posix: implement xsi_single_process and posix_clock_selection

doc/services/portability/posix/option_groups/index.rst

@@ -678,6 +678,21 @@ Enable this option group with :kconfig:option:`CONFIG_XSI_REALTIME`.
 When this option group is enabled, the ``_XOPEN_REALTIME`` feature test macro will be defined to a
 value other than -1.
 
+.. _posix_option_group_xsi_single_process:
+
+XSI_SINGLE_PROCESS
+++++++++++++++++++
+
+Enable this option group with :kconfig:option:`CONFIG_XSI_SINGLE_PROCESS`.
+
+.. csv-table:: XSI_SINGLE_PROCESS
+   :header: API, Supported
+   :widths: 50,10
+
+    gethostid(),yes
+    gettimeofday(),yes
+    putenv(),yes
+
 .. _posix_option_group_xsi_system_logging:
 
 XSI_SYSTEM_LOGGING

include/zephyr/posix/unistd.h

@@ -77,6 +77,10 @@ size_t confstr(int name, char *buf, size_t len);
 long sysconf(int opt);
 #endif /* CONFIG_POSIX_SYSCONF_IMPL_FULL */
 
+#if _XOPEN_SOURCE >= 500
+long gethostid(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif

lib/posix/options/CMakeLists.txt

@@ -2,7 +2,9 @@
 
 set(GEN_DIR ${ZEPHYR_BINARY_DIR}/include/generated)
 
+zephyr_syscall_header_ifdef(CONFIG_POSIX_CLOCK_SELECTION posix_clock.h)
 zephyr_syscall_header_ifdef(CONFIG_POSIX_TIMERS posix_clock.h)
+zephyr_syscall_header_ifdef(CONFIG_XSI_SINGLE_PROCESS posix_clock.h)
 
 if(CONFIG_POSIX_API)
   zephyr_include_directories(${ZEPHYR_BASE}/include/zephyr/posix)
@@ -44,6 +46,13 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_BARRIERS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_BARRIERS barrier.c)
 endif()
 
+if (NOT CONFIG_TC_PROVIDES_POSIX_CLOCK_SELECTION)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK_SELECTION
+    clock_common.c
+    clock_selection.c
+  )
+endif()
+
 if (NOT CONFIG_TC_PROVIDES_POSIX_C_LIB_EXT)
   zephyr_library_sources_ifdef(CONFIG_POSIX_C_LIB_EXT
     fnmatch.c
@@ -102,6 +111,7 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_SINGLE_PROCESS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_SINGLE_PROCESS
     confstr.c
     env.c
+    env_common.c
     sysconf.c
     uname.c
   )
@@ -114,6 +124,7 @@ endif()
 if (NOT CONFIG_TC_PROVIDES_POSIX_TIMERS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_TIMERS
     clock.c
+    clock_common.c
     timer.c
     timespec_to_timeout.c
   )
@@ -153,6 +164,14 @@ endif()
 
 zephyr_library_sources_ifdef(CONFIG_XOPEN_STREAMS stropts.c)
 
+if (NOT CONFIG_TC_PROVIDES_XSI_SINGLE_PROCESS)
+  zephyr_library_sources_ifdef(CONFIG_XSI_SINGLE_PROCESS
+    clock_common.c
+    env_common.c
+    xsi_single_process.c
+  )
+endif()
+
 if (NOT CONFIG_TC_PROVIDES_XSI_SYSTEM_LOGGING)
   zephyr_library_sources_ifdef(CONFIG_XSI_SYSTEM_LOGGING syslog.c)
 endif()

lib/posix/options/Kconfig.clock_selection

@@ -0,0 +1,13 @@
+# Copyright (c) 2025 Tenstorrent AI ULC
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config POSIX_CLOCK_SELECTION
+	bool "POSIX Clock Selection"
+	help
+	  Select 'y' here and Zephyr will provide an implementation of the POSIX_CLOCK_SELECTION Option
+	  Group, which includes the functions clock_nanosleep(), pthread_condattr_getclock(),
+	  pthread_condattr_setclock().
+
+	  For more information, please see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html

lib/posix/options/Kconfig.proc1

@@ -49,8 +49,12 @@ config POSIX_UNAME_NODENAME_LEN
 	help
 	  Defines the maximum string length of nodename version.
 
+endif # POSIX_SINGLE_PROCESS
+
+if POSIX_SINGLE_PROCESS || XSI_SINGLE_PROCESS
+
 module = POSIX_ENV
 module-str = POSIX env logging
 source "subsys/logging/Kconfig.template.log_config"
 
-endif # POSIX_SINGLE_PROCESS
+endif # POSIX_SINGLE_PROCESS || XSI_SINGLE_PROCESS

lib/posix/options/Kconfig.profile

@@ -12,6 +12,7 @@ config POSIX_API
 	imply EVENTFD # eventfd(), eventfd_read(), eventfd_write()
 	imply POSIX_FD_MGMT # open(), close(), read(), write()
 	imply POSIX_MULTI_PROCESS # sleep(), getpid(), etc
+	imply XSI_SINGLE_PROCESS # gettimeofday()
 	help
 	  This option enables the required POSIX System Interfaces (base definitions), all of PSE51,
 	  and some features found in PSE52.

lib/posix/options/Kconfig.xsi_single_process

@@ -4,11 +4,14 @@
 
 config XSI_SINGLE_PROCESS
 	bool "X/Open single process"
-	depends on POSIX_SINGLE_PROCESS
-	depends on POSIX_TIMERS
+	select HWINFO
 	help
 	  Select 'y' here and Zephyr will provide implementations of
 	  gethostid(), gettimeofday(), and putenv().
 
 	  For more information, please see
 	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
+
+module = XSI_SINGLE_PROCESS
+module-str = XSI Single Process
+source "subsys/logging/Kconfig.template.log_config"