[Sanitizer] Make CommonFlags immutable after initialization.

Summary:
Protect CommonFlags singleton by adding const qualifier to
common_flags() accessor. The only ways to modify the flags are
SetCommonFlagsDefaults(), ParseCommonFlagsFromString() and
OverrideCommonFlags() functions, which are only supposed to be
called during initialization.

Test Plan: regression test suite

Reviewers: kcc, eugenis, glider

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6741

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@224736 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 7 deletions

diff --git a/lib/msan/msan.cc b/lib/msan/msan.cc
index fb1829614..33b856bb9 100644
--- a/lib/msan/msan.cc
+++ b/lib/msan/msan.cc
@@ -144,14 +144,17 @@ static void ParseFlagsFromString(Flags *f, const char *str) {
 }
 
 static void InitializeFlags(Flags *f, const char *options) {
-  CommonFlags *cf = common_flags();
   SetCommonFlagsDefaults();
-  cf->external_symbolizer_path = GetEnv("MSAN_SYMBOLIZER_PATH");
-  cf->malloc_context_size = 20;
-  cf->handle_ioctl = true;
-  // FIXME: test and enable.
-  cf->check_printf = false;
-  cf->intercept_tls_get_addr = true;
+  {
+    CommonFlags cf = *common_flags();
+    cf.external_symbolizer_path = GetEnv("MSAN_SYMBOLIZER_PATH");
+    cf.malloc_context_size = 20;
+    cf.handle_ioctl = true;
+    // FIXME: test and enable.
+    cf.check_printf = false;
+    cf.intercept_tls_get_addr = true;
+    OverrideCommonFlags(cf);
+  }
 
   internal_memset(f, 0, sizeof(*f));
   f->poison_heap_with_zeroes = false;