core: add stdio.h to replace stdout functions with stdio_null

core/include/stdio.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2024 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup     sys_stdio_null
+ *
+ * This module a wrapper for the stdio.h header intended to remove all calls
+ * to stdout when stdio_null is used.
+ *
+ * This needs to reside in `core/` so it gets included early.
+ *
+ * @{
+ *
+ * @file
+ * @brief       stdio wrapper to replace the C libs stdio
+ *
+ * @author      Benjamin Valentin <[email protected]>
+ */
+
+#ifndef CORE_STDIO_H
+#define CORE_STDIO_H
+#include_next "stdio.h"
+
+#ifdef MODULE_STDIO_NULL
+
+#include <stdarg.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+static inline int printf_null(const char *restrict format, ...)
+{
+    (void)format;
+    return 0;
+}
+
+static inline int vprintf_null(const char *restrict format, va_list ap)
+{
+    (void)format;
+    (void)ap;
+    return 0;
+}
+
+#undef putchar
+#undef puts
+#undef printf
+#undef vprintf
+
+#define puts(s)     (void)s
+#define putchar(c)  (void)c
+#define printf(...) printf_null(__VA_ARGS__)
+#define vprintf(format, ap) vprintf_null(format, ap)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MODULE_STDIO_NULL */
+
+#endif /* CORE_STDIO_H */
+/** @} */