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 1.2 2004/09/28 19:09:50 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 (c) && isdigit (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; 60 int highest_backup; 61 62 if (backup_type == simple) 63 return concat(file, simple_backup_suffix); 64 base_versions = concat(basename(file), ".~"); 65 if (base_versions == NULL) 66 return NULL; 67 dir = dirname(file); 68 if (dir == NULL) { 69 free(base_versions); 70 return NULL; 71 } 72 highest_backup = max_backup_version(base_versions, dir); 73 free(base_versions); 74 if (backup_type == numbered_existing && highest_backup == 0) 75 return concat(file, simple_backup_suffix); 76 return make_version_name(file, highest_backup + 1); 77 } 78 79 /* 80 * Return the number of the highest-numbered backup file for file FILE in 81 * directory DIR. If there are no numbered backups of FILE in DIR, or an 82 * error occurs reading DIR, return 0. FILE should already have ".~" appended 83 * to it. 84 */ 85 static int 86 max_backup_version(const char *file, const char *dir) 87 { 88 DIR *dirp; 89 struct dirent *dp; 90 int highest_version, this_version, file_name_length; 91 92 dirp = opendir(dir); 93 if (dirp == NULL) 94 return 0; 95 96 highest_version = 0; 97 file_name_length = strlen(file); 98 99 while ((dp = readdir(dirp)) != NULL) { 100 if (dp->d_namlen <= file_name_length) 101 continue; 102 103 this_version = version_number(file, dp->d_name, file_name_length); 104 if (this_version > highest_version) 105 highest_version = this_version; 106 } 107 closedir(dirp); 108 return highest_version; 109 } 110 111 /* 112 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 113 * Return 0 if out of memory. 114 */ 115 static char * 116 make_version_name(const char *file, int version) 117 { 118 char *backup_name; 119 120 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 121 return NULL; 122 return backup_name; 123 } 124 125 /* 126 * If BACKUP is a numbered backup of BASE, return its version number; 127 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 128 * already have ".~" appended to it. 129 */ 130 static int 131 version_number(const char *base, const char *backup, int base_length) 132 { 133 int version; 134 const char *p; 135 136 version = 0; 137 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 138 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 139 version = version * 10 + *p - '0'; 140 if (p[0] != '~' || p[1]) 141 version = 0; 142 } 143 return version; 144 } 145 146 /* 147 * Return the newly-allocated concatenation of STR1 and STR2. If out of 148 * memory, return 0. 149 */ 150 static char * 151 concat(const char *str1, const char *str2) 152 { 153 char *newstr; 154 155 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 156 return NULL; 157 return newstr; 158 } 159 160 /* 161 * If ARG is an unambiguous match for an element of the null-terminated array 162 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 163 * does not match any element or -2 if it is ambiguous (is a prefix of more 164 * than one element). 165 */ 166 static int 167 argmatch(const char *arg, const char **optlist) 168 { 169 int i; /* Temporary index in OPTLIST. */ 170 size_t arglen; /* Length of ARG. */ 171 int matchind = -1; /* Index of first nonexact match. */ 172 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 173 174 arglen = strlen(arg); 175 176 /* Test all elements for either exact match or abbreviated matches. */ 177 for (i = 0; optlist[i]; i++) { 178 if (!strncmp(optlist[i], arg, arglen)) { 179 if (strlen(optlist[i]) == arglen) 180 /* Exact match found. */ 181 return i; 182 else if (matchind == -1) 183 /* First nonexact match found. */ 184 matchind = i; 185 else 186 /* Second nonexact match found. */ 187 ambiguous = 1; 188 } 189 } 190 if (ambiguous) 191 return -2; 192 else 193 return matchind; 194 } 195 196 /* 197 * Error reporting for argmatch. KIND is a description of the type of entity 198 * that was being matched. VALUE is the invalid value that was given. PROBLEM 199 * is the return value from argmatch. 200 */ 201 static void 202 invalid_arg(const char *kind, const char *value, int problem) 203 { 204 fprintf(stderr, "patch: "); 205 if (problem == -1) 206 fprintf(stderr, "invalid"); 207 else /* Assume -2. */ 208 fprintf(stderr, "ambiguous"); 209 fprintf(stderr, " %s `%s'\n", kind, value); 210 } 211 212 static const char *backup_args[] = { 213 "never", "simple", "nil", "existing", "t", "numbered", 0 214 }; 215 216 static enum backup_type backup_types[] = { 217 simple, simple, numbered_existing, 218 numbered_existing, numbered, numbered 219 }; 220 221 /* 222 * Return the type of backup indicated by VERSION. Unique abbreviations are 223 * accepted. 224 */ 225 enum backup_type 226 get_version(const char *version) 227 { 228 int i; 229 230 if (version == NULL || *version == '\0') 231 return numbered_existing; 232 i = argmatch(version, backup_args); 233 if (i >= 0) 234 return backup_types[i]; 235 invalid_arg("version control type", version, i); 236 exit(2); 237 } 238