[PATCH v4 04/34] KVM: selftests: Add strnlen() to the string overrides

[Sean Christopherson <seanjc@google.com>]

From: Aaron Lewis <aaronlewis@google.com>

Add strnlen() to the string overrides to allow it to be called in the
guest.

The implementation for strnlen() was taken from the kernel's generic
version, lib/string.c.

This will be needed when printf() is introduced.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 tools/testing/selftests/kvm/Makefile              | 1 +
 tools/testing/selftests/kvm/lib/string_override.c | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c692cc86e7da..f6c14ab476ac 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -204,6 +204,7 @@ endif
 CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
 	-Wno-gnu-variable-sized-type-not-at-end -MD\
 	-fno-builtin-memcmp -fno-builtin-memcpy -fno-builtin-memset \
+	-fno-builtin-strnlen \
 	-fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) \
 	-I$(LINUX_TOOL_ARCH_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude \
 	-I$(<D) -Iinclude/$(ARCH_DIR) -I ../rseq -I.. $(EXTRA_CFLAGS) \
diff --git a/tools/testing/selftests/kvm/lib/string_override.c b/tools/testing/selftests/kvm/lib/string_override.c
index 632398adc229..5d1c87277c49 100644
--- a/tools/testing/selftests/kvm/lib/string_override.c
+++ b/tools/testing/selftests/kvm/lib/string_override.c
@@ -37,3 +37,12 @@ void *memset(void *s, int c, size_t count)
 		*xs++ = c;
 	return s;
 }
+
+size_t strnlen(const char *s, size_t count)
+{
+	const char *sc;
+
+	for (sc = s; count-- && *sc != '\0'; ++sc)
+		/* nothing */;
+	return sc - s;
+}
-- 
2.41.0.487.g6d72f3e995-goog