Adding upstream version 3.5.24.upstream/3.5.24

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 127 insertions, 0 deletions

diff --git a/src/util/sane_time.c b/src/util/sane_time.c
new file mode 100644
index 0000000..cc86de2
--- /dev/null
+++ b/src/util/sane_time.c
@@ -0,0 +1,127 @@
+/*++
+/* NAME
+/*	sane_time 3
+/* SUMMARY
+/*	time(2) with backward time jump protection.
+/* SYNOPSIS
+/*	#include <sane_time.h>
+/*
+/*	time_t sane_time(void)
+/*
+/* DESCRIPTION
+/*	This module provides time(2) like call for applications
+/*	which need monotonically increasing time function rather
+/*	than the real exact time. It eliminates the need for various
+/*	workarounds all over the application which would handle
+/*	potential problems if time suddenly jumps backward.
+/*	Instead we choose to deal with this problem inside this
+/*	module and let the application focus on its own tasks.
+/*
+/*	sane_time() returns the current timestamp as obtained from
+/*	time(2) call, at least most of the time. In case this routine
+/*	detects that time has jumped backward, it keeps returning
+/*	whatever timestamp it returned before, until this timestamp
+/*	and the time(2) timestamp become synchronized again.
+/*	Additionally, the returned timestamp is slowly increased to
+/*	prevent the faked clock from freezing for too long.
+/* SEE ALSO
+/*	time(2) get current time
+/* DIAGNOSTICS
+/*	Warning message is logged if backward time jump is detected.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Patrik Rak
+/*	Modra 6
+/*	155 00, Prague, Czech Republic
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+
+/* Utility library. */
+
+#include <msg.h>
+
+/* Application-specific. */
+
+#include "sane_time.h"
+
+/*
+ * How many times shall we slow down the real clock when recovering from
+ * time jump.
+ */
+#define SLEW_FACTOR 2
+
+/* sane_time - get current time, protected against time warping */
+
+time_t  sane_time(void)
+{
+    time_t  now;
+    static time_t last_time, last_real;
+    long    delta;
+    static int fraction;
+    static int warned;
+
+    now = time((time_t *) 0);
+
+    if ((delta = now - last_time) < 0 && last_time != 0) {
+	if ((delta = now - last_real) < 0) {
+	    msg_warn("%sbackward time jump detected -- slewing clock",
+		     warned++ ? "another " : "");
+	} else {
+	    delta += fraction;
+	    last_time += delta / SLEW_FACTOR;
+	    fraction = delta % SLEW_FACTOR;
+	}
+    } else {
+	if (warned) {
+	    warned = 0;
+	    msg_warn("backward time jump recovered -- back to normality");
+	    fraction = 0;
+	}
+	last_time = now;
+    }
+    last_real = now;
+
+    return (last_time);
+}
+
+#ifdef TEST
+
+ /*
+  * Proof-of-concept test program. Repeatedly print current system time and
+  * time returned by sane_time(). Meanwhile, try stepping your system clock
+  * back and forth to see what happens.
+  */
+
+#include <stdlib.h>
+#include <msg_vstream.h>
+#include <iostuff.h>			/* doze() */
+
+int     main(int argc, char **argv)
+{
+    int     delay = 1000000;
+    time_t  now;
+
+    msg_vstream_init(argv[0], VSTREAM_ERR);
+
+    if (argc == 2 && (delay = atol(argv[1]) * 1000) > 0)
+	 /* void */ ;
+    else if (argc != 1)
+	msg_fatal("usage: %s [delay in ms (default 1 second)]", argv[0]);
+
+    for (;;) {
+	now = time((time_t *) 0);
+	vstream_printf("real: %s", ctime(&now));
+	now = sane_time();
+	vstream_printf("fake: %s\n", ctime(&now));
+	vstream_fflush(VSTREAM_OUT);
+	doze(delay);
+    }
+}
+
+#endif