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>

4 files changed, 15 insertions, 4 deletions

diff --git a/doc/pacman.8.txt b/doc/pacman.8.txt
index 2a640f8f..59853812 100644
--- a/doc/pacman.8.txt
+++ b/doc/pacman.8.txt
@@ -86,7 +86,7 @@ You can also use `pacman -Su` to upgrade all packages that are out of date. See
 to determine which packages need upgrading. This behavior operates as follows:
 
   Alphanumeric:
-    1.0a < 1.0alpha < 1.0b < 1.0beta < 1.0p < 1.0pre < 1.0rc < 1.0
+    1.0a < 1.0b < 1.0beta < 1.0p < 1.0pre < 1.0rc < 1.0 < 1.0.a < 1.0.1
   Numeric:
     1 < 1.0 < 1.1 < 1.1.1 < 1.2 < 2.0 < 3.0.0
 +
diff --git a/doc/vercmp.8.txt b/doc/vercmp.8.txt
index a3bc5611..4b0490fa 100644
--- a/doc/vercmp.8.txt
+++ b/doc/vercmp.8.txt
@@ -26,7 +26,7 @@ numbers. It outputs values as follows:
 Version comparsion operates as follows:
 
   Alphanumeric:
-    1.0a < 1.0alpha < 1.0b < 1.0beta < 1.0p < 1.0pre < 1.0rc < 1.0
+    1.0a < 1.0b < 1.0beta < 1.0p < 1.0pre < 1.0rc < 1.0 < 1.0.a < 1.0.1
   Numeric:
     1 < 1.0 < 1.1 < 1.1.1 < 1.2 < 2.0 < 3.0.0
 
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;
 
diff --git a/test/util/vercmptest.sh b/test/util/vercmptest.sh
index 54ede04b..6b4bcbc2 100755
--- a/test/util/vercmptest.sh
+++ b/test/util/vercmptest.sh
@@ -118,6 +118,12 @@ runtest 1.5.1    1.5.b   1
 runtest 1.5.b-1  1.5.b   0
 runtest 1.5-1    1.5.b  -1
 
+# same/similar content, differing separators
+runtest 2.0    2_0     0
+runtest 2.0_a  2_0.a   0
+runtest 2.0a   2.0.a  -1
+runtest 2___a  2_a     1
+
 # epoch included version comparisons
 runtest 0:1.0    0:1.0   0
 runtest 0:1.0    0:1.1  -1