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* Broken PQtrace CopyData display
@ 2025-08-29 19:45 Ran Benita <ran@unusedvar.com>
2025-08-31 04:53 ` Re: Broken PQtrace CopyData display Michael Paquier <michael@paquier.xyz>
0 siblings, 1 reply; 4+ messages in thread
From: Ran Benita @ 2025-08-29 19:45 UTC (permalink / raw)
To: pgsql-bugs@lists.postgresql.org
I used PQtrace to trace a logical decoding session, and was confused to see
lines like this:
2025-08-29 22:09:57.633980 F 38 CopyData 'r\x00\x00\x00\x00\xffffff8e\x07\xffffff85x\x00\x00\x00\x00\xffffff8e\x07\xffffff85x\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\xffffffe0\xffffff84\xffffff89R\xffffffd7\xffffffb8\x00'
The data doesn't make sense and has the wrong length. A quick look shows that
the \xffffff85 parts are a signedness issue (on my compiler char is signed).
I instead expect to see output like this:
2025-08-29 22:39:17.041261 F 38 CopyData 'r\x00\x00\x00\x00\x8e\x07\x89\xf8\x00\x00\x00\x00\x8e\x07\x89\xf8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\xe0\x84\xf21Dh\x00'
The diff below fixes this particular problem, though they say bugs are like
mushrooms, if you find one then there are probably others nearby, so a more
comprehensive fix may be warranted.
diff --git i/src/interfaces/libpq/fe-trace.c w/src/interfaces/libpq/fe-trace.c
index a45f0d85587..f487c111fc7 100644
--- i/src/interfaces/libpq/fe-trace.c
+++ w/src/interfaces/libpq/fe-trace.c
@@ -212,7 +212,7 @@ pqTraceOutputNchar(FILE *pfdebug, int len, const char *data, int *cursor, bool s
else
{
fwrite(v + next, 1, i - next, pfdebug);
- fprintf(pfdebug, "\\x%02x", v[i]);
+ fprintf(pfdebug, "\\x%02x", (unsigned char) v[i]);
next = i + 1;
}
}
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Broken PQtrace CopyData display
2025-08-29 19:45 Broken PQtrace CopyData display Ran Benita <ran@unusedvar.com>
@ 2025-08-31 04:53 ` Michael Paquier <michael@paquier.xyz>
2025-09-03 03:58 ` Re: Broken PQtrace CopyData display Michael Paquier <michael@paquier.xyz>
0 siblings, 1 reply; 4+ messages in thread
From: Michael Paquier @ 2025-08-31 04:53 UTC (permalink / raw)
To: Ran Benita <ran@unusedvar.com>; +Cc: pgsql-bugs@lists.postgresql.org
On Fri, Aug 29, 2025 at 10:45:18PM +0300, Ran Benita wrote:
> I used PQtrace to trace a logical decoding session, and was confused to see
> lines like this:
>
> 2025-08-29 22:09:57.633980 F 38 CopyData 'r\x00\x00\x00\x00\xffffff8e\x07\xffffff85x\x00\x00\x00\x00\xffffff8e\x07\xffffff85x\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\xffffffe0\xffffff84\xffffff89R\xffffffd7\xffffffb8\x00'
>
> The data doesn't make sense and has the wrong length. A quick look shows that
> the \xffffff85 parts are a signedness issue (on my compiler char is signed).
>
> @@ -212,7 +212,7 @@ pqTraceOutputNchar(FILE *pfdebug, int len, const char *data, int *cursor, bool s
> else
> {
> fwrite(v + next, 1, i - next, pfdebug);
> - fprintf(pfdebug, "\\x%02x", v[i]);
> + fprintf(pfdebug, "\\x%02x", (unsigned char) v[i]);
> next = i + 1;
> }
> }
Yeah. Not a lot of people use the libpq tracing, but it would be
better to show non-printable data in a consistent way.
> The diff below fixes this particular problem, though they say bugs are like
> mushrooms, if you find one then there are probably others nearby, so a more
> comprehensive fix may be warranted.
There's one more mushroom: pqTraceOutputByte1() also uses a %02X
without a cast for non-printable data. Note as well
logicalmsg_desc(), auth-oauth.c, mbprint.c (which uses an unsigned
char type in input to force things).
--
Michael
Attachments:
[application/pgp-signature] signature.asc (832B, ../../aLPVXkOipoBSWSb1@paquier.xyz/2-signature.asc)
download
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Broken PQtrace CopyData display
2025-08-29 19:45 Broken PQtrace CopyData display Ran Benita <ran@unusedvar.com>
2025-08-31 04:53 ` Re: Broken PQtrace CopyData display Michael Paquier <michael@paquier.xyz>
@ 2025-09-03 03:58 ` Michael Paquier <michael@paquier.xyz>
2025-09-06 08:42 ` Re: Broken PQtrace CopyData display Álvaro Herrera <alvherre@kurilemu.de>
0 siblings, 1 reply; 4+ messages in thread
From: Michael Paquier @ 2025-09-03 03:58 UTC (permalink / raw)
To: Ran Benita <ran@unusedvar.com>; +Cc: pgsql-bugs@lists.postgresql.org
On Sun, Aug 31, 2025 at 01:53:50PM +0900, Michael Paquier wrote:
> Yeah. Not a lot of people use the libpq tracing, but it would be
> better to show non-printable data in a consistent way.
Done this one with db9405493b48.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (832B, ../../aLe89ZdYSZZit_u0@paquier.xyz/2-signature.asc)
download
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Broken PQtrace CopyData display
2025-08-29 19:45 Broken PQtrace CopyData display Ran Benita <ran@unusedvar.com>
2025-08-31 04:53 ` Re: Broken PQtrace CopyData display Michael Paquier <michael@paquier.xyz>
2025-09-03 03:58 ` Re: Broken PQtrace CopyData display Michael Paquier <michael@paquier.xyz>
@ 2025-09-06 08:42 ` Álvaro Herrera <alvherre@kurilemu.de>
0 siblings, 0 replies; 4+ messages in thread
From: Álvaro Herrera @ 2025-09-06 08:42 UTC (permalink / raw)
To: Michael Paquier <michael@paquier.xyz>; +Cc: Ran Benita <ran@unusedvar.com>; pgsql-bugs@lists.postgresql.org
On 2025-Sep-03, Michael Paquier wrote:
> On Sun, Aug 31, 2025 at 01:53:50PM +0900, Michael Paquier wrote:
> > Yeah. Not a lot of people use the libpq tracing, but it would be
> > better to show non-printable data in a consistent way.
>
> Done this one with db9405493b48.
Thanks!
--
Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/
"La persona que no quería pecar / estaba obligada a sentarse
en duras y empinadas sillas / desprovistas, por cierto
de blandos atenuantes" (Patricio Vogel)
^ permalink raw reply [nested|flat] 4+ messages in thread
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Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2025-08-29 19:45 Broken PQtrace CopyData display Ran Benita <ran@unusedvar.com>
2025-08-31 04:53 ` Michael Paquier <michael@paquier.xyz>
2025-09-03 03:58 ` Michael Paquier <michael@paquier.xyz>
2025-09-06 08:42 ` Álvaro Herrera <alvherre@kurilemu.de>
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