1 /* $OpenBSD: backupfile.c,v 1.17 2003/08/01 20:30:48 otto Exp $ */ 2 3 /* 4 * backupfile.c -- make Emacs style backup file names Copyright (C) 1990 Free 5 * Software Foundation, Inc. 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * without restriction. 9 * 10 * This program is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. 13 */ 14 15 /* 16 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. 17 */ 18 19 #ifndef lint 20 static const char rcsid[] = "$OpenBSD: backupfile.c,v 1.17 2003/08/01 20:30:48 otto Exp $"; 21 #endif /* not lint */ 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 (c) && isdigit (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 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 *, int); 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; 61 int highest_backup; 62 63 if (backup_type == simple) 64 return concat(file, simple_backup_suffix); 65 base_versions = concat(basename(file), ".~"); 66 if (base_versions == NULL) 67 return NULL; 68 dir = dirname(file); 69 if (dir == NULL) { 70 free(base_versions); 71 return NULL; 72 } 73 highest_backup = max_backup_version(base_versions, dir); 74 free(base_versions); 75 if (backup_type == numbered_existing && highest_backup == 0) 76 return concat(file, simple_backup_suffix); 77 return make_version_name(file, highest_backup + 1); 78 } 79 80 /* 81 * Return the number of the highest-numbered backup file for file FILE in 82 * directory DIR. If there are no numbered backups of FILE in DIR, or an 83 * error occurs reading DIR, return 0. FILE should already have ".~" appended 84 * to it. 85 */ 86 static int 87 max_backup_version(const char *file, const char *dir) 88 { 89 DIR *dirp; 90 struct dirent *dp; 91 int highest_version, this_version, file_name_length; 92 93 dirp = opendir(dir); 94 if (dirp == NULL) 95 return 0; 96 97 highest_version = 0; 98 file_name_length = strlen(file); 99 100 while ((dp = readdir(dirp)) != NULL) { 101 if (dp->d_namlen <= file_name_length) 102 continue; 103 104 this_version = version_number(file, dp->d_name, file_name_length); 105 if (this_version > highest_version) 106 highest_version = this_version; 107 } 108 closedir(dirp); 109 return highest_version; 110 } 111 112 /* 113 * Return a string, allocated with malloc, containing "FILE.~VERSION~". 114 * Return 0 if out of memory. 115 */ 116 static char * 117 make_version_name(const char *file, int version) 118 { 119 char *backup_name; 120 121 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) 122 return NULL; 123 return backup_name; 124 } 125 126 /* 127 * If BACKUP is a numbered backup of BASE, return its version number; 128 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should 129 * already have ".~" appended to it. 130 */ 131 static int 132 version_number(const char *base, const char *backup, int base_length) 133 { 134 int version; 135 const char *p; 136 137 version = 0; 138 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) { 139 for (p = &backup[base_length]; ISDIGIT(*p); ++p) 140 version = version * 10 + *p - '0'; 141 if (p[0] != '~' || p[1]) 142 version = 0; 143 } 144 return version; 145 } 146 147 /* 148 * Return the newly-allocated concatenation of STR1 and STR2. If out of 149 * memory, return 0. 150 */ 151 static char * 152 concat(const char *str1, const char *str2) 153 { 154 char *newstr; 155 156 if (asprintf(&newstr, "%s%s", str1, str2) == -1) 157 return NULL; 158 return newstr; 159 } 160 161 /* 162 * If ARG is an unambiguous match for an element of the null-terminated array 163 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it 164 * does not match any element or -2 if it is ambiguous (is a prefix of more 165 * than one element). 166 */ 167 static int 168 argmatch(const char *arg, const char **optlist) 169 { 170 int i; /* Temporary index in OPTLIST. */ 171 size_t arglen; /* Length of ARG. */ 172 int matchind = -1; /* Index of first nonexact match. */ 173 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ 174 175 arglen = strlen(arg); 176 177 /* Test all elements for either exact match or abbreviated matches. */ 178 for (i = 0; optlist[i]; i++) { 179 if (!strncmp(optlist[i], arg, arglen)) { 180 if (strlen(optlist[i]) == arglen) 181 /* Exact match found. */ 182 return i; 183 else if (matchind == -1) 184 /* First nonexact match found. */ 185 matchind = i; 186 else 187 /* Second nonexact match found. */ 188 ambiguous = 1; 189 } 190 } 191 if (ambiguous) 192 return -2; 193 else 194 return matchind; 195 } 196 197 /* 198 * Error reporting for argmatch. KIND is a description of the type of entity 199 * that was being matched. VALUE is the invalid value that was given. PROBLEM 200 * is the return value from argmatch. 201 */ 202 static void 203 invalid_arg(const char *kind, const char *value, int problem) 204 { 205 fprintf(stderr, "patch: "); 206 if (problem == -1) 207 fprintf(stderr, "invalid"); 208 else /* Assume -2. */ 209 fprintf(stderr, "ambiguous"); 210 fprintf(stderr, " %s `%s'\n", kind, value); 211 } 212 213 static const char *backup_args[] = { 214 "never", "simple", "nil", "existing", "t", "numbered", 0 215 }; 216 217 static enum backup_type backup_types[] = { 218 simple, simple, numbered_existing, 219 numbered_existing, numbered, numbered 220 }; 221 222 /* 223 * Return the type of backup indicated by VERSION. Unique abbreviations are 224 * accepted. 225 */ 226 enum backup_type 227 get_version(const char *version) 228 { 229 int i; 230 231 if (version == NULL || *version == '\0') 232 return numbered_existing; 233 i = argmatch(version, backup_args); 234 if (i >= 0) 235 return backup_types[i]; 236 invalid_arg("version control type", version, i); 237 exit(2); 238 } 239