1 /*-
2 * Copyright (C) 1990 Free Software Foundation, Inc.
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * without restriction.
6 *
7 * This program is distributed in the hope that it will be useful, but WITHOUT
8 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
9 * FITNESS FOR A PARTICULAR PURPOSE.
10 *
11 * backupfile.c -- make Emacs style backup file names
12 *
13 * David MacKenzie <[email protected]>. Some algorithms adapted from GNU Emacs.
14 *
15 * $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $
16 * $FreeBSD$
17 */
18
19 #include <ctype.h>
20 #include <dirent.h>
21 #include <libgen.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25
26 #include "backupfile.h"
27
28
29 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
30
31 /* Which type of backup file names are generated. */
32 enum backup_type backup_type = none;
33
34 /*
35 * The extension added to file names to produce a simple (as opposed to
36 * numbered) backup file name.
37 */
38 const char *simple_backup_suffix = "~";
39
40 static char *concat(const char *, const char *);
41 static char *make_version_name(const char *, int);
42 static int max_backup_version(const char *, const char *);
43 static int version_number(const char *, const char *, size_t);
44 static int argmatch(const char *, const char **);
45 static void invalid_arg(const char *, const char *, int);
46
47 /*
48 * Return the name of the new backup file for file FILE, allocated with
49 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it
50 * is the root directory. Do not call this function if backup_type == none.
51 */
52 char *
find_backup_file_name(const char * file)53 find_backup_file_name(const char *file)
54 {
55 char *dir, *base_versions, *tmp_file;
56 int highest_backup;
57
58 if (backup_type == simple)
59 return concat(file, simple_backup_suffix);
60 tmp_file = strdup(file);
61 if (tmp_file == NULL)
62 return NULL;
63 base_versions = concat(basename(tmp_file), ".~");
64 free(tmp_file);
65 if (base_versions == NULL)
66 return NULL;
67 tmp_file = strdup(file);
68 if (tmp_file == NULL) {
69 free(base_versions);
70 return NULL;
71 }
72 dir = dirname(tmp_file);
73 if (dir == NULL) {
74 free(base_versions);
75 free(tmp_file);
76 return NULL;
77 }
78 highest_backup = max_backup_version(base_versions, dir);
79 free(base_versions);
80 free(tmp_file);
81 if (backup_type == numbered_existing && highest_backup == 0)
82 return concat(file, simple_backup_suffix);
83 return make_version_name(file, highest_backup + 1);
84 }
85
86 /*
87 * Return the number of the highest-numbered backup file for file FILE in
88 * directory DIR. If there are no numbered backups of FILE in DIR, or an
89 * error occurs reading DIR, return 0. FILE should already have ".~" appended
90 * to it.
91 */
92 static int
max_backup_version(const char * file,const char * dir)93 max_backup_version(const char *file, const char *dir)
94 {
95 DIR *dirp;
96 struct dirent *dp;
97 int highest_version, this_version;
98 size_t file_name_length;
99
100 dirp = opendir(dir);
101 if (dirp == NULL)
102 return 0;
103
104 highest_version = 0;
105 file_name_length = strlen(file);
106
107 while ((dp = readdir(dirp)) != NULL) {
108 if (dp->d_namlen <= file_name_length)
109 continue;
110
111 this_version = version_number(file, dp->d_name, file_name_length);
112 if (this_version > highest_version)
113 highest_version = this_version;
114 }
115 closedir(dirp);
116 return highest_version;
117 }
118
119 /*
120 * Return a string, allocated with malloc, containing "FILE.~VERSION~".
121 * Return 0 if out of memory.
122 */
123 static char *
make_version_name(const char * file,int version)124 make_version_name(const char *file, int version)
125 {
126 char *backup_name;
127
128 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
129 return NULL;
130 return backup_name;
131 }
132
133 /*
134 * If BACKUP is a numbered backup of BASE, return its version number;
135 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should
136 * already have ".~" appended to it.
137 */
138 static int
version_number(const char * base,const char * backup,size_t base_length)139 version_number(const char *base, const char *backup, size_t base_length)
140 {
141 int version;
142 const char *p;
143
144 version = 0;
145 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
146 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
147 version = version * 10 + *p - '0';
148 if (p[0] != '~' || p[1])
149 version = 0;
150 }
151 return version;
152 }
153
154 /*
155 * Return the newly-allocated concatenation of STR1 and STR2. If out of
156 * memory, return 0.
157 */
158 static char *
concat(const char * str1,const char * str2)159 concat(const char *str1, const char *str2)
160 {
161 char *newstr;
162
163 if (asprintf(&newstr, "%s%s", str1, str2) == -1)
164 return NULL;
165 return newstr;
166 }
167
168 /*
169 * If ARG is an unambiguous match for an element of the null-terminated array
170 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
171 * does not match any element or -2 if it is ambiguous (is a prefix of more
172 * than one element).
173 */
174 static int
argmatch(const char * arg,const char ** optlist)175 argmatch(const char *arg, const char **optlist)
176 {
177 int i; /* Temporary index in OPTLIST. */
178 size_t arglen; /* Length of ARG. */
179 int matchind = -1; /* Index of first nonexact match. */
180 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */
181
182 arglen = strlen(arg);
183
184 /* Test all elements for either exact match or abbreviated matches. */
185 for (i = 0; optlist[i]; i++) {
186 if (!strncmp(optlist[i], arg, arglen)) {
187 if (strlen(optlist[i]) == arglen)
188 /* Exact match found. */
189 return i;
190 else if (matchind == -1)
191 /* First nonexact match found. */
192 matchind = i;
193 else
194 /* Second nonexact match found. */
195 ambiguous = 1;
196 }
197 }
198 if (ambiguous)
199 return -2;
200 else
201 return matchind;
202 }
203
204 /*
205 * Error reporting for argmatch. KIND is a description of the type of entity
206 * that was being matched. VALUE is the invalid value that was given. PROBLEM
207 * is the return value from argmatch.
208 */
209 static void
invalid_arg(const char * kind,const char * value,int problem)210 invalid_arg(const char *kind, const char *value, int problem)
211 {
212 fprintf(stderr, "patch: ");
213 if (problem == -1)
214 fprintf(stderr, "invalid");
215 else /* Assume -2. */
216 fprintf(stderr, "ambiguous");
217 fprintf(stderr, " %s `%s'\n", kind, value);
218 }
219
220 static const char *backup_args[] = {
221 "none", "never", "simple", "nil", "existing", "t", "numbered", 0
222 };
223
224 static enum backup_type backup_types[] = {
225 none, simple, simple, numbered_existing,
226 numbered_existing, numbered, numbered
227 };
228
229 /*
230 * Return the type of backup indicated by VERSION. Unique abbreviations are
231 * accepted.
232 */
233 enum backup_type
get_version(const char * version)234 get_version(const char *version)
235 {
236 int i;
237
238 if (version == NULL || *version == '\0')
239 return numbered_existing;
240 i = argmatch(version, backup_args);
241 if (i >= 0)
242 return backup_types[i];
243 invalid_arg("version control type", version, i);
244 exit(2);
245 }
246