[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, 59 insertions, 0 deletions

diff --git a/test/esan/TestCases/workingset-signal-posix.cpp b/test/esan/TestCases/workingset-signal-posix.cpp
new file mode 100644
index 000000000..c0245760c
--- /dev/null
+++ b/test/esan/TestCases/workingset-signal-posix.cpp
@@ -0,0 +1,59 @@
+// RUN: %clang_esan_wset -O0 %s -o %t 2>&1
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <assert.h>
+
+sigjmp_buf mark;
+
+static void SignalHandler(int Sig) {
+  if (Sig == SIGSEGV) {
+    fprintf(stderr, "Handling SIGSEGV for signal\n");
+    siglongjmp(mark, 1);
+  }
+  exit(1);
+}
+
+static void SigactionHandler(int Sig, siginfo_t *Info, void *Ctx) {
+  if (Sig == SIGSEGV) {
+    fprintf(stderr, "Handling SIGSEGV for sigaction\n");
+    siglongjmp(mark, 1);
+  }
+  exit(1);
+}
+
+int main(int argc, char **argv) {
+  __sighandler_t Prior = signal(SIGSEGV, SignalHandler);
+  assert(Prior == SIG_DFL);
+  if (sigsetjmp(mark, 1) == 0)
+    *((volatile int *)(ssize_t)argc) = 42; // Raise SIGSEGV
+  fprintf(stderr, "Past longjmp for signal\n");
+
+  Prior = signal(SIGSEGV, SIG_DFL);
+  assert(Prior == SignalHandler);
+
+  struct sigaction SigAct;
+  SigAct.sa_sigaction = SigactionHandler;
+  int Res = sigfillset(&SigAct.sa_mask);
+  assert(Res == 0);
+  SigAct.sa_flags = SA_SIGINFO;
+  Res = sigaction(SIGSEGV, &SigAct, NULL);
+  assert(Res == 0);
+
+  if (sigsetjmp(mark, 1) == 0)
+    *((volatile int *)(ssize_t)argc) = 42; // Raise SIGSEGV
+  fprintf(stderr, "Past longjmp for sigaction\n");
+
+  Res = sigaction(SIGSEGV, NULL, &SigAct);
+  assert(Res == 0);
+  assert(SigAct.sa_sigaction == SigactionHandler);
+
+  return 0;
+}
+// CHECK:      Handling SIGSEGV for signal
+// CHECK-NEXT: Past longjmp for signal
+// CHECK-NEXT: Handling SIGSEGV for sigaction
+// CHECK-NEXT: Past longjmp for sigaction