[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, 11 insertions, 9 deletions

diff --git a/lib/asan/asan_flags.cc b/lib/asan/asan_flags.cc
index 4099de205..7db1f020c 100644
--- a/lib/asan/asan_flags.cc
+++ b/lib/asan/asan_flags.cc
@@ -172,13 +172,15 @@ void ParseFlagsFromString(Flags *f, const char *str) {
 }
 
 void InitializeFlags(Flags *f) {
-  CommonFlags *cf = common_flags();
   SetCommonFlagsDefaults();
-  cf->detect_leaks = CAN_SANITIZE_LEAKS;
-  cf->external_symbolizer_path = GetEnv("ASAN_SYMBOLIZER_PATH");
-  cf->malloc_context_size = kDefaultMallocContextSize;
-  cf->intercept_tls_get_addr = true;
-  cf->coverage = false;
+  {
+    CommonFlags cf = *common_flags();
+    cf.detect_leaks = CAN_SANITIZE_LEAKS;
+    cf.external_symbolizer_path = GetEnv("ASAN_SYMBOLIZER_PATH");
+    cf.malloc_context_size = kDefaultMallocContextSize;
+    cf.intercept_tls_get_addr = true;
+    OverrideCommonFlags(cf);
+  }
 
   internal_memset(f, 0, sizeof(*f));
   f->quarantine_size = (ASAN_LOW_MEMORY) ? 1UL << 26 : 1UL << 28;
@@ -258,17 +260,17 @@ void InitializeFlags(Flags *f) {
   }
 
   // Flag validation:
-  if (!CAN_SANITIZE_LEAKS && cf->detect_leaks) {
+  if (!CAN_SANITIZE_LEAKS && common_flags()->detect_leaks) {
     Report("%s: detect_leaks is not supported on this platform.\n",
            SanitizerToolName);
-    cf->detect_leaks = false;
+    Die();
   }
   // Make "strict_init_order" imply "check_initialization_order".
   // TODO(samsonov): Use a single runtime flag for an init-order checker.
   if (f->strict_init_order) {
     f->check_initialization_order = true;
   }
-  CHECK_LE((uptr)cf->malloc_context_size, kStackTraceMax);
+  CHECK_LE((uptr)common_flags()->malloc_context_size, kStackTraceMax);
   CHECK_LE(f->min_uar_stack_size_log, f->max_uar_stack_size_log);
   CHECK_GE(f->redzone, 16);
   CHECK_GE(f->max_redzone, f->redzone);