vercmp: ensure 2.0a and 2.0.a do not compare equal

We had this interesting set of facts conundrum, according to vercmp
return values:
    2.0a <  2.0
    2.0  <  2.0.a
    2.0a == 2.0.a

This introduces a code change that ensures '2.0a < 2.0.a' as would be
expected by the first two comparisons. Unfortunately this stays us a bit
further from upstream RPM code, but those are the breaks (in RPM, the
versions involving 'a' do in fact compare the same, but they are both
greater than the bare '2.0').

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/libalpm/version.c b/lib/libalpm/version.c
index 73d6a660..6b65a413 100644
--- a/lib/libalpm/version.c
+++ b/lib/libalpm/version.c
@@ -98,8 +98,8 @@ static int rpmvercmp(const char *a, const char *b)
 	str1 = strdup(a);
 	str2 = strdup(b);
 
-	one = str1;
-	two = str2;
+	one = ptr1 = str1;
+	two = ptr2 = str2;
 
 	/* loop through each version segment of str1 and str2 and compare them */
 	while (*one && *two) {
@@ -109,6 +109,11 @@ static int rpmvercmp(const char *a, const char *b)
 		/* If we ran to the end of either, we are finished with the loop */
 		if (!(*one && *two)) break;
 
+		/* If the separator lengths were different, we are also finished */
+		if ((one - ptr1) != (two - ptr2)) {
+			return (one - ptr1) < (two - ptr2) ? -1 : 1;
+		}
+
 		ptr1 = one;
 		ptr2 = two;