libc: add clang FORTIFY support
This patch adds clang-style FORTIFY to Bionic. For more information on
FORTIFY, please see https://goo.gl/8HS2dW . This implementation works
for versions of clang that don't support diagnose_if, so please see the
"without diagnose_if" sections. We plan to swap to a diagnose_if-based
FORTIFY later this year (since it doesn't really add any features; it
just simplifies the implementation a lot, and it gives us much prettier
diagnostics)
Bug: 32073964
Test: Builds on angler, bullhead, marlin, sailfish. Bionic CTS tests
pass on Angler and Bullhead.
Change-Id: I607aecbeee81529709b1eee7bef5b0836151eb2b
diff --git a/libc/arch-arm/generic/bionic/strlen.c b/libc/arch-arm/generic/bionic/strlen.c
index b9f3a2a..f6b9209 100644
--- a/libc/arch-arm/generic/bionic/strlen.c
+++ b/libc/arch-arm/generic/bionic/strlen.c
@@ -29,7 +29,7 @@
#include <string.h>
#include <stdint.h>
-size_t strlen(const char *s)
+size_t strlen(const char *s) __overloadable
{
__builtin_prefetch(s);
__builtin_prefetch(s+32);