Two things I noticed in __compiletime_strlen:
1. A temporary, __p, is created+used to avoid repeated side effects from
multiple evaluation of the macro parameter, but the macro parameter
was being used accidentally in __builtin_object_size.
2. The temporary has a curious signedness and const-less qualification.
Just use __auto_type.
3. (size_t)-1 is perhaps more readable as -1UL.
4. __p_size == -1UL when __builtin_object_size can't evaluate the
object size at compile time. We could just reuse __ret and use one
less variable here.
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---
include/linux/fortify-string.h | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index c5adad596a3f..aaf73575050f 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -22,11 +22,10 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
#define __compiletime_strlen(p) \
({ \
- unsigned char *__p = (unsigned char *)(p); \
- size_t __ret = (size_t)-1; \
- size_t __p_size = __object_size(p, 1); \
- if (__p_size != (size_t)-1) { \
- size_t __p_len = __p_size - 1; \
+ __auto_type __p = (p); \
+ size_t __ret = __object_size(__p, 1); \
+ if (__ret != -1UL) { \
+ size_t __p_len = __ret - 1; \
if (__builtin_constant_p(__p[__p_len]) && \
__p[__p_len] == '\0') \
__ret = __builtin_strlen(__p); \
--
2.37.2.672.g94769d06f0-goog
