MirBSD manpage: sem_init(3)

SEM_INIT(3)                BSD Programmer's Manual                 SEM_INIT(3)

NAME

     sem_init - initialize an unnamed semaphore

SYNOPSIS

     #include <semaphore.h>

     int
     sem_init(sem_t *sem, int pshared, unsigned int value);

DESCRIPTION

     The sem_init() function initializes the unnamed semaphore pointed to by
     sem to have the value value. A non-zero value for pshared specifies a
     shared semaphore that can be used by multiple processes, which this im-
     plementation is not capable of.

     Following a successful call to sem_init(), sem can be used as an argument
     in subsequent calls to sem_wait, sem_trywait, sem_post, and sem_destroy.
     sem is no longer valid after a successful call to sem_destroy.

RETURN VALUES

     The sem_init() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     sem_init() will fail if:

     [EINVAL]      value exceeds SEM_VALUE_MAX.

     [ENOSPC]      Memory allocation error.

     [EPERM]       Unable to initialize a shared semaphore.

SEE ALSO

     sem_destroy(3), sem_getvalue(3), sem_open(3), sem_post(3), sem_wait(3)

STANDARDS

     sem_init() conforms to ISO/IEC 9945-1:1996 ("POSIX.1").

     This implementation does not support shared semaphores, and reports this
     fact by setting errno to EPERM. This is perhaps a stretch of the inten-
     tion of POSIX, but is compliant, with the caveat that sem_init() always
     reports a permissions error when an attempt to create a shared semaphore
     is made.

MirBSD #10-current            February 15, 2000                              1