backupfile.c (6393B)
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 #include <unistd.h> 26 27 #include "backupfile.h" 28 29 30 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 31 32 /* Which type of backup file names are generated. */ 33 enum backup_type backup_type = none; 34 35 /* 36 * The extension added to file names to produce a simple (as opposed to 37 * numbered) backup file name. 38 */ 39 const char *simple_backup_suffix = "~"; 40 41 static char *concat(const char *, const char *); 42 static char *make_version_name(const char *, int); 43 static int max_backup_version(const char *, const char *); 44 static int version_number(const char *, const char *, size_t); 45 static int argmatch(const char *, const char **); 46 static void invalid_arg(const char *, const char *, int); 47 48 /* 49 * Return the name of the new backup file for file FILE, allocated with 50 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 51 * is the root directory. Do not call this function if backup_type == none. 52 */ 53 char * 54 find_backup_file_name(const char *file) 55 { 56 char *dir, *base_versions, *tmp_file; 57 int highest_backup; 58 59 if (backup_type == simple) 60 return concat(file, simple_backup_suffix); 61 tmp_file = strdup(file); 62 if (tmp_file == NULL) 63 return NULL; 64 base_versions = concat(basename(tmp_file), ".~"); 65 free(tmp_file); 66 if (base_versions == NULL) 67 return NULL; 68 tmp_file = strdup(file); 69 if (tmp_file == NULL) { 70 free(base_versions); 71 return NULL; 72 } 73 dir = dirname(tmp_file); 74 if (dir == NULL) { 75 free(base_versions); 76 free(tmp_file); 77 return NULL; 78 } 79 highest_backup = max_backup_version(base_versions, dir); 80 free(base_versions); 81 free(tmp_file); 82 if (backup_type == numbered_existing && highest_backup == 0) 83 return concat(file, simple_backup_suffix); 84 return make_version_name(file, highest_backup + 1); 85 } 86 87 /* 88 * Return the number of the highest-numbered backup file for file FILE in 89 * directory DIR. If there are no numbered backups of FILE in DIR, or an 90 * error occurs reading DIR, return 0. FILE should already have ".~" appended 91 * to it. 92 */ 93 static int 94 max_backup_version(const char *file, const char *dir) 95 { 96 DIR *dirp; 97 struct dirent *dp; 98 int highest_version, this_version; 99 size_t file_name_length; 100 101 dirp = opendir(dir); 102 if (dirp == NULL) 103 return 0; 104 105 highest_version = 0; 106 file_name_length = strlen(file); 107 108 while ((dp = readdir(dirp)) != NULL) { 109 if (strlen(dp->d_name) <= file_name_length) 110 continue; 111 112 this_version = version_number(file, dp->d_name, file_name_length); 113 if (this_version > highest_version) 114 highest_version = this_version; 115 } 116 closedir(dirp); 117 return highest_version; 118 } 119 120 /* 121 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 122 * Return 0 if out of memory. 123 */ 124 static char * 125 make_version_name(const char *file, int version) 126 { 127 char *backup_name; 128 129 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 130 return NULL; 131 return backup_name; 132 } 133 134 /* 135 * If BACKUP is a numbered backup of BASE, return its version number; 136 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 137 * already have ".~" appended to it. 138 */ 139 static int 140 version_number(const char *base, const char *backup, size_t base_length) 141 { 142 int version; 143 const char *p; 144 145 version = 0; 146 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 147 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 148 version = version * 10 + *p - '0'; 149 if (p[0] != '~' || p[1]) 150 version = 0; 151 } 152 return version; 153 } 154 155 /* 156 * Return the newly-allocated concatenation of STR1 and STR2. If out of 157 * memory, return 0. 158 */ 159 static char * 160 concat(const char *str1, const char *str2) 161 { 162 char *newstr; 163 164 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 165 return NULL; 166 return newstr; 167 } 168 169 /* 170 * If ARG is an unambiguous match for an element of the null-terminated array 171 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 172 * does not match any element or -2 if it is ambiguous (is a prefix of more 173 * than one element). 174 */ 175 static int 176 argmatch(const char *arg, const char **optlist) 177 { 178 int i; /* Temporary index in OPTLIST. */ 179 size_t arglen; /* Length of ARG. */ 180 int matchind = -1; /* Index of first nonexact match. */ 181 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 182 183 arglen = strlen(arg); 184 185 /* Test all elements for either exact match or abbreviated matches. */ 186 for (i = 0; optlist[i]; i++) { 187 if (!strncmp(optlist[i], arg, arglen)) { 188 if (strlen(optlist[i]) == arglen) 189 /* Exact match found. */ 190 return i; 191 else if (matchind == -1) 192 /* First nonexact match found. */ 193 matchind = i; 194 else 195 /* Second nonexact match found. */ 196 ambiguous = 1; 197 } 198 } 199 if (ambiguous) 200 return -2; 201 else 202 return matchind; 203 } 204 205 /* 206 * Error reporting for argmatch. KIND is a description of the type of entity 207 * that was being matched. VALUE is the invalid value that was given. PROBLEM 208 * is the return value from argmatch. 209 */ 210 static void 211 invalid_arg(const char *kind, const char *value, int problem) 212 { 213 fprintf(stderr, "patch: "); 214 if (problem == -1) 215 fprintf(stderr, "invalid"); 216 else /* Assume -2. */ 217 fprintf(stderr, "ambiguous"); 218 fprintf(stderr, " %s `%s'\n", kind, value); 219 } 220 221 static const char *backup_args[] = { 222 "never", "simple", "nil", "existing", "t", "numbered", 0 223 }; 224 225 static enum backup_type backup_types[] = { 226 simple, simple, numbered_existing, 227 numbered_existing, numbered, numbered 228 }; 229 230 /* 231 * Return the type of backup indicated by VERSION. Unique abbreviations are 232 * accepted. 233 */ 234 enum backup_type 235 get_version(const char *version) 236 { 237 int i; 238 239 if (version == NULL || *version == '\0') 240 return numbered_existing; 241 i = argmatch(version, backup_args); 242 if (i >= 0) 243 return backup_types[i]; 244 invalid_arg("version control type", version, i); 245 exit(2); 246 }