RFC: fix problems with errors during quitting (killed.exp)

[J. Johnston]

Daniel Jacobowitz wrote:
> On Fri, Sep 05, 2003 at 11:53:55AM -0400, J. Johnston wrote:
> 
>>The following patch fixes the problem that occurs when an error happens 
>>while
>>quitting.  Often an error() call gets triggered and the poor user is thrown
>>back to the gdb command line where they try to quit again.  I made an 
>>attempt
>>to fix a similar problem by handling ptrace errors in quitting, however, 
>>thread-db.c gets
>>into multiple precarious situations because it has to rely on libthread_db
>>for information.  When the thread has been killed/maimed, it gets errors 
>>when
>>they are not expected and quitting becomes impossible.
>>
>>My new strategy is to intercept error() calls during quitting.  Basically,
>>a simple get/set function is set up to denote when we the user has confirmed
>>a quit.  If we get into top.c:throw_exception() and quit has been 
>>confirmed, it
>>exits the program.  This handles any number of messy kill scenarios and 
>>causes
>>no regressions in the current testsuite.  It fixes gdb.threads/killed.exp.  
>>I made the
>>functions external so other parts of gdb can register a confirmed quit if 
>>necessary.  I could
>>make these routines static if this feature is not needed.  I chose to exit 
>>with the
>>code being passed on the jump.  There may be a better constant choice.
>>
>>If anyone can think of scenario that this code is not going to handle 
>>correctly that might
>>not be exercised by the testsuite, please let me know.
>>
>>Tested on x86 and ia64.
>>
>>Comments?
> 
> 
> My immediate concern is, does killed.exp leave a stopped binary around?
> 

It doesn't, but the debugged process going away was the cause of the error in the
first place.  I don't know if there are can't-quit scenarios where a process
will be left around.  Some fork/exec nightmare perhaps??, but I'm not sure what
gdb could be expected to do in such a situation.

-- Jeff J.

> Other than that I like it.
> 
> 
>>2003-09-04  Jeff Johnston  <jjohnstn@redhat.com>
>>
>>	* top.h (get_quit_confirmed, set_quit_confirmed): New prototypes.
>>	* top.c (get_quit_confirmed, set_quit_confirmed): New functions.
>>	(throw_exception): If quit confirmed, exit instead of jumping.
> 
> 
>