Make '{putchar,fputc}_unfiltered' use 'fputs_unfiltered'
Commit Message
There is currently a regression when using
'{putchar,fputc}_unfiltered' with 'puts_unfiltered' which was
introduced by one of the commits that reworked the unfiltered print
code.
The regression makes it impossible to use '{putchar,fputc}_unfiltered'
with 'puts_unfiltered', because the former writes directly to the
ui_file stream using 'stream->write', while the latter uses a buffered
mechanism (see 'wrap_buffer') and delays the printing.
If you do a quick & dirty hack on e.g. top.c:show_gdb_datadir:
@@ -2088,6 +2088,13 @@ static void
show_gdb_datadir (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
+ putchar_unfiltered ('\n');
+ puts_unfiltered ("TEST");
+ putchar_unfiltered ('>');
+ puts_unfiltered ("PUTS");
+ putchar_unfiltered ('\n');
rebuild GDB and invoke the "show data-directory" command, you will
see:
(gdb) show data-directory
>
TESTPUTSGDB's data directory is "/usr/local/share/gdb".
Note how the '>' was printed before the output, and "TEST" and "PUTS"
were printed together.
My first attempt to fix this was to always call 'flush_wrap_buffer' at
the end of 'fputs_maybe_filtered', since it seemed to me that the
function should always print what was requested. But I wasn't sure
this was the right thing to do, so I talked to Tom on IRC and he gave
me another, simpler idea: make '{putchar,fputc}_unfiltered' call into
the already existing 'fputs_unfiltered' function.
This patch implements the idea. I regtested it on the Buildbot, and
no regressions were detected.
gdb/ChangeLog:
2020-02-20 Sergio Durigan Junior <sergiodj@redhat.com>
Tom Tromey <tom@tromey.com>
* utils.c (fputs_maybe_filtered): Call 'stream->puts' instead
of 'fputc_unfiltered'.
(putchar_unfiltered): Call 'fputc_unfiltered'.
(fputc_unfiltered): Call 'fputs_unfiltered'.
---
gdb/utils.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
Comments
>>>>> "Sergio" == Sergio Durigan Junior <sergiodj@redhat.com> writes:
Sergio> gdb/ChangeLog:
Sergio> 2020-02-20 Sergio Durigan Junior <sergiodj@redhat.com>
Sergio> Tom Tromey <tom@tromey.com>
Sergio> * utils.c (fputs_maybe_filtered): Call 'stream->puts' instead
Sergio> of 'fputc_unfiltered'.
Sergio> (putchar_unfiltered): Call 'fputc_unfiltered'.
Sergio> (fputc_unfiltered): Call 'fputs_unfiltered'.
Looks good to me. Thanks for doing this.
Tom
On Thursday, February 20 2020, Tom Tromey wrote:
>>>>>> "Sergio" == Sergio Durigan Junior <sergiodj@redhat.com> writes:
>
> Sergio> gdb/ChangeLog:
> Sergio> 2020-02-20 Sergio Durigan Junior <sergiodj@redhat.com>
> Sergio> Tom Tromey <tom@tromey.com>
> Sergio> * utils.c (fputs_maybe_filtered): Call 'stream->puts' instead
> Sergio> of 'fputc_unfiltered'.
> Sergio> (putchar_unfiltered): Call 'fputc_unfiltered'.
> Sergio> (fputc_unfiltered): Call 'fputs_unfiltered'.
>
> Looks good to me. Thanks for doing this.
Thanks, pushed.
3f702acd7d562d3a33c59d6398ae74058438d2c7
Hi Sergio and Tom,
On Thu, Feb 20, 2020 at 04:04:05PM -0500, Sergio Durigan Junior wrote:
> On Thursday, February 20 2020, Tom Tromey wrote:
>
> >>>>>> "Sergio" == Sergio Durigan Junior <sergiodj@redhat.com> writes:
> >
> > Sergio> gdb/ChangeLog:
> > Sergio> 2020-02-20 Sergio Durigan Junior <sergiodj@redhat.com>
> > Sergio> Tom Tromey <tom@tromey.com>
> > Sergio> * utils.c (fputs_maybe_filtered): Call 'stream->puts' instead
> > Sergio> of 'fputc_unfiltered'.
> > Sergio> (putchar_unfiltered): Call 'fputc_unfiltered'.
> > Sergio> (fputc_unfiltered): Call 'fputs_unfiltered'.
> >
> > Looks good to me. Thanks for doing this.
>
> Thanks, pushed.
>
> 3f702acd7d562d3a33c59d6398ae74058438d2c7
I think the commit that Sergio incriminated is also in gdb-9-branch.
Do you confirm?
If yes, what about creating a GDB PR, and backporting this change
to the gdb-9-branch (all changes after the .1 must have a PR)?
The change looks relatively safe to me, but maybe it's not as simple
as we might think, especially since this section of the code _is_ quite
central...
Thank you!
