Dead code in ps_status.c

Thomas Munro <thomas.munro@gmail.com> writes:

Therefore I think it is safe to drop the PS_USE_PS_STRING and
PS_USE_CHANGE_ARGV code branches, remove a bunch of outdated comments
and macro tests, and prune the defunct configure/meson probe.

Seems reasonable. Patch passes an eyeball check.

I guess (defined(sun) && !defined(BSD)) || defined(__svr5__) could be
changed to just defined(sun) (surely there are no other living
SysV-derived systems, and I think non-BSD Sun probably meant "Solaris
but not SunOS"), but I don't know so I didn't touch that.

Hm, is "defined(sun)" true on any live systems at all?

regards, tom lane

On Thu, Feb 16, 2023 at 6:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Thomas Munro <thomas.munro@gmail.com> writes:

Therefore I think it is safe to drop the PS_USE_PS_STRING and
PS_USE_CHANGE_ARGV code branches, remove a bunch of outdated comments
and macro tests, and prune the defunct configure/meson probe.

Seems reasonable. Patch passes an eyeball check.

Thanks for looking.

I guess (defined(sun) && !defined(BSD)) || defined(__svr5__) could be
changed to just defined(sun) (surely there are no other living
SysV-derived systems, and I think non-BSD Sun probably meant "Solaris
but not SunOS"), but I don't know so I didn't touch that.

Hm, is "defined(sun)" true on any live systems at all?

My GCC compile farm account seems to have expired, or something, so I
couldn't check on wrasse's host (though whether wrasse is "live" is
debatable: Solaris 11.3 has reached EOL, it's just that the CPU is too
old to be upgraded, so it's not testing a real OS that anyone would
actually run PostgreSQL on). But from some googling[1]https://stackoverflow.com/questions/16618604/solaris-and-preprocessor-macros, I think
__sun, __sun__ and sun should all be defined.

Ohh, but __svr5__ should not be. Solaris boxes define __svr4__, I was
confused by the two fives. __svr5__ was SCO/Unixware, another dead
OS[1]https://stackoverflow.com/questions/16618604/solaris-and-preprocessor-macros, so I think we can just remove that one too. So, yeah, I think
we should replace (defined(sun) && !defined(BSD)) || defined(__svr5__)
with defined(__sun). (Hmph. We have all of __sun__, __sun and sun in
the tree.)

[1]: https://stackoverflow.com/questions/16618604/solaris-and-preprocessor-macros
[2]: https://en.wikipedia.org/wiki/UNIX_System_V#SVR5_/_UnixWare_7

Thomas Munro <thomas.munro@gmail.com> writes:

On Thu, Feb 16, 2023 at 6:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Hm, is "defined(sun)" true on any live systems at all?

My GCC compile farm account seems to have expired, or something, so I
couldn't check on wrasse's host (though whether wrasse is "live" is
debatable: Solaris 11.3 has reached EOL, it's just that the CPU is too
old to be upgraded, so it's not testing a real OS that anyone would
actually run PostgreSQL on). But from some googling[1], I think
__sun, __sun__ and sun should all be defined.

My account still works, and what I see on wrasse's host is

tgl@gcc-solaris11:~$ gcc -x c /dev/null -dM -E | grep -i svr
#define __SVR4 1
#define __svr4__ 1
tgl@gcc-solaris11:~$ gcc -x c /dev/null -dM -E | grep -i sun
#define __sun 1
#define sun 1
#define __sun__ 1

I don't know a way to get the list of predefined macros out of the
compiler wrasse is actually using (/opt/developerstudio12.6/bin/cc),
but doing some experiments with #ifdef confirmed that it defines
__sun, __sun__, and __svr4__, but not __svr5__.

regards, tom lane

On Fri, Feb 17, 2023 at 3:38 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

My account still works, and what I see on wrasse's host is

tgl@gcc-solaris11:~$ gcc -x c /dev/null -dM -E | grep -i svr
#define __SVR4 1
#define __svr4__ 1
tgl@gcc-solaris11:~$ gcc -x c /dev/null -dM -E | grep -i sun
#define __sun 1
#define sun 1
#define __sun__ 1

I don't know a way to get the list of predefined macros out of the
compiler wrasse is actually using (/opt/developerstudio12.6/bin/cc),
but doing some experiments with #ifdef confirmed that it defines
__sun, __sun__, and __svr4__, but not __svr5__.

