[msan] A runtime option to disable wrapping of signal handlers.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@178865 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 37 insertions, 21 deletions

diff --git a/lib/msan/msan.cc b/lib/msan/msan.cc
index 6470144df..dd5e31b34 100644
--- a/lib/msan/msan.cc
+++ b/lib/msan/msan.cc
@@ -129,6 +129,7 @@ static void ParseFlagsFromString(Flags *f, const char *str) {
   ParseFlag(str, &f->strip_path_prefix, "strip_path_prefix");
   ParseFlag(str, &f->fast_unwind_on_fatal, "fast_unwind_on_fatal");
   ParseFlag(str, &f->fast_unwind_on_malloc, "fast_unwind_on_malloc");
+  ParseFlag(str, &f->wrap_signals, "wrap_signals");
 }
 
 static void InitializeFlags(Flags *f, const char *options) {
@@ -144,6 +145,7 @@ static void InitializeFlags(Flags *f, const char *options) {
   f->strip_path_prefix = "";
   f->fast_unwind_on_fatal = false;
   f->fast_unwind_on_malloc = true;
+  f->wrap_signals = true;
 
   // Override from user-specified string.
   if (__msan_default_options)
diff --git a/lib/msan/msan_flags.h b/lib/msan/msan_flags.h
index cfaf96327..dfad8a421 100644
--- a/lib/msan/msan_flags.h
+++ b/lib/msan/msan_flags.h
@@ -30,6 +30,7 @@ struct Flags {
   bool fast_unwind_on_fatal;
   // Use fast (frame-pointer-based) unwinder on malloc/free (if available).
   bool fast_unwind_on_malloc;
+  bool wrap_signals;
 };
 
 Flags *flags();
diff --git a/lib/msan/msan_interceptors.cc b/lib/msan/msan_interceptors.cc
index 0ed00f658..d61075063 100644
--- a/lib/msan/msan_interceptors.cc
+++ b/lib/msan/msan_interceptors.cc
@@ -848,38 +848,51 @@ INTERCEPTOR(int, sigaction, int signo, const __sanitizer_sigaction *act,
   ENSURE_MSAN_INITED();
   // FIXME: check that *act is unpoisoned.
   // That requires intercepting all of sigemptyset, sigfillset, etc.
-  SpinMutexLock lock(&sigactions_mu);
-  CHECK_LT(signo, kMaxSignals);
-  uptr old_cb = sigactions[signo];
-  __sanitizer_sigaction new_act;
-  __sanitizer_sigaction *pnew_act = act ? &new_act : 0;
-  if (act) {
-    internal_memcpy(pnew_act, act, __sanitizer::struct_sigaction_sz);
-    uptr cb = __sanitizer::__sanitizer_get_sigaction_sa_sigaction(pnew_act);
-    uptr new_cb = __sanitizer::__sanitizer_get_sigaction_sa_siginfo(pnew_act) ?
-        (uptr)SignalAction : (uptr)SignalHandler;
-    if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
-      sigactions[signo] = cb;
-      __sanitizer::__sanitizer_set_sigaction_sa_sigaction(pnew_act, new_cb);
+  int res;
+  if (flags()->wrap_signals) {
+    SpinMutexLock lock(&sigactions_mu);
+    CHECK_LT(signo, kMaxSignals);
+    uptr old_cb = sigactions[signo];
+    __sanitizer_sigaction new_act;
+    __sanitizer_sigaction *pnew_act = act ? &new_act : 0;
+    if (act) {
+      internal_memcpy(pnew_act, act, __sanitizer::struct_sigaction_sz);
+      uptr cb = __sanitizer::__sanitizer_get_sigaction_sa_sigaction(pnew_act);
+      uptr new_cb =
+          __sanitizer::__sanitizer_get_sigaction_sa_siginfo(pnew_act) ?
+          (uptr)SignalAction : (uptr)SignalHandler;
+      if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
+        sigactions[signo] = cb;
+        __sanitizer::__sanitizer_set_sigaction_sa_sigaction(pnew_act, new_cb);
+      }
     }
+    res = REAL(sigaction)(signo, pnew_act, oldact);
+    if (res == 0 && oldact) {
+      __sanitizer::__sanitizer_set_sigaction_sa_sigaction(oldact, old_cb);
+    }
+  } else {
+    res = REAL(sigaction)(signo, act, oldact);
   }
-  int res = REAL(sigaction)(signo, pnew_act, oldact);
+
   if (res == 0 && oldact) {
     __msan_unpoison(oldact, __sanitizer::struct_sigaction_sz);
-    __sanitizer::__sanitizer_set_sigaction_sa_sigaction(oldact, old_cb);
   }
   return res;
 }
 
 INTERCEPTOR(int, signal, int signo, uptr cb) {
   ENSURE_MSAN_INITED();
-  CHECK_LT(signo, kMaxSignals);
-  SpinMutexLock lock(&sigactions_mu);
-  if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
-    sigactions[signo] = cb;
-    cb = (uptr)SignalHandler;
+  if (flags()->wrap_signals) {
+    CHECK_LT(signo, kMaxSignals);
+    SpinMutexLock lock(&sigactions_mu);
+    if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
+      sigactions[signo] = cb;
+      cb = (uptr) SignalHandler;
+    }
+    return REAL(signal)(signo, cb);
+  } else {
+    return REAL(signal)(signo, cb);
   }
-  return REAL(signal)(signo, cb);
 }
 
 extern "C" int pthread_attr_init(void *attr);