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pacman/lib/libalpm/version.c

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/*
* 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 "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;
/* 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: */