Add module for parsing command line arguments.

This patch adds a new module that does what current snap-confine main()
does with regards to argument parsing. The module is fully tested and
has simple API sufficient to drive rest of snap-confine.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>

src/Makefile.am

@@ -65,7 +65,9 @@ snap_confine_SOURCES = \
 	apparmor-support.c \
 	apparmor-support.h \
 	error.c \
-	error.h
+	error.h \
+	snap-confine-args.c \
+	snap-confine-args.h
 
 snap_confine_CFLAGS = -Wall -Werror $(AM_CFLAGS)
 snap_confine_LDFLAGS = $(AM_LDFLAGS)
@@ -109,7 +111,8 @@ snap_confine_unit_tests_SOURCES = \
 	apparmor-support.c \
 	apparmor-support.h \
 	mount-opt-test.c \
-	error-test.c
+	error-test.c \
+	snap-confine-args-test.c
 snap_confine_unit_tests_CFLAGS = $(snap_confine_CFLAGS) $(GLIB_CFLAGS)
 snap_confine_unit_tests_LDADD = $(snap_confine_LDADD) $(GLIB_LIBS)
 snap_confine_unit_tests_LDFLAGS = $(snap_confine_LDFLAGS)

src/snap-confine-args-test.c

@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2016 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "snap-confine-args.h"
+#include "snap-confine-args.c"
+
+#include <stdarg.h>
+
+#include <glib.h>
+
+/**
+ * Create an argc + argv pair out of a NULL terminated argument list.
+ **/
+static void
+    __attribute__ ((sentinel)) test_argc_argv(int *argcp, char ***argvp, ...)
+{
+	int argc = 0;
+	char **argv = NULL;
+	g_test_queue_free(argv);
+
+	va_list ap;
+	va_start(ap, argvp);
+	const char *arg;
+	do {
+		arg = va_arg(ap, const char *);
+		// XXX: yeah, wrong way but the worse that can happen is for test to fail
+		argv = realloc(argv, sizeof(const char **) * (argc + 1));
+		g_assert_nonnull(argv);
+		if (arg != NULL) {
+			char *arg_copy = strdup(arg);
+			g_test_queue_free(arg_copy);
+			argv[argc] = arg_copy;
+			argc += 1;
+		} else {
+			argv[argc] = NULL;
+		}
+	} while (arg != NULL);
+	va_end(ap);
+
+	*argcp = argc;
+	*argvp = argv;
+}
+
+static void test_test_argc_argv()
+{
+	// Check that test_argc_argv() correctly stores data
+	int argc;
+	char **argv;
+
+	test_argc_argv(&argc, &argv, NULL);
+	g_assert_cmpint(argc, ==, 0);
+	g_assert_null(argv[0]);
+
+	test_argc_argv(&argc, &argv, "zero", "one", "two", NULL);
+	g_assert_cmpint(argc, ==, 3);
+	g_assert_cmpstr(argv[0], ==, "zero");
+	g_assert_cmpstr(argv[1], ==, "one");
+	g_assert_cmpstr(argv[2], ==, "two");
+	g_assert_null(argv[3]);
+}
+
+static void test_sc_nonfatal_parse_args__typical()
+{
+	// Test that typical invocation of snap-confine is parsed correctly.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv,
+		       "/usr/lib/snapd/snap-confine", "snap.app", "--option",
+		       "arg", NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_test_queue_destroy((GDestroyNotify) sc_args_free, args);
+	g_assert_null(err);
+	g_assert_nonnull(args);
+
+	// Check supported switches and arguments
+	g_assert_cmpstr(sc_args_security_tag(args), ==, "snap.app");
+	g_assert_cmpint(sc_args_is_version_query(args), ==, false);
+
+	// Check remaining arguments
+	g_assert_cmpint(argc, ==, 3);
+	g_assert_cmpstr(argv[0], ==, "/usr/lib/snapd/snap-confine");
+	g_assert_cmpstr(argv[1], ==, "--option");
+	g_assert_cmpstr(argv[2], ==, "arg");
+	g_assert_null(argv[3]);
+}
+
+static void test_sc_nonfatal_parse_args__ubuntu_core_launcher()
+{
+	// Test that typical legacy invocation of snap-confine via the
+	// ubuntu-core-launcher symlink, with duplicated security tag, is parsed
+	// correctly.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv,
+		       "/usr/bin/ubuntu-core-launcher", "snap.app", "snap.app",
+		       "--option", "arg", NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_test_queue_destroy((GDestroyNotify) sc_args_free, args);
+	g_assert_null(err);
+	g_assert_nonnull(args);
+
+	// Check supported switches and arguments
+	g_assert_cmpstr(sc_args_security_tag(args), ==, "snap.app");
+	g_assert_cmpint(sc_args_is_version_query(args), ==, false);
+
+	// Check remaining arguments
+	g_assert_cmpint(argc, ==, 3);
