Re: [PATCH] Fix assert failure in invocation of "[kill|detach] inferiors 1"

[Pedro Alves <palves at redhat dot com>]

On 07/28/2015 09:29 PM, Patrick Palka wrote:
> When only the dummy PID 0 inferior exists, invoking either of the above
> commands triggers the following assert failure:
> 
>   .../binutils-gdb/gdb/thread.c:514: internal-error: any_thread_of_process: Assertion `pid != 0' failed.
> 
> The fix is straightforward.  Tested on x86_64 Debian Stretch.

Thanks.

> 
> gdb/ChangeLog:
> 
> 	* inferior.c (detach_inferior_command): Don't call
> 	any_thread_of_process when pid is 0.
> 	(kill_inferior_command): Likewise.
> 
> gdb/testsuite/ChangeLog:
> 
> 	* gdb.base/no-inferiors.exp: New test file.
> ---
>  gdb/inferior.c                          | 12 ++++++++++--
>  gdb/testsuite/gdb.base/no-inferiors.exp | 24 ++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 2 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.base/no-inferiors.exp
> 
> diff --git a/gdb/inferior.c b/gdb/inferior.c
> index 5e98df5..ff85a1f 100644
> --- a/gdb/inferior.c
> +++ b/gdb/inferior.c
> @@ -626,7 +626,11 @@ detach_inferior_command (char *args, int from_tty)
>  
>        pid = gdb_inferior_id_to_pid (num);
>  
> -      tp = any_thread_of_process (pid);
> +      if (pid != 0)
> +	tp = any_thread_of_process (pid);
> +      else
> +	tp = 0;

Should be tp = NULL.

This is old code that predates the multi-executable support
(6c95b8df7fef), and was never really updated since.  Guess
not many people use it...

Doesn't make that much sense to say "has no threads"
nowadays.  I think this should give out a warning similar
to the error "detach_command" throws, like:

+      if (pid == 0)
+        {
+          warning (_("Inferior ID %s is not being run."), num);
+          continue;
+        }

      tp = any_thread_of_process (pid);
      if (!tp)
	{
	  warning (_("Inferior ID %d has no threads."), num);
	  continue;
	}

The "has no threads" case is then more of an internal error,
but there's no need to be so drastic, so leave it as is.

(Likewise for kill, of course.)

OK with that change.

Thanks,
Pedro Alves