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 *
find_backup_file_name(const char * file)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
max_backup_version(const char * file,const char * dir)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 *
make_version_name(const char * file,int version)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
version_number(const char * base,const char * backup,size_t base_length)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 *
concat(const char * str1,const char * str2)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
argmatch(const char * arg,const char ** optlist)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
invalid_arg(const char * kind,const char * value,int problem)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
get_version(const char * version)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