Experimental Revert of 184577

ASAN bots started timing out consistently last night at the time
this was submitted.  It's a possible culprit.  It doesn't involve
extensions, but it does things with streams and I assume those
are connected to the feeds in this test somehow.

browser_tests browser_tests failed 4 ( 12 mins, 52 secs )
stdio
ParseFeedInvalidFeed1
ParseFeedInvalidFeed2
ParseFeedValidFeed3
ParseFeedValidFeed4

http://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASAN%20Tests%20%281%29/builds/3019
http://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASAN%20Tests%20%282%29/builds/3186
http://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASAN%20Tests%20%283%29/builds/2716


> Fix net::FileStream to handle all errors correctly.
> 
> This CL adds FileStream::Context::IOResult struct that's used to pass
> results of IO operations inside FileStream::Context. Following bugs are
> fixes:
> 
> 1. On POSIX net::FileStream::Read() and net::FileStream::Write() would
> return a positive result in case of an error. This happens because
> POSIX errors are positive integers and FileStream was written with
> assumption that they are negative.
> 2. On Windows Seek() and Flush() errors were not handled correctly.
> This is because CheckForIOError() was assuming that all error codes
> are negative, but RecordAndMapError() was mapping positive errors.
> 3. On Windows results of asynchronous ReadFile() and WriteFile() were
> not handled correctly - ERR_IO_PENDING would be returned even when
> operation completes synchronously.
> 4. On Windows OVERLAPPED struct wasn't set to zeros as necessary.
> 
> Also added unittests to check that error codes are handled correctly
> now.
> 
> TBR=mmenke@chromium.org
> 
> Review URL: https://codereview.chromium.org/12326107

TBR=sergeyu@chromium.org
Review URL: https://codereview.chromium.org/12330144

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@184672 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 151 insertions, 221 deletions

diff --git a/net/base/file_stream_context.cc b/net/base/file_stream_context.cc
index 092302f..53f3c3d 100644
--- a/net/base/file_stream_context.cc
+++ b/net/base/file_stream_context.cc
@@ -22,32 +22,6 @@ void CallInt64ToInt(const net::CompletionCallback& callback, int64 result) {
 
 namespace net {
 
-FileStream::Context::IOResult::IOResult()
-    : result(OK),
-      os_error(0) {
-}
-
-FileStream::Context::IOResult::IOResult(int64 result, int os_error)
-    : result(result),
-      os_error(os_error) {
-}
-
-// static
-FileStream::Context::IOResult FileStream::Context::IOResult::FromOSError(
-    int64 os_error) {
-  return IOResult(MapSystemError(os_error), os_error);
-}
-
-FileStream::Context::OpenResult::OpenResult()
-    : file(base::kInvalidPlatformFileValue) {
-}
-
-FileStream::Context::OpenResult::OpenResult(base::PlatformFile file,
-                                            IOResult error_code)
-    : file(file),
-      error_code(error_code) {
-}
-
 void FileStream::Context::Orphan() {
   DCHECK(!orphaned_);
 
@@ -88,14 +62,14 @@ int FileStream::Context::OpenSync(const base::FilePath& path, int open_flags) {
   OpenResult result = OpenFileImpl(path, open_flags);
   file_ = result.file;
   if (file_ == base::kInvalidPlatformFileValue) {
-    ProcessOpenError(result.error_code);
+    result.error_code = ProcessOpenError(result.error_code);
   } else {
     // TODO(satorux): Remove this once all async clients are migrated to use
     // Open(). crbug.com/114783
     if (open_flags & base::PLATFORM_FILE_ASYNC)
       OnAsyncFileOpened();
   }
-  return result.error_code.result;
+  return result.error_code;
 }
 
 void FileStream::Context::CloseSync() {
@@ -125,9 +99,9 @@ void FileStream::Context::SeekAsync(Whence whence,
 }
 
 int64 FileStream::Context::SeekSync(Whence whence, int64 offset) {
-  IOResult result = SeekFileImpl(whence, offset);
-  RecordError(result, FILE_ERROR_SOURCE_SEEK);
-  return result.result;
+  int64 result = SeekFileImpl(whence, offset);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_SEEK);
+  return result;
 }
 
 void FileStream::Context::FlushAsync(const CompletionCallback& callback) {
@@ -147,32 +121,26 @@ void FileStream::Context::FlushAsync(const CompletionCallback& callback) {
 }
 
 int FileStream::Context::FlushSync() {
-  IOResult result = FlushFileImpl();
-  RecordError(result, FILE_ERROR_SOURCE_FLUSH);
-  return result.result;
+  int64 result = FlushFileImpl();
+  CheckForIOError(&result, FILE_ERROR_SOURCE_FLUSH);
+  return result;
 }
 
