From bf52da0f1bc1fddf55a8ca4fc7ba8f01d48c5f37 Mon Sep 17 00:00:00 2001
From: Joshua Peraza <jperaza@chromium.org>
Date: Wed, 21 Jun 2017 01:17:58 -0700
Subject: [PATCH] posix: Fix Semaphore::TimedWait wait time

TimedWait is implemented using `sem_timedwait` which waits until an
absolute time (time since the epoch) has passed. Previously, the
time to wait (relative to now) was passed without adding the current
time.

Change-Id: I3c169d5b107b8263577c21a8f47dc504058bd708
Reviewed-on: https://chromium-review.googlesource.com/540984
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
---
 util/synchronization/semaphore_posix.cc | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/util/synchronization/semaphore_posix.cc b/util/synchronization/semaphore_posix.cc
index c781e4c6..9696e9da 100644
--- a/util/synchronization/semaphore_posix.cc
+++ b/util/synchronization/semaphore_posix.cc
@@ -15,6 +15,7 @@
 #include "util/synchronization/semaphore.h"
 
 #include <errno.h>
+#include <time.h>
 
 #include <cmath>
 
@@ -25,6 +26,19 @@ namespace crashpad {
 
 #if !defined(OS_MACOSX)
 
+namespace {
+
+void AddTimespec(const timespec& ts1, const timespec& ts2, timespec* result) {
+  result->tv_sec = ts1.tv_sec + ts2.tv_sec;
+  result->tv_nsec = ts1.tv_nsec + ts2.tv_nsec;
+  if (result->tv_nsec > static_cast<long>(1E9)) {
+    ++result->tv_sec;
+    result->tv_nsec -= static_cast<long>(1E9);
+  }
+}
+
+}  // namespace
+
 Semaphore::Semaphore(int value) {
   PCHECK(sem_init(&semaphore_, 0, value) == 0) << "sem_init";
 }
@@ -45,9 +59,15 @@ bool Semaphore::TimedWait(double seconds) {
     return true;
   }
 
+  timespec current_time;
+  if (clock_gettime(CLOCK_REALTIME, &current_time) != 0) {
+    PLOG(ERROR) << "clock_gettime";
+    return false;
+  }
   timespec timeout;
   timeout.tv_sec = seconds;
   timeout.tv_nsec = (seconds - trunc(seconds)) * 1E9;
+  AddTimespec(current_time, timeout, &timeout);
 
   int rv = HANDLE_EINTR(sem_timedwait(&semaphore_, &timeout));
   PCHECK(rv == 0 || errno == ETIMEDOUT) << "sem_timedwait";