Fix crashes due to incorrectly registered alternatives

bin/xbps-alternatives/main.c

@@ -149,8 +149,10 @@ list_alternatives(struct xbps_handle *xhp, const char *pkgname, const char *grp)
 			xbps_array_get_cstring_nocopy(array, x, &str);
 			printf(" - %s%s\n", str, x == 0 ? " (current)" : "");
 			pkgd = xbps_pkgdb_get_pkg(xhp, str);
-			assert(pkgd);
-			list_pkg_alternatives(pkgd, keyname, false);
+			if (pkgd)
+				list_pkg_alternatives(pkgd, keyname, false);
+			else
+				xbps_dbg_printf(xhp, "Not installed package '%s' registered as alternative for '%s'\n", str, grp);
 		}
 	}
 	xbps_object_release(allkeys);

lib/package_alternatives.c

@@ -327,6 +327,31 @@ switch_alt_group(struct xbps_handle *xhp, const char *grpn, const char *pkgn,
 	return create_symlinks(xhp, xbps_dictionary_get(pkgalts, grpn), grpn);
 }
 
+/*
+ * Removes packages that do not provide alternatives for group.
+ * Old xbps versions didn't clean up list on time.
+ */
+static void
+remove_outdated_packages(struct xbps_handle *xhp, const char *groupname, xbps_array_t packages)
+{
+	for (unsigned int i = 0; i < xbps_array_count(packages);) {
+		const char *pkgname = NULL;
+		xbps_dictionary_t pkgdict;
+		xbps_dictionary_t alts;
+		xbps_array_t alts_group;
+		xbps_array_get_cstring_nocopy(packages, i, &pkgname);
+		if (!(pkgdict = xbps_pkgdb_get_pkg(xhp, pkgname)) ||
+			!(alts = xbps_dictionary_get(pkgdict, "alternatives")) ||
+			!(alts_group = xbps_dictionary_get(alts, groupname)) ||
+			xbps_array_count(alts_group) == 0
+		) {
+			xbps_array_remove(packages, i);
+			continue;
+		}
+		i++;
+	}
+}
+
 int
 xbps_alternatives_unregister(struct xbps_handle *xhp, xbps_dictionary_t pkgd)
 {
@@ -380,18 +405,20 @@ xbps_alternatives_unregister(struct xbps_handle *xhp, xbps_dictionary_t pkgd)
 			xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_REMOVED, 0, NULL,
 			    "%s: unregistered '%s' alternatives group", pkgver, keyname);
 			xbps_remove_string_from_array(array, pkgname);
-			xbps_array_get_cstring_nocopy(array, 0, &first);
 		}
 
+		remove_outdated_packages(xhp, keyname, array);
 		if (xbps_array_count(array) == 0) {
 			xbps_dictionary_remove(alternatives, keyname);
 			continue;
 		}
 
+		/* XXX: ... && remove_outdated_packages didn't removed current package) */
 		if (update || !current)
 			continue;
 
 		/* get the new alternative group package */
+		xbps_array_get_cstring_nocopy(array, 0, &first);
 		if (switch_alt_group(xhp, keyname, first, &pkg_alternatives) != 0)
 			break;
 	}
@@ -415,7 +442,8 @@ prune_altgroup(struct xbps_handle *xhp, xbps_dictionary_t repod,
 	xbps_array_t array;
 	xbps_dictionary_t alternatives;
 	xbps_string_t kstr;
-	unsigned int grp_count;
+	unsigned int grp_count, depends_count;
+	uint64_t size = 0;
 	bool current = false;
 
 	xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_REMOVED, 0, NULL,
@@ -442,31 +470,35 @@ prune_altgroup(struct xbps_handle *xhp, xbps_dictionary_t repod,
 		return;
 	}
 
-	if (xbps_array_count(xbps_dictionary_get(repod, "run_depends")) == 0 &&
-	    xbps_array_count(xbps_dictionary_get(repod, "shlib-requires")) == 0) {
+	xbps_dictionary_get_uint64(repod, "installed_size", &size);
+	depends_count = xbps_array_count(xbps_dictionary_get(repod, "run_depends"));
+
+	/*
+	 * Non-empty package is an ordinary package dropping alternatives.
+	 * Empty dependencies indicate a removed package (pure meta).
+	 */
+	if (size == 0 && 0 < depends_count) {
 		/*
-		 * Empty dependencies indicate a removed package (pure meta),
-		 * use the first available group after ours has been pruned
+		 * Use the last group, as this indicates that a transitional metapackage
+		 * is replacing the original and therefore a new package has registered
+		 * a replacement group, which should be last in the array (most recent).
 		 */
-		xbps_array_get_cstring_nocopy(array, 0, &newpkg);
-		switch_alt_group(xhp, keyname, newpkg, NULL);
-		return;
+		xbps_array_get_cstring_nocopy(array, grp_count - 1, &newpkg);
+		/* put the new package as head */
+		kstr = xbps_string_create_cstring(newpkg);
+		xbps_remove_string_from_array(array, newpkg);
+		xbps_array_add_first(array, kstr);
+		xbps_object_release(kstr);
 	}
 
