Unmaps a mapped region. This function is reentrant.

    Format

      #include  <mman.h>

      int munmap  (void *addr, size_t len);

1 - Arguments

 addr

    The address of the region that you want to unmap.

 len

    The length, in bytes, of that region the you want to unmap.

2 - Description

    The munmap function unmaps a mapped file or shared memory region.

    The addr and len arguments specify the address and length, in
    bytes, respectively, of the region to be unmapped.

    The len argument must be a multiple of the page size as returned
    by sysconf(_SC_PAGE_SIZE); otherwise, the length of the region is
    rounded up to the next multiple of the page size.

    The result of using an address that lies in an unmapped region
    and not in any subsequently mapped region is undefined.

    See also sysconf.

3 - Return Values

    0                  Indicates success.
    -1                 Indicates an error; errno is set to one of the
                       following values:

                       o  ENIVAL - The addr argument is not a
                          multiple of the page size as returned by
                          sysconf(_SC_PAGE_SIZE).

                       o  EFAULT - The range [addr, addr + len]
                          includes an invalid address.