Re: [PATCH] Do not pass NULL for the string in catch_errors

[Pedro Alves <palves at redhat dot com>]

On 10/22/2015 01:36 PM, Luis Machado wrote:
> On 10/22/2015 09:50 AM, Pedro Alves wrote:
>> On 10/22/2015 12:23 PM, Luis Machado wrote:

> That would be fine by me. I was just experimenting with 
> TRY/CATCH/END_CATCH after my unsuccessful replacement of catch_errors 
> with catch_exceptions. See below.
>>>

>>> With catch_exceptions, instead of catching the error and letting the
>>> inferior continue, it will just cause the inferior to terminate.
>>
>> I don't understand.  Why do you say this will happen?
>>
> 
> I replaced catch_errors with catch_exceptions in record-full.c. I saw a 
> bunch of failures in gdb.reverse/sigall-reverse.exp, starting at this point:
> 
> Breakpoint 142, handle_TERM (sig=15) at 
> ../../../gdb-head-ro/gdb/testsuite/gdb.reverse/sigall-reverse.c:378^M
> 378     }^M
> (gdb) PASS: gdb.reverse/sigall-reverse.exp: send signal TERM
> continue^M
> Continuing.^M
> The next instruction is syscall exit_group.  It will make the program 
> exit.  Do you want to stop the program?([y] or n) yes^M
> Process record: inferior program stopped.^M
> ^M
> [process 21188] #1 stopped.^M
> 
> The above is a normal run. If i replace catch_errors with 
> catch_exceptions, instead of stopping the inferior, it will terminate. 
> Maybe there is a bug somewhere, or something is being mishandled.

It just sounds to me that you didn't take into account
that the return values of catch_errors and catch_exceptions
differ.

while one does:

  if (exception.reason < 0)
    {
...
      return exception.reason;
    }

the other does:

  if (exception.reason != 0)
    return 0;

This matters because the result is returned by
record_full_message_wrapper_safe, and checked here:

		      if (!record_full_message_wrapper_safe (regcache,
							     GDB_SIGNAL_0))
  			{
                           status->kind = TARGET_WAITKIND_STOPPED;
                           status->value.sig = GDB_SIGNAL_0;
                           break;
  			}

Thanks,
Pedro Alves