1/* $FreeBSD: head/usr.bin/patch/backupfile.c 246074 2013-01-29 17:03:18Z gabor $ */
2/*-
3 *
4 * Copyright (C) 1990 Free Software Foundation, Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * without restriction.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.
12 *
13 * backupfile.c -- make Emacs style backup file names
14 *
15 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
16 *
17 * $OpenBSD: backupfile.c,v 1.19 2006/03/11 19:41:30 otto Exp $
18 * $DragonFly: src/usr.bin/patch/backupfile.c,v 1.5 2008/08/11 00:05:06 joerg Exp $
19 */
20
21#include <ctype.h>
22#include <dirent.h>
23#include <libgen.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27#include <unistd.h>
28
29#include "backupfile.h"
30
31
32#define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
33
34/* Which type of backup file names are generated. */
35enum backup_type backup_type = none;
36
37/*
38 * The extension added to file names to produce a simple (as opposed to
39 * numbered) backup file name.
40 */
41const char *simple_backup_suffix = "~";
42
43static char *concat(const char *, const char *);
44static char *make_version_name(const char *, int);
45static int max_backup_version(const char *, const char *);
46static int version_number(const char *, const char *, size_t);
47static int argmatch(const char *, const char **);
48static void invalid_arg(const char *, const char *, int);
49
50/*
51 * Return the name of the new backup file for file FILE, allocated with
52 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it
53 * is the root directory. Do not call this function if backup_type == none.
54 */
55char *
56find_backup_file_name(const char *file)
57{
58 char *dir, *base_versions, *tmp_file;
59 int highest_backup;
60
61 if (backup_type == simple)
62 return concat(file, simple_backup_suffix);
63 tmp_file = strdup(file);
64 if (tmp_file == NULL)
65 return NULL;
66 base_versions = concat(basename(tmp_file), ".~");
67 free(tmp_file);
68 if (base_versions == NULL)
69 return NULL;
70 tmp_file = strdup(file);
71 if (tmp_file == NULL) {
72 free(base_versions);
73 return NULL;
74 }
75 dir = dirname(tmp_file);
76 if (dir == NULL) {
77 free(base_versions);
78 free(tmp_file);
79 return NULL;
80 }
81 highest_backup = max_backup_version(base_versions, dir);
82 free(base_versions);
83 free(tmp_file);
84 if (backup_type == numbered_existing && highest_backup == 0)
85 return concat(file, simple_backup_suffix);
86 return make_version_name(file, highest_backup + 1);
87}
88
89/*
90 * Return the number of the highest-numbered backup file for file FILE in
91 * directory DIR. If there are no numbered backups of FILE in DIR, or an
92 * error occurs reading DIR, return 0. FILE should already have ".~" appended
93 * to it.
94 */
95static int
96max_backup_version(const char *file, const char *dir)
97{
98 DIR *dirp;
99 struct dirent *dp;
100 int highest_version, this_version;
101 size_t file_name_length;
102
103 dirp = opendir(dir);
104 if (dirp == NULL)
105 return 0;
106
107 highest_version = 0;
108 file_name_length = strlen(file);
109
110 while ((dp = readdir(dirp)) != NULL) {
111 if (dp->d_namlen <= file_name_length)
112 continue;
113
114 this_version = version_number(file, dp->d_name, file_name_length);
115 if (this_version > highest_version)
116 highest_version = this_version;
117 }
118 closedir(dirp);
119 return highest_version;
120}
121
122/*
123 * Return a string, allocated with malloc, containing "FILE.~VERSION~".
124 * Return 0 if out of memory.
125 */
126static char *
127make_version_name(const char *file, int version)
128{
129 char *backup_name;
130
131 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
132 return NULL;
133 return backup_name;
134}
135
136/*
137 * If BACKUP is a numbered backup of BASE, return its version number;
138 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should
139 * already have ".~" appended to it.
140 */
141static int
142version_number(const char *base, const char *backup, size_t base_length)
143{
144 int version;
145 const char *p;
146
147 version = 0;
148 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
149 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
150 version = version * 10 + *p - '0';
151 if (p[0] != '~' || p[1])
152 version = 0;
153 }
154 return version;
155}
156
157/*
158 * Return the newly-allocated concatenation of STR1 and STR2. If out of
159 * memory, return 0.
160 */
161static char *
162concat(const char *str1, const char *str2)
163{
164 char *newstr;
165
166 if (asprintf(&newstr, "%s%s", str1, str2) == -1)
167 return NULL;
168 return newstr;
169}
170
171/*
172 * If ARG is an unambiguous match for an element of the null-terminated array
173 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
174 * does not match any element or -2 if it is ambiguous (is a prefix of more
175 * than one element).
176 */
177static int
178argmatch(const char *arg, const char **optlist)
179{
180 int i; /* Temporary index in OPTLIST. */
181 size_t arglen; /* Length of ARG. */
182 int matchind = -1; /* Index of first nonexact match. */
183 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */
184
185 arglen = strlen(arg);
186
187 /* Test all elements for either exact match or abbreviated matches. */
188 for (i = 0; optlist[i]; i++) {
189 if (!strncmp(optlist[i], arg, arglen)) {
190 if (strlen(optlist[i]) == arglen)
191 /* Exact match found. */
192 return i;
193 else if (matchind == -1)
194 /* First nonexact match found. */
195 matchind = i;
196 else
197 /* Second nonexact match found. */
198 ambiguous = 1;
199 }
200 }
201 if (ambiguous)
202 return -2;
203 else
204 return matchind;
205}
206
207/*
208 * Error reporting for argmatch. KIND is a description of the type of entity
209 * that was being matched. VALUE is the invalid value that was given. PROBLEM
210 * is the return value from argmatch.
211 */
212static void
213invalid_arg(const char *kind, const char *value, int problem)
214{
215 fprintf(stderr, "patch: ");
216 if (problem == -1)
217 fprintf(stderr, "invalid");
218 else /* Assume -2. */
219 fprintf(stderr, "ambiguous");
220 fprintf(stderr, " %s `%s'\n", kind, value);
221}
222
223static const char *backup_args[] = {
224 "never", "simple", "nil", "existing", "t", "numbered", 0
225};
226
227static enum backup_type backup_types[] = {
228 simple, simple, numbered_existing,
229 numbered_existing, numbered, numbered
230};
231
232/*
233 * Return the type of backup indicated by VERSION. Unique abbreviations are
234 * accepted.
235 */
236enum backup_type
237get_version(const char *version)
238{
239 int i;
240
241 if (version == NULL || *version == '\0')
242 return numbered_existing;
243 i = argmatch(version, backup_args);
244 if (i >= 0)
245 return backup_types[i];
246 invalid_arg("version control type", version, i);
247 exit(2);
248}