tools/nolibc: add assert() and assert.h

Add the standard assert() macro from the assert.h header.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260409-nolibc-assert-v1-1-42da8b367e23@weissschuh.net

tools/include/nolibc/Makefile

@@ -20,6 +20,7 @@ OUTPUT ?= $(CURDIR)/
 architectures := arm arm64 loongarch m68k mips powerpc riscv s390 sh sparc x86
 arch_files := arch.h $(addsuffix .h, $(addprefix arch-, $(architectures)))
 all_files := \
+		assert.h \
 		byteswap.h \
 		compiler.h \
 		crt.h \

tools/include/nolibc/assert.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * Assert for NOLIBC
+ * Copyright (C) 2026 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#ifndef _NOLIBC_ASSERT_H
+#define _NOLIBC_ASSERT_H
+
+#include "errno.h"
+#include "stdio.h"
+#include "stdlib.h"
+
+#endif /* _NOLIBC_ASSERT_H */
+
+/* NDEBUG needs to be evaluated on *each* inclusion */
+#ifdef assert
+#undef assert
+#endif
+
+#ifndef NDEBUG
+#define assert(expr)									\
+({											\
+	if (!(expr)) {									\
+		fprintf(stderr, "%s: %s:%d: %s: Assertion `%s' failed.\n",		\
+			program_invocation_short_name, __FILE__, __LINE__, __func__,	\
+			#expr);								\
+		abort();								\
+	}										\
+})
+#else
+#define assert(expr) ((void)0)
+#endif

tools/include/nolibc/nolibc.h

@@ -133,6 +133,7 @@
 #include "err.h"
 #include "byteswap.h"
 #include "endian.h"
+#include "assert.h"
 
 /* Used by programs to avoid std includes */
 #define NOLIBC