#if !defined(ESHUTDOWN)
#define ESHUTDOWN 4099
#endif
+
+/* time_t may be either 32 or 64 bits depending on the host OS, and
+ * can be either signed or unsigned, so we can't just hardcode a
+ * specific maximum value. This is not a C preprocessor constant,
+ * so you can't use TIME_MAX in an #ifdef, but for our purposes
+ * this isn't a problem.
+ */
+
+/* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
+ * Gnulib, and are under the LGPL v2.1 or (at your option) any
+ * later version.
+ */
+
+/* True if the real type T is signed. */
+#define TYPE_SIGNED(t) (!((t)0 < (t)-1))
+
+/* The width in bits of the integer type or expression T.
+ * Padding bits are not supported.
+ */
+#define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
+
+/* The maximum and minimum values for the integer type T. */
+#define TYPE_MAXIMUM(t) \
+ ((t) (!TYPE_SIGNED(t) \
+ ? (t)-1 \
+ : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
+
#ifndef TIME_MAX
-#define TIME_MAX LONG_MAX
+#define TIME_MAX TYPE_MAXIMUM(time_t)
#endif
/* HOST_LONG_BITS is the size of a native pointer in bits. */