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. References to unmapped 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.
EINTR: The call was interrupted by a signal.
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.

Classification:

POSIX 1003.1 SHM|TYM

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes