Implement nanosleep per https://pubs.opengroup.org/onlinepubs/009695399/basedefs/time.h.html

[rtenneti]

Summary

Tested:
Limited unit test: This makes a call and checks that no error was
returned, but we currently don't have the ability to ensure that
time has elapsed as expected.

Co-authored-by: Jeff Bailey <[e-mail]>

[rtenneti]

Hi Siva,

Jeff and I worked on this. Please take a look. Thanks

[sivachandra]

libc/include/llvm-libc-types/CMakeLists.txt

40

Since this depends on time_t.h, we should add a DEPENDS .time_t.

libc/include/llvm-libc-types/struct_timespec.h

17

I think this definition is correct as per the POSIX spec. But, since we are passing structures of this shape to the Linux syscall, we should probably add a comment or TODO in src/time/nanosleep.cpp explaining why this definition is sufficient or incomplete.

libc/spec/stdc.td

17 ↗

(On Diff #460949)

Can you do the changes in the file separately as an obvious change?

libc/src/time/mktime.h

1 ↗

(On Diff #460949)

Can you make the changes in this file also separately?

libc/test/src/time/nanosleep_test.cpp

21

Call it SmokeTest may be? Also, move the above comment inside this test block.

[rtenneti]

Fixed comments.

[rtenneti]

Fixed comments.

libc/include/llvm-libc-types/CMakeLists.txt

 add_header(pthread_t HDR pthread_t.h DEPENDS .__thread_type)
 add_header(pthread_mutexattr_t HDR pthread_mutexattr_t.h)
 add_header(rlim_t HDR rlim_t.h)
 add_header(struct_rlimit HDR struct_rlimit.h DEPENDS .rlim_t)
 add_header(ssize_t HDR ssize_t.h)
 add_header(struct_dirent HDR struct_dirent.h DEPENDS .ino_t .off_t)
 add_header(struct_sigaction HDR struct_sigaction.h)
 add_header(struct_tm HDR struct_tm.h)
 add_header(struct_utsname HDR struct_utsname.h)
-add_header(struct_timespec HDR struct_timespec.h)
 add_header(thrd_start_t HDR thrd_start_t.h)
 add_header(thrd_t HDR thrd_t.h DEPENDS .__thread_type)
 add_header(time_t HDR time_t.h)
+add_header(struct_timespec HDR struct_timespec.h DEPENDS .time_t)
 add_header(tss_t HDR tss_t.h)
 add_header(tss_dtor_t HDR tss_dtor_t.h)
 add_header(__atexithandler_t HDR __atexithandler_t.h)

libc/include/llvm-libc-types/struct_timespec.h

 //===-- Definition of struct timespec -------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef __LLVM_LIBC_TYPES_TIMESPEC_H__
 #define __LLVM_LIBC_TYPES_TIMESPEC_H__
 
 #include <llvm-libc-types/time_t.h>
 
 struct timespec {
   time_t tv_sec;      /* Seconds.  */
+  /* TODO: BIG_ENDIAN may require padding. */
   long   tv_nsec;     /* Nanoseconds.  */
 };
 
 #endif // __LLVM_LIBC_TYPES_TIMESPEC_H__

libc/test/src/time/nanosleep_test.cpp

 #include <time.h>
 
 #include "src/time/nanosleep.h"
 #include "test/ErrnoSetterMatcher.h"
 #include "utils/UnitTest/Test.h"
 
 namespace cpp = __llvm_libc::cpp;
 
+TEST(LlvmLibcNanosleep, SmokeTest) {
   // TODO: When we have the code to read clocks, test that time has passed.
-
-TEST(LlvmLibcNanosleep, sleep) {
   using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
   errno = 0;
 
   struct timespec tim = {1, 500};
   struct timespec tim2 = {0, 0};
   int ret = __llvm_libc::nanosleep(&tim, &tim2);
   ASSERT_EQ(errno, 0);
   ASSERT_EQ(ret, 0);
 }