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 */ 17 18 #include <ctype.h> 19 #include <dirent.h> 20 #include <libgen.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 25 #include "backupfile.h" 26 27 28 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 29 30 /* Which type of backup file names are generated. */ 31 enum backup_type backup_type = none; 32 33 /* 34 * The extension added to file names to produce a simple (as opposed to 35 * numbered) backup file name. 36 */ 37 const char *simple_backup_suffix = "~"; 38 39 static char *concat(const char *, const char *); 40 static char *make_version_name(const char *, int); 41 static int max_backup_version(const char *, const char *); 42 static int version_number(const char *, const char *, size_t); 43 static int argmatch(const char *, const char **); 44 static void invalid_arg(const char *, const char *, int); 45 46 /* 47 * Return the name of the new backup file for file FILE, allocated with 48 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 49 * is the root directory. Do not call this function if backup_type == none. 50 */ 51 char * 52 find_backup_file_name(const char *file) 53 { 54 char *dir, *base_versions, *tmp_file; 55 int highest_backup; 56 57 if (backup_type == simple) 58 return concat(file, simple_backup_suffix); 59 tmp_file = strdup(file); 60 if (tmp_file == NULL) 61 return NULL; 62 base_versions = concat(basename(tmp_file), ".~"); 63 free(tmp_file); 64 if (base_versions == NULL) 65 return NULL; 66 tmp_file = strdup(file); 67 if (tmp_file == NULL) { 68 free(base_versions); 69 return NULL; 70 } 71 dir = dirname(tmp_file); 72 if (dir == NULL) { 73 free(base_versions); 74 free(tmp_file); 75 return NULL; 76 } 77 highest_backup = max_backup_version(base_versions, dir); 78 free(base_versions); 79 free(tmp_file); 80 if (backup_type == numbered_existing && highest_backup == 0) 81 return concat(file, simple_backup_suffix); 82 return make_version_name(file, highest_backup + 1); 83 } 84 85 /* 86 * Return the number of the highest-numbered backup file for file FILE in 87 * directory DIR. If there are no numbered backups of FILE in DIR, or an 88 * error occurs reading DIR, return 0. FILE should already have ".~" appended 89 * to it. 90 */ 91 static int 92 max_backup_version(const char *file, const char *dir) 93 { 94 DIR *dirp; 95 struct dirent *dp; 96 int highest_version, this_version; 97 size_t file_name_length; 98 99 dirp = opendir(dir); 100 if (dirp == NULL) 101 return 0; 102 103 highest_version = 0; 104 file_name_length = strlen(file); 105 106 while ((dp = readdir(dirp)) != NULL) { 107 if (dp->d_namlen <= file_name_length) 108 continue; 109 110 this_version = version_number(file, dp->d_name, file_name_length); 111 if (this_version > highest_version) 112 highest_version = this_version; 113 } 114 closedir(dirp); 115 return highest_version; 116 } 117 118 /* 119 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 120 * Return 0 if out of memory. 121 */ 122 static char * 123 make_version_name(const char *file, int version) 124 { 125 char *backup_name; 126 127 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 128 return NULL; 129 return backup_name; 130 } 131 132 /* 133 * If BACKUP is a numbered backup of BASE, return its version number; 134 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 135 * already have ".~" appended to it. 136 */ 137 static int 138 version_number(const char *base, const char *backup, size_t base_length) 139 { 140 int version; 141 const char *p; 142 143 version = 0; 144 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 145 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 146 version = version * 10 + *p - '0'; 147 if (p[0] != '~' || p[1]) 148 version = 0; 149 } 150 return version; 151 } 152 153 /* 154 * Return the newly-allocated concatenation of STR1 and STR2. If out of 155 * memory, return 0. 156 */ 157 static char * 158 concat(const char *str1, const char *str2) 159 { 160 char *newstr; 161 162 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 163 return NULL; 164 return newstr; 165 } 166 167 /* 168 * If ARG is an unambiguous match for an element of the null-terminated array 169 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 170 * does not match any element or -2 if it is ambiguous (is a prefix of more 171 * than one element). 172 */ 173 static int 174 argmatch(const char *arg, const char **optlist) 175 { 176 int i; /* Temporary index in OPTLIST. */ 177 size_t arglen; /* Length of ARG. */ 178 int matchind = -1; /* Index of first nonexact match. */ 179 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 180 181 arglen = strlen(arg); 182 183 /* Test all elements for either exact match or abbreviated matches. */ 184 for (i = 0; optlist[i]; i++) { 185 if (!strncmp(optlist[i], arg, arglen)) { 186 if (strlen(optlist[i]) == arglen) 187 /* Exact match found. */ 188 return i; 189 else if (matchind == -1) 190 /* First nonexact match found. */ 191 matchind = i; 192 else 193 /* Second nonexact match found. */ 194 ambiguous = 1; 195 } 196 } 197 if (ambiguous) 198 return -2; 199 else 200 return matchind; 201 } 202 203 /* 204 * Error reporting for argmatch. KIND is a description of the type of entity 205 * that was being matched. VALUE is the invalid value that was given. PROBLEM 206 * is the return value from argmatch. 207 */ 208 static void 209 invalid_arg(const char *kind, const char *value, int problem) 210 { 211 fprintf(stderr, "patch: "); 212 if (problem == -1) 213 fprintf(stderr, "invalid"); 214 else /* Assume -2. */ 215 fprintf(stderr, "ambiguous"); 216 fprintf(stderr, " %s `%s'\n", kind, value); 217 } 218 219 static const char *backup_args[] = { 220 "none", "never", "simple", "nil", "existing", "t", "numbered", 0 221 }; 222 223 static enum backup_type backup_types[] = { 224 none, simple, simple, numbered_existing, 225 numbered_existing, numbered, numbered 226 }; 227 228 /* 229 * Return the type of backup indicated by VERSION. Unique abbreviations are 230 * accepted. 231 */ 232 enum backup_type 233 get_version(const char *version) 234 { 235 int i; 236 237 if (version == NULL || *version == '\0') 238 return numbered_existing; 239 i = argmatch(version, backup_args); 240 if (i >= 0) 241 return backup_types[i]; 242 invalid_arg("version control type", version, i); 243 exit(2); 244 } 245