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/include/bits/fortify/strings.h b/libc/include/bits/fortify/strings.h
new file mode 100644
index 0000000..6bda295
--- /dev/null
+++ b/libc/include/bits/fortify/strings.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined(__BIONIC_FORTIFY)
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+void bcopy(const void *src, void* const dst __pass_object_size0, size_t len)
+        __overloadable
+        __clang_error_if(__bos_unevaluated_lt(__bos0(dst), len),
+                         "'bcopy' called with size bigger than buffer") {
+    size_t bos = __bos0(dst);
+    if (__bos_trivially_not_lt(bos, len)) {
+        __builtin_memmove(dst, src, len);
+    } else {
+        __builtin___memmove_chk(dst, src, len, bos);
+    }
+}
+
+__BIONIC_FORTIFY_INLINE
+void bzero(void* const b __pass_object_size0, size_t len)
+        __overloadable
+        __clang_error_if(__bos_unevaluated_lt(__bos0(b), len),
+                         "'bzero' called with size bigger than buffer") {
+    size_t bos = __bos0(b);
+    if (__bos_trivially_not_lt(bos, len)) {
+        __builtin_memset(b, 0, len);
+    } else {
+        __builtin___memset_chk(b, 0, len, bos);
+    }
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#endif /* defined(__BIONIC_FORTIFY) */