mman(5) [hpux man page]

mman(5) 							File Formats Manual							   mman(5)

NAME

       mman - memory mapping definitions

SYNOPSIS

DESCRIPTION

       The header defines the following symbolic constants for use with the function:

	      No further special treatment.
	      Expect random page references.
	      Expect sequential page references.
	      Will need these pages.
	      Will not need these pages.
	      Ensure that resources are reserved.

       The following symbolic constants are defined for use with the and functions:

	      Region can be read.
	      Region can be written.
	      Region can be executed.
	      Region cannot be accessed.

       The following symbolic constants are defined for use with the function:

	      Map a file.
	      Map an unnamed memory region.
	      Place region at implementation-computed address.
	      Place region at specified address.
	      Share changes made to mapped region.
	      Changes to mapped region are private to a process.

       The following symbolic constants are defined for use with the function:

	      Perform synchronous writes.
	      Perform asynchronous writes.
	      Invalidate cached pages.

       The following symbolic constants are defined for use with the and functions:

	      Create semaphore in locked state.
	      Create semaphore in unlocked state.
	      Do not wait if semaphore is locked.
	      Do not unlock if semaphore has no waiters.

       The is defined for use with the and functions.

SEE ALSO

       mmap(2), munmap(2), mprotect(2), msync(2), madvise(2), msem_init(2), msem_remove(2), msem_lock(2), msem_unlock(2).

																	   mman(5)

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)