Issue #539: Try a different way to compute max/min time_t values.

diff --git a/libarchive/archive_read_support_format_mtree.c b/libarchive/archive_read_support_format_mtree.c
index 64d5e6734ac0f05acd0198db491899fd46fd7925..b5f8e30d6d6d6d1e0e232e650a9a7b7f42e554a6 100644 (file)
--- a/libarchive/archive_read_support_format_mtree.c
+++ b/libarchive/archive_read_support_format_mtree.c
@@ -139,16 +139,19 @@ get_time_t_max(void)
 #if defined(TIME_T_MAX)
        return TIME_T_MAX;
 #else
-       static time_t t;
-       time_t a;
-       if (t == 0) {
-               a = 1;
-               while (a > t) {
-                       t = a;
-                       a = a * 2 + 1;
-               }
+       /* ISO C allows time_t to be a floating-point type,
+          but POSIX requires an integer type.  The following
+          should work on any system that follows the POSIX
+          conventions. */
+       if (((time_t)0) < ((time_t)-1)) {
+               /* Time_t is unsigned */
+               return (~(time_t)0);
+       } else {
+               /* Time_t is signed. */
+               const uintmax_t max_unsigned_time_t = (uintmax_t)(~(time_t)0);
+               const uintmax_t max_signed_time_t = max_unsigned_time_t >> 1;
+               return (time_t)max_signed_time_t;
        }
-       return t;
 #endif
 }
 
@@ -158,20 +161,16 @@ get_time_t_min(void)
 #if defined(TIME_T_MIN)
        return TIME_T_MIN;
 #else
-       /* 't' will hold the minimum value, which will be zero (if
-        * time_t is unsigned) or -2^n (if time_t is signed). */
-       static int computed;
-       static time_t t;
-       time_t a;
-       if (computed == 0) {
-               a = (time_t)-1;
-               while (a < t) {
-                       t = a;
-                       a = a * 2;
-               }                       
-               computed = 1;
+       if (((time_t)0) < ((time_t)-1)) {
+               /* Time_t is unsigned */
+               return (time_t)0;
+       } else {
+               /* Time_t is signed. */
+               const uintmax_t max_unsigned_time_t = (uintmax_t)(~(time_t)0);
+               const uintmax_t max_signed_time_t = max_unsigned_time_t >> 1;
+               const intmax_t min_signed_time_t = (intmax_t)~max_signed_time_t;
+               return (time_t)min_signed_time_t;
        }
-       return t;
 #endif
 }