[PATCH 1/7] kasan: Add .kunitconfig for KUnit tests

[PATCH 1/7] kasan: Add .kunitconfig for KUnit tests

[Bill Wendling]

Add a .kunitconfig file for the KASAN test suite so that it can easily
be run via kunit.py:

    ./tools/testing/kunit/kunit.py run --arch=x86_64 --kunitconfig mm/kasan

CONFIG_KASAN_KUNIT_TEST depends on TRACEPOINTS, which is an invisible
Kconfig symbol without a prompt. CONFIG_FTRACE alone only unlocks the
tracer submenu and does not select TRACEPOINTS by itself, so also
enable CONFIG_SCHED_TRACER=y, which selects GENERIC_TRACER -> TRACING
-> TRACEPOINTS. This follows the same pattern used by
security/landlock/.kunitconfig. Verified with:

    make KCONFIG_ALLCONFIG=mm/kasan/.kunitconfig allnoconfig

that CONFIG_TRACEPOINTS=y and CONFIG_KASAN_KUNIT_TEST=y both resolve.

In addition, set CONFIG_LOG_BUF_SHIFT=20 to prevent printk buffer
overflows on serial consoles when running under QEMU, as KASAN generates
extensive reports across its test cases.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Mickaël Salaün" <mic@digikod.net>
Cc: "Günther Noack" <gnoack@google.com>
Cc: linux-kernel@vger.kernel.org
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Cc: linux-security-module@vger.kernel.org
---
 mm/kasan/.kunitconfig | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 mm/kasan/.kunitconfig

diff --git a/mm/kasan/.kunitconfig b/mm/kasan/.kunitconfig
new file mode 100644
index 000000000000..58a7448fa352
--- /dev/null
+++ b/mm/kasan/.kunitconfig
@@ -0,0 +1,15 @@
+CONFIG_KUNIT=y
+CONFIG_KASAN=y
+CONFIG_KASAN_KUNIT_TEST=y
+
+# Additional dependencies.
+# CONFIG_KASAN_KUNIT_TEST depends on TRACEPOINTS, an invisible Kconfig
+# symbol with no prompt. CONFIG_FTRACE alone only unlocks the tracer
+# submenu; CONFIG_SCHED_TRACER is needed to actually select
+# GENERIC_TRACER -> TRACING -> TRACEPOINTS.
+CONFIG_FTRACE=y
+CONFIG_SCHED_TRACER=y
+
+# Prevent printk buffer overflows on serial consoles when running under
+# QEMU, since KASAN generates extensive reports across its test cases.
+CONFIG_LOG_BUF_SHIFT=20
-- 
2.47.3

[PATCH 2/7] x86/word-at-a-time: Instrument load_unaligned_zeropad()

load_unaligned_zeropad() is implemented as inline asm plus an
exception table entry on every architecture, so the compiler never
sees the actual memory access and cannot emit KASAN/KCSAN
instrumentation for it.

Resurrect the instrumentation that was lost when migrating from
read_word_at_a_time() by renaming load_unaligned_zeropad() to
arch_load_unaligned_zeropad() and adding a common instrumented
load_unaligned_zeropad() in the new
asm-generic/word-at-a-time-instrumented.h, pulled in from the bottom
of asm/word-at-a-time.h. This mirrors the existing
arch_atomic_*()/atomic_*() split in linux/atomic/atomic-instrumented.h,
where the arch_* version is the raw, uninstrumented primitive and the
plain name is the instrumented one everyone should call.

The wrapper is __always_inline, so it compiles down to exactly the
same inline asm as before plus instrument_read() -- confirmed via
objdump that no calls or relocations to load_unaligned_zeropad(),
instrument_read(), or the KASAN/KCSAN check functions remain when
KASAN and KCSAN are both disabled.

Convert x86 to the new split here. Follow-up patches convert the
remaining architectures (arm64, arm, riscv, s390, powerpc) that
implement load_unaligned_zeropad().

Fixes: d94c12bd97d5 ("string: Add load_unaligned_zeropad() code path to sized_strscpy()")
Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Kees Cook <kees@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Collingbourne <peter@pcc.me.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-riscv@lists.infradead.org
Cc: x86@kernel.org
---
 arch/x86/include/asm/word-at-a-time.h         |  4 ++-
 .../asm-generic/word-at-a-time-instrumented.h | 25 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 include/asm-generic/word-at-a-time-instrumented.h

diff --git a/arch/x86/include/asm/word-at-a-time.h b/arch/x86/include/asm/word-at-a-time.h
index 422a47746657..483d27dc96b2 100644
--- a/arch/x86/include/asm/word-at-a-time.h
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -67,7 +67,7 @@ static inline unsigned long find_zero(unsigned long mask)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret;
 
