Add overflow check to dump_h5md

src/H5MD/dump_h5md.cpp

@@ -181,6 +181,7 @@ DumpH5MD::DumpH5MD(LAMMPS *lmp, int narg, char **arg) : Dump(lmp, narg, arg)
   // allocate global array for atom coords
 
   bigint n = group->count(igroup);
+  if ((bigint) domain->dimension*n > MAXSMALLINT) error->all(FLERR,"Too many atoms for dump h5md");
   natoms = static_cast<int> (n);
 
   if (every_position>=0)

src/H5MD/dump_h5md.h

@@ -90,6 +90,11 @@ E: Dump h5md requires sorting by atom ID
 
 Use the dump_modify sort command to enable this.
 
+E: Too many atoms for dump h5md
+
+The system size must fit in a 32-bit integer to use this dump
+style.
+
 E: Cannot use variable every setting for dump xtc
 
 The format of this file requires snapshots at regular intervals.