posix: implement other _POSIX_THREAD_SAFE_FUNCTIONS

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

@@ -564,13 +564,13 @@ This table lists service support status in Zephyr for `POSIX_FD_MGMT`:
    :header: API, Supported
    :widths: 50,10
 
-    flockfile(),
-    ftrylockfile(),
-    funlockfile(),
-    getc_unlocked(),
-    getchar_unlocked(),
-    putc_unlocked(),
-    putchar_unlocked(),
+    flockfile(), yes
+    ftrylockfile(), yes
+    funlockfile(), yes
+    getc_unlocked(), yes :ref:`†<posix_undefined_behaviour>`
+    getchar_unlocked(), yes :ref:`†<posix_undefined_behaviour>`
+    putc_unlocked(), yes
+    putchar_unlocked(), yes
 
 .. _posix_option_group_memory_protection:
 
@@ -901,11 +901,11 @@ _POSIX_THREAD_SAFE_FUNCTIONS
 
     asctime_r(),
     ctime_r(),
-    flockfile(),
-    ftrylockfile(),
-    funlockfile(),
-    getc_unlocked(),
-    getchar_unlocked(),
+    flockfile(), yes
+    ftrylockfile(), yes
+    funlockfile(), yes
+    getc_unlocked(), yes :ref:`†<posix_undefined_behaviour>`
+    getchar_unlocked(), yes :ref:`†<posix_undefined_behaviour>`
     getgrgid_r(),
     getgrnam_r(),
     getpwnam_r(),

lib/libc/Kconfig

@@ -75,6 +75,9 @@ config MINIMAL_LIBC
 	imply COMMON_LIBC_MALLOC
 	imply COMMON_LIBC_CALLOC
 	imply COMMON_LIBC_REALLOCARRAY
+	select POSIX_FILE_LOCKING if POSIX_THREAD_SAFE_FUNCTIONS
+	select COMMON_LIBC_PUTC_UNLOCKED if POSIX_THREAD_SAFE_FUNCTIONS
+	select COMMON_LIBC_GETC_UNLOCKED if POSIX_THREAD_SAFE_FUNCTIONS
 	help
 	  Build with minimal C library.
 

lib/libc/common/CMakeLists.txt

@@ -17,5 +17,7 @@ zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_THRD
     source/thrd/tss.c
     )
 
+add_subdirectory(source)
+
 # Prevent compiler from optimizing calloc into an infinite recursive call
 zephyr_library_compile_options($<TARGET_PROPERTY:compiler,no_builtin_malloc>)

lib/libc/common/Kconfig

@@ -82,3 +82,5 @@ config COMMON_LIBC_THRD
 	default y
 	help
 	  Common implementation of C11 <threads.h> API.
+
+rsource "source/Kconfig"

lib/libc/common/source/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2024 Meta Platforms
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory_ifdef(CONFIG_COMMON_LIBC_STDIO stdio)

lib/libc/common/source/Kconfig

@@ -0,0 +1,4 @@
+# Copyright (c) 2024 Meta Platforms
+# SPDX-License-Identifier: Apache-2.0
+
+rsource "stdio/Kconfig"

lib/libc/common/source/stdio/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2024 Meta Platforms
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_GETC_UNLOCKED getc_unlocked.c)
+zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_PUTC_UNLOCKED putc_unlocked.c)

lib/libc/common/source/stdio/Kconfig

@@ -0,0 +1,19 @@
+# Copyright (c) 2024 Meta Platforms
+# SPDX-License-Identifier: Apache-2.0
+
+config COMMON_LIBC_STDIO
+	bool
+	help
+	  common function implementation in stdio.h
+
+config COMMON_LIBC_GETC_UNLOCKED
+	bool
+	select COMMON_LIBC_STDIO
+	help
+	  common implementation of getc_unlocked() & getchar_unlocked().
+
+config COMMON_LIBC_PUTC_UNLOCKED
+	bool
+	select COMMON_LIBC_STDIO
+	help
+	  common implementation of putc_unlocked() & putchar_unlocked().

lib/libc/common/source/stdio/getc_unlocked.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2024 Meta Platforms
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include <zephyr/sys/util.h>
+
+int getc_unlocked(FILE *stream)
+{
+	ARG_UNUSED(stream);
+
+	errno = ENOSYS;
+
+	return EOF;
+}
+
+int getchar_unlocked(void)
+{
+	return getc_unlocked(stdin);
+}

lib/libc/common/source/stdio/putc_unlocked.c

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2024 Meta Platforms
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+
+#include <zephyr/sys/libc-hooks.h>
+
+int putc_unlocked(int c, FILE *stream)
+{
+	return zephyr_fputc(c, stream);
+}
+
+int putchar_unlocked(int c)
+{
+	return putc_unlocked(c, stdout);
+}

lib/libc/minimal/include/stdio.h

@@ -63,6 +63,22 @@ size_t fwrite(const void *ZRESTRICT ptr, size_t size, size_t nitems,
 #define putc(c, stream) fputc(c, stream)
 #define putchar(c) putc(c, stdout)
 
