sem_getvalue(3) — Справочная страница Linux

sem_getvalue(3)         Library Functions Manual         sem_getvalue(3)

ИМЯ

       sem_getvalue - get the value of a semaphore

БИБЛИОТЕКА

       POSIX threads library (libpthread, -lpthread)

СИНТАКСИС

       #include <semaphore.h>

       int sem_getvalue(sem_t *restrict sem, int *restrict sval);

ОПИСАНИЕ

       sem_getvalue() places the current value of the semaphore pointed
       to sem into the integer pointed to by sval.

       If one or more processes or threads are blocked waiting to lock
       the semaphore with sem_wait(3), POSIX.1 permits two possibilities
       for the value returned in sval: either 0 is returned; or a
       negative number whose absolute value is the count of the number
       of processes and threads currently blocked in sem_wait(3).  Linux
       adopts the former behavior.

ЗНАЧЕНИЕ ВОЗВРАТА

       sem_getvalue() returns 0 on success; on error, -1 is returned and
       errno is set to indicate the error.

ОШИБКИ

       EINVAL sem is not a valid semaphore.  (The glibc implementation
              currently does not check whether sem is valid.)

АТРИБУТЫ

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                           │ Attribute     │ Value   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ sem_getvalue()                      │ Thread safety │ MT-Safe │
       └─────────────────────────────────────┴───────────────┴─────────┘

СТАНДАРТЫ

       POSIX.1-2008.

ИСТОРИЯ

       POSIX.1-2001.

ПРИМЕЧАНИЯ

       The value of the semaphore may already have changed by the time
       sem_getvalue() returns.

СМОТРИТЕ ТАКЖЕ

       sem_post(3), sem_wait(3), sem_overview(7)

КОЛОФОН

       This page is part of the man-pages (Linux kernel and C library
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       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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Linux man-pages 6.9.1          2024-05-02                sem_getvalue(3)

Страницы, которые ссылаются на эту страницу: sem_close(3), sem_open(3), sem_post(3), sem_unlink(3), sem_wait(3), sem_overview(7)