Thanks. I went with __sun, because a random man page google found me
for Sun "cc" mentioned that but not __sun__. Pushed.

http://www.polarhome.com/service/man/?qf=cc&amp;tf=2&amp;of=Solaris&amp;sf=1

On Fri, Feb 17, 2023 at 3:38 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Thomas Munro <thomas.munro@gmail.com> writes:

On Thu, Feb 16, 2023 at 6:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
My GCC compile farm account seems to have expired, or something, so I
couldn't check on wrasse's host (though whether wrasse is "live" is
debatable: Solaris 11.3 has reached EOL, it's just that the CPU is too
old to be upgraded, so it's not testing a real OS that anyone would
actually run PostgreSQL on). ...

My account still works, and what I see on wrasse's host is

Just in case it helps someone else who finds themselves locked out of
that, I noticed that I can still connect from my machine with OpenSSH
8.8p1, but not from another dev box which was upgraded to OpenSSH
9.2p1. For reasons I didn't look into, the latter doesn't like
exchanging 1s and 0s with "Sun_SSH_2.4" (something Oracle has
apparently now abandoned in favour of stock OpenSSH, but that machine
is stuck in time).

Hi,

On 2023-03-11 16:59:46 +1300, Thomas Munro wrote:

On Fri, Feb 17, 2023 at 3:38 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Thomas Munro <thomas.munro@gmail.com> writes:

On Thu, Feb 16, 2023 at 6:34 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
My GCC compile farm account seems to have expired, or something, so I
couldn't check on wrasse's host (though whether wrasse is "live" is
debatable: Solaris 11.3 has reached EOL, it's just that the CPU is too
old to be upgraded, so it's not testing a real OS that anyone would
actually run PostgreSQL on). ...

My account still works, and what I see on wrasse's host is

Just in case it helps someone else who finds themselves locked out of
that, I noticed that I can still connect from my machine with OpenSSH
8.8p1, but not from another dev box which was upgraded to OpenSSH
9.2p1. For reasons I didn't look into, the latter doesn't like
exchanging 1s and 0s with "Sun_SSH_2.4" (something Oracle has
apparently now abandoned in favour of stock OpenSSH, but that machine
is stuck in time).

It's the key types supported by the old ssh. I have the following in my
~/.ssh/config to work around that:

Host gcc210.fsffrance.org
PubkeyAcceptedKeyTypes +ssh-rsa
KexAlgorithms +diffie-hellman-group1-sha1
Host gcc211.fsffrance.org
PubkeyAcceptedKeyTypes +ssh-rsa

Greetings,

Andres Freund

Hi,

On Thu, Feb 16, 2023 at 04:52:33PM +1300, Thomas Munro wrote:

Therefore I think it is safe to drop the PS_USE_PS_STRING and
PS_USE_CHANGE_ARGV code branches, remove a bunch of outdated comments
and macro tests, and prune the defunct configure/meson probe.

I noticed Postgres no longer updates the process title on the Hurd, this
is because this was removed along other legacy platforms in this commit
as it was using PS_USE_PS_STRING.

Just doing the same as what Linux does (PS_USE_CLOBBER_ARGV) works, so
I've added the __GNU__ definition to it. Process handling on Linux and
the Hurd are different enough that just changing it to __GLIBC__ would
not be advisable IMV.

Patch attached.

Michael

Hi,

On Tue, Aug 26, 2025 at 03:55:30PM +0200, Michael Banck wrote:

On Thu, Feb 16, 2023 at 04:52:33PM +1300, Thomas Munro wrote:

Therefore I think it is safe to drop the PS_USE_PS_STRING and
PS_USE_CHANGE_ARGV code branches, remove a bunch of outdated comments
and macro tests, and prune the defunct configure/meson probe.