-void FileStream::Context::RecordError(const IOResult& result,
-                                      FileErrorSource source) const {
-  if (result.result >= 0) {
-    // |result| is not an error.
-    return;
-  }
-
+int FileStream::Context::RecordAndMapError(int error,
+                                           FileErrorSource source) const {
   // The following check is against incorrect use or bug. File descriptor
   // shouldn't ever be closed outside of FileStream while it still tries to do
   // something with it.
-  DCHECK_NE(result.result, ERR_INVALID_HANDLE);
+  DCHECK(error != ERROR_BAD_FILE);
+  Error net_error = MapSystemError(error);
 
   if (!orphaned_) {
-    bound_net_log_.AddEvent(
-        NetLog::TYPE_FILE_STREAM_ERROR,
-        base::Bind(&NetLogFileStreamErrorCallback,
-                   source, result.os_error,
-                   static_cast<net::Error>(result.result)));
+    bound_net_log_.AddEvent(NetLog::TYPE_FILE_STREAM_ERROR,
+                            base::Bind(&NetLogFileStreamErrorCallback,
+                                       source, error, net_error));
   }
-
-  RecordFileError(result.os_error, source, record_uma_);
+  RecordFileError(error, source, record_uma_);
+  return net_error;
 }
 
 void FileStream::Context::BeginOpenEvent(const base::FilePath& path) {
@@ -188,27 +156,28 @@ FileStream::Context::OpenResult FileStream::Context::OpenFileImpl(
   // delete the file right after FileStream deletion. Thus we are always
   // adding SHARE_DELETE flag to accommodate such use case.
   open_flags |= base::PLATFORM_FILE_SHARE_DELETE;
-  base::PlatformFile file =
-      base::CreatePlatformFile(path, open_flags, NULL, NULL);
-  if (file == base::kInvalidPlatformFileValue)
-    return OpenResult(file, IOResult::FromOSError(GetLastErrno()));
+  OpenResult result;
+  result.error_code = OK;
+  result.file = base::CreatePlatformFile(path, open_flags, NULL, NULL);
+  if (result.file == base::kInvalidPlatformFileValue)
+    result.error_code = GetLastErrno();
 
-  return OpenResult(file, IOResult(OK, 0));
+  return result;
 }
 
-void FileStream::Context::ProcessOpenError(const IOResult& error_code) {
+int FileStream::Context::ProcessOpenError(int error_code) {
   bound_net_log_.EndEvent(NetLog::TYPE_FILE_STREAM_OPEN);
-  RecordError(error_code, FILE_ERROR_SOURCE_OPEN);
+  return RecordAndMapError(error_code, FILE_ERROR_SOURCE_OPEN);
 }
 
 void FileStream::Context::OnOpenCompleted(const CompletionCallback& callback,
-                                          OpenResult open_result) {
-  file_ = open_result.file;
+                                          OpenResult result) {
+  file_ = result.file;
   if (file_ == base::kInvalidPlatformFileValue)
-    ProcessOpenError(open_result.error_code);
+    result.error_code = ProcessOpenError(result.error_code);
   else if (!orphaned_)
     OnAsyncFileOpened();
-  OnAsyncCompleted(IntToInt64(callback), open_result.error_code.result);
+  OnAsyncCompleted(IntToInt64(callback), result.error_code);
 }
 
 void FileStream::Context::CloseAndDelete() {
@@ -236,12 +205,18 @@ Int64CompletionCallback FileStream::Context::IntToInt64(
   return base::Bind(&CallInt64ToInt, callback);
 }
 
