Allow version comparison to contain epoch specifier

Adapting from RPM, follow the [epoch:]version[-release] syntax. We can also
borrow some of their parsing code for our purposes (thanks!).  Add some new
tests to our vercmp shell script tester for epoch comparisons, and then make
the code work with these newfangled epoch specifiers.

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

1 files changed, 117 insertions, 40 deletions

diff --git a/lib/libalpm/version.c b/lib/libalpm/version.c
index 85cc2f57..eba66210 100644
--- a/lib/libalpm/version.c
+++ b/lib/libalpm/version.c
@@ -23,23 +23,66 @@
 /* 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.
+/**
+ * Some functions in this file have been adopted from the rpm source, notably
+ * 'rpmvercmp' located at lib/rpmvercmp.c and 'parseEVR' located at
+ * lib/rpmds.c. It was most recently updated against rpm version 4.8.1. Small
+ * modifications have been made to make it more consistent with the libalpm
+ * coding style.
  */
-int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
+
+/**
+ * Split EVR into epoch, version, and release components.
+ * @param evr		[epoch:]version[-release] string
+ * @retval *ep		pointer to epoch
+ * @retval *vp		pointer to version
+ * @retval *rp		pointer to release
+ */
+static void parseEVR(char *evr, const char **ep, const char **vp,
+		const char **rp)
+{
+	const char *epoch;
+	const char *version;
+	const char *release;
+	char *s, *se;
+
+	s = evr;
+	/* s points to epoch terminator */
+	while (*s && isdigit(*s)) s++;
+	/* se points to version terminator */
+	se = strrchr(s, '-');
+
+	if(*s == ':') {
+		epoch = evr;
+		*s++ = '\0';
+		version = s;
+		if(*epoch == '\0') {
+			epoch = "0";
+		}
+	} else {
+		/* different from RPM- always assume 0 epoch */
+		epoch = "0";
+		version = evr;
+	}
+	if(se) {
+		*se++ = '\0';
+		release = se;
+	} else {
+		release = NULL;
+	}
+
+	if(ep) *ep = epoch;
+	if(vp) *vp = version;
+	if(rp) *rp = release;
+}
+
+/**
+ * Compare alpha and numeric segments of two versions.
+ * return 1: a is newer than b
+ *        0: a and b are the same version
+ *       -1: b is newer than a
+ */
+static int rpmvercmp(const char *a, const char *b)
 {
 	char oldch1, oldch2;
 	char *str1, *str2;
@@ -49,13 +92,6 @@ int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
 	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);
 
@@ -147,22 +183,6 @@ int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
 		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 */
@@ -179,7 +199,7 @@ int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
 	 * - if one is an alpha, two is newer.
 	 * - otherwise one is newer.
 	 * */
-	if ( ( !*one && !isalpha((int)*two) )
+	if ( (!*one && !isalpha((int)*two))
 			|| isalpha((int)*one) ) {
 		ret = -1;
 	} else {
@@ -192,4 +212,61 @@ cleanup:
 	return(ret);
 }
 
+/** 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.
+ *
+ * Different epoch values for version strings will override any further
+ * comparison. If no epoch is provided, 0 is assumed.
+ *
+ * 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 *full1, *full2;
+	const char *epoch1, *ver1, *rel1;
+	const char *epoch2, *ver2, *rel2;
+	int ret;
+
+	/* ensure our strings are not null */
+	if(!a && !b) {
+		return(0);
+	} else if(!a) {
+		return(-1);
+	} else if(!b) {
+		return(1);
+	}
+	/* another quick shortcut- if full version specs are equal */
+	if(strcmp(a, b) == 0) {
+		return(0);
+	}
+
+	/* Parse both versions into [epoch:]version[-release] triplets. We probably
+	 * don't need epoch and release to support all the same magic, but it is
+	 * easier to just run it all through the same code. */
+	full1 = strdup(a);
+	full2 = strdup(b);
+
+	/* parseEVR modifies passed in version, so have to dupe it first */
+	parseEVR(full1, &epoch1, &ver1, &rel1);
+	parseEVR(full2, &epoch2, &ver2, &rel2);
+
+	ret = rpmvercmp(epoch1, epoch2);
+	if(ret == 0) {
+		ret = rpmvercmp(ver1, ver2);
+		if(ret == 0 && rel1 && rel2) {
+			ret = rpmvercmp(rel1, rel2);
+		}
+	}
+
+	free(full1);
+	free(full2);
+	return(ret);
+}
+
 /* vim: set ts=2 sw=2 noet: */