@@ -81,4 +81,6 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return ret;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
diff --git a/include/asm-generic/word-at-a-time-instrumented.h b/include/asm-generic/word-at-a-time-instrumented.h
new file mode 100644
index 000000000000..8a66d53bf538
--- /dev/null
+++ b/include/asm-generic/word-at-a-time-instrumented.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H
+#define _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H
+
+#include <linux/instrumented.h>
+
+/*
+ * Each arch's asm/word-at-a-time.h defines arch_load_unaligned_zeropad()
+ * as inline asm plus an exception table entry, so the compiler never sees
+ * the actual memory access and cannot emit KASAN/KCSAN instrumentation
+ * for it. Provide the common, instrumented load_unaligned_zeropad() that
+ * every caller uses by wrapping the arch version with instrument_read().
+ *
+ * This is marked __always_inline, and arch_load_unaligned_zeropad() is
+ * itself a tiny inline-asm-only function, so this compiles down to the
+ * same inline asm as before plus instrument_read() (which itself compiles
+ * to nothing when KASAN and KCSAN are both disabled) -- no actual call.
+ */
+static __always_inline unsigned long load_unaligned_zeropad(const void *addr)
+{
+	instrument_read(addr, 1);
+	return arch_load_unaligned_zeropad(addr);
+}
+
+#endif /* _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H */
-- 
2.47.3


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

[PATCH 2/7] x86/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

load_unaligned_zeropad() is implemented as inline asm plus an
exception table entry on every architecture, so the compiler never
sees the actual memory access and cannot emit KASAN/KCSAN
instrumentation for it.

Resurrect the instrumentation that was lost when migrating from
read_word_at_a_time() by renaming load_unaligned_zeropad() to
arch_load_unaligned_zeropad() and adding a common instrumented
load_unaligned_zeropad() in the new
asm-generic/word-at-a-time-instrumented.h, pulled in from the bottom
of asm/word-at-a-time.h. This mirrors the existing
arch_atomic_*()/atomic_*() split in linux/atomic/atomic-instrumented.h,
where the arch_* version is the raw, uninstrumented primitive and the
plain name is the instrumented one everyone should call.

The wrapper is __always_inline, so it compiles down to exactly the
same inline asm as before plus instrument_read() -- confirmed via
objdump that no calls or relocations to load_unaligned_zeropad(),
instrument_read(), or the KASAN/KCSAN check functions remain when
KASAN and KCSAN are both disabled.

Convert x86 to the new split here. Follow-up patches convert the
remaining architectures (arm64, arm, riscv, s390, powerpc) that
implement load_unaligned_zeropad().

Fixes: d94c12bd97d5 ("string: Add load_unaligned_zeropad() code path to sized_strscpy()")
Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Kees Cook <kees@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Collingbourne <peter@pcc.me.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-riscv@lists.infradead.org
Cc: x86@kernel.org
---
 arch/x86/include/asm/word-at-a-time.h         |  4 ++-
 .../asm-generic/word-at-a-time-instrumented.h | 25 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 include/asm-generic/word-at-a-time-instrumented.h

diff --git a/arch/x86/include/asm/word-at-a-time.h b/arch/x86/include/asm/word-at-a-time.h
index 422a47746657..483d27dc96b2 100644
--- a/arch/x86/include/asm/word-at-a-time.h
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -67,7 +67,7 @@ static inline unsigned long find_zero(unsigned long mask)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret;
 
@@ -81,4 +81,6 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return ret;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
diff --git a/include/asm-generic/word-at-a-time-instrumented.h b/include/asm-generic/word-at-a-time-instrumented.h
new file mode 100644
index 000000000000..8a66d53bf538
--- /dev/null
+++ b/include/asm-generic/word-at-a-time-instrumented.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H
+#define _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H
+
+#include <linux/instrumented.h>
+
+/*
+ * Each arch's asm/word-at-a-time.h defines arch_load_unaligned_zeropad()
+ * as inline asm plus an exception table entry, so the compiler never sees
+ * the actual memory access and cannot emit KASAN/KCSAN instrumentation
+ * for it. Provide the common, instrumented load_unaligned_zeropad() that
+ * every caller uses by wrapping the arch version with instrument_read().
+ *
+ * This is marked __always_inline, and arch_load_unaligned_zeropad() is
+ * itself a tiny inline-asm-only function, so this compiles down to the
+ * same inline asm as before plus instrument_read() (which itself compiles
+ * to nothing when KASAN and KCSAN are both disabled) -- no actual call.
+ */
+static __always_inline unsigned long load_unaligned_zeropad(const void *addr)
+{
+	instrument_read(addr, 1);
+	return arch_load_unaligned_zeropad(addr);
+}
+
+#endif /* _ASM_GENERIC_WORD_AT_A_TIME_INSTRUMENTED_H */
-- 
2.47.3

[PATCH 3/7] arm64/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

Convert arm64 to the arch_load_unaligned_zeropad() /
load_unaligned_zeropad() split introduced for x86 in the previous
patch, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
on this architecture (e.g. under CONFIG_KASAN_SW_TAGS).