+void FileStream::Context::CheckForIOError(int64* result,
+                                          FileErrorSource source) {
+  if (*result < 0)
+    *result = RecordAndMapError(static_cast<int>(*result), source);
+}
+
 void FileStream::Context::ProcessAsyncResult(
     const Int64CompletionCallback& callback,
     FileErrorSource source,
-    const IOResult& result) {
-  RecordError(result, source);
-  OnAsyncCompleted(callback, result.result);
+    int64 result) {
+  CheckForIOError(&result, source);
+  OnAsyncCompleted(callback, result);
 }
 
 void FileStream::Context::OnAsyncCompleted(
diff --git a/net/base/file_stream_context.h b/net/base/file_stream_context.h
index 34effea..42fc0eb 100644
--- a/net/base/file_stream_context.h
+++ b/net/base/file_stream_context.h
@@ -116,46 +116,50 @@ class FileStream::Context {
 
  private:
   ////////////////////////////////////////////////////////////////////////////
-  // Platform-independent methods implemented in file_stream_context.cc.
+  // Error code that is platform-dependent but is used in the platform-
+  // independent code implemented in file_stream_context.cc.
   ////////////////////////////////////////////////////////////////////////////
-
-  struct IOResult {
-    IOResult();
-    IOResult(int64 result, int os_error);
-    static IOResult FromOSError(int64 os_error);
-
-    int64 result;
-    int os_error;  // Set only when result < 0.
+  enum {
+#if defined(OS_WIN)
+    ERROR_BAD_FILE = ERROR_INVALID_HANDLE
+#elif defined(OS_POSIX)
+    ERROR_BAD_FILE = EBADF
+#endif
   };
 
+  ////////////////////////////////////////////////////////////////////////////
+  // Platform-independent methods implemented in file_stream_context.cc.
+  ////////////////////////////////////////////////////////////////////////////
+
   struct OpenResult {
-    OpenResult();
-    OpenResult(base::PlatformFile file, IOResult error_code);
     base::PlatformFile file;
-    IOResult error_code;
+    int error_code;
   };
 
-  // Log the error from |result| to |bound_net_log_|.
-  void RecordError(const IOResult& result, FileErrorSource source) const;
+  // Map system error into network error code and log it with |bound_net_log_|.
+  int RecordAndMapError(int error, FileErrorSource source) const;
 
   void BeginOpenEvent(const base::FilePath& path);
 
   OpenResult OpenFileImpl(const base::FilePath& path, int open_flags);
 
-  void ProcessOpenError(const IOResult& result);
-  void OnOpenCompleted(const CompletionCallback& callback,
-                       OpenResult open_result);
+  int ProcessOpenError(int error_code);
+  void OnOpenCompleted(const CompletionCallback& callback, OpenResult result);
 
   void CloseAndDelete();
   void OnCloseCompleted();
 
   Int64CompletionCallback IntToInt64(const CompletionCallback& callback);
 
+  // Checks for IO error that probably happened in async methods.
+  // If there was error reports it.
+  void CheckForIOError(int64* result, FileErrorSource source);
+
   // Called when asynchronous Seek() is completed.
   // Reports error if needed and calls callback.
   void ProcessAsyncResult(const Int64CompletionCallback& callback,
                           FileErrorSource source,
-                          const IOResult& result);
+                          int64 result);
 
   // Called when asynchronous Open() or Seek()
   // is completed. |result| contains the result or a network error code.
@@ -183,27 +187,27 @@ class FileStream::Context {
   ////////////////////////////////////////////////////////////////////////////
 
   // Adjusts the position from where the data is read.
-  IOResult SeekFileImpl(Whence whence, int64 offset);
+  int64 SeekFileImpl(Whence whence, int64 offset);
 
   // Flushes all data written to the stream.
-  IOResult FlushFileImpl();
+  int64 FlushFileImpl();
 
 #if defined(OS_WIN)
   void IOCompletionIsPending(const CompletionCallback& callback, IOBuffer* buf);
 
-  // Implementation of MessageLoopForIO::IOHandler.
+  // Implementation of MessageLoopForIO::IOHandler
   virtual void OnIOCompleted(MessageLoopForIO::IOContext* context,
                              DWORD bytes_read,
                              DWORD error) OVERRIDE;
 #elif defined(OS_POSIX)
   // ReadFileImpl() is a simple wrapper around read() that handles EINTR
   // signals and calls RecordAndMapError() to map errno to net error codes.
-  IOResult ReadFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
+  int64 ReadFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
 
