lib: Fix clock_gettime linking problems.

Until glibc 2.17 clock_* calls needed explicit -lrt and hence linking
with -lltp fails on older distributions.

Since we do not want to link whole LTP with -lrt this commit adds simple
internal functions for clock_gettime() and clock_getres() calls to be
used internally in the test library.

Signed-off-by: Cyril Hrubis <[email protected]>
Acked-by: Jan Stancek <[email protected]>

Author: metan-ucw

include/tst_clocks.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2017 Cyril Hrubis <[email protected]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * clock_gettime() and clock_getres() functions
+ */
+
+#ifndef TST_CLOCKS__
+#define TST_CLOCKS__
+
+int tst_clock_getres(clockid_t clk_id, struct timespec *res);
+
+int tst_clock_gettime(clockid_t clk_id, struct timespec *ts);
+
+#endif /* TST_CLOCKS__ */

lib/tst_clocks.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2017 Cyril Hrubis <[email protected]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * clock_gettime() and clock_getres() functions
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <time.h>
+#include <sys/syscall.h>
+
+#include "tst_clocks.h"
+
+int tst_clock_getres(clockid_t clk_id, struct timespec *res)
+{
+	return syscall(SYS_clock_getres, clk_id, res);
+}
+
+int tst_clock_gettime(clockid_t clk_id, struct timespec *ts)
+{
+	return syscall(SYS_clock_gettime, clk_id, ts);
+}

lib/tst_timer.c

@@ -25,6 +25,7 @@
 
 #include "test.h"
 #include "tst_timer.h"
+#include "tst_clocks.h"
 #include "lapi/posix_clocks.h"
 
 static struct timespec start_time, stop_time;
@@ -56,30 +57,30 @@ static const char *clock_name(clockid_t clk_id)
 
 void tst_timer_check(clockid_t clk_id)
 {
-	if (clock_gettime(clk_id, &start_time)) {
+	if (tst_clock_gettime(clk_id, &start_time)) {
 		if (errno == EINVAL) {
 			tst_brkm(TCONF, NULL,
 			         "Clock id %s(%u) not supported by kernel",
 				 clock_name(clk_id), clk_id);
 			return;
 		}
 
-		tst_brkm(TBROK | TERRNO, NULL, "clock_gettime() failed");
+		tst_brkm(TBROK | TERRNO, NULL, "tst_clock_gettime() failed");
 	}
 }
 
 void tst_timer_start(clockid_t clk_id)
 {
 	clock_id = clk_id;
 
-	if (clock_gettime(clock_id, &start_time))
-		tst_resm(TWARN | TERRNO, "clock_gettime() failed");
+	if (tst_clock_gettime(clock_id, &start_time))
+		tst_resm(TWARN | TERRNO, "tst_clock_gettime() failed");
 }
 
 void tst_timer_stop(void)
 {
-	if (clock_gettime(clock_id, &stop_time))
-		tst_resm(TWARN | TERRNO, "clock_gettime() failed");
+	if (tst_clock_gettime(clock_id, &stop_time))
+		tst_resm(TWARN | TERRNO, "tst_clock_gettime() failed");
 }
 
 struct timespec tst_timer_elapsed(void)