From 69b9b36c114680c87251ab0f140fd5d6b61e1fa9 Mon Sep 17 00:00:00 2001
From: Wei Wang <wvw@google.com>
Date: Mon, 14 Nov 2016 20:05:21 -0800
Subject: [PATCH] init: fix BuildTriggersString for empty string

behavior is undefined if pop_back() on empty std::string

Test: grep init log
Bug: 32712851
Bug: 32838381
Change-Id: I5bfac2fb275036abd0158b78df14019d2e82716d
---
 init/action.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/init/action.cpp b/init/action.cpp
index a12f2253c..e9b2a0dfe 100644
--- a/init/action.cpp
+++ b/init/action.cpp
@@ -249,7 +249,9 @@ std::string Action::BuildTriggersString() const {
         result += event_trigger_;
         result += ' ';
     }
-    result.pop_back();
+    if (!result.empty()) {
+        result.pop_back();
+    }
     return result;
 }