On Thursday, February 20 2020, Joel Brobecker wrote:
> Hi Sergio and Tom,
Hey Joel,
> On Thu, Feb 20, 2020 at 04:04:05PM -0500, Sergio Durigan Junior wrote:
>> On Thursday, February 20 2020, Tom Tromey wrote:
>>
>> >>>>>> "Sergio" == Sergio Durigan Junior <sergiodj@redhat.com> writes:
>> >
>> > Sergio> gdb/ChangeLog:
>> > Sergio> 2020-02-20 Sergio Durigan Junior <sergiodj@redhat.com>
>> > Sergio> Tom Tromey <tom@tromey.com>
>> > Sergio> * utils.c (fputs_maybe_filtered): Call 'stream->puts' instead
>> > Sergio> of 'fputc_unfiltered'.
>> > Sergio> (putchar_unfiltered): Call 'fputc_unfiltered'.
>> > Sergio> (fputc_unfiltered): Call 'fputs_unfiltered'.
>> >
>> > Looks good to me. Thanks for doing this.
>>
>> Thanks, pushed.
>>
>> 3f702acd7d562d3a33c59d6398ae74058438d2c7
>
> I think the commit that Sergio incriminated is also in gdb-9-branch.
> Do you confirm?
Yes, the bug also happens in gdb-9-branch.
> If yes, what about creating a GDB PR, and backporting this change
> to the gdb-9-branch (all changes after the .1 must have a PR)?
I can do that. Just not right now; I need to be in my bed sleeping 30
minutes ago ;-).
> The change looks relatively safe to me, but maybe it's not as simple
> as we might think, especially since this section of the code _is_ quite
> central...
Yeah, this code is quite messy, and even though the change is somewhat
"self-contained". What if we wait a few days/weeks before I open the PR
and do the backport? Due to this code being quite central as you said,
I think it should not take long for complaints to start coming our way,
assuming there is a bug to be found.
Thanks,
> > I think the commit that Sergio incriminated is also in gdb-9-branch.
> > Do you confirm?
>
> Yes, the bug also happens in gdb-9-branch.
>
> > If yes, what about creating a GDB PR, and backporting this change
> > to the gdb-9-branch (all changes after the .1 must have a PR)?
>
> I can do that. Just not right now; I need to be in my bed sleeping 30
> minutes ago ;-).
;-)
> > The change looks relatively safe to me, but maybe it's not as simple
> > as we might think, especially since this section of the code _is_ quite
> > central...
>
> Yeah, this code is quite messy, and even though the change is somewhat
> "self-contained". What if we wait a few days/weeks before I open the PR
> and do the backport? Due to this code being quite central as you said,
> I think it should not take long for complaints to start coming our way,
> assuming there is a bug to be found.
That definitely works. Unless we discover this is a crippling issue
that deserves an emergency release, we have a solid couple of months
to decide, really. More if we need...
Thanks Sergio!
On Friday, February 21 2020, Joel Brobecker wrote:
>> > The change looks relatively safe to me, but maybe it's not as simple
>> > as we might think, especially since this section of the code _is_ quite
>> > central...
>>
>> Yeah, this code is quite messy, and even though the change is somewhat
>> "self-contained". What if we wait a few days/weeks before I open the PR
>> and do the backport? Due to this code being quite central as you said,
>> I think it should not take long for complaints to start coming our way,
>> assuming there is a bug to be found.
>
> That definitely works. Unless we discover this is a crippling issue
> that deserves an emergency release, we have a solid couple of months
> to decide, really. More if we need...
Good deal :-).
> Thanks Sergio!
Thank *you* for bringing this to my attention!
@@ -1776,7 +1776,12 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
newline -- if chars_per_line is right, we
probably just overflowed anyway; if it's wrong,
let us keep going. */
- fputc_unfiltered ('\n', stream);
+ /* XXX: The ideal thing would be to call
+ 'stream->putc' here, but we can't because it
+ currently calls 'fputc_unfiltered', which ends up
+ calling us, which generates an infinite
+ recursion. */
+ stream->puts ("\n");
}
else
{
@@ -1821,7 +1826,12 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
wrap_here ((char *) 0); /* Spit out chars, cancel
further wraps. */
lines_printed++;
- fputc_unfiltered ('\n', stream);
+ /* XXX: The ideal thing would be to call
+ 'stream->putc' here, but we can't because it
+ currently calls 'fputc_unfiltered', which ends up
+ calling us, which generates an infinite
+ recursion. */
+ stream->puts ("\n");
lineptr++;
}
}
@@ -1916,10 +1926,7 @@ fputs_highlighted (const char *str, const compiled_regex &highlight,
int
putchar_unfiltered (int c)
{
- char buf = c;
-
- gdb_stdout->write (&buf, 1);
- return c;
+ return fputc_unfiltered (c, gdb_stdout);
}
/* Write character C to gdb_stdout using GDB's paging mechanism and return C.
@@ -1934,9 +1941,11 @@ putchar_filtered (int c)
int
fputc_unfiltered (int c, struct ui_file *stream)
{
- char buf = c;
+ char buf[2];
- stream->write (&buf, 1);
+ buf[0] = c;
+ buf[1] = 0;
+ fputs_unfiltered (buf, stream);
return c;
}