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.

       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)


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