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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:46:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:46:30 +0000
commitb5896ba9f6047e7031e2bdee0622d543e11a6734 (patch)
treefd7b460593a2fee1be579bec5697e6d887ea3421 /src/global/mail_date.c
parentInitial commit. (diff)
downloadpostfix-upstream.tar.xz
postfix-upstream.zip
Adding upstream version 3.4.23.upstream/3.4.23upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/global/mail_date.c')
-rw-r--r--src/global/mail_date.c141
1 files changed, 141 insertions, 0 deletions
diff --git a/src/global/mail_date.c b/src/global/mail_date.c
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+/*++
+/* 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