[esan] Intercept and chain signal handlers

Summary:
In preparation for fault-based shadow memory iteration, we add support for
our own signal handler by adding app signal handler interception as well as
chaining for SIGSEGV.  This is done in a simple manner: we do not honor the
app's alternate stack nor any sigaction flags for SIGSEGV.

Adds a new test of transparency in app signal handling.

Reviewers: aizatsky

Subscribers: filcab, kubabrecka, vitalybuka, zhaoqin, kcc, eugenis, llvm-commits

Differential Revision: http://reviews.llvm.org/D20577

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@271272 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/esan/esan.cpp b/lib/esan/esan.cpp
index 2711e4b97..c9629d65c 100644
--- a/lib/esan/esan.cpp
+++ b/lib/esan/esan.cpp
@@ -73,6 +73,18 @@ void processRangeAccess(uptr PC, uptr Addr, int Size, bool IsWrite) {
   }
 }
 
+bool processSignal(int SigNum, void (*Handler)(int), void (**Result)(int)) {
+  if (WhichTool == ESAN_WorkingSet)
+    return processWorkingSetSignal(SigNum, Handler, Result);
+  return true;
+}
+
+bool processSigaction(int SigNum, const void *Act, void *OldAct) {
+  if (WhichTool == ESAN_WorkingSet)
+    return processWorkingSetSigaction(SigNum, Act, OldAct);
+  return true;
+}
+
 #if SANITIZER_DEBUG
 static bool verifyShadowScheme() {
   // Sanity checks for our shadow mapping scheme.