инициализировать безымянный семафор (initialize an unnamed semaphore)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
sem_init — initialize an unnamed semaphore
Синопсис (Synopsis)
#include <semaphore.h>
int sem_init(sem_t *sem, int pshared, unsigned value);
Описание (Description)
The sem_init() function shall initialize the unnamed semaphore
referred to by sem. The value of the initialized semaphore shall
be value. Following a successful call to sem_init(), the
semaphore may be used in subsequent calls to sem_wait(),
sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy().
This semaphore shall remain usable until the semaphore is
destroyed.
If the pshared argument has a non-zero value, then the semaphore
is shared between processes; in this case, any process that can
access the semaphore sem can use sem for performing sem_wait(),
sem_timedwait(), sem_trywait(), sem_post(), and sem_destroy()
operations.
If the pshared argument is zero, then the semaphore is shared
between threads of the process; any thread in this process can
use sem for performing sem_wait(), sem_timedwait(),
sem_trywait(), sem_post(), and sem_destroy() operations.
See Section 2.9.9, Synchronization Object Copies and Alternative
Mappings for further requirements.
Attempting to initialize an already initialized semaphore results
in undefined behavior.
Возвращаемое значение (Return value)
Upon successful completion, the sem_init() function shall
initialize the semaphore in sem and return 0. Otherwise, it shall
return -1 and set errno to indicate the error.
Ошибки (Error)
The sem_init() function shall fail if:
EINVAL The value argument exceeds {SEM_VALUE_MAX}.
ENOSPC A resource required to initialize the semaphore has been
exhausted, or the limit on semaphores ({SEM_NSEMS_MAX})
has been reached.
EPERM The process lacks appropriate privileges to initialize the
semaphore.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
sem_destroy(3p), sem_post(3p), sem_timedwait(3p), sem_trywait(3p)
The Base Definitions volume of POSIX.1‐2017, semaphore.h(0p)
