From bb3ef1f5acfde9658c922d0aef9283fe60328c33 Mon Sep 17 00:00:00 2001
From: Ariadne Conill <ariadne@dereferenced.org>
Date: Fri, 21 Aug 2020 06:46:22 +0000
Subject: [PATCH 04/33] Turn on -D_FORTIFY_SOURCE=2 by default for C, C++,
ObjC, ObjC++, if the optimization level is > 0
---
gcc/c-family/c-cppbuiltin.cc | 4 ++++
gcc/doc/invoke.texi | 6 ++++++
2 files changed, 10 insertions(+)
diff --git a/gcc/c-family/c-cppbuiltin.cc b/gcc/c-family/c-cppbuiltin.cc
index 5d64625fcd7..868d69506e4 100644
--- a/gcc/c-family/c-cppbuiltin.cc
+++ b/gcc/c-family/c-cppbuiltin.cc
@@ -1546,6 +1546,10 @@ c_cpp_builtins (cpp_reader *pfile)
builtin_define_with_value ("__REGISTER_PREFIX__", REGISTER_PREFIX, 0);
builtin_define_with_value ("__USER_LABEL_PREFIX__", user_label_prefix, 0);
+ /* Fortify Source enabled by default for optimization levels > 0 */
+ if (optimize)
+ builtin_define_with_int_value ("_FORTIFY_SOURCE", 2);
+
/* Misc. */
if (flag_gnu89_inline)
cpp_define (pfile, "__GNUC_GNU_INLINE__");
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index cb34e6d40c9..7f1aa660285 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11866,6 +11866,12 @@ also turns on the following optimization flags:
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
+NOTE: In Alpine Linux, @option{-D_FORTIFY_SOURCE=2} is
+set by default, and is activated when @option{-O} is set to 2 or higher.
+This enables additional compile-time and run-time checks for several libc
+functions. To disable, specify either @option{-U_FORTIFY_SOURCE} or
+@option{-D_FORTIFY_SOURCE=0}.
+
@opindex O3
@item -O3
Optimize yet more. @option{-O3} turns on all optimizations specified
--
2.41.0