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MS_$UNMAP                         Domain/OS                          MS_$UNMAP


NAME
     ms_$unmap - unmap an object

SYNOPSIS (C)
     #include <apollo/base.h>
     #include <apollo/ms.h>

     void ms_$unmap(
          void *&address,
          unsigned long int &length,
          status_$t *status)

SYNOPSIS (Pascal)
     %include '/sys/ins/base.ins.pas';
     %include '/sys/ins/ms.ins.pas';

     procedure ms_$unmap(
          in address: univ_ptr;
          in length: linteger;
          out status: status_$t);

SYNOPSIS (FORTRAN)
     %include '/sys/ins/base.ins.ftn'
     %include '/sys/ins/ms.ins.ftn'

           integer*4 status, length

           integer*4 address, dummy
           pointer /address/ dummy

           call ms_$unmap(address, length, status)

DESCRIPTION
     This call unmaps the portion of an object mapped at address.  When a pro-
     cess unmaps the first portion of an object it has mapped, it also
     releases all locks it holds on the object.

     address
          A pointer to the portion of the mapped object to unmap.

     length
          The number of bytes mapped at address to be written to the file sys-
          tem object.  The length argument should usually be set equal to the
          number of bytes actually mapped by the call that returned the
          pointer supplied in address.  Any data in the mapped portion beyond
          length bytes from address cannot be recovered after the call to
          ms_$unmap.

     status
          The completion status.  If the pointer passed in address does not
          point to a mapped object, ms_$unmap will return with ms_$not_mapped
          in status.

NOTES
     If the mapped object resides on a remote volume, changes made in the
     mapped portion will have been written back to the original object by the
     time ms_$unmap returns.  If the mapped object resides on a local volume,
     it may be wise to call ms_$fw_file or ms_$fw_partial before unmapping the
     object to ensure that the object is stored safely in the event of a sys-
     tem crash.

     If a process has extended a mapped object, the object's length attribute
     may not be accurate when unmapped.  Call ms_$truncate before ms_$unmap if
     an extended object's length attribute is important.

SEE ALSO
     ms_$addmap, ms_$crmapl, ms_$crtemp, ms_$mapl, ms_$mapl_stream,
     ms_$mk_permanent, ms_$mk_temporary, ms_$remap.