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Re: Refuse following the vfork parent if not letting the child run.
On Monday 08 June 2009 15:31:11, Daniel Jacobowitz wrote:
> On Mon, Jun 08, 2009 at 02:31:38PM +0100, Pedro Alves wrote:
> > A patched GDB shows this:
> > (gdb) set detach-on-fork off
> > (gdb) start
> > Temporary breakpoint 1 at 0x4005c0: file ../../../src/gdb/testsuite/gdb.base/foll-vfork.c, line 12.
> > Starting program: /home/pedro/gdb/sspaces/build/gdb/testsuite/gdb.base/foll-vfork
> > Temporary breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.base/foll-vfork.c:12
> > 12 pid = vfork ();
> > (gdb) n
> > warning: Can not debug the parent of a vfork in the foreground if not letting
> > the child run until it execs or exits, as it would deadlock the terminal.
> > 0x00007ffff789aee4 in vfork () from /lib/libc.so.6
> > (gdb)
> None of your explanation, the patch, or the example output tells me
> what GDB is doing instead :-)
I suck at output messages and docs. It's sort of in the patch :-). Returning
1 from follow_fork makes the caller not carry on with resuming.
> IOW, I think a "warning" about the
> situation here is strange; something has happened, and we don't say
> Is this actually a fork-following error, and we've stopped execution?
I guess you could call it an error. We can't satisfy the users request,
so we kind of stopped execution --- in reality, we're refusing to
continue execution, as the inferior is stopped already.