posix: separate option groups into c library ext and system interfaces

Separate the POSIX implementation into two categories:

- Extensions to ISO C
- System Interfaces

The first category include standalone functions that generally do not
require OS support or depend on any other features within the POSIX
specification. The Option Groups that comprise this category include

- POSIX_C_LIB_EXT: e.g. strnlen(), fnmatch()
- POSIX_C_LANG_SUPPORT_R: e.g. gmtime_r(), strtok_r()

The second category includes the majority of other POSIX Option Groups
that do require OS support. The latter group may also be categorized
generally as being NATIVE_LIBC_INCOMPATIBLE, although that might
eventually become more granular.

Signed-off-by: Chris Friedt <[email protected]>

Author: cfriedt

lib/posix/CMakeLists.txt

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
-add_subdirectory(options)
 add_subdirectory_ifdef(CONFIG_EVENTFD eventfd)
+add_subdirectory_ifdef(CONFIG_POSIX_C_LANG_SUPPORT_R c_lang_support_r)
+add_subdirectory_ifdef(CONFIG_POSIX_C_LIB_EXT c_lib_ext)
 add_subdirectory_ifdef(CONFIG_POSIX_SHELL shell)
+add_subdirectory_ifdef(CONFIG_POSIX_SYSTEM_INTERFACES options)

lib/posix/Kconfig

@@ -1,11 +1,42 @@
 # Copyright (c) 2024 Meta
+# Copyright (c) 2025 Tenstorrent AI ULC
 #
 # SPDX-License-Identifier: Apache-2.0
 
 menu "POSIX API Support"
 
+# POSIX Subprofile Definitions
+rsource "Kconfig.profile"
+
+# Toolchain hooks for external implementations
+rsource "Kconfig.toolchain"
+
+# POSIX C Library Extensions
+# This menu is for POSIX Option Groups that do not require OS support.
+menu "POSIX C Library Extensions"
+rsource "c_lang_support_r/Kconfig"
+rsource "c_lib_ext/Kconfig"
+endmenu
+
+# POSIX System Interfaces
+menuconfig POSIX_SYSTEM_INTERFACES
+	bool "POSIX System Interfaces"
+	select NATIVE_LIBC_INCOMPATIBLE
+	help
+	  Select 'y' here to support POSIX System Interfaces within Zephyr.
+
+	  Options in this menu are organized by POSIX subprofiling Option Group.
+
+	  For more information, see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
+
+
+if POSIX_SYSTEM_INTERFACES
 rsource "options/Kconfig"
+
+# POSIX Shell utilities
 rsource "shell/Kconfig"
+endif
 
 endmenu
 

lib/posix/options/Kconfig.profile renamed to lib/posix/Kconfig.profile

@@ -2,16 +2,15 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-config POSIX_SYSTEM_HEADERS
+config POSIX_SYSTEM_INTERFACES
 	bool
 	select NATIVE_LIBC_INCOMPATIBLE
 	help
 	  Make POSIX headers available to the system without the "zephyr/posix" prefix.
 
 config POSIX_API
 	bool "POSIX APIs"
-	select NATIVE_LIBC_INCOMPATIBLE
-	select POSIX_SYSTEM_HEADERS
+	select POSIX_SYSTEM_INTERFACES
 	select POSIX_BASE_DEFINITIONS # clock_gettime(), pthread_create(), sem_get(), etc
 	select POSIX_AEP_REALTIME_MINIMAL # CLOCK_MONOTONIC, pthread_attr_setstack(), etc
 	select POSIX_NETWORKING if NETWORKING # inet_ntoa(), socket(), etc
@@ -38,13 +37,13 @@ choice POSIX_AEP_CHOICE
 	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
 
 config POSIX_AEP_CHOICE_NONE
-	bool "No pre-defined POSIX subprofile"
+	bool "No POSIX subprofile"
 	help
-	  No pre-defined POSIX profile is selected.
+	  No POSIX subprofile is selected.
 
 config POSIX_AEP_CHOICE_BASE
-	bool "Base definitions (system interfaces)"
-	select NATIVE_LIBC_INCOMPATIBLE
+	bool "Minimal POSIX System Profile"
+	select POSIX_SYSTEM_INTERFACES
 	select POSIX_BASE_DEFINITIONS
 	help
 	  Only enable the base definitions required for all POSIX systems.
@@ -54,7 +53,7 @@ config POSIX_AEP_CHOICE_BASE
 
 config POSIX_AEP_CHOICE_PSE51
 	bool "Minimal Realtime System Profile (PSE51)"
-	select NATIVE_LIBC_INCOMPATIBLE
+	select POSIX_SYSTEM_INTERFACES
 	select POSIX_BASE_DEFINITIONS
 	select POSIX_AEP_REALTIME_MINIMAL
 	help
@@ -67,7 +66,7 @@ config POSIX_AEP_CHOICE_PSE51
 
 config POSIX_AEP_CHOICE_PSE52
 	bool "Realtime Controller System Profile (PSE52)"
-	select NATIVE_LIBC_INCOMPATIBLE
+	select POSIX_SYSTEM_INTERFACES
 	select POSIX_BASE_DEFINITIONS
 	select POSIX_AEP_REALTIME_MINIMAL
 	select POSIX_AEP_REALTIME_CONTROLLER
@@ -81,7 +80,7 @@ config POSIX_AEP_CHOICE_PSE52
 
 config POSIX_AEP_CHOICE_PSE53
 	bool "Dedicated Realtime System Profile (PSE53)"
-	select NATIVE_LIBC_INCOMPATIBLE
+	select POSIX_SYSTEM_INTERFACES
 	select POSIX_BASE_DEFINITIONS
 	select POSIX_AEP_REALTIME_MINIMAL
 	select POSIX_AEP_REALTIME_CONTROLLER
@@ -98,10 +97,11 @@ config POSIX_AEP_CHOICE_PSE53
 
 endchoice # POSIX_AEP_CHOICE
 
-# Base Definitions (System Interfaces)
+if POSIX_SYSTEM_INTERFACES
+
+# Mandatory POSIX System Interfaces (base profile)
 config POSIX_BASE_DEFINITIONS
 	bool
-	select POSIX_SYSTEM_HEADERS
 	select POSIX_ASYNCHRONOUS_IO
 	select POSIX_BARRIERS
 	select POSIX_CLOCK_SELECTION
@@ -187,3 +187,5 @@ config POSIX_AEP_REALTIME_DEDICATED
 
 	  For more information, please see
 	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
+
+endif # POSIX_SYSTEM_INTERFACE

lib/posix/options/Kconfig.toolchain renamed to lib/posix/Kconfig.toolchain

@@ -0,0 +1,8 @@
+# Copyright The Zephyr Project Contributors
+# SPDX-License-Identifier: Apache-2.0
+
+set(POSIX_VERSION 200809L)
+
+if (CONFIG_POSIX_C_LANG_SUPPORT_R)
+  zephyr_compile_definitions(-D_POSIX_THREAD_SAFE_FUNCTIONS=${POSIX_VERSION})
+endif()

lib/posix/c_lang_support_r/CMakeLists.txt

@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_include_directories(getopt)
+
+if (CONFIG_TC_PROVIDES_POSIX_C_LIB_EXT)
+  return()
+endif()
+
+zephyr_library()
+zephyr_library_sources(
+  fnmatch.c
+  getentropy.c
+  getopt/getopt.c
+  getopt/getopt_common.c
+)
+
+zephyr_library_sources_ifdef(CONFIG_GETOPT_LONG getopt/getopt_long.c)