1/* Determine whether two file names refer to the same file. 2 3 Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006 Free 4 Software Foundation, Inc. 5 6 This program is free software: you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 18 19/* written by Jim Meyering */ 20 21#include <config.h> 22 23#include <stdbool.h> 24#include <stdio.h> 25#include <unistd.h> 26#include <stdlib.h> 27#include <sys/types.h> 28#include <sys/stat.h> 29#include <ctype.h> 30#include <errno.h> 31 32#include <string.h> 33 34#include <limits.h> 35#ifndef _POSIX_NAME_MAX 36# define _POSIX_NAME_MAX 14 37#endif 38 39#include "same.h" 40#include "dirname.h" 41#include "error.h" 42#include "same-inode.h" 43#include "xalloc.h" 44 45#ifndef MIN 46# define MIN(a, b) ((a) < (b) ? (a) : (b)) 47#endif 48 49/* Return nonzero if SOURCE and DEST point to the same name in the same 50 directory. */ 51 52bool 53same_name (const char *source, const char *dest) 54{ 55 /* Compare the basenames. */ 56 char const *source_basename = last_component (source); 57 char const *dest_basename = last_component (dest); 58 size_t source_baselen = base_len (source_basename); 59 size_t dest_baselen = base_len (dest_basename); 60 bool identical_basenames = 61 (source_baselen == dest_baselen 62 && memcmp (source_basename, dest_basename, dest_baselen) == 0); 63 bool compare_dirs = identical_basenames; 64 bool same = false; 65 66#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX 67 /* This implementation silently truncates components of file names. If 68 the base names might be truncated, check whether the truncated 69 base names are the same, while checking the directories. */ 70 size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX; 71 size_t min_baselen = MIN (source_baselen, dest_baselen); 72 if (slen_max <= min_baselen 73 && memcmp (source_basename, dest_basename, slen_max) == 0) 74 compare_dirs = true; 75#endif 76 77 if (compare_dirs) 78 { 79 struct stat source_dir_stats; 80 struct stat dest_dir_stats; 81 char *source_dirname, *dest_dirname; 82 83 /* Compare the parent directories (via the device and inode numbers). */ 84 source_dirname = dir_name (source); 85 dest_dirname = dir_name (dest); 86 87 if (stat (source_dirname, &source_dir_stats)) 88 { 89 /* Shouldn't happen. */ 90 error (1, errno, "%s", source_dirname); 91 } 92 93 if (stat (dest_dirname, &dest_dir_stats)) 94 { 95 /* Shouldn't happen. */ 96 error (1, errno, "%s", dest_dirname); 97 } 98 99 same = SAME_INODE (source_dir_stats, dest_dir_stats); 100 101#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX 102 if (same && ! identical_basenames) 103 { 104 long name_max = (errno = 0, pathconf (dest_dirname, _PC_NAME_MAX)); 105 if (name_max < 0) 106 { 107 if (errno) 108 { 109 /* Shouldn't happen. */ 110 error (1, errno, "%s", dest_dirname); 111 } 112 same = false; 113 } 114 else 115 same = (name_max <= min_baselen 116 && memcmp (source_basename, dest_basename, name_max) == 0); 117 } 118#endif 119 120 free (source_dirname); 121 free (dest_dirname); 122 } 123 124 return same; 125} 126