input/archive: use AtScopeExit() for exception-safety

src/input/plugins/ArchiveInputPlugin.cxx

@@ -27,6 +27,7 @@
 #include "../InputPlugin.hxx"
 #include "fs/Path.hxx"
 #include "Log.hxx"
+#include "util/ScopeExit.hxx"
 
 #include <stdlib.h>
 
@@ -34,15 +35,17 @@ InputStream *
 OpenArchiveInputStream(Path path, Mutex &mutex, Cond &cond, Error &error)
 {
 	const ArchivePlugin *arplug;
-	InputStream *is;
 
 	char *pname = strdup(path.c_str());
+	AtScopeExit(pname) {
+		free(pname);
+	};
+
 	// archive_lookup will modify pname when true is returned
 	const char *archive, *filename, *suffix;
 	if (!archive_lookup(pname, &archive, &filename, &suffix)) {
 		FormatDebug(archive_domain,
 			    "not an archive, lookup %s failed", pname);
-		free(pname);
 		return nullptr;
 	}
 
@@ -51,22 +54,19 @@ OpenArchiveInputStream(Path path, Mutex &mutex, Cond &cond, Error &error)
 	if (!arplug) {
 		FormatWarning(archive_domain,
 			      "can't handle archive %s", archive);
-		free(pname);
 		return nullptr;
 	}
 
 	auto file = archive_file_open(arplug, Path::FromFS(archive), error);
 	if (file == nullptr) {
-		free(pname);
 		return nullptr;
 	}
 
-	//setup fileops
-	is = file->OpenStream(filename, mutex, cond, error);
-	free(pname);
-	file->Close();
+	AtScopeExit(file) {
+		file->Close();
+	};
 
-	return is;
+	return file->OpenStream(filename, mutex, cond, error);
 }
 
 static InputStream *