1 /* 2 * $OpenBSD: backupfile.c,v 1.19 2006/03/11 19:41:30 otto Exp $ 3 * $DragonFly: src/usr.bin/patch/backupfile.c,v 1.5 2008/08/11 00:05:06 joerg Exp $ 4 */ 5 6 /* 7 * backupfile.c -- make Emacs style backup file names 8 * 9 * Copyright (C) 1990 Free Software Foundation, Inc. 10 * 11 * This program is free software; you can redistribute it and/or modify it 12 * without restriction. 13 * 14 * This program is distributed in the hope that it will be useful, but WITHOUT 15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 16 * FITNESS FOR A PARTICULAR PURPOSE. 17 */ 18 19 /* 20 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. 21 */ 22 23 #include <ctype.h> 24 #include <dirent.h> 25 #include <libgen.h> 26 #include <stdio.h> 27 #include <stdlib.h> 28 #include <string.h> 29 #include <unistd.h> 30 31 #include "backupfile.h" 32 33 34 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 35 36 /* Which type of backup file names are generated. */ 37 enum backup_type backup_type = none; 38 39 /* 40 * The extension added to file names to produce a simple (as opposed to 41 * numbered) backup file name. 42 */ 43 const char *simple_backup_suffix = "~"; 44 45 static char *concat(const char *, const char *); 46 static char *make_version_name(const char *, int); 47 static int max_backup_version(const char *, const char *); 48 static int version_number(const char *, const char *, size_t); 49 static int argmatch(const char *, const char **); 50 static void invalid_arg(const char *, const char *, int); 51 52 /* 53 * Return the name of the new backup file for file FILE, allocated with 54 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 55 * is the root directory. Do not call this function if backup_type == none. 56 */ 57 char * 58 find_backup_file_name(const char *file) 59 { 60 char *dir, *base_versions, *tmp_file; 61 int highest_backup; 62 63 if (backup_type == simple) 64 return concat(file, simple_backup_suffix); 65 tmp_file = strdup(file); 66 if (tmp_file == NULL) 67 return NULL; 68 base_versions = concat(basename(tmp_file), ".~"); 69 free(tmp_file); 70 if (base_versions == NULL) 71 return NULL; 72 tmp_file = strdup(file); 73 if (tmp_file == NULL) { 74 free(base_versions); 75 return NULL; 76 } 77 dir = dirname(tmp_file); 78 if (dir == NULL) { 79 free(base_versions); 80 free(tmp_file); 81 return NULL; 82 } 83 highest_backup = max_backup_version(base_versions, dir); 84 free(base_versions); 85 free(tmp_file); 86 if (backup_type == numbered_existing && highest_backup == 0) 87 return concat(file, simple_backup_suffix); 88 return make_version_name(file, highest_backup + 1); 89 } 90 91 /* 92 * Return the number of the highest-numbered backup file for file FILE in 93 * directory DIR. If there are no numbered backups of FILE in DIR, or an 94 * error occurs reading DIR, return 0. FILE should already have ".~" appended 95 * to it. 96 */ 97 static int 98 max_backup_version(const char *file, const char *dir) 99 { 100 DIR *dirp; 101 struct dirent *dp; 102 int highest_version, this_version; 103 size_t file_name_length; 104 105 dirp = opendir(dir); 106 if (dirp == NULL) 107 return 0; 108 109 highest_version = 0; 110 file_name_length = strlen(file); 111 112 while ((dp = readdir(dirp)) != NULL) { 113 if (dp->d_namlen <= file_name_length) 114 continue; 115 116 this_version = version_number(file, dp->d_name, file_name_length); 117 if (this_version > highest_version) 118 highest_version = this_version; 119 } 120 closedir(dirp); 121 return highest_version; 122 } 123 124 /* 125 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 126 * Return 0 if out of memory. 127 */ 128 static char * 129 make_version_name(const char *file, int version) 130 { 131 char *backup_name; 132 133 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 134 return NULL; 135 return backup_name; 136 } 137 138 /* 139 * If BACKUP is a numbered backup of BASE, return its version number; 140 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 141 * already have ".~" appended to it. 142 */ 143 static int 144 version_number(const char *base, const char *backup, size_t base_length) 145 { 146 int version; 147 const char *p; 148 149 version = 0; 150 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 151 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 152 version = version * 10 + *p - '0'; 153 if (p[0] != '~' || p[1]) 154 version = 0; 155 } 156 return version; 157 } 158 159 /* 160 * Return the newly-allocated concatenation of STR1 and STR2. If out of 161 * memory, return 0. 162 */ 163 static char * 164 concat(const char *str1, const char *str2) 165 { 166 char *newstr; 167 168 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 169 return NULL; 170 return newstr; 171 } 172 173 /* 174 * If ARG is an unambiguous match for an element of the null-terminated array 175 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 176 * does not match any element or -2 if it is ambiguous (is a prefix of more 177 * than one element). 178 */ 179 static int 180 argmatch(const char *arg, const char **optlist) 181 { 182 int i; /* Temporary index in OPTLIST. */ 183 size_t arglen; /* Length of ARG. */ 184 int matchind = -1; /* Index of first nonexact match. */ 185 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 186 187 arglen = strlen(arg); 188 189 /* Test all elements for either exact match or abbreviated matches. */ 190 for (i = 0; optlist[i]; i++) { 191 if (!strncmp(optlist[i], arg, arglen)) { 192 if (strlen(optlist[i]) == arglen) 193 /* Exact match found. */ 194 return i; 195 else if (matchind == -1) 196 /* First nonexact match found. */ 197 matchind = i; 198 else 199 /* Second nonexact match found. */ 200 ambiguous = 1; 201 } 202 } 203 if (ambiguous) 204 return -2; 205 else 206 return matchind; 207 } 208 209 /* 210 * Error reporting for argmatch. KIND is a description of the type of entity 211 * that was being matched. VALUE is the invalid value that was given. PROBLEM 212 * is the return value from argmatch. 213 */ 214 static void 215 invalid_arg(const char *kind, const char *value, int problem) 216 { 217 fprintf(stderr, "patch: "); 218 if (problem == -1) 219 fprintf(stderr, "invalid"); 220 else /* Assume -2. */ 221 fprintf(stderr, "ambiguous"); 222 fprintf(stderr, " %s `%s'\n", kind, value); 223 } 224 225 static const char *backup_args[] = { 226 "never", "simple", "nil", "existing", "t", "numbered", 0 227 }; 228 229 static enum backup_type backup_types[] = { 230 simple, simple, numbered_existing, 231 numbered_existing, numbered, numbered 232 }; 233 234 /* 235 * Return the type of backup indicated by VERSION. Unique abbreviations are 236 * accepted. 237 */ 238 enum backup_type 239 get_version(const char *version) 240 { 241 int i; 242 243 if (version == NULL || *version == '\0') 244 return numbered_existing; 245 i = argmatch(version, backup_args); 246 if (i >= 0) 247 return backup_types[i]; 248 invalid_arg("version control type", version, i); 249 exit(2); 250 } 251