Fix crash when metaurl contains unsupported URI or text

src/Metalink2RequestGroup.cc

@@ -222,7 +222,7 @@ Metalink2RequestGroup::createRequestGroup
         createRequestGroupForUri(result, optionTemplate, uris,
                                  /* ignoreForceSequential = */true,
                                  /* ignoreLocalPath = */true);
-        if(!uris.empty()) {
+        if(!result.empty()) {
           torrentRg = result[0];
         }
       }

test/Makefile.am

@@ -282,7 +282,8 @@ EXTRA_DIST = 4096chunk.txt\
 	metalink4-groupbymetaurl.xml\
 	serialize_session.meta4\
 	metalink4-dosdirtraversal.xml\
-	base_uri.xml
+	base_uri.xml\
+	local-metaurl.meta4
 
 clean-local:
 	-rm -rf ${a2_test_outdir}

test/Metalink2RequestGroupTest.cc

@@ -17,6 +17,7 @@ class Metalink2RequestGroupTest:public CppUnit::TestFixture {
 
   CPPUNIT_TEST_SUITE(Metalink2RequestGroupTest);
   CPPUNIT_TEST(testGenerate);
+  CPPUNIT_TEST(testGenerate_with_local_metaurl);
   CPPUNIT_TEST(testGenerate_groupByMetaurl);
   CPPUNIT_TEST(testGenerate_dosDirTraversal);
   CPPUNIT_TEST_SUITE_END();
@@ -31,6 +32,7 @@ public:
   }
 
   void testGenerate();
+  void testGenerate_with_local_metaurl();
   void testGenerate_groupByMetaurl();
   void testGenerate_dosDirTraversal();
 };
@@ -125,6 +127,20 @@ void Metalink2RequestGroupTest::testGenerate()
   }
 }
 
+void Metalink2RequestGroupTest::testGenerate_with_local_metaurl()
+{
+  std::vector<std::shared_ptr<RequestGroup> > groups;
+  option_->put(PREF_DIR, "/tmp");
+  // local metaurl does not work without --metalink-base-uri option.
+  // Make sure that it does not crash with local metaurl.
+  Metalink2RequestGroup().generate(groups, A2_TEST_DIR"/local-metaurl.meta4",
+                                   option_);
+  CPPUNIT_ASSERT_EQUAL((size_t)1, groups.size());
+  CPPUNIT_ASSERT_EQUAL(std::string("http://example.org/README"),
+                       groups[0]->getDownloadContext()->getFirstFileEntry()
+                       ->getRemainingUris()[0]);
+}
+
 void Metalink2RequestGroupTest::testGenerate_groupByMetaurl()
 {
   std::vector<std::shared_ptr<RequestGroup> > groups;

test/local-metaurl.meta4

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<metalink xmlns="urn:ietf:params:xml:ns:metalink">
+  <file name="t/README">
+    <!-- require absolute URI here -->
+    <metaurl mediatype="torrent">README.torrent</metaurl>
+    <url type="http">http://example.org/README</url>
+  </file>
+</metalink>