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libs/ck-libs/ampi/romio/adio/ad_bgl/ad_bgl_getsh.c

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/* ---------------------------------------------------------------- */
/* (C)Copyright IBM Corp.  2007, 2008                               */
/* ---------------------------------------------------------------- */
/* -*- Mode: C; c-basic-offset:4 ; -*- */
/* 
 *   Copyright (C) 1997 University of Chicago. 
 *   See COPYRIGHT notice in top-level directory.
 */

#include "ad_bgl.h"

/* returns the current location of the shared_fp in terms of the
   no. of etypes relative to the current view, and also increments the
   shared_fp by the number of etypes to be accessed (incr) in the read
   or write following this function. */

void ADIOI_BGL_Get_shared_fp(ADIO_File fd, int incr, ADIO_Offset *shared_fp, 
             int *error_code)
{
    ADIO_Offset new_fp;
    int err;
    MPI_Comm dupcommself;
    static char myname[] = "ADIOI_BGL_GET_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;
    *shared_fp = 0;
    ADIOI_WRITE_LOCK(fd->shared_fp_fd, 0, SEEK_SET, sizeof(ADIO_Offset));
    err = read(fd->shared_fp_fd->fd_sys, shared_fp, sizeof(ADIO_Offset));
        /* if the file is empty, the above read may return error
           (reading beyond end of file). In that case, shared_fp = 0, 
           set above, is the correct value. */
    }
    else {
    ADIOI_WRITE_LOCK(fd->shared_fp_fd, 0, SEEK_SET, sizeof(ADIO_Offset));

    err = lseek(fd->shared_fp_fd->fd_sys, 0, SEEK_SET);
    if (err == 0) {
        err = read(fd->shared_fp_fd->fd_sys, shared_fp,
               sizeof(ADIO_Offset));
    }
    if (err == -1) {
        ADIOI_UNLOCK(fd->shared_fp_fd, 0, SEEK_SET, sizeof(ADIO_Offset));
        *error_code = MPIO_Err_create_code(MPI_SUCCESS,
                           MPIR_ERR_RECOVERABLE, myname,
                           __LINE__, MPI_ERR_IO, "**io",
                           "**io %s", strerror(errno));
        return;
    }
    }

    new_fp = *shared_fp + incr;

    err = lseek(fd->shared_fp_fd->fd_sys, 0, SEEK_SET);
    if (err == 0) {
    err = write(fd->shared_fp_fd->fd_sys, &new_fp, sizeof(ADIO_Offset));
    }
    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;
}

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