   // WriteFileImpl() is a simple wrapper around write() that handles EINTR
   // signals and calls MapSystemError() to map errno to net error codes.
   // It tries to write to completion.
-  IOResult WriteFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
+  int64 WriteFileImpl(scoped_refptr<IOBuffer> buf, int buf_len);
 #endif
 
   base::PlatformFile file_;
diff --git a/net/base/file_stream_context_posix.cc b/net/base/file_stream_context_posix.cc
index 87fa106..d39b17a 100644
--- a/net/base/file_stream_context_posix.cc
+++ b/net/base/file_stream_context_posix.cc
@@ -68,11 +68,8 @@ FileStream::Context::~Context() {
 
 int64 FileStream::Context::GetFileSize() const {
   struct stat info;
-  if (fstat(file_, &info) != 0) {
-    IOResult result = IOResult::FromOSError(errno);
-    RecordError(result, FILE_ERROR_SOURCE_GET_SIZE);
-    return result.result;
-  }
+  if (fstat(file_, &info) != 0)
+    return RecordAndMapError(errno, FILE_ERROR_SOURCE_GET_SIZE);
 
   return static_cast<int64>(info.st_size);
 }
@@ -99,9 +96,9 @@ int FileStream::Context::ReadAsync(IOBuffer* in_buf,
 
 int FileStream::Context::ReadSync(char* in_buf, int buf_len) {
   scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(in_buf);
-  IOResult result = ReadFileImpl(buf, buf_len);
-  RecordError(result, FILE_ERROR_SOURCE_READ);
-  return result.result;
+  int64 result = ReadFileImpl(buf, buf_len);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_READ);
+  return result;
 }
 
 int FileStream::Context::WriteAsync(IOBuffer* in_buf,
@@ -126,59 +123,54 @@ int FileStream::Context::WriteAsync(IOBuffer* in_buf,
 
 int FileStream::Context::WriteSync(const char* in_buf, int buf_len) {
   scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(in_buf);
-  IOResult result = WriteFileImpl(buf, buf_len);
-  RecordError(result, FILE_ERROR_SOURCE_WRITE);
-  return result.result;
+  int64 result = WriteFileImpl(buf, buf_len);
+  CheckForIOError(&result, FILE_ERROR_SOURCE_WRITE);
+  return result;
 }
 
 int FileStream::Context::Truncate(int64 bytes) {
-  if (ftruncate(file_, bytes) != 0) {
-    IOResult result = IOResult::FromOSError(errno);
-    RecordError(result, FILE_ERROR_SOURCE_SET_EOF);
-    return result.result;
-  }
+  int result = ftruncate(file_, bytes);
+  if (result == 0)
+    return bytes;
 
-  return bytes;
+  return RecordAndMapError(errno, FILE_ERROR_SOURCE_SET_EOF);
 }
 
-FileStream::Context::IOResult FileStream::Context::SeekFileImpl(Whence whence,
-                                                                int64 offset) {
+int64 FileStream::Context::SeekFileImpl(Whence whence, int64 offset) {
   off_t res = lseek(file_, static_cast<off_t>(offset),
                     static_cast<int>(whence));
   if (res == static_cast<off_t>(-1))
-    return IOResult::FromOSError(errno);
+    return errno;
 
-  return IOResult(res, 0);
+  return res;
 }
 
-FileStream::Context::IOResult FileStream::Context::FlushFileImpl() {
+int64 FileStream::Context::FlushFileImpl() {
   ssize_t res = HANDLE_EINTR(fsync(file_));
   if (res == -1)
-    return IOResult::FromOSError(errno);
+    return errno;
 
-  return IOResult(res, 0);
+  return res;
 }
 
-FileStream::Context::IOResult FileStream::Context::ReadFileImpl(
-    scoped_refptr<IOBuffer> buf,
-    int buf_len) {
+int64 FileStream::Context::ReadFileImpl(scoped_refptr<IOBuffer> buf,
+                                        int buf_len) {
   // Loop in the case of getting interrupted by a signal.
   ssize_t res = HANDLE_EINTR(read(file_, buf->data(),
                                   static_cast<size_t>(buf_len)));
   if (res == -1)
-    return IOResult::FromOSError(errno);
+    return errno;
 
