SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_File_set_size(MPI_File fh, MPI_Offset size)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_FILE_SET_SIZE(FH, SIZE, IERROR)
               INTEGER FH, IERROR
               INTEGER(KIND=MPI_OFFSET_KIND)   SIZE

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_File_set_size(fh, size, ierror)
               TYPE(MPI_File), INTENT(IN) :: fh
               INTEGER(KIND=MPI_OFFSET_KIND), INTENT(IN) :: size
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       • fh: File handle (handle).

       • size: Size to truncate or expand file (integer).

OUTPUT PARAMETER

       • ierror: Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_set_size  resizes  the  file  associated  with  the  file  handle  fh,  truncating UNIX files as
       necessary. MPI_File_set_size is collective; all processes in the group must  pass  identical  values  for
       size.

       When  using MPI_File_set_size on a UNIX file, if size is larger than the current file size, the file size
       becomes size. If size is smaller than the current file size,  the  file  is  truncated  at  the  position
       defined  by  size  (from the beginning of the file and measured in bytes). Regions of the file which have
       been previously written are unaffected.

       MPI_File_set_size does not affect the individual file pointers or the shared file pointer.

       Note  that  the  actual  amount  of  storage  space  cannot  be  allocated  by   MPI_File_set_size.   Use
       MPI_File_preallocate to accomplish this.

       It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified when the file was opened.

ERRORS

       Almost  all  MPI  routines  return  an  error  value; C routines as the return result of the function and
       Fortran routines in the last argument.

       Before the error value is returned, the current MPI  error  handler  associated  with  the  communication
       object  (e.g.,  communicator, window, file) is called.  If no communication object is associated with the
       MPI call, then the call is considered attached to MPI_COMM_SELF and will call the  associated  MPI  error
       handler.   When   MPI_COMM_SELF   is   not  initialized  (i.e.,  before  MPI_Init/MPI_Init_thread,  after
       MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial  error  handler.
       The  initial  error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using
       the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info  key  to  MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.   If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
       error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is  called  for  all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called  on  a  communicator,  it  acts  as if MPI_Abort was called on that communicator. If called on a
         window or file, acts as if MPI_Abort was called on a communicator containing the group of processes  in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       See the Error Handling section of the MPI-3.1 standard for more information.

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                              MPI_FILE_SET_SIZE(3)