clock-util: make clock_is_localtime() testable and add initial tests

Add path argument to clock_is_localtime() and default to "/etc/adjtime" if it's
NULL. This makes the function testable.

Add test-clock: initial test cases for some scenarios, using a temporary file.
This also checks the behaviour with a NULL (i. e. the system's /etc/adjtime)
file.

1 files changed, 93 insertions, 0 deletions

diff --git a/src/test/test-clock.c b/src/test/test-clock.c
new file mode 100644
index 0000000000..27f6b8cfd2
--- /dev/null
+++ b/src/test/test-clock.c
@@ -0,0 +1,93 @@
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2016 Canonical Ltd.
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "macro.h"
+#include "fileio.h"
+#include "log.h"
+#include "clock-util.h"
+
+static void test_clock_is_localtime(void) {
+        char adjtime[] = "/tmp/test-adjtime.XXXXXX";
+        int fd;
+        FILE* f;
+
+        const struct scenario {
+                const char* contents;
+                int expected_result;
+        } scenarios[] = {
+                /* adjtime configures UTC */
+                {"0.0 0 0\n0\nUTC\n", 0},
+                /* adjtime configures local time */
+                {"0.0 0 0\n0\nLOCAL\n", 1},
+                /* no final EOL */
+                {"0.0 0 0\n0\nUTC", 0},
+                {"0.0 0 0\n0\nLOCAL", 1},
+                /* unknown value -> defaults to UTC */
+                {"0.0 0 0\n0\nFOO\n", 0},
+                /* gibberish */
+                {"br0ken", -EIO},
+        };
+
+        /* without an adjtime file we default to UTC */
+        assert_se(clock_is_localtime("/nonexisting/adjtime") == 0);
+
+        fd = mkostemp_safe(adjtime, O_WRONLY|O_CLOEXEC);
+        assert(fd > 0);
+        log_info("adjtime test file: %s", adjtime);
+        f = fdopen(fd, "w");
+        assert(f);
+
+        for (size_t i = 0; i < ELEMENTSOF(scenarios); ++i) {
+                log_info("scenario #%zu:, expected result %i", i, scenarios[i].expected_result);
+                log_info("%s", scenarios[i].contents);
+                rewind(f);
+                ftruncate(fd, 0);
+                assert_se(write_string_stream(f, scenarios[i].contents, false) == 0);
+                assert_se(clock_is_localtime(adjtime) == scenarios[i].expected_result);
+        }
+
+        unlink(adjtime);
+}
+
+/* Test with the real /etc/adjtime */
+static void test_clock_is_localtime_system(void) {
+        int r;
+        r = clock_is_localtime(NULL);
+
+        if (access("/etc/adjtime", F_OK) == 0) {
+                log_info("/etc/adjtime exists, clock_is_localtime() == %i", r);
+                /* we cannot assert much if /etc/adjtime exists, just that we
+                 * expect either an answer, or an EIO if the local file really
+                 * is badly malformed. I. e. we don't expect any other error
+                 * code or crash. */
+                assert(r == 0 || r == 1 || r == -EIO);
+        } else
+                /* default is UTC if there is no /etc/adjtime */
+                assert(r == 0);
+}
+
+int main(int argc, char *argv[]) {
+        test_clock_is_localtime();
+        test_clock_is_localtime_system();
+
+        return 0;
+}