1 /*- 2 * Copyright (C) 1990 Free Software Foundation, Inc. 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * without restriction. 6 * 7 * This program is distributed in the hope that it will be useful, but WITHOUT 8 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 9 * FITNESS FOR A PARTICULAR PURPOSE. 10 * 11 * backupfile.c -- make Emacs style backup file names 12 * 13 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. 14 * 15 * $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $ 16 * $FreeBSD$ 17 */ 18 19 #include <ctype.h> 20 #include <dirent.h> 21 #include <libgen.h> 22 #include <stdio.h> 23 #include <stdlib.h> 24 #include <string.h> 25 26 #include "backupfile.h" 27 28 29 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 30 31 /* Which type of backup file names are generated. */ 32 enum backup_type backup_type = none; 33 34 /* 35 * The extension added to file names to produce a simple (as opposed to 36 * numbered) backup file name. 37 */ 38 const char *simple_backup_suffix = "~"; 39 40 static char *concat(const char *, const char *); 41 static char *make_version_name(const char *, int); 42 static int max_backup_version(const char *, const char *); 43 static int version_number(const char *, const char *, size_t); 44 static int argmatch(const char *, const char **); 45 static void invalid_arg(const char *, const char *, int); 46 47 /* 48 * Return the name of the new backup file for file FILE, allocated with 49 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 50 * is the root directory. Do not call this function if backup_type == none. 51 */ 52 char * 53 find_backup_file_name(const char *file) 54 { 55 char *dir, *base_versions, *tmp_file; 56 int highest_backup; 57 58 if (backup_type == simple) 59 return concat(file, simple_backup_suffix); 60 tmp_file = strdup(file); 61 if (tmp_file == NULL) 62 return NULL; 63 base_versions = concat(basename(tmp_file), ".~"); 64 free(tmp_file); 65 if (base_versions == NULL) 66 return NULL; 67 tmp_file = strdup(file); 68 if (tmp_file == NULL) { 69 free(base_versions); 70 return NULL; 71 } 72 dir = dirname(tmp_file); 73 if (dir == NULL) { 74 free(base_versions); 75 free(tmp_file); 76 return NULL; 77 } 78 highest_backup = max_backup_version(base_versions, dir); 79 free(base_versions); 80 free(tmp_file); 81 if (backup_type == numbered_existing && highest_backup == 0) 82 return concat(file, simple_backup_suffix); 83 return make_version_name(file, highest_backup + 1); 84 } 85 86 /* 87 * Return the number of the highest-numbered backup file for file FILE in 88 * directory DIR. If there are no numbered backups of FILE in DIR, or an 89 * error occurs reading DIR, return 0. FILE should already have ".~" appended 90 * to it. 91 */ 92 static int 93 max_backup_version(const char *file, const char *dir) 94 { 95 DIR *dirp; 96 struct dirent *dp; 97 int highest_version, this_version; 98 size_t file_name_length; 99 100 dirp = opendir(dir); 101 if (dirp == NULL) 102 return 0; 103 104 highest_version = 0; 105 file_name_length = strlen(file); 106 107 while ((dp = readdir(dirp)) != NULL) { 108 if (dp->d_namlen <= file_name_length) 109 continue; 110 111 this_version = version_number(file, dp->d_name, file_name_length); 112 if (this_version > highest_version) 113 highest_version = this_version; 114 } 115 closedir(dirp); 116 return highest_version; 117 } 118 119 /* 120 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 121 * Return 0 if out of memory. 122 */ 123 static char * 124 make_version_name(const char *file, int version) 125 { 126 char *backup_name; 127 128 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 129 return NULL; 130 return backup_name; 131 } 132 133 /* 134 * If BACKUP is a numbered backup of BASE, return its version number; 135 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 136 * already have ".~" appended to it. 137 */ 138 static int 139 version_number(const char *base, const char *backup, size_t base_length) 140 { 141 int version; 142 const char *p; 143 144 version = 0; 145 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 146 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 147 version = version * 10 + *p - '0'; 148 if (p[0] != '~' || p[1]) 149 version = 0; 150 } 151 return version; 152 } 153 154 /* 155 * Return the newly-allocated concatenation of STR1 and STR2. If out of 156 * memory, return 0. 157 */ 158 static char * 159 concat(const char *str1, const char *str2) 160 { 161 char *newstr; 162 163 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 164 return NULL; 165 return newstr; 166 } 167 168 /* 169 * If ARG is an unambiguous match for an element of the null-terminated array 170 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 171 * does not match any element or -2 if it is ambiguous (is a prefix of more 172 * than one element). 173 */ 174 static int 175 argmatch(const char *arg, const char **optlist) 176 { 177 int i; /* Temporary index in OPTLIST. */ 178 size_t arglen; /* Length of ARG. */ 179 int matchind = -1; /* Index of first nonexact match. */ 180 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 181 182 arglen = strlen(arg); 183 184 /* Test all elements for either exact match or abbreviated matches. */ 185 for (i = 0; optlist[i]; i++) { 186 if (!strncmp(optlist[i], arg, arglen)) { 187 if (strlen(optlist[i]) == arglen) 188 /* Exact match found. */ 189 return i; 190 else if (matchind == -1) 191 /* First nonexact match found. */ 192 matchind = i; 193 else 194 /* Second nonexact match found. */ 195 ambiguous = 1; 196 } 197 } 198 if (ambiguous) 199 return -2; 200 else 201 return matchind; 202 } 203 204 /* 205 * Error reporting for argmatch. KIND is a description of the type of entity 206 * that was being matched. VALUE is the invalid value that was given. PROBLEM 207 * is the return value from argmatch. 208 */ 209 static void 210 invalid_arg(const char *kind, const char *value, int problem) 211 { 212 fprintf(stderr, "patch: "); 213 if (problem == -1) 214 fprintf(stderr, "invalid"); 215 else /* Assume -2. */ 216 fprintf(stderr, "ambiguous"); 217 fprintf(stderr, " %s `%s'\n", kind, value); 218 } 219 220 static const char *backup_args[] = { 221 "none", "never", "simple", "nil", "existing", "t", "numbered", 0 222 }; 223 224 static enum backup_type backup_types[] = { 225 none, simple, simple, numbered_existing, 226 numbered_existing, numbered, numbered 227 }; 228 229 /* 230 * Return the type of backup indicated by VERSION. Unique abbreviations are 231 * accepted. 232 */ 233 enum backup_type 234 get_version(const char *version) 235 { 236 int i; 237 238 if (version == NULL || *version == '\0') 239 return numbered_existing; 240 i = argmatch(version, backup_args); 241 if (i >= 0) 242 return backup_types[i]; 243 invalid_arg("version control type", version, i); 244 exit(2); 245 } 246