I noticed Postgres no longer updates the process title on the Hurd, this
is because this was removed along other legacy platforms in this commit
as it was using PS_USE_PS_STRING.

By the way, on the back branches from 13-15 (before the above commit)
process title changes don't work either, presumably because __hurd__ (as
opposed to __GNU__ and __gnu_hurd__) has not been defined on GNU/Hurd
for ages (or ever?), see
https://github.com/gcc-mirror/gcc/blob/master/gcc/config/gnu.h#L25

So in case this get backpatched, I think it should be changed to
PS_USE_CLOBBER_ARGV there as well.

Michael

Replying to Michael's message:

/messages/by-id/68adbcd3.500a0220.8d4c9.9460@mx.google.com

Sorry I missed this. I had some trouble with your messages being
deleted as spam, which I've hopefully fixed now...

-#elif defined(__linux__) || defined(__sun) || defined(__darwin__)
+#elif defined(__linux__) || defined(__sun) || defined(__darwin__) ||
defined(__GNU__)

Would __gnu_hurd__ be a better bet, less confusable with GNU userspace
stuff? I think these platform macros might come from this file in
GCC:

https://github.com/gcc-mirror/gcc/blob/faf7053346110cbd11fb22ff75f56a964047b19c/gcc/config/gnu.h#L30

But maybe not only there, if __hurd__ (as removed by d2ea2d31)
actually worked...

On Tue, Nov 11, 2025 at 11:04 AM Thomas Munro <thomas.munro@gmail.com> wrote:

/messages/by-id/68adbcd3.500a0220.8d4c9.9460@mx.google.com

Sorry I missed this. I had some trouble with your messages being
deleted as spam, which I've hopefully fixed now...

-#elif defined(__linux__) || defined(__sun) || defined(__darwin__)
+#elif defined(__linux__) || defined(__sun) || defined(__darwin__) ||
defined(__GNU__)

Would __gnu_hurd__ be a better bet, less confusable with GNU userspace
stuff? I think these platform macros might come from this file in
GCC:

https://github.com/gcc-mirror/gcc/blob/faf7053346110cbd11fb22ff75f56a964047b19c/gcc/config/gnu.h#L30

But maybe not only there, if __hurd__ (as removed by d2ea2d31)
actually worked...

I failed to locate a definitive source in a manual or porting guide or
such, but I see patches making the same change in other projects in
their mailing lists[1]https://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=__GNU__&amp;submit=Search%21&amp;idxname=bug-hurd&amp;max=20&amp;result=normal&amp;sort=score, so it seems that __GNU__ is indeed their
preferred way of detecting a GNU/Hurd (or IIUC 100% "GNU") system, and
it's certainly not defined on my Debian GNU/Linux machine according to
GCC and Clang. So although it was slightly confusing to this human,
being used to seeing __GNUC__ and similar, it doesn't appear to be
confusing to computers.

Pushed, and back-patched to 16, where it applied without problems.

The REL_{14,15}_STABLE branches don't have commit d2ea2d31. I thought
about doing s/__hurd__/__GNU__/ instead, but it actually said:

#elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
#define PS_USE_CHANGE_ARGV

The right thing to do might be to remove it from there, define
PS_USE_CLOBBER_ARGV like in the newer branches and also apply the
second hunk about padding strategy (in other words: be exactly like
GNU/Linux), but I can't test that. If 14 and 15 are still interesting
to you, let me know if that makes sense and works as expected,
otherwise I'll assume you just want to let sleeping dogs lie.

[1]: https://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=__GNU__&amp;submit=Search%21&amp;idxname=bug-hurd&amp;max=20&amp;result=normal&amp;sort=score

Hi Thomas,

On Mon, Nov 17, 2025 at 12:54:44PM +1300, Thomas Munro wrote:

On Tue, Nov 11, 2025 at 11:04 AM Thomas Munro <thomas.munro@gmail.com> wrote:

/messages/by-id/68adbcd3.500a0220.8d4c9.9460@mx.google.com

Sorry I missed this. I had some trouble with your messages being
deleted as spam, which I've hopefully fixed now...

