munmap

SYNOPSIS
       #include <sys/mman.h>

       int munmap(void *addr, size_t len);


DESCRIPTION
       The  munmap() function shall remove any mappings for those entire pages
       containing any part of the address space of  the  process  starting  at
       addr  and  continuing for len bytes.  Further references to these pages
       shall result in the generation of a SIGSEGV signal to the  process.  If
       there are no mappings in the specified address range, then munmap() has
       no effect.

       The implementation shall require that addr be a multiple  of  the  page
       size {PAGESIZE}.

       If  a mapping to be removed was private, any modifications made in this
       address range shall be discarded.

       Any memory locks (see mlock() and mlockall()  )  associated  with  this
       address  range  shall  be  removed,  as  if  by  an appropriate call to
       munlock().

       If a mapping removed from a typed memory object causes the  correspond-
       ing  address range of the memory pool to be inaccessible by any process
       in the system except through allocatable mappings (that is, mappings of
       typed  memory  objects  opened with the POSIX_TYPED_MEM_MAP_ALLOCATABLE
       flag), then that range of the memory pool shall become deallocated  and
       may   become  available  to  satisfy  future  typed  memory  allocation
       requests.

       A  mapping  removed  from  a  typed  memory  object  opened  with   the
       POSIX_TYPED_MEM_MAP_ALLOCATABLE  flag  shall  not affect in any way the
       availability of that typed memory for allocation.

       The behavior of this function is unspecified if  the  mapping  was  not
       established by a call to mmap().

RETURN VALUE
       Upon  successful  completion,  munmap()  shall  return 0; otherwise, it
       shall return -1 and set errno to indicate the error.

ERRORS
       The munmap() function shall fail if:

       EINVAL Addresses in the range [addr,addr+len)  are  outside  the  valid
              range for the address space of a process.

       EINVAL The len argument is 0.

       EINVAL The addr argument is not a multiple of the page size as returned
              by sysconf().

       The  munmap() function corresponds to SVR4, just as the mmap() function
       does.

       It is possible that an application has applied process  memory  locking
       to a region that contains shared memory. If this has occurred, the mun-
       map() call ignores those locks and, if necessary, causes those locks to
       be removed.

FUTURE DIRECTIONS
       None.

SEE ALSO
       mlock()  ,  mlockall()  , mmap() , posix_typed_mem_open() , sysconf() ,
       the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,   <signal.h>,
       <sys/mman.h>

COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                            MUNMAP(P)