pmaports/cross/gcc-armhf/0004-Turn-on-D_FORTIFY_SOURCE-2-by-default-for-C-C-ObjC-O.patch

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From 36fde4108ebb872cbf0e45d815e76fc3ef69ded5 Mon Sep 17 00:00:00 2001
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From: Ariadne Conill <ariadne@dereferenced.org>
Date: Fri, 21 Aug 2020 06:46:22 +0000
Subject: [PATCH] Turn on -D_FORTIFY_SOURCE=2 by default for C, C++, ObjC,
ObjC++, if the optimization level is > 0
---
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gcc/c-family/c-cppbuiltin.c | 4 ++++
gcc/doc/invoke.texi | 6 ++++++
2 files changed, 10 insertions(+)
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diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 9f993c4aff2..7db314195ff 100644
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--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -1421,6 +1421,10 @@ c_cpp_builtins (cpp_reader *pfile)
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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 4b8335bbd1f..833164e0a2b 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10224,6 +10224,12 @@ 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}.
+
@item -O3
@opindex O3
Optimize yet more. @option{-O3} turns on all optimizations specified
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--
2.34.1
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