summaryrefslogtreecommitdiffstats
path: root/lib/libalpm/version.c
blob: 1c838f415ac81d34d57eedc3deb6b6b9b682ff22 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
/*
 *  Copyright (c) 2006-2010 Pacman Development Team <pacman-dev@archlinux.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <string.h>
#include <ctype.h>

/* libalpm */
#include "log.h"
#include "util.h"

/** Compare two version strings and determine which one is 'newer'.
 * Returns a value comparable to the way strcmp works. Returns 1
 * if a is newer than b, 0 if a and b are the same version, or -1
 * if b is newer than a.
 *
 * This function has been adopted from the rpmvercmp function located
 * at lib/rpmvercmp.c, and was most recently updated against rpm
 * version 4.4.2.3. Small modifications have been made to make it more
 * consistent with the libalpm coding style.
 *
 * Keep in mind that the pkgrel is only compared if it is available
 * on both versions handed to this function. For example, comparing
 * 1.5-1 and 1.5 will yield 0; comparing 1.5-1 and 1.5-2 will yield
 * -1 as expected. This is mainly for supporting versioned dependencies
 * that do not include the pkgrel.
 */
int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
{
	char oldch1, oldch2;
	char *str1, *str2;
	char *ptr1, *ptr2;
	char *one, *two;
	int rc;
	int isnum;
	int ret = 0;

	ALPM_LOG_FUNC;

	/* libalpm added code. ensure our strings are not null */
	if(!a) {
		if(!b) return(0);
		return(-1);
	}
	if(!b) return(1);

	/* easy comparison to see if versions are identical */
	if(strcmp(a, b) == 0) return(0);

	str1 = strdup(a);
	str2 = strdup(b);

	one = str1;
	two = str2;

	/* loop through each version segment of str1 and str2 and compare them */
	while(*one && *two) {
		while(*one && !isalnum((int)*one)) one++;
		while(*two && !isalnum((int)*two)) two++;

		/* If we ran to the end of either, we are finished with the loop */
		if(!(*one && *two)) break;

		ptr1 = one;
		ptr2 = two;

		/* grab first completely alpha or completely numeric segment */
		/* leave one and two pointing to the start of the alpha or numeric */
		/* segment and walk ptr1 and ptr2 to end of segment */
		if(isdigit((int)*ptr1)) {
			while(*ptr1 && isdigit((int)*ptr1)) ptr1++;
			while(*ptr2 && isdigit((int)*ptr2)) ptr2++;
			isnum = 1;
		} else {
			while(*ptr1 && isalpha((int)*ptr1)) ptr1++;
			while(*ptr2 && isalpha((int)*ptr2)) ptr2++;
			isnum = 0;
		}

		/* save character at the end of the alpha or numeric segment */
		/* so that they can be restored after the comparison */
		oldch1 = *ptr1;
		*ptr1 = '\0';
		oldch2 = *ptr2;
		*ptr2 = '\0';

		/* this cannot happen, as we previously tested to make sure that */
		/* the first string has a non-null segment */
		if (one == ptr1) {
			ret = -1;	/* arbitrary */
			goto cleanup;
		}

		/* take care of the case where the two version segments are */
		/* different types: one numeric, the other alpha (i.e. empty) */
		/* numeric segments are always newer than alpha segments */
		/* XXX See patch #60884 (and details) from bugzilla #50977. */
		if (two == ptr2) {
			ret = isnum ? 1 : -1;
			goto cleanup;
		}

		if (isnum) {
			/* this used to be done by converting the digit segments */
			/* to ints using atoi() - it's changed because long  */
			/* digit segments can overflow an int - this should fix that. */

			/* throw away any leading zeros - it's a number, right? */
			while (*one == '0') one++;
			while (*two == '0') two++;

			/* whichever number has more digits wins */
			if (strlen(one) > strlen(two)) {
				ret = 1;
				goto cleanup;
			}
			if (strlen(two) > strlen(one)) {
				ret = -1;
				goto cleanup;
			}
		}

		/* strcmp will return which one is greater - even if the two */
		/* segments are alpha or if they are numeric.  don't return  */
		/* if they are equal because there might be more segments to */
		/* compare */
		rc = strcmp(one, two);
		if (rc) {
			ret = rc < 1 ? -1 : 1;
			goto cleanup;
		}

		/* restore character that was replaced by null above */
		*ptr1 = oldch1;
		one = ptr1;
		*ptr2 = oldch2;
		two = ptr2;

		/* libalpm added code. check if version strings have hit the pkgrel
		 * portion. depending on which strings have hit, take correct action.
		 * this is all based on the premise that we only have one dash in
		 * the version string, and it separates pkgver from pkgrel. */
		if(*ptr1 == '-' && *ptr2 == '-') {
			/* no-op, continue comparing since we are equivalent throughout */
		} else if(*ptr1 == '-') {
			/* ptr1 has hit the pkgrel and ptr2 has not. continue version
			 * comparison after stripping the pkgrel from ptr1. */
			*ptr1 = '\0';
		} else if(*ptr2 == '-') {
			/* ptr2 has hit the pkgrel and ptr1 has not. continue version
			 * comparison after stripping the pkgrel from ptr2. */
			*ptr2 = '\0';
		}
	}

	/* this catches the case where all numeric and alpha segments have */
	/* compared identically but the segment separating characters were */
	/* different */
	if ((!*one) && (!*two)) {
		ret = 0;
		goto cleanup;
	}

	/* the final showdown. we never want a remaining alpha string to
	 * beat an empty string. the logic is a bit weird, but:
	 * - if one is empty and two is not an alpha, two is newer.
	 * - if one is an alpha, two is newer.
	 * - otherwise one is newer.
	 * */
	if ( ( !*one && !isalpha((int)*two) )
			|| isalpha((int)*one) ) {
		ret = -1;
	} else {
		ret = 1;
	}

cleanup:
	free(str1);
	free(str2);
	return(ret);
}

/* vim: set ts=2 sw=2 noet: */