From 51a7ff85c2af34f97e845710998b18e691092565 Mon Sep 17 00:00:00 2001
From: Thomas Inskip <tinskip@google.com>
Date: Fri, 13 Nov 2015 18:43:25 -0800
Subject: [PATCH] Fixed a miniscule odds race condition found by tsan (Thread
 sanitizer) in ThreadedIofile. Added loop to handle partial writes in
 ThreadedIoFile.

Change-Id: Ib62855ab849ffbfd00afc5b226dd81d4cd38ff51
---
 packager/media/file/threaded_io_file.cc | 35 +++++++++++++++----------
 packager/media/file/threaded_io_file.h  |  5 ++--
 2 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/packager/media/file/threaded_io_file.cc b/packager/media/file/threaded_io_file.cc
index c14ee8169c..98d3ce9fa7 100644
--- a/packager/media/file/threaded_io_file.cc
+++ b/packager/media/file/threaded_io_file.cc
@@ -14,6 +14,9 @@
 namespace edash_packager {
 namespace media {
 
+using base::subtle::NoBarrier_Load;
+using base::subtle::NoBarrier_Store;
+
 ThreadedIoFile::ThreadedIoFile(scoped_ptr<File, FileCloser> internal_file,
                                Mode mode,
                                uint64_t io_cache_size,
@@ -70,12 +73,12 @@ int64_t ThreadedIoFile::Read(void* buffer, uint64_t length) {
   DCHECK(thread_);
   DCHECK_EQ(kInputMode, mode_);
 
-  if (internal_file_error_)
-    return internal_file_error_;
-
-  if (eof_ && !cache_.BytesCached())
+  if (NoBarrier_Load(&eof_) && !cache_.BytesCached())
     return 0;
 
+  if (NoBarrier_Load(&internal_file_error_))
+    return NoBarrier_Load(&internal_file_error_);
+
   return cache_.Read(buffer, length);
 }
 
@@ -84,8 +87,8 @@ int64_t ThreadedIoFile::Write(const void* buffer, uint64_t length) {
   DCHECK(thread_);
   DCHECK_EQ(kOutputMode, mode_);
 
-  if (internal_file_error_)
-    return internal_file_error_;
+  if (NoBarrier_Load(&internal_file_error_))
+    return NoBarrier_Load(&internal_file_error_);
 
   size_ += length;
   return cache_.Write(buffer, length);
@@ -118,8 +121,8 @@ void ThreadedIoFile::RunInInputMode() {
     int64_t read_result = internal_file_->Read(&io_buffer_[0],
                                                io_buffer_.size());
     if (read_result <= 0) {
-      eof_ = read_result == 0;
-      internal_file_error_ = read_result;
+      NoBarrier_Store(&eof_, read_result == 0);
+      NoBarrier_Store(&internal_file_error_, read_result);
       cache_.Close();
       return;
     }
@@ -153,13 +156,17 @@ void ThreadedIoFile::RunInOutputMode() {
         return;
       }
     } else {
-      int64_t write_result = internal_file_->Write(&io_buffer_[0], write_bytes);
-      if (write_result < 0) {
-        internal_file_error_ = write_result;
-        cache_.Close();
-        return;
+      uint64_t bytes_written(0);
+      while (bytes_written < write_bytes) {
+        int64_t write_result = internal_file_->Write(
+            &io_buffer_[bytes_written], write_bytes - bytes_written);
+        if (write_result < 0) {
+          NoBarrier_Store(&internal_file_error_, write_result);
+          cache_.Close();
+          return;
+        }
+        bytes_written += write_result;
       }
-      CHECK_EQ(write_result, static_cast<int64_t>(write_bytes));
     }
   }
 }
diff --git a/packager/media/file/threaded_io_file.h b/packager/media/file/threaded_io_file.h
index 70e37f3f71..4d961c2461 100644
--- a/packager/media/file/threaded_io_file.h
+++ b/packager/media/file/threaded_io_file.h
@@ -7,6 +7,7 @@
 #ifndef PACKAGER_FILE_THREADED_IO_FILE_H_
 #define PACKAGER_FILE_THREADED_IO_FILE_H_
 
+#include "packager/base/atomicops.h"
 #include "packager/base/memory/scoped_ptr.h"
 #include "packager/base/synchronization/lock.h"
 #include "packager/base/synchronization/waitable_event.h"
@@ -58,10 +59,10 @@ class ThreadedIoFile : public File {
   std::vector<uint8_t> io_buffer_;
   scoped_ptr<ClosureThread> thread_;
   uint64_t size_;
-  bool eof_;
+  base::subtle::Atomic32 eof_;
   bool flushing_;
   base::WaitableEvent flush_complete_event_;
-  int64_t internal_file_error_;
+  base::subtle::Atomic32 internal_file_error_;
 
   DISALLOW_COPY_AND_ASSIGN(ThreadedIoFile);
 };