net: socketpair: fcntl non-functional with socketpair-provided sockets on posix arch

[cfriedt]

Describe the bug
Encountered in #54747, fcntl() does not seem to be working on socketpair()-provided sockets with CONFIG_ARCH_POSIX.

The result is that non-blocking I/O on socketpair()-provided sockets are non-functional (but only on native_posix and related ARCH_POSIX boards).

Please also mention any information which could help others to understand
the problem you're facing:

• What target platform are you using?: native_posix, native_posix_64, nrf52_bsim.
• What have you tried to diagnose or workaround this issue?: skipped tests with the known bad configuration in tests: net: socketpair: clean up tests and provide coverage for all libcs #54747
• Is this a regression? Who knows at this point. It's likely that socketpair worked on native_posix originally because we were linking it in from the native libc. If there was a regression, then it was caused by the massive workaround for splitting networking off to run under native_posix and making CONFIG_ARCH_POSIX and CONFIG_POSIX_API mutually exclusive. But that in itself was just fixing issues with which code paths were actually linked-in (i.e. not mixing native posix and zephyr system calls).
• ...

To Reproduce
Steps to reproduce the behavior:

1. Remove blocks containing ztest_test_skip() added in tests: net: socketpair: clean up tests and provide coverage for all libcs #54747
2. west build -p auto -b native_posix tests/net/sockets/socketpair
3. See error

Expected behavior
Test cases should pass and non-blocking I/O on socketpair sockets under native_posix should be supported.

Impact
Non-blocking I/O on socketpair sockets under native_posix are not supported until this is fixed.

In the larger scope, this is just one of many issues that need to be fixed to support CONFIG_POSIX_API under CONFIG_ARCH_POSIX.

Logs and console output

*** Booting Zephyr OS build zephyr-v3.3.0-196-g4c70a99d0a0f ***
Running TESTSUITE net_socketpair
===================================================================
START - AF_LOCAL__SOCK_STREAM__0
 PASS - AF_LOCAL__SOCK_STREAM__0 in 0.000 seconds
===================================================================
START - AF_UNIX__SOCK_STREAM__0
 PASS - AF_UNIX__SOCK_STREAM__0 in 0.000 seconds
===================================================================
START - close_one_end_and_read_from_the_other
 PASS - close_one_end_and_read_from_the_other in 0.000 seconds
===================================================================
START - close_one_end_and_write_to_the_other
 PASS - close_one_end_and_write_to_the_other in 0.000 seconds
===================================================================
START - expected_failures
 PASS - expected_failures in 0.000 seconds
===================================================================
START - poll_close_remote_end_POLLIN
 PASS - poll_close_remote_end_POLLIN in 1.010 seconds
===================================================================
START - poll_close_remote_end_POLLOUT
 PASS - poll_close_remote_end_POLLOUT in 1.010 seconds
===================================================================
START - poll_delayed_data
 PASS - poll_delayed_data in 0.220 seconds
===================================================================
START - poll_immediate_data
 PASS - poll_immediate_data in 0.000 seconds
===================================================================
START - poll_signalling_POLLIN
 PASS - poll_signalling_POLLIN in 0.000 seconds
===================================================================
START - poll_signalling_POLLOUT
 PASS - poll_signalling_POLLOUT in 0.000 seconds
===================================================================
START - poll_timeout
 PASS - poll_timeout in 0.040 seconds
===================================================================
START - poll_timeout_nonblocking
 PASS - poll_timeout_nonblocking in 0.040 seconds
===================================================================
START - read_block
 PASS - read_block in 0.220 seconds
===================================================================
START - read_nonblock
non-blocking socketpair I/O is unsupported with CONFIG_ARCH_POSIX
 SKIP - read_nonblock in 0.000 seconds
===================================================================
START - unsupported_calls
 PASS - unsupported_calls in 0.000 seconds
===================================================================
START - write_block
 PASS - write_block in 0.000 seconds
===================================================================
START - write_nonblock
non-blocking socketpair I/O is unsupported with CONFIG_ARCH_POSIX
 SKIP - write_nonblock in 0.000 seconds
===================================================================
START - zsock_fcntl_wrapper
non-blocking socketpair I/O is unsupported with CONFIG_ARCH_POSIX

    Assertion failed at WEST_TOPDIR/zephyr/tests/net/socket/socketpair/src/fcntl.c:38: net_socketpair_zsock_fcntl_wrapper: (res ^ flags not equal to O_NONBLOCK)
expected O_NONBLOCK set
 FAIL - zsock_fcntl_wrapper in 0.000 seconds
===================================================================
TESTSUITE net_socketpair failed.

------ TESTSUITE SUMMARY START ------

SUITE FAIL -  94.12% [net_socketpair]: pass = 16, fail = 1, skip = 2, total = 19 duration = 2.540 seconds
 - PASS - [net_socketpair.AF_LOCAL__SOCK_STREAM__0] duration = 0.000 seconds
 - PASS - [net_socketpair.AF_UNIX__SOCK_STREAM__0] duration = 0.000 seconds
 - PASS - [net_socketpair.close_one_end_and_read_from_the_other] duration = 0.000 seconds
 - PASS - [net_socketpair.close_one_end_and_write_to_the_other] duration = 0.000 seconds
 - PASS - [net_socketpair.expected_failures] duration = 0.000 seconds
 - PASS - [net_socketpair.poll_close_remote_end_POLLIN] duration = 1.010 seconds
 - PASS - [net_socketpair.poll_close_remote_end_POLLOUT] duration = 1.010 seconds
 - PASS - [net_socketpair.poll_delayed_data] duration = 0.220 seconds
 - PASS - [net_socketpair.poll_immediate_data] duration = 0.000 seconds
 - PASS - [net_socketpair.poll_signalling_POLLIN] duration = 0.000 seconds
 - PASS - [net_socketpair.poll_signalling_POLLOUT] duration = 0.000 seconds
 - PASS - [net_socketpair.poll_timeout] duration = 0.040 seconds
 - PASS - [net_socketpair.poll_timeout_nonblocking] duration = 0.040 seconds
 - PASS - [net_socketpair.read_block] duration = 0.220 seconds
 - SKIP - [net_socketpair.read_nonblock] duration = 0.000 seconds
 - PASS - [net_socketpair.unsupported_calls] duration = 0.000 seconds
 - PASS - [net_socketpair.write_block] duration = 0.000 seconds
 - SKIP - [net_socketpair.write_nonblock] duration = 0.000 seconds
 - FAIL - [net_socketpair.zsock_fcntl_wrapper] duration = 0.000 seconds

------ TESTSUITE SUMMARY END ------

===================================================================
PROJECT EXECUTION FAILED

Environment (please complete the following information):

• OS: (e.g. Linux, MacOS, Windows): Linux
• Toolchain (e.g Zephyr SDK, ...): Zephyr SDK v0.15.2
• Commit SHA or Version used: 4c70a99

Additional context
This is one of many other conflicts that exist between CONFIG_ARCH_POSIX and CONFIG_POSIX_API and should be addressed along with LTSv3 RoadMap.

Also, socketpair() will be continue to be marked as experimental until it is stable on native_posix.