Re: deferred breakpoints

["Kris Warkentin" <kewarken at qnx dot com>]

I took a look at the sources from apple and it looks like what they're doing
is relatively simple.  I think most of the wiring is already in gdb.

1) Attempt to set break. If that fails:
2) Create a raw breakpoint and set it to be shlib_disabled.  That way gdb
attempts to reset it every time a shlib is loaded.

I believe that you might get a lot of error messages with this method when
gdb complains about not being able to set the breakpoints but I may be
wrong.  The relevant code is below.  Interesting.  I'll see if I can do it
with a newer version (the apple source is for gdb-4.18)

cheers,

Kris

      struct symtab_and_line sal =
      {0, 0};
      struct breakpoint *b = set_raw_breakpoint (sal);

      printf_unfiltered
 ("Will attempt to resolve \"%s\" on future dynamic loads.\n", args);

      b->number = ++breakpoint_count;
      b->addr_string = savestring (args, strlen (args));
      b->enable = shlib_disabled;
      b->inserted = 0;
      b->disposition = donttouch;
      b->type = bp_breakpoint;
      if (modify_breakpoint_hook)
 modify_breakpoint_hook (b);

> How difficult do you think deferred breakpoints would be to implement?  We
> have a customer who does a lot of work with shared objects and they'd like
> to be able to set breakpoints in them and have them persist across runs.
> I'm thinking that creating a list of breakpoints that could be run through
> every time a shared object was loaded would do the trick.  Can anyone
point
> out any obvious gotcha's?
>
> Kris
>