1/* backupfile.c -- make Emacs style backup file names 2 Copyright (C) 1990,91,92,93,94,95,96,97,98,99,2000, 2001, 2002 Free Software 3 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 2, or (at your option) 8 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; see the file COPYING. 17 If not, write to the Free Software Foundation, 18 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 19 20/* Written by David MacKenzie <djm@gnu.ai.mit.edu>. 21 Some algorithms adapted from GNU Emacs. */ 22 23#if HAVE_CONFIG_H 24# include <config.h> 25#endif 26 27#include <stdio.h> 28#include <sys/types.h> 29#if HAVE_STRING_H 30# include <string.h> 31#else 32# include <strings.h> 33#endif 34 35#if HAVE_DIRENT_H 36# include <dirent.h> 37# define NLENGTH(direct) strlen ((direct)->d_name) 38#else 39# define dirent direct 40# define NLENGTH(direct) ((size_t) (direct)->d_namlen) 41# if HAVE_SYS_NDIR_H 42# include <sys/ndir.h> 43# endif 44# if HAVE_SYS_DIR_H 45# include <sys/dir.h> 46# endif 47# if HAVE_NDIR_H 48# include <ndir.h> 49# endif 50#endif 51 52#if CLOSEDIR_VOID 53/* Fake a return value. */ 54# define CLOSEDIR(d) (closedir (d), 0) 55#else 56# define CLOSEDIR(d) closedir (d) 57#endif 58 59#if HAVE_STDLIB_H 60# include <stdlib.h> 61#endif 62 63#ifndef HAVE_DECL_GETENV 64"this configure-time declaration test was not run" 65#endif 66#if !HAVE_DECL_GETENV 67char *getenv (); 68#endif 69 70#ifndef HAVE_DECL_MALLOC 71"this configure-time declaration test was not run" 72#endif 73#if !HAVE_DECL_MALLOC 74char *malloc (); 75#endif 76 77#if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H 78# define HAVE_DIR 1 79#else 80# define HAVE_DIR 0 81#endif 82 83#if HAVE_LIMITS_H 84# include <limits.h> 85#endif 86#ifndef CHAR_BIT 87# define CHAR_BIT 8 88#endif 89/* Upper bound on the string length of an integer converted to string. 90 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit; 91 add 1 for integer division truncation; add 1 more for a minus sign. */ 92#define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2) 93 94/* ISDIGIT differs from isdigit, as follows: 95 - Its arg may be any int or unsigned int; it need not be an unsigned char. 96 - It's guaranteed to evaluate its argument exactly once. 97 - It's typically faster. 98 POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to 99 ISDIGIT_LOCALE unless it's important to use the locale's definition 100 of `digit' even when the host does not conform to POSIX. */ 101#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9) 102 103#if D_INO_IN_DIRENT 104# define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0) 105#else 106# define REAL_DIR_ENTRY(dp) 1 107#endif 108 109#include "argmatch.h" 110#include "backupfile.h" 111#include "dirname.h" 112 113/* The extension added to file names to produce a simple (as opposed 114 to numbered) backup file name. */ 115const char *simple_backup_suffix = "~"; 116 117static int max_backup_version PARAMS ((const char *, const char *)); 118static int version_number PARAMS ((const char *, const char *, size_t)); 119 120/* Return the name of the new backup file for file FILE, 121 allocated with malloc. Return 0 if out of memory. 122 FILE must not end with a '/' unless it is the root directory. 123 Do not call this function if backup_type == none. */ 124 125char * 126find_backup_file_name (const char *file, enum backup_type backup_type) 127{ 128 size_t backup_suffix_size_max; 129 size_t file_len = strlen (file); 130 size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4; 131 char *s; 132 const char *suffix = simple_backup_suffix; 133 134 /* Allow room for simple or `.