added exclusive flag when opening output file to make sure there is no

corruption if the same output name is used twice for some reason


git-svn-id: https://svn.mcs.anl.gov/repos/darshan/trunk@152 3b7491f3-a168-0410-bf4b-c445ed680a29

lib/darshan-mpi-io.c

@@ -1398,7 +1398,7 @@ static int cp_log_write(struct darshan_job_runtime* final_job, int rank,
     MPI_Type_commit(&mtype); 
 
     ret = PMPI_File_open(MPI_COMM_WORLD, logfile_name, MPI_MODE_CREATE |
-        MPI_MODE_WRONLY, MPI_INFO_NULL, &fh);
+        MPI_MODE_WRONLY | MPI_MODE_EXCL, MPI_INFO_NULL, &fh);
     if(ret != MPI_SUCCESS)
     {
         /* TODO: keep this print or not? */