Adds USB writing for OS X.

chrome/utility/image_writer/image_writer_mac.cc

+// Copyright 2014 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 <sys/socket.h>
+#include <IOKit/storage/IOStorageProtocolCharacteristics.h>
+
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/message_loop/message_pump_mac.h"
+#include "base/posix/eintr_wrapper.h"
+#include "chrome/common/extensions/image_writer_util_mac.h"
+#include "chrome/utility/image_writer/disk_unmounter_mac.h"
+#include "chrome/utility/image_writer/error_messages.h"
+#include "chrome/utility/image_writer/image_writer.h"
+
+namespace image_writer {
+
+bool ImageWriter::IsValidDevice() {
+  base::ScopedCFTypeRef<DASessionRef> session(DASessionCreate(NULL));
+  DADiskRef disk = DADiskCreateFromBSDName(
+      kCFAllocatorDefault, session, device_path_.value().c_str());
+
+  if (!disk)
+    return false;
+
+  base::ScopedCFTypeRef<CFDictionaryRef> dict(DADiskCopyDescription(disk));
+
+  return extensions::image_writer::IsRemovableDevice(dict.get());
+}
+
+void ImageWriter::UnmountVolumes(const base::Closure& continuation) {
+  if (unmounter_ == NULL) {
+    unmounter_.reset(new DiskUnmounterMac());
+  }
+
+  unmounter_->Unmount(
+      device_path_.value(),
+      continuation,
+      base::Bind(
+          &ImageWriter::Error, base::Unretained(this), error::kUnmountVolumes));
+}
+
+bool ImageWriter::OpenDevice() {
+  int sockets[2];  // [parent's end, child's end]
+  int result = socketpair(AF_UNIX, SOCK_STREAM, 0, sockets);
+  if (result == -1) {
+    LOG(ERROR) << "Unable to allocate socket pair.";
+    return false;
+  }
+
+  char rdwr[10];
+  snprintf(rdwr, sizeof(rdwr), "%d", O_RDWR);
+
+  pid_t childPid = fork();

[Robert Sesek, 2014/06/10 19:47:46]

This should probably use base/process/launch.h.

[Drew Haven, 2014/06/12 02:24:26]

Done.

+  if (childPid == -1) {
+    LOG(ERROR) << "Fork failed.";
+    return false;
+  }
+
+  if (childPid == 0) {  // child
+    HANDLE_EINTR(dup2(sockets[1], STDOUT_FILENO));
+    close(sockets[0]);
+    close(sockets[1]);
+
+    base::FilePath real_device_path;
+    if (device_path_.IsAbsolute()) {
+      real_device_path = device_path_;
+    } else {
+      real_device_path = base::FilePath("/dev").Append(device_path_);

[Robert Sesek, 2014/06/10 19:47:46]

Yikes, this is going to do allocation between fork/exec. You can't trust Libc
right now, so this won't fly. C.f.
https://code.google.com/p/chromium/issues/detail?id=36678

[Drew Haven, 2014/06/12 02:24:26]

With the switch to LaunchProcess I think we should be fine.

+    }
+
+    const char authopenPath[] = "/usr/libexec/authopen";
+    execl(authopenPath,
+          authopenPath,
+          "-stdoutpipe",
+          "-o",
+          rdwr,
+          real_device_path.value().c_str(),
+          NULL);
+    _exit(errno);
+  } else {  // parent
+    close(sockets[1]);
+    int fd = -1;
+
+    msghdr message = {0};

[Robert Sesek, 2014/06/10 19:47:47]

What is this code supposed to do? Commentary definitely required.

[Drew Haven, 2014/06/12 02:24:26]

I commented it up a bit.  I couldn't figure out a good way to do this simple
receive with any of the IPC classes because they are built around the idea of
Listeners and Senders and I just want to receive a single known message without
setting up any of that.

+    const size_t kDataBufferSize = 1024;
+    char dataBuffer[kDataBufferSize];
+    iovec ioVec[1];
+    ioVec[0].iov_base = dataBuffer;
+    ioVec[0].iov_len = kDataBufferSize;
+    message.msg_iov = ioVec;
+    message.msg_iovlen = 1;
+    const socklen_t kCmsgSocketSize = (socklen_t)CMSG_SPACE(sizeof(int));
+    char cmsgSocket[kCmsgSocketSize];
+    message.msg_control = cmsgSocket;
+    message.msg_controllen = kCmsgSocketSize;
+    ssize_t size = HANDLE_EINTR(recvmsg(sockets[0], &message, 0));
+    if (size > 0) {
+      cmsghdr* cmsgSocketHeader = CMSG_FIRSTHDR(&message);
+      // Paranoia.
+      if (cmsgSocketHeader && cmsgSocketHeader->cmsg_level == SOL_SOCKET &&
+          cmsgSocketHeader->cmsg_type == SCM_RIGHTS)
+        fd = *((int*)CMSG_DATA(cmsgSocketHeader));
+    }
+
+    int childStat;
+    result = HANDLE_EINTR(waitpid(childPid, &childStat, 0));
+    close(sockets[0]);
+
+    if (result != -1 && WIFEXITED(childStat)) {
+      int exitStatus = WEXITSTATUS(childStat);
+      if (exitStatus) {
+        LOG(ERROR) << "Child process returned failure.";
+        return false;
+      }
+    }
+
+    device_file_ = base::File(fd);
+
+    return device_file_.IsValid();
+  }
+}
+
+}  // namespace image_writer