separating gdb & inferior output

separating gdb & inferior output

[Bob Rossi]

Hi,

Is there a better way to separate GDB's and the inferior's output
besides using the tty command?

I have the feeling the tty command does not port properly everywhere
that GDB does (mingw, cygwin). I've personally had problems with it on
some version of Windows with cygwin. Besides, figuring out how to open a
tty on different machines is a real pain.

Is there a better, more portable way, to accomplish the same task?
I was thinking of having GDB output it's output to a UNIX or TCP/IP
port. How about a FIFO(portable?)? Any other ideas? 

I have a feeling this has been brought up before.

Thanks,
Bob Rossi

Re: separating gdb & inferior output

[Eli Zaretskii]

> Date: Tue, 24 Aug 2004 12:11:47 -0400
> From: Bob Rossi <bob@brasko.net>
> 
> I have the feeling the tty command does not port properly everywhere
> that GDB does (mingw, cygwin). I've personally had problems with it on
> some version of Windows with cygwin. Besides, figuring out how to open a
> tty on different machines is a real pain.
> 
> Is there a better, more portable way, to accomplish the same task?

What can be more portable than file descriptor redirection?  Even
MS-DOS supports it.

> I was thinking of having GDB output it's output to a UNIX or TCP/IP
> port. How about a FIFO(portable?)? Any other ideas? 

Both are less portable than redirection, IMHO.  FIFOs are
Unix-specific, and ports will not work on a system without a network
interface.

Perhaps you could state what are the problems with `tty'?

Re: separating gdb & inferior output

[Bob Rossi]

On Tue, Aug 24, 2004 at 10:00:11PM +0300, Eli Zaretskii wrote:
> > Date: Tue, 24 Aug 2004 12:11:47 -0400
> > From: Bob Rossi <bob@brasko.net>
> > 
> > I have the feeling the tty command does not port properly everywhere
> > that GDB does (mingw, cygwin). I've personally had problems with it on
> > some version of Windows with cygwin. Besides, figuring out how to open a
> > tty on different machines is a real pain.
> > 
> > Is there a better, more portable way, to accomplish the same task?
> 
> What can be more portable than file descriptor redirection?  Even
> MS-DOS supports it.
> 
> > I was thinking of having GDB output it's output to a UNIX or TCP/IP
> > port. How about a FIFO(portable?)? Any other ideas? 
> 
> Both are less portable than redirection, IMHO.  FIFOs are
> Unix-specific, and ports will not work on a system without a network
> interface.
> 
> Perhaps you could state what are the problems with `tty'?

O, you need to actually get a new tty. Windows doesn't have the concept
of a tty. File descriptor redirection is fine. Maybe we could have
something like

   gdb --i=mi --out_fd=n
where n is the descriptor you plan on reading from GDB.

What does it mean to open a 'tty' on a windows platform, or some other
non-unix platform?

Thanks,
Bob Rossi

Re: separating gdb & inferior output

[Eli Zaretskii]

> Date: Tue, 24 Aug 2004 15:09:12 -0400
> From: Bob Rossi <bob@brasko.net>
> Cc: gdb@sources.redhat.com
> 
> > Perhaps you could state what are the problems with `tty'?
> 
> O, you need to actually get a new tty.

Sorry, I still don't get it: I know what the `tty' command does, but I
don't understand what is its problem on non-Unix platforms.  I don't
see anything dubious in the code that implements the command.

> Windows doesn't have the concept of a tty.

Of course, it does.

> File descriptor redirection is fine.

And that's exactly what win32-nat.c does, please take a look.

> Maybe we could have something like
> 
>    gdb --i=mi --out_fd=n
> where n is the descriptor you plan on reading from GDB.

How is this different from what GDB already does?

> What does it mean to open a 'tty' on a windows platform, or some other
> non-unix platform?

Again, see win32-nat.c (search for "inferior_io_terminal").

I'm afraid I'm missing something.

Re: separating gdb & inferior output

[Bob Rossi]

On Wed, Aug 25, 2004 at 07:01:32AM +0300, Eli Zaretskii wrote:
> > Date: Tue, 24 Aug 2004 15:09:12 -0400
> > From: Bob Rossi <bob@brasko.net>
> > Cc: gdb@sources.redhat.com
> > 
> > > Perhaps you could state what are the problems with `tty'?
> > 
> > O, you need to actually get a new tty.
> 
> Sorry, I still don't get it: I know what the `tty' command does, but I
> don't understand what is its problem on non-Unix platforms.  I don't
> see anything dubious in the code that implements the command.
> 
> > Windows doesn't have the concept of a tty.
> 
> Of course, it does.
> 
> > File descriptor redirection is fine.
> 
> And that's exactly what win32-nat.c does, please take a look.
> 
> > Maybe we could have something like
> > 
> >    gdb --i=mi --out_fd=n
> > where n is the descriptor you plan on reading from GDB.
> 
> How is this different from what GDB already does?
> 
> > What does it mean to open a 'tty' on a windows platform, or some other
> > non-unix platform?
> 
> Again, see win32-nat.c (search for "inferior_io_terminal").
> 
> I'm afraid I'm missing something.

OK, lately I have been making assertions when I probably should be
asking questions. Shame on me.

I understand on Unix, the client can open a tty, and direct the output of the inferior to it.
On windows, how would the client do that?

Does native windows actually support opening a 'tty'? Something I didn't
know.

Finally, using cygwin windows, do I use the tty option as if I was on
UNIX?

Thanks,
Bob Rossi

Re: separating gdb & inferior output

[Eli Zaretskii]

> Date: Wed, 25 Aug 2004 07:41:01 -0400
> From: Bob Rossi <bob@brasko.net>
> 
> I understand on Unix, the client can open a tty, and direct the output of the inferior to it.
> On windows, how would the client do that?

The same way, essentially.  Windows has a similar device, and any
Posix-compliant environment (such as Cygwin) converts operations on
"/dev/tty" into operations on the Windows console device.

> Finally, using cygwin windows, do I use the tty option as if I was on
> UNIX?

Yes.

But I don't have a Cygwin install to test this, so I'll let it to
Chris to give definitive answers to your questions.

Re: separating gdb & inferior output

[Christopher Faylor]

On Wed, Aug 25, 2004 at 07:41:01AM -0400, Bob Rossi wrote:
>Finally, using cygwin windows, do I use the tty option as if I was on
>UNIX?

Did you try looking in the source files that Eli suggested?

Yes, cygwin supports the concept of ttys.  It would be a pretty
limited implementation if it didn't.

cgf