1 /* 2 * $OpenBSD: backupfile.c,v 1.18 2004/08/05 21:47:24 deraadt Exp $ 3 * $DragonFly: src/usr.bin/patch/backupfile.c,v 1.3 2006/04/10 08:11:43 joerg Exp $ 4 */ 5 6 /* 7 * backupfile.c -- make Emacs style backup file names Copyright (C) 1990 Free 8 * Software Foundation, Inc. 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * without restriction. 12 * 13 * This program is distributed in the hope that it will be useful, but WITHOUT 14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 15 * FITNESS FOR A PARTICULAR PURPOSE. 16 */ 17 18 /* 19 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. 20 */ 21 22 #include <ctype.h> 23 #include <dirent.h> 24 #include <libgen.h> 25 #include <stdio.h> 26 #include <stdlib.h> 27 #include <string.h> 28 #include <unistd.h> 29 30 #include "backupfile.h" 31 32 33 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c)) 34 35 /* Which type of backup file names are generated. */ 36 enum backup_type backup_type = none; 37 38 /* 39 * The extension added to file names to produce a simple (as opposed to 40 * numbered) backup file name. 41 */ 42 const char *simple_backup_suffix = "~"; 43 44 static char *concat(const char *, const char *); 45 static char *make_version_name(const char *, int); 46 static int max_backup_version(const char *, const char *); 47 static int version_number(const char *, const char *, int); 48 static int argmatch(const char *, const char **); 49 static void invalid_arg(const char *, const char *, int); 50 51 /* 52 * Return the name of the new backup file for file FILE, allocated with 53 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it 54 * is the root directory. Do not call this function if backup_type == none. 55 */ 56 char * 57 find_backup_file_name(const char *file) 58 { 59 char *dir, *base_versions, *tmp_file; 60 int highest_backup; 61 62 if (backup_type == simple) 63 return concat(file, simple_backup_suffix); 64 tmp_file = strdup(file); 65 if (tmp_file == NULL) 66 return NULL; 67 base_versions = concat(basename(tmp_file), ".~"); 68 free(tmp_file); 69 if (base_versions == NULL) 70 return NULL; 71 tmp_file = strdup(file); 72 if (tmp_file == NULL) { 73 free(base_versions); 74 return NULL; 75 } 76 dir = dirname(tmp_file); 77 if (dir == NULL) { 78 free(base_versions); 79 free(tmp_file); 80 return NULL; 81 } 82 highest_backup = max_backup_version(base_versions, dir); 83 free(base_versions); 84 free(tmp_file); 85 if (backup_type == numbered_existing && highest_backup == 0) 86 return concat(file, simple_backup_suffix); 87 return make_version_name(file, highest_backup + 1); 88 } 89 90 /* 91 * Return the number of the highest-numbered backup file for file FILE in 92 * directory DIR. If there are no numbered backups of FILE in DIR, or an 93 * error occurs reading DIR, return 0. FILE should already have ".~" appended 94 * to it. 95 */ 96 static int 97 max_backup_version(const char *file, const char *dir) 98 { 99 DIR *dirp; 100 struct dirent *dp; 101 int highest_version, this_version, file_name_length; 102 103 dirp = opendir(dir); 104 if (dirp == NULL) 105 return 0; 106 107 highest_version = 0; 108 file_name_length = strlen(file); 109 110 while ((dp = readdir(dirp)) != NULL) { 111 if (dp->d_namlen <= file_name_length) 112 continue; 113 114 this_version = version_number(file, dp->d_name, file_name_length); 115 if (this_version > highest_version) 116 highest_version = this_version; 117 } 118 closedir(dirp); 119 return highest_version; 120 } 121 122 /* 123 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 124 * Return 0 if out of memory. 125 */ 126 static char * 127 make_version_name(const char *file, int version) 128 { 129 char *backup_name; 130 131 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 132 return NULL; 133 return backup_name; 134 } 135 136 /* 137 * If BACKUP is a numbered backup of BASE, return its version number; 138 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 139 * already have ".~" appended to it. 140 */ 141 static int 142 version_number(const char *base, const char *backup, int base_length) 143 { 144 int version; 145 const char *p; 146 147 version = 0; 148 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 149 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 150 version = version * 10 + *p - '0'; 151 if (p[0] != '~' || p[1]) 152 version = 0; 153 } 154 return version; 155 } 156 157 /* 158 * Return the newly-allocated concatenation of STR1 and STR2. If out of 159 * memory, return 0. 160 */ 161 static char * 162 concat(const char *str1, const char *str2) 163 { 164 char *newstr; 165 166 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 167 return NULL; 168 return newstr; 169 } 170 171 /* 172 * If ARG is an unambiguous match for an element of the null-terminated array 173 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 174 * does not match any element or -2 if it is ambiguous (is a prefix of more 175 * than one element). 176 */ 177 static int 178 argmatch(const char *arg, const char **optlist) 179 { 180 int i; /* Temporary index in OPTLIST. */ 181 size_t arglen; /* Length of ARG. */ 182 int matchind = -1; /* Index of first nonexact match. */ 183 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 184 185 arglen = strlen(arg); 186 187 /* Test all elements for either exact match or abbreviated matches. */ 188 for (i = 0; optlist[i]; i++) { 189 if (!strncmp(optlist[i], arg, arglen)) { 190 if (strlen(optlist[i]) == arglen) 191 /* Exact match found. */ 192 return i; 193 else if (matchind == -1) 194 /* First nonexact match found. */ 195 matchind = i; 196 else 197 /* Second nonexact match found. */ 198 ambiguous = 1; 199 } 200 } 201 if (ambiguous) 202 return -2; 203 else 204 return matchind; 205 } 206 207 /* 208 * Error reporting for argmatch. KIND is a description of the type of entity 209 * that was being matched. VALUE is the invalid value that was given. PROBLEM 210 * is the return value from argmatch. 211 */ 212 static void 213 invalid_arg(const char *kind, const char *value, int problem) 214 { 215 fprintf(stderr, "patch: "); 216 if (problem == -1) 217 fprintf(stderr, "invalid"); 218 else /* Assume -2. */ 219 fprintf(stderr, "ambiguous"); 220 fprintf(stderr, " %s `%s'\n", kind, value); 221 } 222 223 static const char *backup_args[] = { 224 "never", "simple", "nil", "existing", "t", "numbered", 0 225 }; 226 227 static enum backup_type backup_types[] = { 228 simple, simple, numbered_existing, 229 numbered_existing, numbered, numbered 230 }; 231 232 /* 233 * Return the type of backup indicated by VERSION. Unique abbreviations are 234 * accepted. 235 */ 236 enum backup_type 237 get_version(const char *version) 238 { 239 int i; 240 241 if (version == NULL || *version == '\0') 242 return numbered_existing; 243 i = argmatch(version, backup_args); 244 if (i >= 0) 245 return backup_types[i]; 246 invalid_arg("version control type", version, i); 247 exit(2); 248 } 249