posix: Map CLOCK_REALTIME and CLOCK_MONOTONIC to Zephyr clock IDs

Some toolchains may define CLOCK_REALTIME and
CLOCK_MONOTONIC in their libc headers
with values that differ from Zephyr's internal
SYS_CLOCK_REALTIME and SYS_CLOCK_MONOTONIC.

To ensure consistent behavior across all boards and
toolchains, Introduce a helper function to map
CLOCK_REALTIME and CLOCK_MONOTONIC to Zephyr's internal
clock IDs (SYS_CLOCK_REALTIME and SYS_CLOCK_MONOTONIC).

This prevents mismatched clock IDs being passed to
the kernel, avoiding invalid clockid errors when using
functions like clock_gettime().

Signed-off-by: Mohamed Moawad <[email protected]>

Author: M-Moawad

include/zephyr/sys/clock.h

@@ -378,6 +378,9 @@ static inline bool sys_timepoint_expired(k_timepoint_t timepoint)
 /** @cond INTERNAL_HIDDEN */
 /* forward declaration as workaround for time.h */
 struct timespec;
+
+/* Convert a POSIX clock (cast to int) to a sys_clock identifier */
+int sys_clock_from_clockid(int clock_id);
 /** @endcond INTERNAL_HIDDEN */
 
 /**

lib/os/clock.c

@@ -50,6 +50,22 @@ static void timespec_from_ticks(uint64_t ticks, struct timespec *ts)
 	};
 }
 
+int sys_clock_from_clockid(int clock_id)
+{
+	switch (clock_id) {
+#if defined(CLOCK_REALTIME) || defined(_POSIX_C_SOURCE)
+	case (int)CLOCK_REALTIME:
+		return SYS_CLOCK_REALTIME;
+#endif
+#if defined(CLOCK_MONOTONIC) || defined(_POSIX_MONOTONIC_CLOCK)
+	case (int)CLOCK_MONOTONIC:
+		return SYS_CLOCK_MONOTONIC;
+#endif
+	default:
+		return -EINVAL;
+	}
+}
+
 int sys_clock_gettime(int clock_id, struct timespec *ts)
 {
 	if (!is_valid_clock_id(clock_id)) {

lib/posix/options/clock.c

@@ -18,7 +18,7 @@ int clock_gettime(clockid_t clock_id, struct timespec *ts)
 {
 	int ret;
 
-	ret = sys_clock_gettime((int)clock_id, ts);
+	ret = sys_clock_gettime(sys_clock_from_clockid((int)clock_id), ts);
 	if (ret < 0) {
 		errno = -ret;
 		return -1;
@@ -61,7 +61,7 @@ int clock_settime(clockid_t clock_id, const struct timespec *tp)
 {
 	int ret;
 
-	ret = sys_clock_settime((int)clock_id, tp);
+	ret = sys_clock_settime(sys_clock_from_clockid((int)clock_id), tp);
 	if (ret < 0) {
 		errno = -ret;
 		return -1;

lib/posix/options/clock_selection.c

@@ -26,7 +26,7 @@ int clock_nanosleep(clockid_t clock_id, int flags, const struct timespec *rqtp,
 		return -1;
 	}
 
-	ret = sys_clock_nanosleep((int)clock_id, flags, rqtp, rmtp);
+	ret = sys_clock_nanosleep(sys_clock_from_clockid((int)clock_id), flags, rqtp, rmtp);
 	if (ret < 0) {
 		errno = -ret;
 		return -1;

lib/posix/options/timespec_to_timeout.c

@@ -17,7 +17,7 @@ uint32_t timespec_to_timeoutms(int clock_id, const struct timespec *abstime)
 {
 	struct timespec curtime;
 
-	if (sys_clock_gettime(clock_id, &curtime) < 0) {
+	if (sys_clock_gettime(sys_clock_from_clockid(clock_id), &curtime) < 0) {
 		return 0;
 	}