[libc] Add mktime() function

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/sys/time.h

@@ -1,20 +1,18 @@
 #ifndef _SYS_TIME_H
 #define _SYS_TIME_H
 
-#include <time.h>
+/** @file
+ *
+ * Date and time
+ */
 
-typedef unsigned long suseconds_t;
+#include <stdint.h>
 
-struct timeval {
-	time_t tv_sec;		/* seconds */
-	suseconds_t tv_usec;	/* microseconds */
-};
-
-struct timezone {
-	int tz_minuteswest;	/* minutes W of Greenwich */
-	int tz_dsttime;		/* type of dst correction */
-};
-
-extern int gettimeofday ( struct timeval *tv, struct timezone *tz );
+/** Seconds since the Epoch
+ *
+ * We use a 64-bit type to avoid Y2K38 issues, since we may have to
+ * handle distant future dates (e.g. X.509 certificate expiry dates).
+ */
+typedef int64_t time_t;
 
 #endif /* _SYS_TIME_H */

src/include/time.h

@@ -1,22 +1,35 @@
 #ifndef _TIME_H
 #define _TIME_H
 
-typedef unsigned long time_t;
+/** @file
+ *
+ * Date and time
+ */
 
+#include <sys/time.h>
+
+/** Broken-down time */
 struct tm {
-	int tm_sec;	/* seconds */
-	int tm_min;	/* minutes */
-	int tm_hour;	/* hours */
-	int tm_mday;	/* day of the month */
-	int tm_mon;	/* month */
-	int tm_year;	/* year */
-	int tm_wday;	/* day of the week */
-	int tm_yday;	/* day in the year */
-	int tm_isdst;	/* daylight saving time */
+	/** Seconds [0,60] */
+	int tm_sec;
+	/** Minutes [0,59] */
+	int tm_min;
+	/** Hour [0,23] */
+	int tm_hour;
+	/** Day of month [1,31] */
+	int tm_mday;
+	/** Month of year [0,11] */
+	int tm_mon;
+	/** Years since 1900 */
+	int tm_year;
+	/** Day of week [0,6] (Sunday=0) */
+	int tm_wday;
+	/** Day of year [0,365] */
+	int tm_yday;
+	/** Daylight savings flag */
+	int tm_isdst;
 };
 
-extern time_t time ( time_t *t );
-
 extern time_t mktime ( struct tm *tm );
 
 #endif /* _TIME_H */