du: don't print junk when diagnosing out-of-range time stamps

* src/du.c (show_date): Fix call to fputs with a buffer that
contains some uninitialized data.
* tests/Makefile.am (TESTS): Add du/big-timestamp.
* tests/du/bigtime: New file, which checks for the bug.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/du.c b/src/du.c
index 3d9257934..4951826ea 100644
--- a/src/du.c
+++ b/src/du.c
@@ -351,8 +351,9 @@ show_date (const char *format, struct timespec when)
   if (! tm)
     {
       char buf[INT_BUFSIZE_BOUND (intmax_t)];
-      error (0, 0, _("time %s is out of range"), timetostr (when.tv_sec, buf));
-      fputs (buf, stdout);
+      char *when_str = timetostr (when.tv_sec, buf);
+      error (0, 0, _("time %s is out of range"), when_str);
+      fputs (when_str, stdout);
       return;
     }