Add a "native_support" service.

services/native_support/redirectors.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "services/native_support/redirectors.h"
+
+#include <errno.h>
+#include <string.h>
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+
+namespace native_support {
+
+// FDToMojoFileRedirector ------------------------------------------------------
+
+FDToMojoFileRedirector::FDToMojoFileRedirector(int fd,
+                                               mojo::files::File* file,
+                                               size_t buffer_size)
+    : fd_(fd),
+      file_(file),
+      buffer_size_(buffer_size),
+      num_bytes_(0),
+      offset_(0),
+      weak_factory_(this) {
+  DCHECK_NE(fd_, -1);
+  DCHECK(file_);
+}
+
+FDToMojoFileRedirector::~FDToMojoFileRedirector() {}
+
+void FDToMojoFileRedirector::Start() {
+  // One-shot watch (since we'll need to wait for write callbacks).
+  bool success = base::MessageLoopForIO::current()->WatchFileDescriptor(
+      fd_, false, base::MessageLoopForIO::WATCH_READ, &watcher_, this);
+  DCHECK(success);
+}
+
+void FDToMojoFileRedirector::Stop() {
+  watcher_.StopWatchingFileDescriptor();
+}
+
+void FDToMojoFileRedirector::OnFileCanReadWithoutBlocking(int fd) {
+  DCHECK_EQ(fd, fd_);
+
+  if (!buffer_)
+    buffer_.reset(new char[buffer_size_]);
+
+  ssize_t result = HANDLE_EINTR(read(fd_, buffer_.get(), buffer_size_));
+  if (result < 0) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK) {
+      LOG(WARNING) << "Could not read from FD without blocking";
+      Start();
+      return;
+    }
+    PLOG(WARNING) << "Failed to read from FD";
+    // TODO(vtl): Should maybe close |file_|?
+    return;
+  }
+  if (!result) {  // EOF.
+    // TODO(vtl): Should maybe close |file_|?
+    return;
+  }
+
+  num_bytes_ = static_cast<size_t>(result);
+  offset_ = 0;
+  DoWrite();
+}
+
+void FDToMojoFileRedirector::OnFileCanWriteWithoutBlocking(int /*fd*/) {
+  NOTREACHED();
+}
+
+void FDToMojoFileRedirector::DoWrite() {
+  CHECK_GT(num_bytes_, offset_);
+  size_t num_bytes_to_write = num_bytes_ - offset_;
+
+  // TODO(vtl): Is there a more natural (or efficient) way to do this?
+  mojo::Array<uint8_t> bytes_to_write(num_bytes_to_write);
+  memcpy(&bytes_to_write[offset_], buffer_.get(), num_bytes_to_write);
+
+  file_->Write(bytes_to_write.Pass(), 0, mojo::files::WHENCE_FROM_CURRENT,
+               base::Bind(&FDToMojoFileRedirector::DidWrite,
+                          weak_factory_.GetWeakPtr()));
+}
+
+void FDToMojoFileRedirector::DidWrite(mojo::files::Error error,
+                                      uint32_t num_bytes_written) {
+  if (error != mojo::files::ERROR_OK) {
+    LOG(WARNING) << "Failed to write to Mojo File";
+    // TODO(vtl): Should maybe close |file_|?
+    return;
+  }
+
+  CHECK_GT(num_bytes_, offset_);
+  size_t num_bytes_to_write = num_bytes_ - offset_;
+  if (num_bytes_written > num_bytes_to_write) {
+    LOG(ERROR) << "Bad result from write to Mojo File";
+    return;
+  }
+
+  offset_ += num_bytes_written;
+  if (offset_ < num_bytes_) {
+    DoWrite();
+  } else {
+    num_bytes_ = 0;
+    offset_ = 0;
+    Start();
+  }
+}
+
+// MojoFileToFDRedirector ------------------------------------------------------
+
+MojoFileToFDRedirector::MojoFileToFDRedirector(mojo::files::File* file,
+                                               int fd,
+                                               size_t buffer_size)
+    : file_(file),
+      fd_(fd),
+      buffer_size_(buffer_size),
+      running_(false),
+      read_pending_(false),
+      weak_factory_(this) {}
+
+MojoFileToFDRedirector::~MojoFileToFDRedirector() {}
+
+void MojoFileToFDRedirector::Start() {
+  running_ = true;
+
+  if (read_pending_)
+    return;
+
+  file_->Read(
+      static_cast<uint32_t>(buffer_size_), 0, mojo::files::WHENCE_FROM_CURRENT,
+      base::Bind(&MojoFileToFDRedirector::DidRead, weak_factory_.GetWeakPtr()));
+  read_pending_ = true;
+}
+
+void MojoFileToFDRedirector::Stop() {
+  running_ = false;
+}
+
+void MojoFileToFDRedirector::DidRead(mojo::files::Error error,
+                                     mojo::Array<uint8_t> bytes_read) {
+  DCHECK(read_pending_);
+  read_pending_ = false;
+
+  if (error != mojo::files::ERROR_OK) {
+    LOG(ERROR) << "Read failed";
+    // TODO(vtl): Should maybe close |file_|?
+    return;
+  }
+
+  ssize_t result = HANDLE_EINTR(write(fd_, &bytes_read[0], bytes_read.size()));
+  if (result < 0) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK) {
+      LOG(ERROR) << "Could not write to FD without blocking";
+      if (running_)
+        Start();
+      return;
+    }
+    PLOG(WARNING) << "Failed to write to FD";
+    // TODO(vtl): Should maybe close |file_|?
+    return;
+  }
+  if (static_cast<size_t>(result) != bytes_read.size())
+    LOG(ERROR) << "Failed to write everything to FD";
+
+  if (running_)
+    Start();
+}
+
+}  // namespace native_support