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libc: unify semantic of sleep functions 

sleep(), usleep(), and nanosleep() now return immediately on
zero-timeout. Also, non-zero timeouts sleep at least 1 ms (the current
minimal timeout in libc), which compensates rounding errors.

Issue #3550
This commit is contained in:
Christian Helmuth 2020-02-05 10:59:32 +01:00 committed by Norman Feske
parent ee7a77643e
commit 3d4bed3374
1 changed files with 20 additions and 5 deletions
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25
repos/libports/src/lib/libc/sleep.cc
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@ -53,10 +53,15 @@ static void millisleep(Genode::uint64_t timeout_ms)
extern "C" __attribute__((weak))
int nanosleep(const struct timespec *req, struct timespec *rem)
{
/* XXX nanosleep({0,0}) may yield but is not required to do so */
if (!req->tv_sec && !req->tv_nsec) return 0;
Genode::uint64_t sleep_ms = (Genode::uint64_t)req->tv_sec*1000;
if (req->tv_nsec)
sleep_ms += req->tv_nsec / 1000000;
millisleep(sleep_ms);
/* sleep at least 1 ms */
millisleep(sleep_ms ? : 1);
if (rem)
*rem = { 0, 0 };
@ -101,8 +106,13 @@ int __sys_clock_nanosleep(clockid_t clock_id, int flags,
extern "C" __attribute__((weak))
unsigned int sleep(unsigned int seconds)
{
Genode::uint64_t const sleep_ms = 1000 * (Genode::uint64_t)seconds;
millisleep(sleep_ms);
/* XXX sleep(0) may yield but is not required to do so */
if (!seconds) return 0;
Libc::uint64_t const sleep_ms = (Libc::uint64_t)seconds*1000;
/* sleep at least 1 ms */
millisleep(sleep_ms ? : 1);
return 0;
}
@ -110,8 +120,13 @@ unsigned int sleep(unsigned int seconds)
extern "C" __attribute__((weak))
int usleep(useconds_t useconds)
{
if (useconds)
millisleep(useconds / 1000);
/* XXX usleep(0) may yield but is not required to do so */
if (!useconds) return 0;
Libc::uint64_t const sleep_ms = (Libc::uint64_t)useconds/1000;
/* sleep at least 1 ms */
millisleep(sleep_ms ? : 1);
return 0;
}