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.

7 files changed, 103 insertions, 7 deletions

diff --git a/src/basic/clock-util.c b/src/basic/clock-util.c
index 507e757ff0..dd6c043af9 100644
--- a/src/basic/clock-util.c
+++ b/src/basic/clock-util.c
@@ -69,9 +69,12 @@ int clock_set_hwclock(const struct tm *tm) {
         return 0;
 }
 
-int clock_is_localtime(void) {
+int clock_is_localtime(const char* adjtime_path) {
         _cleanup_fclose_ FILE *f;
 
+        if (adjtime_path == NULL)
+                adjtime_path = "/etc/adjtime";
+
         /*
          * The third line of adjtime is "UTC" or "LOCAL" or nothing.
          *   # /etc/adjtime
@@ -79,7 +82,7 @@ int clock_is_localtime(void) {
          *   0
          *   UTC
          */
-        f = fopen("/etc/adjtime", "re");
+        f = fopen(adjtime_path, "re");
         if (f) {
                 char line[LINE_MAX];
                 bool b;
diff --git a/src/basic/clock-util.h b/src/basic/clock-util.h
index f471f2abcf..8830cd2f38 100644
--- a/src/basic/clock-util.h
+++ b/src/basic/clock-util.h
@@ -21,7 +21,7 @@
 
 #include <time.h>
 
-int clock_is_localtime(void);
+int clock_is_localtime(const char* adjtime_path);
 int clock_set_timezone(int *min);
 int clock_reset_timewarp(void);
 int clock_get_hwclock(struct tm *tm);
diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index f939196397..00372b92b4 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -139,7 +139,7 @@ static int property_get_tainted(
         if (access("/proc/cgroups", F_OK) < 0)
                 e = stpcpy(e, "cgroups-missing:");
 
-        if (clock_is_localtime() > 0)
+        if (clock_is_localtime(NULL) > 0)
                 e = stpcpy(e, "local-hwclock:");
 
         /* remove the last ':' */
diff --git a/src/core/main.c b/src/core/main.c
index b4e96fd6f4..2c315930ed 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1375,7 +1375,7 @@ int main(int argc, char *argv[]) {
                 }
 
                 if (!skip_setup) {
-                        if (clock_is_localtime() > 0) {
+                        if (clock_is_localtime(NULL) > 0) {
                                 int min;
 
                                 /*
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;
+}
diff --git a/src/timedate/timedated.c b/src/timedate/timedated.c
index 2a10135fba..55c24ac4f0 100644
--- a/src/timedate/timedated.c
+++ b/src/timedate/timedated.c
@@ -78,7 +78,7 @@ static int context_read_data(Context *c) {
         c->zone = t;
         t = NULL;
 
-        c->local_rtc = clock_is_localtime() > 0;
+        c->local_rtc = clock_is_localtime(NULL) > 0;
 
         return 0;
 }
diff --git a/src/timesync/timesyncd.c b/src/timesync/timesyncd.c
index 23e19159e0..b67d672a6a 100644
--- a/src/timesync/timesyncd.c
+++ b/src/timesync/timesyncd.c
@@ -122,7 +122,7 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
-        if (clock_is_localtime() > 0) {
+        if (clock_is_localtime(NULL) > 0) {
                 log_info("The system is configured to read the RTC time in the local time zone. "
                          "This mode can not be fully supported. All system time to RTC updates are disabled.");
                 m->rtc_local_time = true;