git: 37bd69d43c70 - main - sys: Add sys/ckdint.h

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=37bd69d43c70346b9191f7ce07ee9ed783ce528f

commit 37bd69d43c70346b9191f7ce07ee9ed783ce528f
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-08-17 17:06:04 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-08-17 18:41:36 +0000

    sys: Add sys/ckdint.h
    
    We have a C23 stdckdint.h header for userspace, which provides checked
    addition, subtraction and multiplication.  We lack similar helpers in
    the kernel, where they are regularly needed.
    
    Let's just adopt the C23 macros.  For bonus points, I added a wrapper to
    ensure that ignored an return value is raised as an error by the
    compiler.
    
    Reviewed by:    kib, emaste
    MFC after:      2 weeks
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D58773
---
 include/stdckdint.h | 26 ++------------------------
 sys/sys/ckdint.h    | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 24 deletions(-)

diff --git a/include/stdckdint.h b/include/stdckdint.h
index 9cb877fe8198..fe1e100abe32 100644
--- a/include/stdckdint.h
+++ b/include/stdckdint.h
@@ -7,33 +7,11 @@
 #ifndef __STDC_VERSION_STDCKDINT_H__
 #define __STDC_VERSION_STDCKDINT_H__ 202311L
 
-#include <sys/cdefs.h>
+#include <sys/_visible.h>
 
 #if __BSD_VISIBLE || __ISO_C_VISIBLE >= 2023
 
-#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_add_overflow)
-#define ckd_add(result, a, b)						\
-	__builtin_add_overflow((a), (b), (result))
-#else
-#define ckd_add(result, a, b)						\
-	_Static_assert(0, "checked addition not supported")
-#endif
-
-#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_sub_overflow)
-#define ckd_sub(result, a, b)						\
-	__builtin_sub_overflow((a), (b), (result))
-#else
-#define ckd_sub(result, a, b)						\
-	_Static_assert(0, "checked subtraction not supported")
-#endif
-
-#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_mul_overflow)
-#define ckd_mul(result, a, b)						\
-	__builtin_mul_overflow((a), (b), (result))
-#else
-#define ckd_mul(result, a, b)						\
-	_Static_assert(0, "checked multiplication not supported")
-#endif
+#include <sys/ckdint.h>
 
 #endif
 
diff --git a/sys/sys/ckdint.h b/sys/sys/ckdint.h
new file mode 100644
index 000000000000..273d38fd713b
--- /dev/null
+++ b/sys/sys/ckdint.h
@@ -0,0 +1,47 @@
+/*-
+ * Copyright (c) 2023 Dag-Erling Smørgrav
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#ifndef _SYS_CKDINT_H_
+#define	_SYS_CKDINT_H_
+
+#include <sys/cdefs.h>
+
+#ifdef _KERNEL
+/* If you're not checking the return value, what's the point? */
+__nodiscard static inline bool
+__ckd_result(bool result)
+{
+	return (result);
+}
+#else
+#define	__ckd_result(result)	(result)
+#endif
+
+#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_add_overflow)
+#define ckd_add(result, a, b)						\
+	__ckd_result(__builtin_add_overflow((a), (b), (result)))
+#else
+#define ckd_add(result, a, b)						\
+	_Static_assert(0, "checked addition not supported")
+#endif
+
+#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_sub_overflow)
+#define ckd_sub(result, a, b)						\
+	__ckd_result(__builtin_sub_overflow((a), (b), (result)))
+#else
+#define ckd_sub(result, a, b)						\
+	_Static_assert(0, "checked subtraction not supported")
+#endif
+
+#if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_mul_overflow)
+#define ckd_mul(result, a, b)						\
+	__ckd_result(__builtin_mul_overflow((a), (b), (result)))
+#else
+#define ckd_mul(result, a, b)						\
+	_Static_assert(0, "checked multiplication not supported")
+#endif
+
+#endif /* _SYS_CKDINT_H_ */