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posix: Map CLOCK_REALTIME and CLOCK_MONOTONIC to Zephyr clock IDs #93075

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Merged
merged 1 commit into from
Jul 19, 2025
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posix: Map CLOCK_REALTIME and CLOCK_MONOTONIC to Zephyr clock IDs #93075

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3 changes: 3 additions & 0 deletions include/zephyr/sys/clock.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */

/**
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16 changes: 16 additions & 0 deletions lib/os/clock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Comment on lines +56 to +63
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hey are this right? traced a regression in a downstream application down to this neither of the two options are complied in, is this missing an #include <zephyr/posix/time.h> possibly?

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You’re right , but I have an inquiry: which libc are you using, and does it actually define CLOCK_REALTIME and CLOCK_MONOTONIC?
From my side, I see the include path in lib/os/clock.c as:

lib/os/clock.c → zephyr/sys/timeutil.h → zephyr/posix/time.h → libc <time.h>

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Just the picolibc one that ships with Zephyr SDK, building on an STM32 not doing really anything special.

Looking at clock.c.i on my build I see zephyr/include/zephyr/sys/timeutil.h but no zephyr/posix/time.h

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@cfriedt cfriedt Sep 17, 2025 •
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@fabiobaltieri - can you provide a repro recipe?

We shouldn't necessarily need to include posix/time.h if the libc time.h is included assuming the libc time.h defines either of these two.

It might require a #define _POSIX_C_SOURCE before including time.h though.

Also, please see if #95226 helps.

If there is a corner case where we need to define CLOCK_REALTIME or CLOCK_MONOTONIC, we may be able to do that locally within this file.

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Hey Chris, yeah looks like #95226 fixes it, let's get on with it. Thanks!

default:
return -EINVAL;
}
}

int sys_clock_gettime(int clock_id, struct timespec *ts)
{
if (!is_valid_clock_id(clock_id)) {
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4 changes: 2 additions & 2 deletions lib/posix/options/clock.c
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Expand Up @@ -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;
Expand Down Expand Up @@ -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;
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2 changes: 1 addition & 1 deletion lib/posix/options/clock_selection.c
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Expand Up @@ -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;
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2 changes: 1 addition & 1 deletion lib/posix/options/timespec_to_timeout.c
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Expand Up @@ -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;
}

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