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>

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@@ -86,7 +86,7 @@ You can also use `pacman -Su` to upgrade all packages that are out of date.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
 +

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
 

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;
+	one = ptr1 = str1;
-	two = str2;
+	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;
 

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