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 * $NetBSD: backupfile.c,v 1.16 2021/02/19 17:46:53 nia Exp $ 5 */ 6 7 /* 8 * backupfile.c -- make Emacs style backup file names 9 * 10 * Copyright (C) 1990 Free Software Foundation, Inc. 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * without restriction. 14 * 15 * This program is distributed in the hope that it will be useful, but WITHOUT 16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 17 * FITNESS FOR A PARTICULAR PURPOSE. 18 */ 19 20 /* 21 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. 22 */ 23 24 #include <sys/cdefs.h> 25 __RCSID("$NetBSD: backupfile.c,v 1.16 2021/02/19 17:46:53 nia Exp $"); 26 27 #include <ctype.h> 28 #include <dirent.h> 29 #include <libgen.h> 30 #include <stdio.h> 31 #include <stdlib.h> 32 #include <string.h> 33 #include <unistd.h> 34 35 #include "backupfile.h" 36 37 38 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 39 40 /* Which type of backup file names are generated. */ 41 enum backup_type backup_type = undefined; 42 43 /* 44 * The extension added to file names to produce a simple (as opposed to 45 * numbered) backup file name. 46 */ 47 const char *simple_backup_suffix = "~"; 48 49 static char *concat(const char *, const char *); 50 static char *make_version_name(const char *, int); 51 static int max_backup_version(const char *, const char *); 52 static int version_number(const char *, const char *, size_t); 53 static int argmatch(const char *, const char **); 54 static void invalid_arg(const char *, const char *, int); 55 56 /* 57 * Return the name of the new backup file for file FILE, allocated with 58 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 59 * is the root directory. Do not call this function if backup_type == none. 60 */ 61 char * 62 find_backup_file_name(const char *file) 63 { 64 char *dir, *base_versions, *tmp_file; 65 int highest_backup; 66 67 if (backup_type == simple) 68 return concat(file, simple_backup_suffix); 69 tmp_file = strdup(file); 70 if (tmp_file == NULL) 71 return NULL; 72 base_versions = concat(basename(tmp_file), ".~"); 73 free(tmp_file); 74 if (base_versions == NULL) 75 return NULL; 76 tmp_file = strdup(file); 77 if (tmp_file == NULL) { 78 free(base_versions); 79 return NULL; 80 } 81 dir = dirname(tmp_file); 82 if (dir == NULL) { 83 free(base_versions); 84 free(tmp_file); 85 return NULL; 86 } 87 highest_backup = max_backup_version(base_versions, dir); 88 free(base_versions); 89 free(tmp_file); 90 if (backup_type == numbered_existing && highest_backup == 0) 91 return concat(file, simple_backup_suffix); 92 return make_version_name(file, highest_backup + 1); 93 } 94 95 /* 96 * Return the number of the highest-numbered backup file for file FILE in 97 * directory DIR. If there are no numbered backups of FILE in DIR, or an 98 * error occurs reading DIR, return 0. FILE should already have ".~" appended 99 * to it. 100 */ 101 static int 102 max_backup_version(const char *file, const char *dir) 103 { 104 DIR *dirp; 105 struct dirent *dp; 106 int highest_version, this_version; 107 size_t file_name_length; 108 109 dirp = opendir(dir); 110 if (dirp == NULL) 111 return 0; 112 113 highest_version = 0; 114 file_name_length = strlen(file); 115 116 while ((dp = readdir(dirp)) != NULL) { 117 if (dp->d_namlen <= file_name_length) 118 continue; 119 120 this_version = version_number(file, dp->d_name, file_name_length); 121 if (this_version > highest_version) 122 highest_version = this_version; 123 } 124 closedir(dirp); 125 return highest_version; 126 } 127 128 /* 129 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 130 * Return 0 if out of memory. 131 */ 132 static char * 133 make_version_name(const char *file, int version) 134 { 135 char *backup_name; 136 137 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 138 return NULL; 139 return backup_name; 140 } 141 142 /* 143 * If BACKUP is a numbered backup of BASE, return its version number; 144 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 145 * already have ".~" appended to it. 146 */ 147 static int 148 version_number(const char *base, const char *backup, size_t base_length) 149 { 150 int version; 151 const char *p; 152 153 version = 0; 154 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 155 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 156 version = version * 10 + *p - '0'; 157 if (p[0] != '~' || p[1]) 158 version = 0; 159 } 160 return version; 161 } 162 163 /* 164 * Return the newly-allocated concatenation of STR1 and STR2. If out of 165 * memory, return 0. 166 */ 167 static char * 168 concat(const char *str1, const char *str2) 169 { 170 char *newstr; 171 172 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 173 return NULL; 174 return newstr; 175 } 176 177 /* 178 * If ARG is an unambiguous match for an element of the null-terminated array 179 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 180 * does not match any element or -2 if it is ambiguous (is a prefix of more 181 * than one element). 182 */ 183 static int 184 argmatch(const char *arg, const char **optlist) 185 { 186 int i; /* Temporary index in OPTLIST. */ 187 size_t arglen; /* Length of ARG. */ 188 int matchind = -1; /* Index of first nonexact match. */ 189 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 190 191 arglen = strlen(arg); 192 193 /* Test all elements for either exact match or abbreviated matches. */ 194 for (i = 0; optlist[i]; i++) { 195 if (!strncmp(optlist[i], arg, arglen)) { 196 if (strlen(optlist[i]) == arglen) 197 /* Exact match found. */ 198 return i; 199 else if (matchind == -1) 200 /* First nonexact match found. */ 201 matchind = i; 202 else 203 /* Second nonexact match found. */ 204 ambiguous = 1; 205 } 206 } 207 if (ambiguous) 208 return -2; 209 else 210 return matchind; 211 } 212 213 /* 214 * Error reporting for argmatch. KIND is a description of the type of entity 215 * that was being matched. VALUE is the invalid value that was given. PROBLEM 216 * is the return value from argmatch. 217 */ 218 static void 219 invalid_arg(const char *kind, const char *value, int problem) 220 { 221 fprintf(stderr, "patch: "); 222 if (problem == -1) 223 fprintf(stderr, "invalid"); 224 else /* Assume -2. */ 225 fprintf(stderr, "ambiguous"); 226 fprintf(stderr, " %s `%s'\n", kind, value); 227 } 228 229 static const char *backup_args[] = { 230 "none", "never", "simple", "nil", "existing", "t", "numbered", 0 231 }; 232 233 static enum backup_type backup_types[] = { 234 none, simple, simple, numbered_existing, 235 numbered_existing, numbered, numbered 236 }; 237 238 /* 239 * Return the type of backup indicated by VERSION. Unique abbreviations are 240 * accepted. 241 */ 242 enum backup_type 243 get_version(const char *version) 244 { 245 int i; 246 247 if (version == NULL || *version == '\0') 248 return numbered_existing; 249 i = argmatch(version, backup_args); 250 if (i >= 0) 251 return backup_types[i]; 252 invalid_arg("version control type", version, i); 253 exit(2); 254 } 255