From 179e88bec91cfe58096900dc5509a080ff37b083 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Fri, 20 Jan 2017 16:03:48 +0100
Subject: rdate: make it do something remotely sane, facing 32-bit time
overflow
function old new delta
rdate_main 251 254 +3
packed_usage 31029 31023 -6
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
networking/inetd.c | 2 +-
util-linux/rdate.c | 33 +++++++++++++++++++++++++++------
2 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/networking/inetd.c b/networking/inetd.c
index 4d0ab2e0d..612284e76 100644
--- a/networking/inetd.c
+++ b/networking/inetd.c
@@ -1677,7 +1677,7 @@ static uint32_t machtime(void)
struct timeval tv;
gettimeofday(&tv, NULL);
- return htonl((uint32_t)(tv.tv_sec + 2208988800));
+ return htonl((uint32_t)(tv.tv_sec + 2208988800U));
}
/* ARGSUSED */
static void FAST_FUNC machtime_stream(int s, servtab_t *sep UNUSED_PARAM)
diff --git a/util-linux/rdate.c b/util-linux/rdate.c
index 8dd784d3d..a62591914 100644
--- a/util-linux/rdate.c
+++ b/util-linux/rdate.c
@@ -21,11 +21,11 @@
//kbuild:lib-$(CONFIG_RDATE) += rdate.o
//usage:#define rdate_trivial_usage
-//usage: "[-sp] HOST"
+//usage: "[-s/-p] HOST"
//usage:#define rdate_full_usage "\n\n"
-//usage: "Get and possibly set system time from a remote HOST\n"
-//usage: "\n -s Set system time (default)"
-//usage: "\n -p Print time"
+//usage: "Set and print time from HOST using RFC 868\n"
+//usage: "\n -s Only set system time"
+//usage: "\n -p Only print time"
#include "libbb.h"
@@ -58,8 +58,22 @@ static time_t askremotedate(const char *host)
* the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
* Subtract the RFC 868 time to get Linux epoch.
*/
-
- return ntohl(nett) - RFC_868_BIAS;
+ nett = ntohl(nett) - RFC_868_BIAS;
+
+ if (sizeof(time_t) > 4) {
+ /* Now we have 32-bit lsb of a wider time_t
+ * Imagine that nett = 0x00000001,
+ * current time cur = 0x123ffffffff.
+ * Assuming our time is not some 40 years off,
+ * remote time must be 0x12400000001.
+ * Need to adjust out time by (int32_t)(nett - cur).
+ */
+ time_t cur = time(NULL);
+ int32_t adjust = (int32_t)(nett - (uint32_t)cur);
+ return cur + adjust;
+ }
+ /* This is not going to work, but what can we do */
+ return (time_t)nett;
}
int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -73,6 +87,13 @@ int rdate_main(int argc UNUSED_PARAM, char **argv)
remote_time = askremotedate(argv[optind]);
+ /* Manpages of various Unixes are confusing. What happens is:
+ * (no opts) set and print time
+ * -s: set time ("do not print the time")
+ * -p: print time ("do not set, just print the remote time")
+ * -sp: print time (that's what we do, not sure this is right)
+ */
+
if (!(flags & 2)) { /* no -p (-s may be present) */
time_t current_time;
--
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