fortify: replace bzero/bcmp defines
__builtin_*_chk will emit warnings when things are trivially broken.
Emitting errors instead is probably better (and we can be a bit smarter
about how we emit code for trivially safe cases.)
Bug: 131861088
Test: checkbuild + bionic-unit-tests on blueline
Change-Id: I33957ad419922d0760304758ecb9bc8ad33e0b64
diff --git a/libc/bionic/ndk_cruft.cpp b/libc/bionic/ndk_cruft.cpp
index 2c3299f..f0a7026 100644
--- a/libc/bionic/ndk_cruft.cpp
+++ b/libc/bionic/ndk_cruft.cpp
@@ -243,15 +243,23 @@
return signal(signum, handler);
}
+// bcopy/bzero were previously `#define`d, so we only have `static` wrappers in
+// Bionic headers. Since we have header definitions, we need some way to
+// overload these implementations; __never_call will ensure that any calls to
+// bcopy/bzero call the in-header implementation. Since the implementations
+// should end up functionally identical, it doesn't matter which we actually
+// call.
+#define __never_call __attribute__((enable_if(false, "never selected")))
+
// This was removed from POSIX 2008.
-#undef bcopy
-void bcopy(const void* src, void* dst, size_t n) {
+void bcopy(const void* src, void* dst, size_t n) __never_call __RENAME(bcopy);
+void bcopy(const void* src, void* dst, size_t n) __never_call {
memmove(dst, src, n);
}
// This was removed from POSIX 2008.
-#undef bzero
-void bzero(void* dst, size_t n) {
+void bzero(void* dst, size_t n) __never_call __RENAME(bzero);
+void bzero(void* dst, size_t n) __never_call {
memset(dst, 0, n);
}