-  return IOResult(res, 0);
+  return res;
 }
 
-FileStream::Context::IOResult FileStream::Context::WriteFileImpl(
-    scoped_refptr<IOBuffer> buf,
-    int buf_len) {
+int64 FileStream::Context::WriteFileImpl(scoped_refptr<IOBuffer> buf,
+                                         int buf_len) {
   ssize_t res = HANDLE_EINTR(write(file_, buf->data(), buf_len));
   if (res == -1)
-    return IOResult::FromOSError(errno);
+    return errno;
 
-  return IOResult(res, 0);
+  return res;
 }
 
 }  // namespace net
diff --git a/net/base/file_stream_context_win.cc b/net/base/file_stream_context_win.cc
index 7072f1d..f5656a3 100644
--- a/net/base/file_stream_context_win.cc
+++ b/net/base/file_stream_context_win.cc
@@ -47,7 +47,6 @@ FileStream::Context::Context(const BoundNetLog& bound_net_log)
       bound_net_log_(bound_net_log),
       error_source_(FILE_ERROR_SOURCE_COUNT) {
   io_context_.handler = this;
-  memset(&io_context_.overlapped, 0, sizeof(io_context_.overlapped));
 }
 
 FileStream::Context::Context(base::PlatformFile file,
@@ -61,7 +60,6 @@ FileStream::Context::Context(base::PlatformFile file,
       bound_net_log_(bound_net_log),
       error_source_(FILE_ERROR_SOURCE_COUNT) {
   io_context_.handler = this;
-  memset(&io_context_.overlapped, 0, sizeof(io_context_.overlapped));
   if (file_ != base::kInvalidPlatformFileValue &&
       (open_flags & base::PLATFORM_FILE_ASYNC)) {
     OnAsyncFileOpened();
@@ -74,10 +72,9 @@ FileStream::Context::~Context() {
 int64 FileStream::Context::GetFileSize() const {
   LARGE_INTEGER file_size;
   if (!GetFileSizeEx(file_, &file_size)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    LOG(WARNING) << "GetFileSizeEx failed: " << error.os_error;
-    RecordError(error, FILE_ERROR_SOURCE_GET_SIZE);
-    return error.result;
+    DWORD error = GetLastError();
+    LOG(WARNING) << "GetFileSizeEx failed: " << error;
+    return RecordAndMapError(error, FILE_ERROR_SOURCE_GET_SIZE);
   }
 
   return file_size.QuadPart;
@@ -89,39 +86,44 @@ int FileStream::Context::ReadAsync(IOBuffer* buf,
   DCHECK(!async_in_progress_);
   error_source_ = FILE_ERROR_SOURCE_READ;
 
+  int rv = 0;
+
   DWORD bytes_read;
   if (!ReadFile(file_, buf->data(), buf_len,
                 &bytes_read, &io_context_.overlapped)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    if (error.os_error == ERROR_IO_PENDING) {
+    DWORD error = GetLastError();
+    if (error == ERROR_IO_PENDING) {
       IOCompletionIsPending(callback, buf);
-    } else if (error.os_error == ERROR_HANDLE_EOF) {
-      return 0;  // Report EOF by returning 0 bytes read.
+      rv = ERR_IO_PENDING;
+    } else if (error == ERROR_HANDLE_EOF) {
+      rv = 0;  // Report EOF by returning 0 bytes read.
     } else {
-      LOG(WARNING) << "ReadFile failed: " << error.os_error;
-      RecordError(error, FILE_ERROR_SOURCE_READ);
+      LOG(WARNING) << "ReadFile failed: " << error;
+      rv = RecordAndMapError(error, FILE_ERROR_SOURCE_READ);
     }
-    return error.result;
+  } else {
+    IOCompletionIsPending(callback, buf);
+    rv = ERR_IO_PENDING;
   }
-
-  IOCompletionIsPending(callback, buf);
-  return ERR_IO_PENDING;
+  return rv;
 }
 
