libc: minimal: implement putc_unlocked & putchar_unlocked

Add a simple implementation for putc_unlocked() &
putchar_unlocked().

Signed-off-by: Yong Cong Sin <ycsin@meta.com>

Author: ycsin

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

@@ -569,8 +569,8 @@ This table lists service support status in Zephyr for `POSIX_FD_MGMT`:
     funlockfile(), yes
     getc_unlocked(),
     getchar_unlocked(),
-    putc_unlocked(),
-    putchar_unlocked(),
+    putc_unlocked(), yes
+    putchar_unlocked(), yes
 
 .. _posix_option_group_memory_protection:
 

lib/libc/Kconfig

@@ -76,6 +76,8 @@ config MINIMAL_LIBC
 	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);
+}