1 files changed, 141 insertions, 0 deletions
diff --git a/src/global/mail_date.c b/src/global/mail_date.c
new file mode 100644
index 0000000..55d8907
--- /dev/null
+++ b/src/global/mail_date.c
@@ -0,0 +1,141 @@
+/*++
+/* NAME
+/*	mail_date 3
+/* SUMMARY
+/*	return formatted time
+/* SYNOPSIS
+/*	#include <mail_date.h>
+/*
+/*	const char *mail_date(when)
+/*	time_t	when;
+/* DESCRIPTION
+/*	mail_date() converts the time specified in \fIwhen\fR to the
+/*	form: "Mon, 9 Dec 1996 05:38:26 -0500 (EST)" and returns
+/*	a pointer to the result. The result is overwritten upon
+/*	each call.
+/* DIAGNOSTICS
+/*	Panic: the offset from UTC is more than a whole day. Fatal
+/*	error: out of memory.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <time.h>
+#include <stdlib.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <vstring.h>
+
+/* Global library. */
+
+#include "mail_date.h"
+
+ /*
+  * Application-specific.
+  */
+#define DAY_MIN		(24 * HOUR_MIN)	/* minutes in a day */
+#define	HOUR_MIN	60		/* minutes in an hour */
+#define MIN_SEC		60		/* seconds in a minute */
+
+/* mail_date - return formatted time */
+
+const char *mail_date(time_t when)
+{
+    static VSTRING *vp;
+    struct tm *lt;
+    struct tm gmt;
+    int     gmtoff;
+
+    /*
+     * As if strftime() isn't expensive enough, we're dynamically adjusting
+     * the size for the result, so we won't be surprised by long names etc.
+     */
+    if (vp == 0)
+	vp = vstring_alloc(100);
+    else
+	VSTRING_RESET(vp);
+
+    /*
+     * POSIX does not require that struct tm has a tm_gmtoff field, so we
+     * must compute the time offset from UTC by hand.
+     * 
+     * Starting with the difference in hours/minutes between 24-hour clocks,
+     * adjust for differences in years, in yeardays, and in (leap) seconds.
+     * 
+     * Assume 0..23 hours in a day, 0..59 minutes in an hour. The library spec
+     * has changed: we can no longer assume that there are 0..59 seconds in a
+     * minute.
+     */
+    gmt = *gmtime(&when);
+    lt = localtime(&when);
+    gmtoff = (lt->tm_hour - gmt.tm_hour) * HOUR_MIN + lt->tm_min - gmt.tm_min;
+    if (lt->tm_year < gmt.tm_year)
+	gmtoff -= DAY_MIN;
+    else if (lt->tm_year > gmt.tm_year)
+	gmtoff += DAY_MIN;
+    else if (lt->tm_yday < gmt.tm_yday)
+	gmtoff -= DAY_MIN;
+    else if (lt->tm_yday > gmt.tm_yday)
+	gmtoff += DAY_MIN;
+    if (lt->tm_sec <= gmt.tm_sec - MIN_SEC)
+	gmtoff -= 1;
+    else if (lt->tm_sec >= gmt.tm_sec + MIN_SEC)
+	gmtoff += 1;
+
+    /*
+     * First, format the date and wall-clock time. XXX The %e format (day of
+     * month, leading zero replaced by blank) isn't in my POSIX book, but
+     * many vendors seem to support it.
+     */
+#ifdef MISSING_STRFTIME_E
+#define STRFTIME_FMT "%a, %d %b %Y %H:%M:%S "
+#else
+#define STRFTIME_FMT "%a, %e %b %Y %H:%M:%S "
+#endif
+
+    while (strftime(vstring_end(vp), vstring_avail(vp), STRFTIME_FMT, lt) == 0)
+	VSTRING_SPACE(vp, 100);
+    VSTRING_SKIP(vp);
+
+    /*
+     * Then, add the UTC offset.
+     */
+    if (gmtoff < -DAY_MIN || gmtoff > DAY_MIN)
+	msg_panic("UTC time offset %d is larger than one day", gmtoff);
+    vstring_sprintf_append(vp, "%+03d%02d", (int) (gmtoff / HOUR_MIN),
+			   (int) (abs(gmtoff) % HOUR_MIN));
+
+    /*
+     * Finally, add the time zone name.
+     */
+    while (strftime(vstring_end(vp), vstring_avail(vp), " (%Z)", lt) == 0)
+	VSTRING_SPACE(vp, vstring_avail(vp) + 100);
+    VSTRING_SKIP(vp);
+
+    return (vstring_str(vp));
+}
+
+#ifdef TEST
+
+#include <vstream.h>
+
+int     main(void)
+{
+    vstream_printf("%s\n", mail_date(time((time_t *) 0)));
+    vstream_fflush(VSTREAM_OUT);
+    return (0);
+}
+
+#endif