(Sorry about that, I think I fixed it now (after Alvaro mentioned it
again to me at pgconf.eu). Ironically, your previous mail from November
11 was flagged as spam by my provider so I didn't see it until now,
either)

-#elif defined(__linux__) || defined(__sun) || defined(__darwin__)
+#elif defined(__linux__) || defined(__sun) || defined(__darwin__) ||
defined(__GNU__)

Would __gnu_hurd__ be a better bet, less confusable with GNU userspace
stuff? I think these platform macros might come from this file in
GCC:

https://github.com/gcc-mirror/gcc/blob/faf7053346110cbd11fb22ff75f56a964047b19c/gcc/config/gnu.h#L30

But maybe not only there, if __hurd__ (as removed by d2ea2d31)
actually worked...

I failed to locate a definitive source in a manual or porting guide or
such, but I see patches making the same change in other projects in
their mailing lists[1], so it seems that __GNU__ is indeed their
preferred way of detecting a GNU/Hurd (or IIUC 100% "GNU") system, and
it's certainly not defined on my Debian GNU/Linux machine according to
GCC and Clang.

Yeah, __GNU__ is the usual way to distinguish that, I didn't even know
about __gnu_hurd__ until I looked up the same file above when I wrote
the patch...

So although it was slightly confusing to this human, being used to
seeing __GNUC__ and similar, it doesn't appear to be confusing to
computers.

Pushed, and back-patched to 16, where it applied without problems.

Thanks!

The REL_{14,15}_STABLE branches don't have commit d2ea2d31. I thought
about doing s/__hurd__/__GNU__/ instead, but it actually said:

#elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
#define PS_USE_CHANGE_ARGV

The right thing to do might be to remove it from there, define
PS_USE_CLOBBER_ARGV like in the newer branches and also apply the
second hunk about padding strategy (in other words: be exactly like
GNU/Linux), but I can't test that. If 14 and 15 are still interesting
to you, let me know if that makes sense and works as expected,
otherwise I'll assume you just want to let sleeping dogs lie.

I mentioned that in a follow-up[0]/messages/by-id/68add009.170a0220.16b3ca.d01e@mx.google.com to my original mail that you
apparently did not see eiter:

|By the way, on the back branches from 13-15 (before the above commit)
|process title changes don't work either, presumably because __hurd__ (as
|opposed to __GNU__ and __gnu_hurd__) has not been defined on GNU/Hurd
|for ages (or ever?), see
|https://github.com/gcc-mirror/gcc/blob/master/gcc/config/gnu.h#L25
|
|So in case this get backpatched, I think it should be changed to
|PS_USE_CLOBBER_ARGV there as well.

So yeah, I think those would be useful to fix. If you have a patch, I am
happy to test it, or I can come up with one (but not sure I manage this
week).

Thanks,

Michael

[0]: /messages/by-id/68add009.170a0220.16b3ca.d01e@mx.google.com

On Mon, Nov 17, 2025 at 10:36 PM Michael Banck <mbanck@gmx.net> wrote:

I mentioned that in a follow-up[0] to my original mail that you
apparently did not see eiter:

|By the way, on the back branches from 13-15 (before the above commit)
|process title changes don't work either, presumably because __hurd__ (as
|opposed to __GNU__ and __gnu_hurd__) has not been defined on GNU/Hurd
|for ages (or ever?), see
|https://github.com/gcc-mirror/gcc/blob/master/gcc/config/gnu.h#L25
|
|So in case this get backpatched, I think it should be changed to
|PS_USE_CLOBBER_ARGV there as well.

So yeah, I think those would be useful to fix. If you have a patch, I am
happy to test it, or I can come up with one (but not sure I manage this
week).

Ahh, yeah, I'd missed that one too. The mail is definitely getting
through now, though.

With that information, it seemed pretty clear what to do, so I went
ahead and back-patched to 14 and 15.