-	/*
-	 * Use the last group, as this indicates that a transitional metapackage
-	 * is replacing the original and therefore a new package has registered
-	 * a replacement group, which should be last in the array (most recent).
-	 */
-	xbps_array_get_cstring_nocopy(array, grp_count - 1, &newpkg);
+	remove_outdated_packages(xhp, keyname, array);
+	if (xbps_array_count(array) == 0) {
+		/* it was the last one, ditch the whole thing */
+		xbps_dictionary_remove(alternatives, keyname);
+		return;
+	}
 
-	/* put the new package as head */
-	kstr = xbps_string_create_cstring(newpkg);
-	xbps_remove_string_from_array(array, newpkg);
-	xbps_array_add_first(array, kstr);
 	xbps_array_get_cstring_nocopy(array, 0, &newpkg);
-	xbps_object_release(kstr);
-
 	switch_alt_group(xhp, keyname, newpkg, NULL);
 }
 

tests/xbps/xbps-alternatives/main_test.sh

@@ -263,6 +263,84 @@ unregister_multi_body() {
 	atf_check_equal $rv 0
 }
 
+atf_test_case alternative_unregister
+
+alternative_unregister_head() {
+	atf_set "descr" "xbps-alternatives: removal of the alternative group from pkgdb"
+}
+alternative_unregister_body() {
+	mkdir -p repo pkg_A/usr/bin
+	mkdir -p repo pkg_B/usr/bin
+	touch pkg_A/usr/bin/gcc
+	touch pkg_B/usr/bin/clang
+
+	cd repo
+	xbps-create -A noarch -n pkgA-1.1_1 -s "A pkg" --alternatives "cc:cc:/usr/bin/A" ../pkg_A
+	atf_check_equal $? 0
+	xbps-create -A noarch -n pkgB-1.1_1 -s "B pkg" --alternatives "cc:cc:/usr/bin/B" ../pkg_B
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+
+	xbps-install -r root --repository=repo -ydv pkgA pkgB
+	atf_check_equal $? 0
+	atf_check_equal "$(grep -c '			<string>pkgA</string>' root/var/db/xbps/pkgdb*.plist)"A 1A
+	atf_check_equal "$(grep -c '			<string>pkgB</string>' root/var/db/xbps/pkgdb*.plist)"B 1B
+
+	cd repo
+	xbps-create -A noarch -n pkgA-1.1_2 -s "A pkg" ../pkg_A
+	atf_check_equal $? 0
+	xbps-create -A noarch -n pkgB-1.1_2 -s "B pkg" --alternatives "cc:cc:/usr/bin/B" ../pkg_B
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+
+	xbps-install -r root --repository=repo -dvyu
+	atf_check_equal $? 0
+	xbps-remove -r root -dvy pkgA
+	atf_check_equal $? 0
+	atf_check_equal "$(grep -c '			<string>pkgA</string>' root/var/db/xbps/pkgdb*.plist)"A 0A
+	atf_check_equal "$(grep -c '			<string>pkgB</string>' root/var/db/xbps/pkgdb*.plist)"B 1B
+}
+
+
+atf_test_case handle_0_57_1_pkgdb
+
+handle_0_57_1_pkgdb_head() {
+	atf_set "descr" "xbps-alternatives: processing old pkgdb containing removed packages in _XBPS_ALTERNATIVES_"
+}
+handle_0_57_1_pkgdb_body() {
+	mkdir -p repo pkg_A/usr/bin
+	mkdir -p repo pkg_B/usr/bin
+	touch pkg_A/usr/bin/gcc
+	touch pkg_B/usr/bin/clang
+
+	cd repo
+	xbps-create -A noarch -n pkgA-1.1_1 -s "A pkg" ../pkg_A
+	atf_check_equal $? 0
+	xbps-create -A noarch -n pkgB-1.1_1 -s "B pkg" --alternatives "cc:cc:/usr/bin/B" ../pkg_B
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+
+	xbps-install -r root --repository=repo -ydv pkgB
+	atf_check_equal $? 0
+
+	atf_check_equal "$(grep -c '			<string>pkgA</string>' root/var/db/xbps/pkgdb*.plist)"A 0A
+	atf_check_equal "$(grep -c '			<string>pkgB</string>' root/var/db/xbps/pkgdb*.plist)"B 1B
+	sed -e 's:<string>pkgB</string>:&			<string>pkgA</string>:' -i root/var/db/xbps/pkgdb*.plist
+	atf_check_equal "$(grep -c '			<string>pkgA</string>' root/var/db/xbps/pkgdb*.plist)"A 1A
+
+	xbps-alternatives -r root -l
+	atf_check_equal $? 0
+
+	xbps-remove -r root -dvy pkgB
+	atf_check_equal $? 0
+}
+
 atf_test_case set_pkg
 
 set_pkg_head() {
@@ -951,6 +1029,8 @@ atf_init_test_cases() {
 	atf_add_test_case unregister_one
 	atf_add_test_case unregister_one_relative
 	atf_add_test_case unregister_multi
+	atf_add_test_case alternative_unregister
+	atf_add_test_case handle_0_57_1_pkgdb
 	atf_add_test_case set_pkg
 	atf_add_test_case set_pkg_group
 	atf_add_test_case update_pkgs