From 12e1ae9d72b46620249fe077351958038dddf506 Mon Sep 17 00:00:00 2001
From: Christian Prochaska <christian.prochaska@genode-labs.com>
Date: Tue, 20 Mar 2012 16:57:58 +0100
Subject: [PATCH] Implement '_nanosleep()'

This patch provides an implementation of the '_nanosleep()' libc function,
which blocks on a timed semaphore for the given time, but at least 10ms.
This should result in better performance than creating a timer connection
on every call (for thread-safety), but could still be improved.

Fixes #158.
---
 libports/lib/mk/libc.mk            |  2 +-
 libports/src/lib/libc/dummies.cc   |  1 -
 libports/src/lib/libc/nanosleep.cc | 41 ++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 libports/src/lib/libc/nanosleep.cc

diff --git a/libports/lib/mk/libc.mk b/libports/lib/mk/libc.mk
index f80892775..ed744e325 100644
--- a/libports/lib/mk/libc.mk
+++ b/libports/lib/mk/libc.mk
@@ -12,7 +12,7 @@ LIBS  += timed_semaphore cxx
 SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc readlink.cc munmap.cc \
          issetugid.cc errno.cc gai_strerror.cc clock_gettime.cc \
          gettimeofday.cc malloc.cc progname.cc fd_alloc.cc file_operations.cc \
-         plugin.cc plugin_registry.cc select.cc exit.cc environ.cc
+         plugin.cc plugin_registry.cc select.cc exit.cc environ.cc nanosleep.cc
 
 #
 # Files from string library that are not included in libc-raw_string because
diff --git a/libports/src/lib/libc/dummies.cc b/libports/src/lib/libc/dummies.cc
index 4ba13d106..60d4a39aa 100644
--- a/libports/src/lib/libc/dummies.cc
+++ b/libports/src/lib/libc/dummies.cc
@@ -86,7 +86,6 @@ DUMMY(-1, mkfifo)
 DUMMY(-1, mknod)
 DUMMY(-1, mprotect)
 DUMMY(-1, nanosleep)
-DUMMY(-1, _nanosleep)
 DUMMY(-1, __nsdefaultsrc)
 DUMMY(-1, _nsdispatch)
 DUMMY(-1, _openat)
diff --git a/libports/src/lib/libc/nanosleep.cc b/libports/src/lib/libc/nanosleep.cc
new file mode 100644
index 000000000..a28984606
--- /dev/null
+++ b/libports/src/lib/libc/nanosleep.cc
@@ -0,0 +1,41 @@
+/*
+ * \brief  C-library back end
+ * \author Christian Prochaska
+ * \date   2012-03-20
+ */
+
+/*
+ * Copyright (C) 2008-2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#include <os/timed_semaphore.h>
+
+#include <sys/time.h>
+
+using namespace Genode;
+
+extern "C" __attribute__((weak))
+int _nanosleep(const struct timespec *req, struct timespec *rem)
+{
+	Genode::Alarm::Time sleep_msec = (req->tv_sec * 1000) + (req->tv_nsec / 1000000);
+
+	/* Timed_semaphore does not support timeouts < 10ms */
+	if (sleep_msec < 10)
+		sleep_msec = 10;
+
+	Timed_semaphore sem(0);
+	try {
+		sem.down(sleep_msec);
+	} catch(Timeout_exception) {
+	}
+
+	if (rem) {
+		rem->tv_sec = 0;
+		rem->tv_nsec = 0;
+	}
+
+	return 0;
+}