 int FileStream::Context::ReadSync(char* buf, int buf_len) {
+  int rv = 0;
+
   DWORD bytes_read;
   if (!ReadFile(file_, buf, buf_len, &bytes_read, NULL)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    if (error.os_error == ERROR_HANDLE_EOF) {
-      return 0;  // Report EOF by returning 0 bytes read.
+    DWORD error = GetLastError();
+    if (error == ERROR_HANDLE_EOF) {
+      rv = 0;  // Report EOF by returning 0 bytes read.
     } else {
-      LOG(WARNING) << "ReadFile failed: " << error.os_error;
-      RecordError(error, FILE_ERROR_SOURCE_READ);
+      LOG(WARNING) << "ReadFile failed: " << error;
+      rv = RecordAndMapError(error, FILE_ERROR_SOURCE_READ);
     }
-    return error.result;
+  } else {
+    rv = static_cast<int>(bytes_read);
   }
-
-  return bytes_read;
+  return rv;
 }
 
 int FileStream::Context::WriteAsync(IOBuffer* buf,
@@ -129,68 +131,69 @@ int FileStream::Context::WriteAsync(IOBuffer* buf,
                                     const CompletionCallback& callback) {
   error_source_ = FILE_ERROR_SOURCE_WRITE;
 
+  int rv = 0;
   DWORD bytes_written = 0;
   if (!WriteFile(file_, buf->data(), buf_len,
                  &bytes_written, &io_context_.overlapped)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    if (error.os_error == ERROR_IO_PENDING) {
+    DWORD error = GetLastError();
+    if (error == ERROR_IO_PENDING) {
       IOCompletionIsPending(callback, buf);
+      rv = ERR_IO_PENDING;
     } else {
-      LOG(WARNING) << "WriteFile failed: " << error.os_error;
-      RecordError(error, FILE_ERROR_SOURCE_WRITE);
+      LOG(WARNING) << "WriteFile failed: " << error;
+      rv = RecordAndMapError(error, FILE_ERROR_SOURCE_WRITE);
     }
-    return error.result;
+  } else {
+    IOCompletionIsPending(callback, buf);
+    rv = ERR_IO_PENDING;
   }
-
-  IOCompletionIsPending(callback, buf);
-  return ERR_IO_PENDING;
+  return rv;
 }
 
 int FileStream::Context::WriteSync(const char* buf, int buf_len) {
+  int rv = 0;
   DWORD bytes_written = 0;
   if (!WriteFile(file_, buf, buf_len, &bytes_written, NULL)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    LOG(WARNING) << "WriteFile failed: " << error.os_error;
-    RecordError(error, FILE_ERROR_SOURCE_WRITE);
-    return error.result;
+    DWORD error = GetLastError();
+    LOG(WARNING) << "WriteFile failed: " << error;
+    rv = RecordAndMapError(error, FILE_ERROR_SOURCE_WRITE);
+  } else {
+    rv = static_cast<int>(bytes_written);
   }
-
-  return bytes_written;
+  return rv;
 }
 
 int FileStream::Context::Truncate(int64 bytes) {
-  if (!SetEndOfFile(file_)) {
-    IOResult error = IOResult::FromOSError(GetLastError());
-    LOG(WARNING) << "SetEndOfFile failed: " << error.os_error;
-    RecordError(error, FILE_ERROR_SOURCE_SET_EOF);
-    return error.result;
-  }
+  BOOL result = SetEndOfFile(file_);
+  if (result)
+    return bytes;
 
-  return bytes;
+  DWORD error = GetLastError();
+  LOG(WARNING) << "SetEndOfFile failed: " << error;
+  return RecordAndMapError(error, FILE_ERROR_SOURCE_SET_EOF);
 }
 
 void FileStream::Context::OnAsyncFileOpened() {
   MessageLoopForIO::current()->RegisterIOHandler(file_, this);
 }
 
-FileStream::Context::IOResult FileStream::Context::SeekFileImpl(Whence whence,
-                                                                int64 offset) {
+int64 FileStream::Context::SeekFileImpl(Whence whence, int64 offset) {
   LARGE_INTEGER distance, res;
   distance.QuadPart = offset;
   DWORD move_method = static_cast<DWORD>(whence);
   if (SetFilePointerEx(file_, distance, &res, move_method)) {
     SetOffset(&io_context_.overlapped, res);
-    return IOResult(res.QuadPart, 0);
+    return res.QuadPart;
   }
 
