lib: libc: common: provide a common clock() implementation #57800

cfriedt · 2023-05-11T15:38:32Z

The clock() function was originally part of ISO C89 and it is also a POSIX extension of the C standard.

Both newlib and picolibc have implementations of clock() that reference the POSIX times() function. However, POSIX is optional in Zephyr while C is non-optional. Due to this, the newlib and picolibc implementations inadvertantly cause a layering violation that would otherwise not exist on full POSIX operating systems like Linux or BSD.

Provide a simple implementation here that is independent of POSIX.

Fixes #51978

Compliance issue is a false positive

lib/libc/common/source/time/clock.c

lib/libc/common/Kconfig

lib/libc/minimal/include/time.h

lib/libc/common/source/time/clock.c

lib/libc/Kconfig

cfriedt · 2023-05-11T19:07:39Z

We'll see how this does in CI. @evgeniy-paltsev - I can add something here for ARC if you like as well.

keith-packard

Note that newlib and picolibc use unsigned long for _CLOCK_T_.

lib/libc/minimal/include/sys/_types.h

lib/libc/minimal/include/time.h

cfriedt · 2023-05-13T14:07:02Z

used uint64_t for clock_t in the minimal libc
ensure clock() always succeeds in the common libc by rolling over (clock_t)-1
check for (clock_t)-1 (failure) in test

Note: in the future it may be possible for clock() to fail if there is an underlying hardware or software issue.

keith-packard · 2023-05-13T14:52:36Z

Coding guidelines check is currently failing due to this patch defining clock. Compliance checks are failing due to adding the clock_t typedef. Both are spurious.

cfriedt · 2023-08-05T13:18:29Z

Doing a minor respin. I might as well add the POSIX bits as well, it's so simple to implement. Until we have k_clock_get() and friends though, the per-process and per-thread clock ids will not work, so tests using those should be skipped.

keith-packard

This is looking good; there's an unresolved comment in test_clock about getting a reasonable delay like you used in test_times. And, of course, the compliance checker has 'some issues'. Seems like it's almost ready ?

cfriedt

Some comments..

lib/libc/common/source/time/clock.c

lib/posix/clock.c

cfriedt · 2023-08-06T09:50:45Z

tests/lib/c_lib/src/main.c

+	clock_t now;
+
+	then = clock();
+	k_sleep(K_TICKS(1));


Yep - I'll change that shortly.

cfriedt · 2023-08-07T14:34:40Z

Note: this is back in draft, so no need to review yet.

github-actions · 2023-10-07T00:29:41Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

The `clock()` function was originally part of ISO C89, and it is also a POSIX extension of the C standard. Both newlib and picolibc have implementations of `clock()` that reference the POSIX `times()` function. However, POSIX is optional in Zephyr while C is non-optional. Due to this, the newlib and picolibc implementations cause a layering violation. Provide a simple implementation here that is independent of POSIX to avoid the layering violation. Signed-off-by: Christopher Friedt <cfriedt@meta.com>

Add a test for the ISO C `clock()` function, which has been present since C89. Signed-off-by: Christopher Friedt <cfriedt@meta.com>

github-actions · 2024-01-01T00:30:31Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

github-actions · 2024-03-02T00:29:32Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

github-actions · 2024-05-17T00:29:49Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

github-actions · 2024-07-17T00:30:02Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

cfriedt requested a review from nashif as a code owner May 11, 2023 15:38

cfriedt requested review from stephanosio, galak and keith-packard May 11, 2023 15:38

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cfriedt force-pushed the common-libc-clock-implementation branch from 1e957e5 to 8163da8 Compare May 11, 2023 15:53

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include: posix: add sig_atomic_t type to signal.h #57804

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tests: lib: c_lib: add a test for clock()

52d7a66

Add a test for the ISO C `clock()` function, which has been present since C89. Signed-off-by: Christopher Friedt <cfriedt@meta.com>

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lib: libc: common: provide a common clock() implementation #57800

lib: libc: common: provide a common clock() implementation #57800

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lib: libc: common: provide a common clock() implementation #57800

lib: libc: common: provide a common clock() implementation #57800

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