sem_trywait

Synopsis

#include <semaphore.h>

int sem_trywait(sem_t *sem);

Status

Implemented

Conformance

IEEE Std 1003.1-2024

Description

The sem_trywait() function shall lock the semaphore referenced by sem only if it can be locked without delay, that is if its value is greater than zero. The call never blocks.

Both named and unnamed semaphores are accepted.

Return value

Upon successful completion, sem_trywait() shall return 0 with the semaphore locked. Otherwise it shall return -1, the semaphore state shall be unchanged, and errno shall be set to indicate the error.

Errors

This function shall fail if:

• EAGAIN - the semaphore was already locked, so it cannot be locked without delay,

• EINVAL - sem is a null pointer or does not refer to a valid semaphore,

• EBADF - the named semaphore has been closed or removed.

POSIX deviations

No POSIX deviations discovered.