fix issue 791: validate ncid for classic files

Author: wkliao

libdispatch/nclistmgr.c

@@ -88,6 +88,11 @@ find_in_NCList(int ext_ncid)
    unsigned int ncid = ((unsigned int)ext_ncid) >> ID_SHIFT;
    if(numfiles > 0 && nc_filelist != NULL && ncid < NCFILELISTLENGTH)
 	f = nc_filelist[ncid];
+
+   /* for classic files, ext_ncid must be a multiple of (1<<ID_SHIFT) */
+   if (f != NULL && f->model == NC_FORMATX_NC3 && (ext_ncid % (1<<ID_SHIFT)))
+       return NULL;
+
    return f;
 }
 

nc_test4/tst_dims.c

@@ -49,6 +49,7 @@ main(int argc, char **argv)
       /* Create a netcdf-3 file with one dim. */
       if (nc_create(FILE_NAME, 0, &ncid)) ERR;
       if (nc_def_dim(ncid, LAT_NAME, LAT_LEN, &dimid)) ERR;
+      if (nc_def_dim(ncid + TEST_VAL_42, LAT_NAME, LAT_LEN, &dimid) != NC_EBADID) ERR;
       if (nc_close(ncid)) ERR;
 
       /* Open the file and make sure nc_inq_dimids yeilds correct