gh-63760: Don't declare gethostname() on Solaris

[vstinner]

Since at least 2013, Oracle Solaris defines gethostname(). socketmodule.c no longer has to define gethostname() for Solaris.

Oracle Solaris and OpenSolaris have patches to remove the gethostname() definition in Python:

• https://github.com/oracle/solaris-userland/blob/master/components/python/python37/patches/15-gethostname.patch
• https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/components/python/python37/patches/15-gethostname.patch
• https://github.com/omniosorg/omnios-build/blob/master/build/python27/patches/24-gethostname.patch

• Issue: request to reopen Issue837046 - pyport.h redeclares gethostname() if SOLARIS is defined #63760

[vstinner]

@kulikjak: Would you mind to review my PR? (And test it if possible?)

I saw your PR #23208, but I tried to add more documentation about the change from the issue and your latest comments.

I plan to backport the change manually to Python 3.12 (the function was defined in pyport.h), and then to 3.11.

[kulikjak]

@vstinner, I tried running tests but sadly the build failed due to what seems like unrelated issue:

/builds/cpython-main/Modules/termios.c: In function 'termios_tcgetwinsize_impl':
/builds/cpython-main/Modules/termios.c:389:9: error: implicit declaration of function 'ioctl' [-Werror=implicit-function-declaration]
389 |     r = ioctl(fd, TIOCGWINSZ, &w);
    |         ^~~~~
/builds/cpython-main/Modules/_multiprocessing/multiprocessing.c: In function 'multiprocessing_exec':
/builds/cpython-main/Modules/_multiprocessing/multiprocessing.h:44:32: error: implicit declaration of function 'sysconf'; did you mean '_sysconf'? [-Werror=implicit-function-declaration]
44 |         # define SEM_VALUE_MAX sysconf(_SC_SEM_VALUE_MAX)
   |                                ^~~~~

but I don't see how this change can break anything as it's how we compile Python for many years now.

Just two minor nits for the NEWS fragment - it's at least since 2005 (when Solaris was opened) and it's not just Oracle Solaris but Solaris in general.

[vstinner]

/builds/cpython-main/Modules/_multiprocessing/multiprocessing.c: In function 'multiprocessing_exec':
/builds/cpython-main/Modules/_multiprocessing/multiprocessing.h:44:32: error: implicit declaration of function 'sysconf'; did you mean '_sysconf'? [-Werror=implicit-function-declaration]
44 |         # define SEM_VALUE_MAX sysconf(_SC_SEM_VALUE_MAX)
   |                                ^~~~~

I wrote PR #108823 to fix warning.

For Modules/termios.c, I don't know which include is missing on Solaris to get ioctl(). Is it also unistd.h? On Linux, man ioctl asks to #include <sys/ioctl.h>.

[vstinner]

Just two minor nits for the NEWS fragment - it's at least since 2005 (when Solaris was opened) and it's not just Oracle Solaris but Solaris in general.

Ok, I updated the PR. Would you mind to review it again?

[kulikjak]

Thanks!

[kulikjak]

For Modules/termios.c, I don't know which include is missing on Solaris to get ioctl(). Is it also unistd.h? On Linux, man ioctl asks to #include <sys/ioctl.h>.

Yes, I needed to add unistd.h there for build to pass. With #108823 there seems to be no issues anymore. Thanks!

[bedevere-bot]

GH-108824 is a backport of this pull request to the 3.12 branch.

[vstinner]

Yes, I needed to add unistd.h there for build to pass. With #108823 there seems to be no issues anymore. Thanks!

Please create a PR for Modules/termios.c.

[kulikjak]

I created #108825 to fix it.