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 <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
14 *
15 * $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $
16 * $FreeBSD: head/usr.bin/patch/backupfile.c 246091 2013-01-29 20:05:16Z delphij $
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#include <unistd.h>
26
27#include "backupfile.h"
28
29
30#define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
31
32/* Which type of backup file names are generated. */
33enum backup_type backup_type = none;
34
35/*
36 * The extension added to file names to produce a simple (as opposed to
37 * numbered) backup file name.
38 */
39const char *simple_backup_suffix = "~";
40
41static char *concat(const char *, const char *);
42static char *make_version_name(const char *, int);
43static int max_backup_version(const char *, const char *);
44static int version_number(const char *, const char *, size_t);
45static int argmatch(const char *, const char **);
46static void invalid_arg(const char *, const char *, int);
47
48/*
49 * Return the name of the new backup file for file FILE, allocated with
50 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it
51 * is the root directory. Do not call this function if backup_type == none.
52 */
53char *
54find_backup_file_name(const char *file)
55{
56 char *dir, *base_versions, *tmp_file;
57 int highest_backup;
58
59 if (backup_type == simple)
60 return concat(file, simple_backup_suffix);
61 tmp_file = strdup(file);
62 if (tmp_file == NULL)
63 return NULL;
64 base_versions = concat(basename(tmp_file), ".~");
65 free(tmp_file);
66 if (base_versions == NULL)
67 return NULL;
68 tmp_file = strdup(file);
69 if (tmp_file == NULL) {
70 free(base_versions);
71 return NULL;
72 }
73 dir = dirname(tmp_file);
74 if (dir == NULL) {
75 free(base_versions);
76 free(tmp_file);
77 return NULL;
78 }
79 highest_backup = max_backup_version(base_versions, dir);
80 free(base_versions);
81 free(tmp_file);
82 if (backup_type == numbered_existing && highest_backup == 0)
83 return concat(file, simple_backup_suffix);
84 return make_version_name(file, highest_backup + 1);
85}
86
87/*
88 * Return the number of the highest-numbered backup file for file FILE in
89 * directory DIR. If there are no numbered backups of FILE in DIR, or an
90 * error occurs reading DIR, return 0. FILE should already have ".~" appended
91 * to it.
92 */
93static int
94max_backup_version(const char *file, const char *dir)
95{
96 DIR *dirp;
97 struct dirent *dp;
98 int highest_version, this_version;
99 size_t file_name_length;
100
101 dirp = opendir(dir);
102 if (dirp == NULL)
103 return 0;
104
105 highest_version = 0;
106 file_name_length = strlen(file);
107
108 while ((dp = readdir(dirp)) != NULL) {
109 if (dp->d_namlen <= file_name_length)
110 continue;
111
112 this_version = version_number(file, dp->d_name, file_name_length);
113 if (this_version > highest_version)
114 highest_version = this_version;
115 }
116 closedir(dirp);
117 return highest_version;
118}
119
120/*
121 * Return a string, allocated with malloc, containing "FILE.~VERSION~".
122 * Return 0 if out of memory.
123 */
124static char *
125make_version_name(const char *file, int version)
126{
127 char *backup_name;
128
129 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
130 return NULL;
131 return backup_name;
132}
133
134/*
135 * If BACKUP is a numbered backup of BASE, return its version number;
136 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should
137 * already have ".~" appended to it.
138 */
139static int
140version_number(const char *base, const char *backup, size_t base_length)
141{
142 int version;
143 const char *p;
144
145 version = 0;
146 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
147 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
148 version = version * 10 + *p - '0';
149 if (p[0] != '~' || p[1])
150 version = 0;
151 }
152 return version;
153}
154
155/*
156 * Return the newly-allocated concatenation of STR1 and STR2. If out of
157 * memory, return 0.
158 */
159static char *
160concat(const char *str1, const char *str2)
161{
162 char *newstr;
163
164 if (asprintf(&newstr, "%s%s", str1, str2) == -1)
165 return NULL;
166 return newstr;
167}
168
169/*
170 * If ARG is an unambiguous match for an element of the null-terminated array
171 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
172 * does not match any element or -2 if it is ambiguous (is a prefix of more
173 * than one element).
174 */
175static int
176argmatch(const char *arg, const char **optlist)
177{
178 int i; /* Temporary index in OPTLIST. */
179 size_t arglen; /* Length of ARG. */
180 int matchind = -1; /* Index of first nonexact match. */
181 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */
182
183 arglen = strlen(arg);
184
185 /* Test all elements for either exact match or abbreviated matches. */
186 for (i = 0; optlist[i]; i++) {
187 if (!strncmp(optlist[i], arg, arglen)) {
188 if (strlen(optlist[i]) == arglen)
189 /* Exact match found. */
190 return i;
191 else if (matchind == -1)
192 /* First nonexact match found. */
193 matchind = i;
194 else
195 /* Second nonexact match found. */
196 ambiguous = 1;
197 }
198 }
199 if (ambiguous)
200 return -2;
201 else
202 return matchind;
203}
204
205/*
206 * Error reporting for argmatch. KIND is a description of the type of entity
207 * that was being matched. VALUE is the invalid value that was given. PROBLEM
208 * is the return value from argmatch.
209 */
210static void
211invalid_arg(const char *kind, const char *value, int problem)
212{
213 fprintf(stderr, "patch: ");
214 if (problem == -1)
215 fprintf(stderr, "invalid");
216 else /* Assume -2. */
217 fprintf(stderr, "ambiguous");
218 fprintf(stderr, " %s `%s'\n", kind, value);
219}
220
221static const char *backup_args[] = {
222 "never", "simple", "nil", "existing", "t", "numbered", 0
223};
224
225static enum backup_type backup_types[] = {
226 simple, simple, numbered_existing,
227 numbered_existing, numbered, numbered
228};
229
230/*
231 * Return the type of backup indicated by VERSION. Unique abbreviations are
232 * accepted.
233 */
234enum backup_type
235get_version(const char *version)
236{
237 int i;
238
239 if (version == NULL || *version == '\0')
240 return numbered_existing;
241 i = argmatch(version, backup_args);
242 if (i >= 0)
243 return backup_types[i];
244 invalid_arg("version control type", version, i);
245 exit(2);
246}