-  return IOResult::FromOSError(GetLastError());
+  return -static_cast<int>(GetLastError());
 }
 
-FileStream::Context::IOResult FileStream::Context::FlushFileImpl() {
+int64 FileStream::Context::FlushFileImpl() {
   if (FlushFileBuffers(file_))
-    return IOResult(OK, 0);
+    return OK;
 
-  return IOResult::FromOSError(GetLastError());
+  return -static_cast<int>(GetLastError());
 }
 
 void FileStream::Context::IOCompletionIsPending(
@@ -217,17 +220,12 @@ void FileStream::Context::OnIOCompleted(MessageLoopForIO::IOContext* context,
     return;
   }
 
-  int result;
-  if (error == ERROR_HANDLE_EOF) {
-    result = 0;
-  } else if (error) {
-    IOResult error_result = IOResult::FromOSError(error);
-    RecordError(error_result, error_source_);
-    result = error_result.result;
-  } else {
-    result = bytes_read;
+  int result = static_cast<int>(bytes_read);
+  if (error && error != ERROR_HANDLE_EOF)
+    result = RecordAndMapError(error, error_source_);
+
+  if (bytes_read)
     IncrementOffset(&io_context_.overlapped, bytes_read);
-  }
 
   CompletionCallback temp_callback = callback_;
   callback_.Reset();
diff --git a/net/base/file_stream_unittest.cc b/net/base/file_stream_unittest.cc
index 1f79747..1757918 100644
--- a/net/base/file_stream_unittest.cc
+++ b/net/base/file_stream_unittest.cc
@@ -1031,44 +1031,6 @@ TEST_F(FileStreamTest, AsyncOpenAndDelete) {
   EXPECT_FALSE(open_callback.have_result());
 }
 
-// Verify that async Write() errors are mapped correctly.
-TEST_F(FileStreamTest, AsyncWriteError) {
-  scoped_ptr<FileStream> stream(new FileStream(NULL));
-  int flags = base::PLATFORM_FILE_CREATE_ALWAYS |
-              base::PLATFORM_FILE_WRITE |
-              base::PLATFORM_FILE_ASYNC;
-  int rv = stream->OpenSync(temp_file_path(), flags);
-  EXPECT_EQ(OK, rv);
-
-  TestCompletionCallback callback;
-
-  // Try passing NULL buffer to Write() and check that it fails.
-  scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(NULL);
-  rv = stream->Write(buf, 1, callback.callback());
-  if (rv == ERR_IO_PENDING)
-    rv = callback.WaitForResult();
-  EXPECT_LT(rv, 0);
-}
-
-// Verify that async Read() errors are mapped correctly.
-TEST_F(FileStreamTest, AsyncReadError) {
-  scoped_ptr<FileStream> stream(new FileStream(NULL));
-  int flags = base::PLATFORM_FILE_OPEN |
-              base::PLATFORM_FILE_READ |
-              base::PLATFORM_FILE_ASYNC;
-  int rv = stream->OpenSync(temp_file_path(), flags);
-  EXPECT_EQ(OK, rv);
-
-  TestCompletionCallback callback;
-
-  // Try passing NULL buffer to Read() and check that it fails.
-  scoped_refptr<IOBuffer> buf = new WrappedIOBuffer(NULL);
-  rv = stream->Read(buf, 1, callback.callback());
-  if (rv == ERR_IO_PENDING)
-    rv = callback.WaitForResult();
-  EXPECT_LT(rv, 0);
-}
-
 }  // namespace
 
 }  // namespace net
diff --git a/net/base/net_errors_win.cc b/net/base/net_errors_win.cc
index c56225f..74ed228 100644
--- a/net/base/net_errors_win.cc
+++ b/net/base/net_errors_win.cc
@@ -19,7 +19,6 @@ Error MapSystemError(int os_error) {
   // find interesting.
   switch (os_error) {
     case WSAEWOULDBLOCK:
-    case WSA_IO_PENDING:
       return ERR_IO_PENDING;
     case WSAEACCES:
       return ERR_ACCESS_DENIED;