/*
 * Copyright (C) by Argonne National Laboratory
 *     See COPYRIGHT in top-level directory
 */

#include "ad_nfs.h"

/* set the shared file pointer to "offset" etypes relative to the current
   view */

/*
This looks very similar to ADIOI_GEN_Set_shared_fp, except this
function avoids locking the file twice.  The generic version does

Write lock
ADIO_WriteContig
Unlock

For NFS, ADIOI_NFS_WriteContig does a lock before writing to disable
caching. To avoid the lock being called twice, this version for NFS does

Write lock
Lseek
Write
Unlock

*/

void ADIOI_NFS_Set_shared_fp(ADIO_File fd, ADIO_Offset offset, int *error_code)
{
    ssize_t err;
    MPI_Comm dupcommself;
    static char myname[] = "ADIOI_NFS_SET_SHARED_FP";

    if (fd->shared_fp_fd == ADIO_FILE_NULL) {
        MPI_Comm_dup(MPI_COMM_SELF, &dupcommself);
        fd->shared_fp_fd = ADIO_Open(MPI_COMM_SELF, dupcommself,
                                     fd->shared_fp_fname,
                                     fd->file_system, fd->fns,
                                     ADIO_CREATE | ADIO_RDWR | ADIO_DELETE_ON_CLOSE,
                                     0, MPI_BYTE, MPI_BYTE, MPI_INFO_NULL,
                                     ADIO_PERM_NULL, error_code);
    }

    if (*error_code != MPI_SUCCESS)
        return;

    ADIOI_WRITE_LOCK(fd->shared_fp_fd, 0, SEEK_SET, sizeof(ADIO_Offset));
#ifdef ADIOI_MPE_LOGGING
    MPE_Log_event(ADIOI_MPE_lseek_a, 0, NULL);
#endif
    lseek(fd->shared_fp_fd->fd_sys, 0, SEEK_SET);
#ifdef ADIOI_MPE_LOGGING
    MPE_Log_event(ADIOI_MPE_lseek_b, 0, NULL);
#endif
#ifdef ADIOI_MPE_LOGGING
    MPE_Log_event(ADIOI_MPE_write_a, 0, NULL);
#endif
    err = write(fd->shared_fp_fd->fd_sys, &offset, sizeof(ADIO_Offset));
#ifdef ADIOI_MPE_LOGGING
    MPE_Log_event(ADIOI_MPE_write_b, 0, NULL);
#endif
    ADIOI_UNLOCK(fd->shared_fp_fd, 0, SEEK_SET, sizeof(ADIO_Offset));

    if (err == -1) {
        *error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
                                           myname, __LINE__, MPI_ERR_IO,
                                           "**io", "**io %s", strerror(errno));
    } else
        *error_code = MPI_SUCCESS;
}
