From: Roy Marples <roy@marples.name>
Date: Fri, 1 Aug 2008 13:15:11 +0000 (+0000)
Subject: Brute force detection of monotonic clock as sysconf is unreliable. Instead rely on... 
X-Git-Tag: v4.0.2~95
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b5329d0e46028d623454756a1da81013474aab65;p=thirdparty%2Fdhcpcd.git

Brute force detection of monotonic clock as sysconf is unreliable. Instead rely on clock_gettime failing gracefully with an invalid clockid (which it should do).
---

diff --git a/README b/README
index ef7e7842..b3550c13 100644
--- a/README
+++ b/README
@@ -18,15 +18,6 @@ OS=BSD | Linux
 If you're building for an MMU-less system where fork() does not work, you
 should add -DTHERE_IS_NO_FORK to your CPPFLAGS.
 
-dhcpcd will try and use a monotonic clock when possible.
-Some libc implementations do not correctly report that they have a monotonic
-clock, but they have the headers to make it work. dhcpcd will warn about this.
-Without a monotonic clock, we fall victim of the year 2038 time_t bug on
-32-bit platforms AND the timers will be sufer from clock skew if the system
-clock changes.
-To force the use of a monotonic clock you can add -DFORCE_MONOTONIC
-to your CPPFLAGS.
-
 You can change the default dir with these knobs.
 For example, to satisfy FHS compliance you would do this:-
 LIBEXECDIR=/lib/dhcpcd
diff --git a/common.c b/common.c
index 9bedc6de..55e4e5ff 100644
--- a/common.c
+++ b/common.c
@@ -193,25 +193,16 @@ get_monotonic(struct timeval *tp)
 	struct timespec ts;
 	static clockid_t posix_clock;
 
-#ifdef FORCE_MONOTONIC
 	if (!posix_clock_set) {
-		posix_clock = CLOCK_MONOTONIC;
-		posix_clock_set = 1;
-		clock_monotonic = 1;
-	}
-#else
-	if (!posix_clock_set) {
-		if (sysconf(_SC_MONOTONIC_CLOCK) >= 0) {
+		if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
 			posix_clock = CLOCK_MONOTONIC;
 			clock_monotonic = 1;
 		} else {
 			posix_clock = CLOCK_REALTIME;
 			logger(LOG_WARNING, NO_MONOTONIC);
 		}
-
 		posix_clock_set = 1;
 	}
-#endif
 
 	if (clock_gettime(posix_clock, &ts) == -1)
 		return -1;
@@ -220,7 +211,6 @@ get_monotonic(struct timeval *tp)
 	tp->tv_usec = ts.tv_nsec / 1000;
 	return 0;
 #else
-
 	if (!posix_clock_set) {
 		logger(LOG_WARNING, NO_MONOTONIC);
 		posix_clock_set = 1;