munmap()

Unmap previously mapped addresses

Synopsis:

#include <sys/mman.h>

int munmap( void * addr,
            size_t len );

Arguments:

addr

The beginning of the range of addresses that you want to unmap.

len

The length of the range of addresses, in bytes.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The munmap() function removes any mappings for pages in the address range starting at addr and continuing for len bytes, rounded up to the next multiple of the page size. Subsequent references to these pages cause a SIGSEGV signal to be set on the process.

If there are no mappings in the specified address range, then munmap() has no effect.

Returns:

0

Success.

-1

Failure; errno is set.

Errors:

EINVAL

The addresses in the specified range are outside the range allowed for the address space of a process.

ENOMEM

The memory manager fails to allocate memory to handle a user's munmap() request. This allocation of memory is necessary for internal structures to represent the new state of mapped memory.

ENOSYS

The function munmap() isn't supported by this implementation.

Classification:

POSIX 1003.1 MF|SHM|TYM

Caveats:

Currently, you can't munmap() just a part of an area mapped with mmap().

See also:

mmap(), mprotect(), munmap_flags(), shm_open(), shm_unlink()

“Initializing allocated memory” in the Interprocess Communication (IPC) chapter of the System Architecture guide