* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
@ 2018-07-20 22:02 Ken Brown
2018-07-21 6:53 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Ken Brown @ 2018-07-20 22:02 UTC (permalink / raw
To: 32230; +Cc: Paul Eggert
The Cygwin-w32 build has turned up another GCC 7 warning:
../../master/src/w32term.c: In function ‘x_draw_glyph_string’:
../../master/src/w32term.c:1477:27: warning: ‘__builtin___sprintf_chk’
may write a terminating nul past the end of the destination
[-Wformat-overflow=]
sprintf ((char *) buf, "%0*X",
^
../../master/src/w32term.c:1477:4: note: ‘__builtin___sprintf_chk’
output between 5 and 8 bytes into a destination of size 7
sprintf ((char *) buf, "%0*X",
^
The method that Paul used in bug#32189 could be used here too, but I'm
not sure it's worth the trouble. My inclination is to just increase the
buffer size from 7 to 8.
Ken
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-20 22:02 bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow Ken Brown
@ 2018-07-21 6:53 ` Eli Zaretskii
2018-07-21 7:26 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Eli Zaretskii @ 2018-07-21 6:53 UTC (permalink / raw
To: Ken Brown; +Cc: 32230, eggert
> From: Ken Brown <kbrown@cornell.edu>
> Date: Fri, 20 Jul 2018 18:02:07 -0400
> Cc: Paul Eggert <eggert@cs.ucla.edu>
>
> The Cygwin-w32 build has turned up another GCC 7 warning:
>
> ../../master/src/w32term.c: In function ‘x_draw_glyph_string’:
> ../../master/src/w32term.c:1477:27: warning: ‘__builtin___sprintf_chk’
> may write a terminating nul past the end of the destination
> [-Wformat-overflow=]
> sprintf ((char *) buf, "%0*X",
> ^
> ../../master/src/w32term.c:1477:4: note: ‘__builtin___sprintf_chk’
> output between 5 and 8 bytes into a destination of size 7
> sprintf ((char *) buf, "%0*X",
> ^
> The method that Paul used in bug#32189 could be used here too, but I'm
> not sure it's worth the trouble. My inclination is to just increase the
> buffer size from 7 to 8.
Yes, with a comment explaining why 8.
But do you understand why it says "between 5 and 8 bytes"? The
corresponding argument to snprintf is either 4 or 6, so it should be
between 5 and 7. Where could the extra byte come from? Is that
because glyphless.ch is a 25-bit field?
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-21 6:53 ` Eli Zaretskii
@ 2018-07-21 7:26 ` Eli Zaretskii
2018-07-21 12:42 ` Ken Brown
0 siblings, 1 reply; 7+ messages in thread
From: Eli Zaretskii @ 2018-07-21 7:26 UTC (permalink / raw
To: kbrown; +Cc: 32230, eggert
> Date: Sat, 21 Jul 2018 09:53:04 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 32230@debbugs.gnu.org, eggert@cs.ucla.edu
>
> But do you understand why it says "between 5 and 8 bytes"? The
> corresponding argument to snprintf is either 4 or 6, so it should be
> between 5 and 7. Where could the extra byte come from? Is that
> because glyphless.ch is a 25-bit field?
I meant sprintf, of course. And if the above is the reason, then
perhaps using something like
(unsigned int) glyph->u.glyphless.ch & 0xffffff
is a cleaner solution (assuming it shuts up the warning)?
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-21 7:26 ` Eli Zaretskii
@ 2018-07-21 12:42 ` Ken Brown
2018-07-21 12:47 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Ken Brown @ 2018-07-21 12:42 UTC (permalink / raw
To: Eli Zaretskii; +Cc: 32230, eggert
On 7/21/2018 3:26 AM, Eli Zaretskii wrote:
>> Date: Sat, 21 Jul 2018 09:53:04 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 32230@debbugs.gnu.org, eggert@cs.ucla.edu
>>
>> But do you understand why it says "between 5 and 8 bytes"? The
>> corresponding argument to snprintf is either 4 or 6, so it should be
>> between 5 and 7. Where could the extra byte come from? Is that
>> because glyphless.ch is a 25-bit field?
Yes. Changing the field size to 24 silences the warning.
> I meant sprintf, of course. And if the above is the reason, then
> perhaps using something like
>
> (unsigned int) glyph->u.glyphless.ch & 0xffffff
>
> is a cleaner solution (assuming it shuts up the warning)?
Yes, it does shut up the warning. Thanks, I'll make that change. I
assume it should go to master, or would you rather have it in the
emacs-26 branch?
Ken
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-21 12:42 ` Ken Brown
@ 2018-07-21 12:47 ` Eli Zaretskii
2018-07-21 16:26 ` Ken Brown
0 siblings, 1 reply; 7+ messages in thread
From: Eli Zaretskii @ 2018-07-21 12:47 UTC (permalink / raw
To: Ken Brown; +Cc: 32230, eggert
> Cc: 32230@debbugs.gnu.org, eggert@cs.ucla.edu
> From: Ken Brown <kbrown@cornell.edu>
> Date: Sat, 21 Jul 2018 08:42:09 -0400
>
> > I meant sprintf, of course. And if the above is the reason, then
> > perhaps using something like
> >
> > (unsigned int) glyph->u.glyphless.ch & 0xffffff
> >
> > is a cleaner solution (assuming it shuts up the warning)?
>
> Yes, it does shut up the warning. Thanks, I'll make that change. I
> assume it should go to master, or would you rather have it in the
> emacs-26 branch?
I think it should go to master, thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-21 12:47 ` Eli Zaretskii
@ 2018-07-21 16:26 ` Ken Brown
2018-07-21 16:40 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Ken Brown @ 2018-07-21 16:26 UTC (permalink / raw
To: Eli Zaretskii; +Cc: 32230-done, eggert
On 7/21/2018 8:47 AM, Eli Zaretskii wrote:
> I think it should go to master, thanks.
Done, as commit f3f67cf. But I forgot to reference the bug number in
the commit message. I guess there's no way to fix that, except to edit
ChangeLog.3. Sorry.
Ken
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow
2018-07-21 16:26 ` Ken Brown
@ 2018-07-21 16:40 ` Eli Zaretskii
0 siblings, 0 replies; 7+ messages in thread
From: Eli Zaretskii @ 2018-07-21 16:40 UTC (permalink / raw
To: Ken Brown; +Cc: 32230, eggert
> Cc: 32230-done@debbugs.gnu.org, eggert@cs.ucla.edu
> From: Ken Brown <kbrown@cornell.edu>
> Date: Sat, 21 Jul 2018 12:26:41 -0400
>
> Done, as commit f3f67cf. But I forgot to reference the bug number in
> the commit message.
Happens to me as well.
> I guess there's no way to fix that, except to edit ChangeLog.3.
> Sorry.
No sweat.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-07-21 16:40 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-07-20 22:02 bug#32230: 27.0.50; GCC 7 warning due to -Wformat-overflow Ken Brown
2018-07-21 6:53 ` Eli Zaretskii
2018-07-21 7:26 ` Eli Zaretskii
2018-07-21 12:42 ` Ken Brown
2018-07-21 12:47 ` Eli Zaretskii
2018-07-21 16:26 ` Ken Brown
2018-07-21 16:40 ` Eli Zaretskii
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.