Re: [PATCH v3 2/6] Share parts of gdb/terminal.h with gdbserver

[Sergio Durigan Junior <sergiodj at redhat dot com>]

Hey Pedro,

Thanks for the review.  Comments below.

On Wednesday, February 15 2017, Pedro Alves wrote:

> On 02/08/2017 03:22 AM, Sergio Durigan Junior wrote:
>> As part of the bigger work of sharing fork_inferior with gdbserver,
>> some parts of gdb/terminal.h also needed to be moved to a common
>> place.  These parts are:
>> 
>> - The code responsible for determining some terminal-based define's
>>   based on available features;
>> 
>> - job control;
>> 
>> - terminal-related functions needed by fork_inferior;
>> 
>
>
>> diff --git a/gdb/common/common-terminal.h b/gdb/common/common-terminal.h
>> new file mode 100644
>> index 0000000..956bfcc
>> --- /dev/null
>> +++ b/gdb/common/common-terminal.h
>> @@ -0,0 +1,125 @@
>
>
>> +#ifndef COMMON_TERMINAL_H
>> +#define COMMON_TERMINAL_H
>> +
>> +/* If we're using autoconf, it will define HAVE_TERMIOS_H,
>> +   HAVE_TERMIO_H and HAVE_SGTTY_H for us.  One day we can rewrite
>> +   ser-unix.c and inflow.c to inspect those names instead of
>> +   HAVE_TERMIOS, HAVE_TERMIO and the implicit HAVE_SGTTY (when neither
>> +   HAVE_TERMIOS or HAVE_TERMIO is set).  Until then, make sure that
>> +   nothing has already defined the one of the names, and do the right
>> +   thing.  */
>
> We try to keep common/ self-contained wrt autoconf -- i.e.,
> corresponding autoconf checks should be added to common/common.m4.

Done.  Thanks for bringing this to my attention.

>> +
>> +#if !defined (HAVE_TERMIOS) && !defined(HAVE_TERMIO) && !defined(HAVE_SGTTY)
>> +#if defined(HAVE_TERMIOS_H)
>> +#define HAVE_TERMIOS
>
>
>> +/* Do we have job control?  Can be assumed to always be the same
>> +   within a given run of GDB.  Use in gdb/inflow.c and
>> +   common/common-inflow.c.  */
>> +extern int job_control;
>> +
>
> ...
>
>> +/* Set the process group of the caller to its own pid, or do nothing
>> +   if we lack job control.  */
>> +extern int gdb_setpgid (void);
>> +
>> +/* Determine whether we have job control, and set variable JOB_CONTROL
>> +   accordingly.  */
>> +extern void have_job_control (void);
>
> It had been clearer if these three were moved in the patch that
> moves the corresponding .c code.  I was going to comment in that
> patch that the "have_job_control" documentation should
> mention that it must be called early, before "job_control"
> is ever used.  And that that patch would have better been the one
> that adds the have_job_control() calls to the appropriate
> places.  With the split as is, this detail ends up easily missed.

Hm, OK.  I'll reorganize this part of the patch, then.  Sorry about
that.

>> +#endif /* ! COMMON_TERMINAL_H */
>> diff --git a/gdb/gdbserver/terminal.c b/gdb/gdbserver/terminal.c
>> new file mode 100644
>> index 0000000..42ac651
>> --- /dev/null
>> +++ b/gdb/gdbserver/terminal.c
>> @@ -0,0 +1,88 @@
>
>> +/* See common/common-terminal.h.  */
>> +
>> +pid_t
>> +create_tty_session (void)
>> +{
>> +  /* Placeholder needed by fork_inferior.  For now, this function is
>> +     not needed nor useful to have on gdbserver.  When/If we properly
>> +     handle terminal modes, we can revisit and implement the needed
>> +     support.  */
>> +  return (pid_t) 1;
>
> Without looking at the caller, it would seem to me that -1 / 0 
> would make more sense, and "1" kind of looks like a typo/bug.
> Please add a comment mentioning why this returns 1.

You're right, this should have been 0.  Fixed now.

>> +}
>> +
>> +/* See common/common-inferior.h.  */
>> +
>> +void
>> +set_inferior_io_terminal (const char *terminal_name)
>> +{
>> +  /* Placeholder needed by fork_inferior.  For now, this function is
>> +     not needed nor useful to have on gdbserver.  When/If we properly
>> +     handle terminal modes, we can revisit and implement the needed
>> +     support.  */
>> +}
>> +
>> +/* See common/common-inferior.h.  */
>> +
>> +const char *
>> +get_inferior_io_terminal (void)
>> +{
>> +  /* Placeholder needed by fork_inferior.  For now, this function is
>> +     not needed nor useful to have on gdbserver.  When/If we properly
>> +     handle terminal modes, we can revisit and implement the needed
>> +     support.  */
>
> How about instead of repeating the same comment multiple times,
> we add it once at the top:
>
>   /* Placeholders needed by fork_inferior.  For now, these functions are
>      not needed nor useful to have on gdbserver.  When/If we properly
>      handle terminal modes, we can revisit and implement the needed
>      support.  */
>
> ?

Yeah, I did that on the other file but forgot about this one.  Done,
thanks.

I'll wait until all of your comments are addressed before I send v4.

Cheers,

-- 
Sergio
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