Add first chance exception handler API

This change adds the option for Breakpad hosts to register a callback
that gets the first chance to handle an exception. The handler will 
return true if it handled the exception and false otherwise.

The primary use case is V8's trap-based bounds checking support for
WebAssembly.

Bug:
Change-Id: I5aa5b87d1229f1cef905a00404fa2027ee86be56
Reviewed-on: https://chromium-review.googlesource.com/509994
Reviewed-by: Mark Mentovai <mark@chromium.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/src/client/linux/handler/exception_handler_unittest.cc b/src/client/linux/handler/exception_handler_unittest.cc
index 17d84cf7..cede40bd 100644
--- a/src/client/linux/handler/exception_handler_unittest.cc
+++ b/src/client/linux/handler/exception_handler_unittest.cc
@@ -1177,3 +1177,26 @@ TEST(ExceptionHandlerTest, WriteMinidumpForChild) {
   close(fds[1]);
   unlink(minidump_filename.c_str());
 }
+
+namespace {
+const int kSimpleFirstChanceReturnStatus = 42;
+bool SimpleFirstChanceHandler(int, void*, void*) {
+  exit(kSimpleFirstChanceReturnStatus);
+}
+}
+
+TEST(ExceptionHandlerTest, FirstChanceHandlerRuns) {
+  AutoTempDir temp_dir;
+
+  const pid_t child = fork();
+  if (child == 0) {
+    ExceptionHandler handler(
+        MinidumpDescriptor(temp_dir.path()), NULL, NULL, NULL, true, -1);
+    google_breakpad::SetFirstChanceExceptionHandler(SimpleFirstChanceHandler);
+    DoNullPointerDereference();
+  }
+  int status;
+  ASSERT_NE(HANDLE_EINTR(waitpid(child, &status, 0)), -1);
+  ASSERT_TRUE(WIFEXITED(status));
+  ASSERT_EQ(kSimpleFirstChanceReturnStatus, WEXITSTATUS(status));
+}