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/arm64/include/asm/word-at-a-time.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h
index 824ca6987a51..656e3274ed7a 100644
--- a/arch/arm64/include/asm/word-at-a-time.h
+++ b/arch/arm64/include/asm/word-at-a-time.h
@@ -47,7 +47,7 @@ static inline unsigned long zero_bytemask(unsigned long bits)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret;
 
@@ -66,4 +66,6 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return ret;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif /* __ASM_WORD_AT_A_TIME_H */
-- 
2.47.3

[PATCH 4/7] arm/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

Convert arm to the arch_load_unaligned_zeropad() /
load_unaligned_zeropad() split introduced for x86 earlier in this
series, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
on this architecture.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
Cc: Liyuan Pang <pangliyuan1@huawei.com>
Cc: Xie Yuanbin <xieyuanbin1@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/arm/include/asm/word-at-a-time.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h
index 5023f98d8293..ef0002d16dc1 100644
--- a/arch/arm/include/asm/word-at-a-time.h
+++ b/arch/arm/include/asm/word-at-a-time.h
@@ -65,7 +65,7 @@ static inline unsigned long find_zero(unsigned long mask)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret, tmp;
 
@@ -96,5 +96,7 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return ret;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif	/* DCACHE_WORD_ACCESS */
 #endif /* __ASM_ARM_WORD_AT_A_TIME_H */
-- 
2.47.3

[PATCH 5/7] riscv/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

Convert riscv to the arch_load_unaligned_zeropad() /
load_unaligned_zeropad() split introduced for x86 earlier in this
series, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
on this architecture.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: linux-riscv@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/riscv/include/asm/word-at-a-time.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/word-at-a-time.h b/arch/riscv/include/asm/word-at-a-time.h
index 3802cda71ab7..a4294b50c918 100644
--- a/arch/riscv/include/asm/word-at-a-time.h
+++ b/arch/riscv/include/asm/word-at-a-time.h
@@ -56,7 +56,7 @@ static inline unsigned long find_zero(unsigned long mask)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret;
 
@@ -71,6 +71,8 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return ret;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif	/* CONFIG_DCACHE_WORD_ACCESS */
 
 #endif /* _ASM_RISCV_WORD_AT_A_TIME_H */
-- 
2.47.3


_______________________________________________
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

[PATCH 6/7] s390/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

Convert s390 to the arch_load_unaligned_zeropad() /
load_unaligned_zeropad() split introduced for x86 earlier in this
series, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
on this architecture.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 arch/s390/include/asm/word-at-a-time.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/word-at-a-time.h b/arch/s390/include/asm/word-at-a-time.h
index eaa19dee7699..6a055bee5ba0 100644
--- a/arch/s390/include/asm/word-at-a-time.h
+++ b/arch/s390/include/asm/word-at-a-time.h
@@ -48,7 +48,7 @@ static inline unsigned long zero_bytemask(unsigned long data)
  * and the next page not being mapped, take the exception and
  * return zeroes in the non-existing part.
  */
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long data;
 
@@ -62,4 +62,6 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 	return data;
 }
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
-- 
2.47.3

Re: [PATCH 6/7] s390/word-at-a-time: Instrument load_unaligned_zeropad()

[sashiko-bot]

> Convert s390 to the arch_load_unaligned_zeropad() /
> load_unaligned_zeropad() split introduced for x86 earlier in this
> series, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
> on this architecture.
> 
> Assisted-by: Claude:claude-sonnet-5
> Signed-off-by: Bill Wendling <morbo@google.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911070346.801948-1-morbo@google.com?part=6

[PATCH 7/7] powerpc/word-at-a-time: Instrument load_unaligned_zeropad()

[Bill Wendling]

Convert powerpc to the arch_load_unaligned_zeropad() /
load_unaligned_zeropad() split introduced for x86 earlier in this
series, so KASAN/KCSAN also see reads through load_unaligned_zeropad()
on this architecture.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/include/asm/word-at-a-time.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
index 54653a863414..9a09620ca776 100644
--- a/arch/powerpc/include/asm/word-at-a-time.h
+++ b/arch/powerpc/include/asm/word-at-a-time.h
@@ -164,7 +164,7 @@ static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits,
 #define FIXUP_SECTION ".fixup"
 #endif
 
-static inline unsigned long load_unaligned_zeropad(const void *addr)
+static inline unsigned long arch_load_unaligned_zeropad(const void *addr)
 {
 	unsigned long ret, offset, tmp;
 
@@ -203,4 +203,6 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
 
 #undef FIXUP_SECTION
 
+#include <asm-generic/word-at-a-time-instrumented.h>
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
-- 
2.47.3