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SEM_POST(3) Library Functions Manual SEM_POST(3) NAME sem_post -- increment (unlock) a semaphore LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <semaphore.h> int sem_post(sem_t *sem); DESCRIPTION The sem_post() function increments (unlocks) the semaphore pointed to by sem. If there are threads blocked on the semaphore when sem_post() is called, then the highest priority thread that has been blocked the longest on the semaphore will be allowed to return from sem_wait(). The sem_post() function is signal-reentrant and may be called within signal handlers. RETURN VALUES The sem_post() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi- cate the error. ERRORS The sem_post() function will fail if: [EINVAL] The sem argument points to an invalid semaphore. [EOVERFLOW] The semaphore value would exceed SEM_VALUE_MAX. SEE ALSO sem_getvalue(3), sem_trywait(3), sem_wait(3) STANDARDS The sem_post() function conforms to ISO/IEC 9945-1:1996 ("POSIX.1"). FreeBSD 15.0 January 28, 2015 SEM_POST(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS
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