posix: options: add custom Zephyr POSIX subprofile

lib/posix/CMakeLists.txt

@@ -1,4 +1,9 @@
 # SPDX-License-Identifier: Apache-2.0
 
-add_subdirectory(options)
+# zephyr-keep-sorted-start
+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)
+# zephyr-keep-sorted-stop

lib/posix/Kconfig

@@ -1,10 +1,44 @@
 # 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
 
-endmenu # "POSIX API Support"
+# Eventfd Support (not officially POSIX)
+rsource "eventfd/Kconfig"

lib/posix/options/Kconfig.profile → 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
@@ -27,7 +26,7 @@ config POSIX_API
 
 choice POSIX_AEP_CHOICE
 	prompt "POSIX Subprofile"
-	default POSIX_AEP_CHOICE_NONE
+	default POSIX_AEP_CHOICE_ZEPHYR
 	help
 	  This choice is intended to help users select the correct POSIX profile for their
 	  application. Choices are based on IEEE 1003.13-2003 (now inactive / reserved) and
@@ -38,13 +37,35 @@ 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 POSIX subprofile is selected.
+
+config POSIX_AEP_CHOICE_ZEPHYR
+	bool "Minimal Zephyr System Profile"
+	select POSIX_C_LIB_EXT
+	select POSIX_C_LANG_SUPPORT_R
 	help
-	  No pre-defined POSIX profile is selected.
+	  Zephyr expects certain POSIX functions to be available throughout the build environment,
+	  such as gmtime_r(), strnlen(), strtok_r(), and possibly others.
+
+	  These functions are divided into two standalone Option Groups that may be enabled
+	  independently of the remainder of the POSIX API implementation; namely POSIX_C_LIB_EXT and
+	  POSIX_C_LANG_SUPPORT_R. If not referenced by the Zephyr kernel or application, there are no
+	  resource implications for enabling these option groups.
+
+	  Unlike pre-defined, standard POSIX subprofiles, this subprofile is custom to Zephyr and
+	  therefore does not need to include the base definitions or system interfaces that would
+	  otherwise be required for a conformant POSIX system or subprofile. This system profile
+	  does not itself meet the requirements for POSIX implementation conformance.
+
+	  For more information, see
+	  https://docs.zephyrproject.org/latest/contribute/coding_guidelines/index.html
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
 
 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 +75,7 @@ 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 +88,7 @@ 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 +102,7 @@ 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 +119,11 @@ 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 +209,5 @@ 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/c_lang_support_r/CMakeLists.txt

@@ -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_lib_ext/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)

lib/posix/options/getopt/getopt.c → lib/posix/c_lib_ext/getopt/getopt.c

@@ -1,4 +1,4 @@
 /*	$NetBSD: getopt.c,v 1.26 2003/08/07 16:43:40 agc Exp $	*/
 /* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1987, 1993, 1994
@@ -41,9 +41,9 @@
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(getopt);
 
-#define	BADCH	((int)'?')
-#define	BADARG	((int)':')
-#define	EMSG	""
+#define BADCH  ((int)'?')
+#define BADARG ((int)':')
+#define EMSG   ""
 
 void getopt_init(void)
 {
@@ -61,7 +61,7 @@
 
 #if CONFIG_GETOPT_LONG
 	state->nonopt_start = -1; /* first non option argument (for permute) */
-	state->nonopt_end = -1; /* first option after non options (for permute) */
+	state->nonopt_end = -1;   /* first option after non options (for permute) */
 #endif
 
 	opterr = 1;
@@ -151,8 +151,7 @@
 				return BADARG;
 			}
 			if (state->opterr) {
-				LOG_DBG("option requires an argument -- %c",
-					state->optopt);
+				LOG_DBG("option requires an argument -- %c", state->optopt);
 			}
 			z_getopt_global_state_update(state);
 			return BADCH;
@@ -161,5 +160,5 @@
 		++state->optind;
 	}
 	z_getopt_global_state_update(state);
-	return state->optopt;	/* return option letter */
+	return state->optopt; /* return option letter */
 }

lib/posix/options/getopt/getopt.h → lib/posix/c_lib_ext/getopt/getopt.h

@@ -14,29 +14,29 @@ extern "C" {
 #include <zephyr/kernel.h>
 
 struct getopt_state {
-	int opterr;	/* if error message should be printed */
-	int optind;	/* index into parent argv vector */
-	int optopt;	/* character checked for validity */
-	int optreset;	/* reset getopt */
-	char *optarg;	/* argument associated with option */
+	int opterr;   /* if error message should be printed */
+	int optind;   /* index into parent argv vector */
+	int optopt;   /* character checked for validity */
+	int optreset; /* reset getopt */
+	char *optarg; /* argument associated with option */
 
-	char *place;	/* option letter processing */
+	char *place; /* option letter processing */
 
 #if CONFIG_GETOPT_LONG
 	int nonopt_start;
 	int nonopt_end;
 #endif
 };
 
-extern int optreset;	/* reset getopt */
+extern int optreset; /* reset getopt */
 extern char *optarg;
 extern int opterr;
 extern int optind;
 extern int optopt;
 
-#define no_argument        0
-#define required_argument  1
-#define optional_argument  2
+#define no_argument       0
+#define required_argument 1
+#define optional_argument 2
 
 struct option {
 	/* name of long option */
@@ -79,9 +79,8 @@ struct getopt_state *getopt_state_get(void);
  * @return		If an option was successfully found, function returns
  *			the option character.
  */
-int getopt_long(int nargc, char *const *nargv,
-		const char *options, const struct option *long_options,
-		int *idx);
+int getopt_long(int nargc, char *const *nargv, const char *options,
+		const struct option *long_options, int *idx);
 
 /**
  * @brief Parses the command-line arguments.
@@ -106,9 +105,8 @@ int getopt_long(int nargc, char *const *nargv,
  * @return		If an option was successfully found, function returns
  *			the option character.
  */
-int getopt_long_only(int nargc, char *const *nargv,
-		     const char *options, const struct option *long_options,
-		     int *idx);
+int getopt_long_only(int nargc, char *const *nargv, const char *options,
+		     const struct option *long_options, int *idx);
 
 #ifdef __cplusplus
 }

lib/posix/options/getopt/getopt_common.c → lib/posix/c_lib_ext/getopt/getopt_common.c

@@ -16,11 +16,11 @@
  * When more threads are using getopt please call getopt_state_get to know
  * getopt state for the current thread.
  */
-int opterr = 1;	/* if error message should be printed */
-int optind = 1;	/* index into parent argv vector */
-int optopt;	/* character checked for validity */
-int optreset;	/* reset getopt */
-char *optarg;	/* argument associated with option */
+int opterr = 1; /* if error message should be printed */
+int optind = 1; /* index into parent argv vector */
+int optopt;     /* character checked for validity */
+int optreset;   /* reset getopt */
+char *optarg;   /* argument associated with option */
 
 /* Common state for all threads that did not have own getopt state. */
 static struct getopt_state m_getopt_common_state = {
@@ -34,7 +34,7 @@ static struct getopt_state m_getopt_common_state = {
 
 #if CONFIG_GETOPT_LONG
 	.nonopt_start = -1, /* first non option argument (for permute) */
-	.nonopt_end = -1, /* first option after non options (for permute) */
+	.nonopt_end = -1,   /* first option after non options (for permute) */
 #endif
 };