selftests/timens: added selftest for /proc/stat btime

Test that btime value of /proc/stat is as expected in the time namespace
using a simple parser to get btime from /proc/stat.

Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
Reviewed-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20201027204258.7869-4-michael.weiss@aisec.fraunhofer.de

diff --git a/tools/testing/selftests/timens/procfs.c b/tools/testing/selftests/timens/procfs.c
index 7f14f0f..f251915 100644 (file)
--- a/tools/testing/selftests/timens/procfs.c
+++ b/tools/testing/selftests/timens/procfs.c
@@ -93,6 +93,33 @@ static int read_proc_uptime(struct timespec *uptime)
        return 0;
 }
 
+static int read_proc_stat_btime(unsigned long long *boottime_sec)
+{
+       FILE *proc;
+       char line_buf[2048];
+
+       proc = fopen("/proc/stat", "r");
+       if (proc == NULL) {
+               pr_perror("Unable to open /proc/stat");
+               return -1;
+       }
+
+       while (fgets(line_buf, 2048, proc)) {
+               if (sscanf(line_buf, "btime %llu", boottime_sec) != 1)
+                       continue;
+               fclose(proc);
+               return 0;
+       }
+       if (errno) {
+               pr_perror("fscanf");
+               fclose(proc);
+               return -errno;
+       }
+       pr_err("failed to parse /proc/stat");
+       fclose(proc);
+       return -1;
+}
+
 static int check_uptime(void)
 {
        struct timespec uptime_new, uptime_old;
@@ -123,18 +150,47 @@ static int check_uptime(void)
        return 0;
 }
 
+static int check_stat_btime(void)
+{
+       unsigned long long btime_new, btime_old;
+       unsigned long long btime_expected;
+
+       if (switch_ns(parent_ns))
+               return pr_err("switch_ns(%d)", parent_ns);
+
+       if (read_proc_stat_btime(&btime_old))
+               return 1;
+
+       if (switch_ns(child_ns))
+               return pr_err("switch_ns(%d)", child_ns);
+
+       if (read_proc_stat_btime(&btime_new))
+               return 1;
+
+       btime_expected = btime_old - TEN_DAYS_IN_SEC;
+       if (btime_new != btime_expected) {
+               pr_fail("btime in /proc/stat: old %llu, new %llu [%llu]",
+                       btime_old, btime_new, btime_expected);
+               return 1;
+       }
+
+       ksft_test_result_pass("Passed for /proc/stat btime\n");
+       return 0;
+}
+
 int main(int argc, char *argv[])
 {
        int ret = 0;
 
        nscheck();
 
-       ksft_set_plan(1);
+       ksft_set_plan(2);
 
        if (init_namespaces())
                return 1;
 
        ret |= check_uptime();
+       ret |= check_stat_btime();
 
        if (ret)
                ksft_exit_fail();