posix: options: add custom Zephyr POSIX subprofile

[cfriedt]

• eventfd: bring config to top-level of posix dir, since it is not posix
• posix: separate option groups into c library ext and system interfaces
• posix: c_lib_ext: apply clang-format to getopt sources
• posix: profiles: add custom Zephyr POSIX subprofile
• posix: profiles: make POSIX_AEP_CHOICE_ZEPHYR the default
• posix: options: add keep-sorted-start and -stop

Fixes #75843

Should only be merged after

• posix + tests: correct timing functions to use CLOCK_REALTIME #88762
• tests: posix: rwlocks: ensure test is not skipped #88767
• tests: posix: semaphores: ensure test is not skipped #88769
• sys: timeutil: add utility functions for struct timespec #90060
• sys: clock: add sys_clock api and remove posix from iso c time #90096
• posix: move limit definitions to posix_limits.h #94612
• util: move utf8 utils to a separate header #95355
• posix: system_database_r: remove invalid compilation filters #95224
• tests: posix: common: use realtime clock instead of monotonic #95225
• libc: newlib: limits.h: include zephyr's posix limits #95196
• posix: use posix_time.h and posix_signal.h [v2] #96589

Note

The sources used when CONFIG_POSIX_C_LANG_SUPPORT_R=y and CONFIG_POSIX_C_LIB_EXT=y can still be
overridden with CONFIG_TC_PROVIDES_POSIX_C_LANG_SUPPORT_R=y an CONFIG_TC_PROVIDES_POSIX_C_LIB_EXT=y (which must be used with select <option> in Kconfig), as they are primarily meant for toolchain maintainers.

A comparison when building samples/hello_world for native_sim.

Before:

wc -l build-main/zephyr/.config
   1295 build-main/zephyr/.config

After:

wc -l build-branch/zephyr/.config
   1220 build-branch/zephyr/.config

diff -Nua build-{main,branch}/zephyr/.config

--- build-main/zephyr/.config   2025-05-24 11:33:53.697011215 -0400
+++ build-branch/zephyr/.config 2025-05-24 11:34:27.140913656 -0400
@@ -900,98 +900,23 @@
 #
 # POSIX API Support
 #
-
-#
-# POSIX Options
-#
 # CONFIG_POSIX_API is not set
-CONFIG_POSIX_AEP_CHOICE_NONE=y
-# CONFIG_POSIX_AEP_CHOICE_BASE is not set
-# CONFIG_POSIX_AEP_CHOICE_PSE51 is not set
-# CONFIG_POSIX_AEP_CHOICE_PSE52 is not set
-# CONFIG_POSIX_AEP_CHOICE_PSE53 is not set
-# CONFIG_POSIX_ASYNCHRONOUS_IO is not set
-# CONFIG_POSIX_BARRIERS is not set
-# CONFIG_POSIX_C_LANG_SUPPORT_R is not set
-# CONFIG_POSIX_C_LIB_EXT is not set
-
-#
-# POSIX device I/O
-#
-# CONFIG_POSIX_DEVICE_IO is not set
-CONFIG_POSIX_OPEN_MAX=4
-# end of POSIX device I/O
-
-# CONFIG_POSIX_FD_MGMT is not set
-# CONFIG_POSIX_FILE_SYSTEM_R is not set
-# CONFIG_POSIX_FILE_SYSTEM is not set
-
-#
-# POSIX memory
-#
-CONFIG_POSIX_PAGE_SIZE=0x40
-# CONFIG_POSIX_SHARED_MEMORY_OBJECTS is not set
-# CONFIG_POSIX_MAPPED_FILES is not set
-# CONFIG_POSIX_MEMORY_PROTECTION is not set
-# end of POSIX memory
-
-# CONFIG_POSIX_MESSAGE_PASSING is not set
-# CONFIG_POSIX_SINGLE_PROCESS is not set
-# CONFIG_POSIX_MULTI_PROCESS is not set
-# CONFIG_POSIX_THREADS is not set
-# CONFIG_POSIX_READER_WRITER_LOCKS is not set
-
-#
-# POSIX scheduler options
-#
-# CONFIG_POSIX_PRIORITY_SCHEDULING is not set
-# end of POSIX scheduler options
-
-# CONFIG_POSIX_SEMAPHORES is not set
-
-#
-# POSIX signals
-#
-# CONFIG_POSIX_REALTIME_SIGNALS is not set
-# CONFIG_POSIX_SIGNALS is not set
-# end of POSIX signals
-
-# CONFIG_POSIX_SPIN_LOCKS is not set
-
-#
-# POSIX synchronized I/O
-#
-# CONFIG_POSIX_FSYNC is not set
-# CONFIG_POSIX_SYNCHRONIZED_IO is not set
-# end of POSIX synchronized I/O
-
-# CONFIG_POSIX_TIMERS is not set
-
-#
-# X/Open system interfaces
-#
-# CONFIG_XSI_REALTIME is not set
-# CONFIG_XSI_SINGLE_PROCESS is not set
-# CONFIG_XOPEN_STREAMS is not set
-# CONFIG_XSI_SYSTEM_LOGGING is not set
-# CONFIG_XSI_THREADS_EXT is not set
-# end of X/Open system interfaces
-
-#
-# Miscellaneous POSIX-related options
-#
-# CONFIG_EVENTFD is not set
-# end of Miscellaneous POSIX-related options
-
+# CONFIG_POSIX_AEP_CHOICE_NONE is not set
+CONFIG_POSIX_AEP_CHOICE_ZEPHYR=y
 CONFIG_TC_PROVIDES_POSIX_C_LANG_SUPPORT_R=y
-# end of POSIX Options
 
 #
-# POSIX Shell Utilities
+# POSIX C Library Extensions
 #
-# end of POSIX Shell Utilities
+CONFIG_POSIX_C_LANG_SUPPORT_R=y
+CONFIG_POSIX_C_LIB_EXT=y
+# CONFIG_GETOPT_LONG is not set
+# end of POSIX C Library Extensions
+
+# CONFIG_POSIX_SYSTEM_INTERFACES is not set
 # end of POSIX API Support
 
+# CONFIG_EVENTFD is not set
 # CONFIG_OPENAMP_RSC_TABLE is not set
 # CONFIG_SMF is not set
 CONFIG_LIBGCC_RTLIB=y

[cfriedt]

Probably one or two follow-up PRs can be made to ensure that the POSIX_C_LIB_EXT Option Group is complete. I think there are some string manipulation functions missing (not ISO C).

Currently, all of the implementation of POSIX_C_LANG_SUPPORT_R is done in libc/common, which ... doesn't matter too much, but that could be corrected later if necessary.

[cfriedt]

Shell utilities should probably also be gated by the new Kconfig.

[jukkar]

Thanks Chris, this helps to understand what is going on with the POSIX options.

[cfriedt]

I'll give this a rebase shorty

[sonarqubecloud]

Quality Gate passed

Issues
36 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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