+#if defined(CONFIG_COMMON_LIBC_PUTC_UNLOCKED) || defined(__DOXYGEN__)
+int putc_unlocked(int c, FILE *stream);
+int putchar_unlocked(int c);
+#endif /* CONFIG_COMMON_LIBC_PUTC_UNLOCKED || __DOXYGEN__ */
+
+#if defined(CONFIG_COMMON_LIBC_GETC_UNLOCKED) || defined(__DOXYGEN__)
+int getc_unlocked(FILE *stream);
+int getchar_unlocked(void);
+#endif /* CONFIG_COMMON_LIBC_GETC_UNLOCKED || __DOXYGEN__ */
+
+#if defined(CONFIG_POSIX_FILE_LOCKING) || defined(__DOXYGEN__)
+void flockfile(FILE *file);
+int ftrylockfile(FILE *file);
+void funlockfile(FILE *file);
+#endif /* CONFIG_POSIX_FILE_LOCKING || __DOXYGEN__ */
+
 #ifdef __cplusplus
 }
 #endif

lib/os/fdtable.c

@@ -392,6 +392,35 @@ int zvfs_fsync(int fd)
 	return z_fdtable_call_ioctl(fdtable[fd].vtable, fdtable[fd].obj, ZFD_IOCTL_FSYNC);
 }
 
+#if defined(CONFIG_POSIX_FILE_LOCKING)
+void zvfs_flockfile(int fd)
+{
+	if (_check_fd(fd) < 0) {
+		return;
+	}
+
+	(void)k_mutex_lock(&fdtable[fd].lock, K_FOREVER);
+}
+
+int zvfs_ftrylockfile(int fd)
+{
+	if (_check_fd(fd) < 0) {
+		return -1;
+	}
+
+	return k_mutex_lock(&fdtable[fd].lock, K_NO_WAIT);
+}
+
+void zvfs_funlockfile(int fd)
+{
+	if (_check_fd(fd) < 0) {
+		return;
+	}
+
+	(void)k_mutex_unlock(&fdtable[fd].lock);
+}
+#endif /* CONFIG_POSIX_FILE_LOCKING */
+
 static inline off_t zvfs_lseek_wrap(int fd, int cmd, ...)
 {
 	off_t res;

lib/posix/options/CMakeLists.txt

@@ -55,6 +55,7 @@ zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK mlockall.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MEMLOCK_RANGE mlock.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MEMORY_PROTECTION mprotect.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MAPPED_FILES mmap.c)
+zephyr_library_sources_ifdef(CONFIG_POSIX_FILE_LOCKING file_locking.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MESSAGE_PASSING mqueue.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MULTI_PROCESS
   sleep.c

lib/posix/options/Kconfig

@@ -13,6 +13,7 @@ rsource "Kconfig.barrier"
 rsource "Kconfig.c_lib_ext"
 rsource "Kconfig.device_io"
 rsource "Kconfig.fd_mgmt"
+rsource "Kconfig.file_locking"
 rsource "Kconfig.fs"
 rsource "Kconfig.mem"
 rsource "Kconfig.mqueue"

lib/posix/options/Kconfig.file_locking

@@ -0,0 +1,38 @@
+# Copyright (c) 2024 Meta Platforms
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config POSIX_FILE_LOCKING
+	bool "POSIX file locking [EXPERIMENTAL]"
+	select EXPERIMENTAL
+	select FDTABLE
+	help
+	  Select 'y' here and Zephyr will provide implementations for the POSIX_FILE_LOCKING Option
+	  Group.
+	  This includes support for flockfile(), ftrylockfile(), funlockfile(), getc_unlocked(),
+	  getchar_unlocked(), putc_unlocked() and putchar_unlocked().
+
+	  For more information, please see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
+
+if POSIX_FILE_LOCKING
+
+# These options are intended to be used for compatibility with external POSIX
+# implementations such as those in Newlib or Picolibc.
+
+config POSIX_FD_MGMT_ALIAS_FLOCKFILE
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for flockfile() as _flockfile().
+
+config POSIX_FD_MGMT_ALIAS_FTRYLOCKFILE
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for ftrylockfile() as _ftrylockfile().
+
+config POSIX_FD_MGMT_ALIAS_FUNLOCKFILE
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for funlockfile() as _funlockfile().
+
+endif # POSIX_FILE_LOCKING

lib/posix/options/Kconfig.pthread

@@ -156,6 +156,7 @@ config POSIX_THREAD_PRIO_PROTECT
 
 config POSIX_THREAD_SAFE_FUNCTIONS
 	bool "POSIX thread-safe functions"
+	select POSIX_FILE_LOCKING
 	help
 	  Select 'y' here to enable POSIX thread-safe functions including asctime_r(), ctime_r(),
 	  flockfile(), ftrylockfile(), funlockfile(), getc_unlocked(), getchar_unlocked(),

lib/posix/options/file_locking.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2024 Meta Platforms
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include <zephyr/sys/libc-hooks.h>
+#include <zephyr/sys/util.h>
+
+void zvfs_flockfile(int fd);
+int zvfs_ftrylockfile(int fd);
+void zvfs_funlockfile(int fd);
+
+void flockfile(FILE *file)
+{
+	zvfs_flockfile(POINTER_TO_INT(file));
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_FLOCKFILE
+FUNC_ALIAS(flockfile, _flockfile, void);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_FLOCKFILE */
+
+int ftrylockfile(FILE *file)
+{
+	return zvfs_ftrylockfile(POINTER_TO_INT(file));
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_FTRYLOCKFILE
+FUNC_ALIAS(ftrylockfile, _ftrylockfile, int);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_FTRYLOCKFILE */
+
+void funlockfile(FILE *file)
+{
+	zvfs_funlockfile(POINTER_TO_INT(file));
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_FUNLOCKFILE
+FUNC_ALIAS(funlockfile, _funlockfile, void);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_FUNLOCKFILE */