+	g_assert_cmpstr(argv[0], ==, "/usr/bin/ubuntu-core-launcher");
+	g_assert_cmpstr(argv[1], ==, "--option");
+	g_assert_cmpstr(argv[2], ==, "arg");
+	g_assert_null(argv[3]);
+}
+
+static void test_sc_nonfatal_parse_args__version()
+{
+	// Test that snap-confine --version is detected.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv,
+		       "/usr/lib/snapd/snap-confine", "--version", "ignored",
+		       "garbage", NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_test_queue_destroy((GDestroyNotify) sc_args_free, args);
+	g_assert_null(err);
+	g_assert_nonnull(args);
+
+	// Check supported switches and arguments
+	g_assert_null(sc_args_security_tag(args));
+	g_assert_cmpint(sc_args_is_version_query(args), ==, true);
+
+	// Check remaining arguments
+	g_assert_cmpint(argc, ==, 3);
+	g_assert_cmpstr(argv[0], ==, "/usr/lib/snapd/snap-confine");
+	g_assert_cmpstr(argv[1], ==, "ignored");
+	g_assert_cmpstr(argv[2], ==, "garbage");
+	g_assert_null(argv[3]);
+}
+
+static void test_sc_nonfatal_parse_args__nothing_to_parse()
+{
+	// Check that calling without any arguments is reported as error.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv, NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_assert_nonnull(err);
+	g_assert_null(args);
+
+	// Check the error that we've got
+	g_assert_cmpstr(sc_error_msg(err), ==,
+			"cannot parse arguments, argc is zero");
+}
+
+static void test_sc_nonfatal_parse_args__no_security_tag()
+{
+	// Check that lack of security tag is reported as error.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv, "/usr/lib/snapd/snap-confine", NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_assert_nonnull(err);
+	g_assert_null(args);
+
+	// Check the error that we've got
+	g_assert_cmpstr(sc_error_msg(err), ==,
+			"application or hook security tag was not provided");
+}
+
+static void test_sc_nonfatal_parse_args__unknown_option()
+{
+	// Check that unrecognized option switch is reported as error.
+	struct sc_error *err __attribute__ ((cleanup(sc_cleanup_error))) = NULL;
+	struct sc_args *args;
+
+	int argc;
+	char **argv;
+	test_argc_argv(&argc, &argv, "/usr/lib/snapd/snap-confine",
+		       "--frozbonicator", NULL);
+
+	args = sc_nonfatal_parse_args(&argc, &argv, &err);
+	g_assert_nonnull(err);
+	g_assert_null(args);
+
+	// Check the error that we've got
+	g_assert_cmpstr(sc_error_msg(err), ==,
+			"unrecognized command line option: --frozbonicator");
+}
+
+static void test_sc_nonfatal_parse_args__forwards_error()
+{
+	// Check that sc_nonfatal_parse_args() forwards errors.
+	if (g_test_subprocess()) {
+		int argc;
+		char **argv;
+		test_argc_argv(&argc, &argv, "/usr/lib/snapd/snap-confine",
+			       "--frozbonicator", NULL);
+
+		// Call sc_nonfatal_parse_args() without an error handle
+		sc_nonfatal_parse_args(&argc, &argv, NULL);
+
+		g_test_message("expected not to reach this place");
+		g_test_fail();
+		return;
+	}
+	g_test_trap_subprocess(NULL, 0, 0);
+	g_test_trap_assert_failed();
+	g_test_trap_assert_stderr
+	    ("unrecognized command line option: --frozbonicator\n");
+}
+
+static void __attribute__ ((constructor)) init()
+{
+	g_test_add_func("/args/test_argc_argv", test_test_argc_argv);
+	g_test_add_func("/args/sc_nonfatal_parse_args/typical",
+			test_sc_nonfatal_parse_args__typical);
+	g_test_add_func("/args/sc_nonfatal_parse_args/ubuntu_core_launcher",
+			test_sc_nonfatal_parse_args__ubuntu_core_launcher);
+	g_test_add_func("/args/sc_nonfatal_parse_args/version",
+			test_sc_nonfatal_parse_args__version);
+	g_test_add_func("/args/sc_nonfatal_parse_args/nothing_to_parse",
+			test_sc_nonfatal_parse_args__nothing_to_parse);
+	g_test_add_func("/args/sc_nonfatal_parse_args/no_security_tag",
+			test_sc_nonfatal_parse_args__no_security_tag);
+	g_test_add_func("/args/sc_nonfatal_parse_args/unknown_option",
+			test_sc_nonfatal_parse_args__unknown_option);
+	g_test_add_func("/args/sc_nonfatal_parse_args/forwards_error",
+			test_sc_nonfatal_parse_args__forwards_error);
+}