250. Querying File Parameters

MPI_FILE_GET_GROUP(fh, group)
IN fh	file handle (handle)
OUT group	group which opened the file (handle)

int MPI_File_get_group(MPI_File fh, MPI_Group *group)
MPI_FILE_GET_GROUP(FH, GROUP, IERROR)
INTEGER FH, GROUP, IERROR
MPI::Group MPI::File::Get_group() const

MPI_FILE_GET_GROUP returns a duplicate of the group of the communicator used to open the file associated with fh. The group is returned in group. The user is responsible for freeing group.

MPI_FILE_GET_AMODE(fh, amode)
IN fh	file handle (handle)
OUT amode	file access mode used to open the file (integer)

int MPI_File_get_amode(MPI_File fh, int *amode)
MPI_FILE_GET_AMODE(FH, AMODE, IERROR)
INTEGER FH, AMODE, IERROR
int MPI::File::Get_amode() const

MPI_FILE_GET_AMODE returns, in amode, the access mode of the file associated with fh.

Example In Fortran 77, decoding an amode bit vector will require a routine such as the following:

      SUBROUTINE BIT_QUERY(TEST_BIT, MAX_BIT, AMODE, BIT_FOUND) 
! 
!   TEST IF THE INPUT TEST_BIT IS SET IN THE INPUT AMODE 
!   IF SET, RETURN 1 IN BIT_FOUND, 0 OTHERWISE 
! 
      INTEGER TEST_BIT, AMODE, BIT_FOUND, CP_AMODE, HIFOUND 
      BIT_FOUND = 0 
      CP_AMODE = AMODE 
 100  CONTINUE 
      LBIT = 0 
      HIFOUND = 0 
      DO 20 L = MAX_BIT, 0, -1 
         MATCHER = 2**L 
         IF (CP_AMODE .GE. MATCHER .AND. HIFOUND .EQ. 0) THEN 
            HIFOUND = 1 
            LBIT = MATCHER 
            CP_AMODE = CP_AMODE - MATCHER 
         END IF 
  20  CONTINUE 
      IF (HIFOUND .EQ. 1 .AND. LBIT .EQ. TEST_BIT) BIT_FOUND = 1 
      IF (BIT_FOUND .EQ. 0 .AND. HIFOUND .EQ. 1 .AND. & 
          CP_AMODE .GT. 0) GO TO 100 
      END 

This routine could be called successively to decode amode, one bit at a time. For example, the following code fragment would check for MPI_MODE_RDONLY.

      CALL BIT_QUERY(MPI_MODE_RDONLY, 30, AMODE, BIT_FOUND) 
      IF (BIT_FOUND .EQ. 1) THEN 
         PRINT *, ' FOUND READ-ONLY BIT IN AMODE=', AMODE 
      ELSE 
         PRINT *, ' READ-ONLY BIT NOT FOUND IN AMODE=', AMODE 
      END IF