clock-util: be more tolerant in parsing /etc/adjtime

As we default to "hardware clock is in UTC" if /etc/adjtime is not present, it
also makes sense to have that default if /etc/adjtime contains only one or two
lines.

Drop the "gibberish" test case, as this was just EIO because of not containing
three lines, which is already contained in other tests. clock_is_localtime()
never actually validated the format of the first two lines, and there is little
point in doing that.

This addresses the reading half of issue #2638.

2 files changed, 12 insertions, 8 deletions

diff --git a/src/basic/clock-util.c b/src/basic/clock-util.c
index dd6c043af9..7fe8d35ea5 100644
--- a/src/basic/clock-util.c
+++ b/src/basic/clock-util.c
@@ -91,7 +91,8 @@ int clock_is_localtime(const char* adjtime_path) {
                         fgets(line, sizeof(line), f) &&
                         fgets(line, sizeof(line), f);
                 if (!b)
-                        return -EIO;
+                        /* less than three lines -> default to UTC */
+                        return 0;
 
                 truncate_nl(line);
                 return streq(line, "LOCAL");
@@ -99,6 +100,7 @@ int clock_is_localtime(const char* adjtime_path) {
         } else if (errno != ENOENT)
                 return -errno;
 
+        /* adjtime not present -> default to UTC */
         return 0;
 }
 
diff --git a/src/test/test-clock.c b/src/test/test-clock.c
index 27f6b8cfd2..92c4f79b98 100644
--- a/src/test/test-clock.c
+++ b/src/test/test-clock.c
@@ -41,10 +41,14 @@ static void test_clock_is_localtime(void) {
                 /* no final EOL */
                 {"0.0 0 0\n0\nUTC", 0},
                 {"0.0 0 0\n0\nLOCAL", 1},
+                /* empty value -> defaults to UTC */
+                {"0.0 0 0\n0\n", 0},
                 /* unknown value -> defaults to UTC */
                 {"0.0 0 0\n0\nFOO\n", 0},
-                /* gibberish */
-                {"br0ken", -EIO},
+                /* no third line */
+                {"0.0 0 0", 0},
+                {"0.0 0 0\n", 0},
+                {"0.0 0 0\n0", 0},
         };
 
         /* without an adjtime file we default to UTC */
@@ -75,11 +79,9 @@ static void test_clock_is_localtime_system(void) {
 
         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);
+                /* if /etc/adjtime exists we expect some answer, no error or
+                 * crash */
+                assert(r == 0 || r == 1);
         } else
                 /* default is UTC if there is no /etc/adjtime */
                 assert(r == 0);