Ensure mktime sets errno on error [BZ #23789]aaribaud/bugzilla/23789/v4

Posix mandates that mktime set errno to EOVERFLOW
on error, but the glibc mktime wasn't doing it so
far.

Fix this and add a test to prevent regressions.
The fix also fixes the same issue in timegm.

Tested with 'make check' on x86-linux-gnu and
i686-linux-gnu.

        * time/Makefile: Add bug-mktime4.
	* time/bug-mktime4.c: New file.
	* time/mktime.c
	(__mktime_internal): Set errno to EOVERFLOW on error.
	(mktime): Move call to __tzset inside conditional.

1 files changed, 27 insertions, 0 deletions

diff --git a/time/bug-mktime4.c b/time/bug-mktime4.c
new file mode 100644
index 0000000000..14d04c669b
--- /dev/null
+++ b/time/bug-mktime4.c
@@ -0,0 +1,27 @@
+#include <time.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+
+static int
+do_test (void)
+{
+  struct tm tm = { .tm_year = INT_MIN, .tm_mon = INT_MIN, .tm_mday = INT_MIN,
+		    .tm_hour = INT_MIN, .tm_min = INT_MIN, .tm_sec = INT_MIN };
+  errno = 0;
+  time_t tt = mktime (&tm);
+  if (tt != -1)
+    {
+      printf ("mktime() should have returned -1, returned %ld\n", (long int) tt);
+      return 1;
+    }
+  if (errno != EOVERFLOW)
+    {
+      printf ("mktime() returned -1, errno should be %d (EOVERFLOW) but is %d (%s)\n", EOVERFLOW, errno, strerror(errno));
+      return 1;
+    }
+  return 0;
+}
+
+#include "support/test-driver.c"