osf1 man page for msem_init

msem_init(3)						     Library Functions Manual						      msem_init(3)

NAME
       msem_init - Initializes a semaphore in a mapped file or shared memory region

LIBRARY
       Standard C Library (libc.a)

SYNOPSIS
       #include <sys/mman.h>
       msemaphore *msem_init (	    msemaphore *sem,	  int initial_value );

PARAMETERS
       Points to an msemaphore structure in which the state of the semaphore is stored.  Determines whether the semaphore is locked or unlocked at
       allocation.

DESCRIPTION
       The msem_init() function allocates a new binary semaphore and initializes the state of the new semaphore.

       If the initial_value parameter is MSEM_LOCKED, the new semaphore is initialized in the locked state.  If  the  initial_value  parameter	is
       MSEM_UNLOCKED, the new semaphore is initialized in the unlocked state.

       The  msemaphore	structure  is located within a mapped file or shared memory region created by a successful call to the mmap() function and
       having both read and write access.

       If a semaphore is created in a mapped file region, any reference by a process which has mapped the same file, using a (struct msemaphore *)
       pointer	which  resolves to the same file offset, is taken as a reference to the same semaphore.  If a semaphore is created in an anonymous
       shared memory region, any reference by a process which shares the same region, using a (struct msemaphore *) pointer which resolves to  the
       same offset from the start of the region, is taken as a reference to the same semaphore.

       Any previous semaphore state stored in the msemaphore structure is ignored and overwritten.

NOTES
       Trial use

RETURN VALUES
       Upon  successful completion, the msem_init() function returns a pointer to the initialized msemaphore structure.  On error, the msem_init()
       function returns null and sets errno to indicate the error.

ERRORS
       If the msem_init() function fails, errno may be set to one of the following values: The initial_value parameter is not valid.  A new  sema-
       phore could not be created.

RELATED INFORMATION
       Functions: mmap(2), msem_lock(3), msem_remove(3), msem_unlock(3) delim off

																      msem_init(3)