errno.h> 30 31#include <string.h> 32 33#include <limits.h> 34#ifndef _POSIX_NAME_MAX 35# define _POSIX_NAME_MAX 14 36#endif 37 38#include "same.h" 39#include "dirname.h" 40#include "error.h" 41#include "same-inode.h" 42 43#ifndef MIN 44# define MIN(a, b) ((a) < (b) ? (a) : (b)) 45#endif 46 47/* Return nonzero if SOURCE and DEST point to the same name in the same 48 directory. */ 49 50bool 51same_name (const char *source, const char *dest) 52{ 53 /* Compare the basenames. */ 54 char const *source_basename = last_component (source); 55 char const *dest_basename = last_component (dest); 56 size_t source_baselen = base_len (source_basename); 57 size_t dest_baselen = base_len (dest_basename); 58 bool identical_basenames = 59 (source_baselen == dest_baselen 60 && memcmp (source_basename, dest_basename, dest_baselen) == 0); 61 bool compare_dirs = identical_basenames; 62 bool same = false; 63 64#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX 65 /* This implementation silently truncates components of file names. If 66 the base names might be truncated, check whether the truncated 67 base names are the same, while checking the directories. */ 68 size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX; 69 size_t min_baselen = MIN (source_baselen, dest_baselen); 70 if (slen_max <= min_baselen 71 && memcmp (source_basename, dest_basename, slen_max) == 0) 72 compare_dirs = true; 73#endif 74 75 if (compare_dirs) 76 { 77 struct stat source_dir_stats; 78 struct stat dest_dir_stats; 79 char *source_dirname, *dest_dirname; 80 81 /* Compare the parent directories (via the device and inode numbers). */ 82 source_dirname = dir_name (source); 83 dest_dirname = dir_name (dest); 84 85 if (stat (source_dirname, &source_dir_stats)) 86 { 87 /* Shouldn't happen. */ 88 error (1, errno, "%s", source_dirname); 89 } 90 91 if (stat (dest_dirname, &dest_dir_stats)) 92 { 93 /* Shouldn't happen. */ 94 error (1, errno, "%s", dest_dirname); 95 } 96 97 same = SAME_INODE (source_dir_stats, dest_dir_stats); 98 99#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX 100 if (same && ! identical_basenames) 101 { 102 long name_max = (errno = 0, pathconf (dest_dirname, _PC_NAME_MAX)); 103 if (name_max < 0) 104 { 105 if (errno) 106 { 107 /* Shouldn't happen. */ 108 error (1, errno, "%s", dest_dirname); 109 } 110 same = false; 111 } 112 else 113 same = (name_max <= min_baselen 114 && memcmp (source_basename, dest_basename, name_max) == 0); 115 } 116#endif 117 118 free (source_dirname); 119 free (dest_dirname); 120 } 121 122 return same; 123} 124