~N~' backups. */ 135 backup_suffix_size_max = strlen (simple_backup_suffix) + 1; 136 if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max) 137 backup_suffix_size_max = numbered_suffix_size_max; 138 139 s = malloc (file_len + 1 140 + backup_suffix_size_max + numbered_suffix_size_max); 141 if (s) 142 { 143#if HAVE_DIR 144 if (backup_type != simple) 145 { 146 int highest_backup; 147 size_t dirlen = dir_len (file); 148 149 memcpy (s, file, dirlen); 150 if (dirlen == FILESYSTEM_PREFIX_LEN (file)) 151 s[dirlen++] = '.'; 152 s[dirlen] = '\0'; 153 highest_backup = max_backup_version (base_name (file), s); 154 if (! (backup_type == numbered_existing && highest_backup == 0)) 155 { 156 char *numbered_suffix = s + (file_len + backup_suffix_size_max); 157 sprintf (numbered_suffix, ".~%d~", highest_backup + 1); 158 suffix = numbered_suffix; 159 } 160 } 161#endif /* HAVE_DIR */ 162 163 strcpy (s, file); 164 addext (s, suffix, '~'); 165 } 166 return s; 167} 168 169#if HAVE_DIR 170 171/* Return the number of the highest-numbered backup file for file 172 FILE in directory DIR. If there are no numbered backups 173 of FILE in DIR, or an error occurs reading DIR, return 0. 174 */ 175 176static int 177max_backup_version (const char *file, const char *dir) 178{ 179 DIR *dirp; 180 struct dirent *dp; 181 int highest_version; 182 int this_version; 183 size_t file_name_length; 184 185 dirp = opendir (dir); 186 if (!dirp) 187 return 0; 188 189 highest_version = 0; 190 file_name_length = base_len (file); 191 192 while ((dp = readdir (dirp)) != 0) 193 { 194 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4) 195 continue; 196 197 this_version = version_number (file, dp->d_name, file_name_length); 198 if (this_version > highest_version) 199 highest_version = this_version; 200 } 201 if (CLOSEDIR (dirp)) 202 return 0; 203 return highest_version; 204} 205 206/* If BACKUP is a numbered backup of BASE, return its version number; 207 otherwise return 0. BASE_LENGTH is the length of BASE. 208 */ 209 210static int 211version_number (const char *base, const char *backup, size_t base_length) 212{ 213 int version; 214 const char *p; 215 216 version = 0; 217 if (strncmp (base, backup, base_length) == 0 218 && backup[base_length] == '.' 219 && backup[base_length + 1] == '~') 220 { 221 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p) 222 version = version * 10 + *p - '0'; 223 if (p[0] != '~' || p[1]) 224 version = 0; 225 } 226 return version; 227} 228#endif /* HAVE_DIR */ 229 230static const char * const backup_args[] = 231{ 232 /* In a series of synonyms, present the most meaning full first, so 233 that argmatch_valid be more readable. */ 234 "none", "off", 235 "simple", "never", 236 "existing", "nil", 237 "numbered", "t", 238 0 239}; 240 241static const enum backup_type backup_types[] = 242{ 243 none, none, 244 simple, simple, 245 numbered_existing, numbered_existing, 246 numbered, numbered 247}; 248 249/* Return the type of backup specified by VERSION. 250 If VERSION is NULL or the empty string, return numbered_existing. 251 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate 252 for the specified CONTEXT. Unambiguous abbreviations are accepted. */ 253 254enum backup_type 255get_version (const char *context, const char *version) 256{ 257 if (version == 0 || *version == 0) 258 return numbered_existing; 259 else 260 return XARGMATCH (context, version, backup_args, backup_types); 261} 262 263 264/* Return the type of backup specified by VERSION. 265 If VERSION is NULL, use the value of the envvar VERSION_CONTROL. 266 If the specified string is invalid or ambiguous, fail with a diagnostic 267 appropriate for the specified CONTEXT. 268 Unambiguous abbreviations are accepted. */ 269 270enum backup_type 271xget_version (const char *context, const char *version) 272{ 273 if (version && *version) 274 return get_version (context, version); 275 else 276 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL")); 277} 278