MPI_File_set_size(3)MPI_File_set_size(3)NAMEMPI_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)
DESCRIPTIONMPI_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.
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MPI_File_set_size(3)MPI_File_set_size(3)
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 ALSOMPI_File_open(3), MPI_File_preallocate(3), MPI_IO(3)
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