Segmentation fault while using MPI_File_open - mpi

Question

I'm trying to read from a file for an MPI application. The cluster has 4 nodes with 12 cores in each node. I have tried running a basic program to compute rank and that works. When I added MPI_File_open it throws an exception at runtime
BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES = EXIT CODE: 139
The cluster has MPICH2 installed and has a Network File System. I check MPI_File_open with different parameters like ReadOnly mode, MPI_COMM_WORLD etc.
Can I use MPI_File_open with Network File System?
int main(int argc, char* argv[])
{
int myrank = 0;
int nprocs = 0;
int i = 0;
MPI_Comm icomm = MPI_COMM_WORLD;
MPI_Status status;
MPI_Info info;
MPI_File *fh = NULL;
int error = 0;
MPI_Init(&argc, &argv);
MPI_Barrier(MPI_COMM_WORLD); // Wait for all processor to start
MPI_Comm_size(MPI_COMM_WORLD, &nprocs); // Get number of processes
MPI_Comm_rank(MPI_COMM_WORLD, &myrank); // Get own rank
usleep(myrank*100000);
if ( myrank == 1 || myrank == 0 )
printf("Hello from %d\r\n", myrank);
if (myrank == 0)
{
error = MPI_File_open( MPI_COMM_SELF, "lw1.wei", MPI_MODE_UNIQUE_OPEN,
MPI_INFO_NULL, fh);
if ( error )
{
printf("Error in opening file\r\n");
}
else
{
printf("File successfully opened\r\n");
}
MPI_File_close(fh);
}
MPI_Barrier(MPI_COMM_WORLD); //! Wait for all the processors to end
MPI_Finalize();
if ( myrank == 0 )
{
printf("Number of Processes %d\n\r", nprocs);
}
return 0;
}

Answer 1

You forgot to allocate an MPI_File object before opening the file. You may either change this line:
MPI_File *fh = NULL;
into:
MPI_File fh;
and open file by giving fh's address to MPI_File_open(..., &fh). Or you may simply allocate memory from heap using malloc().
MPI_File *fh = malloc(sizeof(MPI_File));