Go one step further. Your error code doesn't mean anything by itself. But, you can feed that code to MPI_Error_string and get something more human readable. I have this function in every MPI-IO code I write:
static void handle_error(int errcode, char *str)
{
char msg[MPI_MAX_ERROR_STRING];
int resultlen;
MPI_Error_string(errcode, msg, &resultlen);
fprintf(stderr, "%s: %s\n", str, msg);
MPI_Abort(MPI_COMM_WORLD, 1);
}
And then define this macro:
#define MPI_CHECK(fn) { int errcode; errcode = (fn);\
if (errcode != MPI_SUCCESS) handle_error (errcode, #fn ); }
So I can call routines like this:
CHECK(MPI_File_open(comm, "testfile",
MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &file) );