* gmt_mktime.c (gmt_mktime): Handle years earlier than 1970.

(main) [TEST_LEAP]: New routine, driver for testing.
* Makefile.in (t_mktime): New target.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@13055 dc483132-0cff-0310-8789-dd5450dbe970

1 files changed, 49 insertions, 2 deletions

diff --git a/src/lib/krb5/os/gmt_mktime.c b/src/lib/krb5/os/gmt_mktime.c
index 1e3eebd..d0053ad 100644
--- a/src/lib/krb5/os/gmt_mktime.c
+++ b/src/lib/krb5/os/gmt_mktime.c
@@ -43,8 +43,18 @@ time_t gmt_mktime(t)
 
 #define assert_time(cnd) if(!(cnd)) return (time_t) -1
 
-  assert_time(t->tm_year>=70);
+  /*
+   * For 32-bit signed time_t centered on 1/1/1970, the range is:
+   * time 0x80000000 -> Fri Dec 13 16:45:52 1901
+   * time 0x7fffffff -> Mon Jan 18 22:14:07 2038
+   *
+   * So years 1901 and 2038 are allowable, but we can't encode all
+   * dates in those years, and we're not doing overflow/underflow
+   * checking for such cases.
+   */
+  assert_time(t->tm_year>=1);
   assert_time(t->tm_year<=138);
+
   assert_time(t->tm_mon>=0);
   assert_time(t->tm_mon<=11);
   assert_time(t->tm_mday>=1);
@@ -63,7 +73,10 @@ time_t gmt_mktime(t)
   accum *= 365;			/* 365 days/normal year */
 
   /* add in leap day for all previous years */
-  accum += (t->tm_year - 69) / 4;
+  if (t->tm_year >= 70)
+    accum += (t->tm_year - 69) / 4;
+  else
+    accum -= (72 - t->tm_year) / 4;
   /* add in leap day for this year */
   if(t->tm_mon >= 2)		/* march or later */
     if(hasleapday((t->tm_year + 1900))) accum += 1;
@@ -79,3 +92,37 @@ time_t gmt_mktime(t)
 
   return accum;
 }
+
+#ifdef TEST_LEAP
+int
+main (int argc, char *argv[])
+{
+  int yr;
+  time_t t;
+  struct tm tm = {
+    .tm_mon = 0, .tm_mday = 1,
+    .tm_hour = 0, .tm_min = 0, .tm_sec = 0,
+  };
+  for (yr = 60; yr <= 104; yr++)
+    {
+      printf ("1/1/%d%c -> ", 1900 + yr, hasleapday((1900+yr)) ? '*' : ' ');
+      tm.tm_year = yr;
+      t = gmt_mktime (&tm);
+      if (t == (time_t) -1)
+	printf ("-1\n");
+      else
+	{
+	  long u;
+	  if (t % (24 * 60 * 60))
+	    printf ("(not integral multiple of days) ");
+	  u = t / (24 * 60 * 60);
+	  printf ("%3ld*365%+ld\t0x%08lx\n",
+		  (long) (u / 365), (long) (u % 365),
+		  (long) t);
+	}
+    }
+  t = 0x80000000, printf ("time 0x%lx -> %s", t, ctime (&t));
+  t = 0x7fffffff, printf ("time 0x%lx -> %s", t, ctime (&t));
+  return 0;
+}
+#endif