preventing SEGV in TDatabasePDG::ReadPDGTable()

If users call TDatabasePDG::ReadPDGTable() twice for the same input file the code SEGV's because AddParticle(), which normally returns a pointer to the newly added TParticlePDG, returns 0 if the particle already exists. If the entry also has decay info then it attempts to use the null pointer to AddDecayChannel(). The SEGV can be avoided by the addition of a simple "if (part)" conditional:

• montecarlo/eg/src/TDatabasePDG.cxx (revision 32529) +++ montecarlo/eg/src/TDatabasePDG.cxx (working copy) @@ -623,7 +623,7 @@ } // add decay channel
  • part->AddDecayChannel
    (decay_type,branching_ratio,ndau,dau);
    + if (part) part->AddDecayChannel
    (decay_type,branching_ratio,ndau,dau);
    ich++; } // skip end of line

This isn't necessarily ideal in that it generates a lot of "already defined" warning messages (from the AddParticle calls) but it avoids a premature exit from the program.

-robert

Robert W. Hatcher | rhatcher_at_fnal.gov 630-840-3102 FNAL CD/REX (MINOS) | MS 220, PO Box 500, Batavia IL 60510 Received on Fri Mar 12 2010 - 03:37:19 CET