Craig Ringer wrote: > See the attached demo (pop all files in the same directory then run "make"). > > > > I would have > > imagined that ultimately, the call to the Pg C function must return, > > and therefore cannot affect stack unwinding within the C++ part of the > > program. > > That's the whole point; a longjmp breaks the call chain, and the > guarantee that eventually the stack will unwind as functions return. > > It's OK if you setjmp(a), do some work, setjmp(b), longjmp(a), do some > work, longjmp(b), return. > > My understanding, which is likely imperfect, is that Pg's error handling > does NOT guarantee that, ie it's quite possible that a function may call > longjmp() without preparing any jmp_env to "jump back to" and therefore > will never return. You are correct that a longjump() jumps back to the query entry loop, hopping over any user-defined C or C++ functions in the call stack, and you are right that if we were just using longjump() without unwinding C++ calls, we would be OK using non-POD structures. -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + None of us is going to be here forever. + -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
