MPI_File_set_size(3)

NAME
     MPI_File_set_size - Sets the file size

SYNOPSIS
     C:

          #include "mpi.h"

          int MPI_File_set_size(MPI_File fh, MPI_Offset size)


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

          INTEGER fh, ierror
          INTEGER(KIND=MPI_OFFSET_KIND) size

          CALL MPI_FILE_SET_SIZE(fh, size, ierror)


DESCRIPTION
     MPI_File_set_size resizes the file associated with the file handle, fh.
     This routine accepts the following arguments:

     fh        Specifies the file handle (handle).

     size      Specifies the size to which to truncate or expand the file
               (nonnegative integer). Size is measured in bytes from the
               beginning of the file.

     ierror    Specifies the return code value for successful completion,
               which is in MPI_SUCCESS.  MPI_SUCCESS is defined in the mpif.h
               file.

     MPI_File_set_size is collective; all processes in the group must pass
     identical values for size.

     If size is smaller than the current file size, the file is truncated at
     the position defined by size.  The implementation is free to deallocate
     file blocks located beyond this position.

     If size is larger than the current file size, the file size becomes size.
     Regions of the file that have been previously written are unaffected.
     The values of data in the new regions in the file (those locations with
     displacements between old file size and size) are undefined.  It is
     implementation dependent whether the MPI_File_set_size routine allocates
     file space.  Use MPI_File_preallocate to force file space to be reserved.

     MPI_File_set_size does not affect the individual file pointers or the
     shared file pointer.  If MPI_MODE_SEQUENTIAL mode was specified when the
     file was opened, you must not call this routine.
     It is possible for the file pointers to point beyond the end of file
     after a MPI_File_set_size operation truncates a file. This is legal, and
     equivalent to seeking beyond the current end of file.

     All nonblocking requests and split collective operations on fh must be
     completed before MPI_File_set_size is called. Otherwise, calling
     MPI_File_set_size is erroneous.  As far as consistency semantics are
     concerned, MPI_File_set_size is a write operation that conflicts with
     operations that access bytes at displacements between the old and new
     file sizes.

   Notes for Fortran
     All MPI objects (for example, MPI_Datatype, MPI_Comm, MPI_File) are of
     type INTEGER.

SEE ALSO
     MPI_File_open(3), MPI_File_preallocate(3), MPI_IO(3)