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 // Copyright (c) 2008 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 "chrome/common/ipc_channel_posix.h"

 #include <errno.h>

 #include <fcntl.h>

 #include <stddef.h>

 #include <unistd.h>

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <sys/stat.h>

 #include <sys/un.h>

 #include <sys/uio.h>

 #include <string>

 #include <map>

 #include "base/command_line.h"

 #include "base/eintr_wrapper.h"

 #include "base/lock.h"

 #include "base/logging.h"

 #include "base/process_util.h"

 #include "base/scoped_ptr.h"

 #include "base/string_util.h"

 #include "base/singleton.h"

 #include "base/stats_counters.h"

 #include "chrome/common/chrome_switches.h"

 #include "chrome/common/file_descriptor_set_posix.h"

 #include "chrome/common/ipc_logging.h"

 #include "chrome/common/ipc_message_utils.h"

 #include "mozilla/ipc/ProtocolUtils.h"

 #ifdef MOZ_TASK_TRACER

 #include "GeckoTaskTracerImpl.h"

 using namespace mozilla::tasktracer;

 #endif

 namespace IPC {

 // IPC channels on Windows use named pipes (CreateNamedPipe()) with

 // channel ids as the pipe names.  Channels on POSIX use anonymous

 // Unix domain sockets created via socketpair() as pipes.  These don't

 // quite line up.

 //

 // When creating a child subprocess, the parent side of the fork

 // arranges it such that the initial control channel ends up on the

 // magic file descriptor kClientChannelFd in the child.  Future

 // connections (file descriptors) can then be passed via that

 // connection via sendmsg().

 //------------------------------------------------------------------------------

 namespace {

 // The PipeMap class works around this quirk related to unit tests:

 //

 // When running as a server, we install the client socket in a

 // specific file descriptor number (@kClientChannelFd). However, we

 // also have to support the case where we are running unittests in the

 // same process.  (We do not support forking without execing.)

 //

 // Case 1: normal running

 //   The IPC server object will install a mapping in PipeMap from the

 //   name which it was given to the client pipe. When forking the client, the

 //   GetClientFileDescriptorMapping will ensure that the socket is installed in

 //   the magic slot (@kClientChannelFd). The client will search for the

 //   mapping, but it won't find any since we are in a new process. Thus the

 //   magic fd number is returned. Once the client connects, the server will

 //   close its copy of the client socket and remove the mapping.

 //

 // Case 2: unittests - client and server in the same process

 //   The IPC server will install a mapping as before. The client will search

 //   for a mapping and find out. It duplicates the file descriptor and

 //   connects. Once the client connects, the server will close the original

 //   copy of the client socket and remove the mapping. Thus, when the client

 //   object closes, it will close the only remaining copy of the client socket

 //   in the fd table and the server will see EOF on its side.

 //

 // TODO(port): a client process cannot connect to multiple IPC channels with

 // this scheme.

 class PipeMap {

  public:

   // Lookup a given channel id. Return -1 if not found.

   int Lookup(const std::string& channel_id) {

     AutoLock locked(lock_);

     ChannelToFDMap::const_iterator i = map_.find(channel_id);

     if (i == map_.end())

       return -1;

     return i->second;

   }

   // Remove the mapping for the given channel id. No error is signaled if the

   // channel_id doesn't exist

   void Remove(const std::string& channel_id) {

     AutoLock locked(lock_);

     ChannelToFDMap::iterator i = map_.find(channel_id);

     if (i != map_.end())

       map_.erase(i);

   }

   // Insert a mapping from @channel_id to @fd. It's a fatal error to insert a

   // mapping if one already exists for the given channel_id

   void Insert(const std::string& channel_id, int fd) {

     AutoLock locked(lock_);

     DCHECK(fd != -1);

     ChannelToFDMap::const_iterator i = map_.find(channel_id);

     CHECK(i == map_.end()) << "Creating second IPC server for '"

                            << channel_id

                            << "' while first still exists";

     map_[channel_id] = fd;

   }

  private:

   Lock lock_;

   typedef std::map<std::string, int> ChannelToFDMap;

   ChannelToFDMap map_;

 };

 // This is the file descriptor number that a client process expects to find its

 // IPC socket.

 static const int kClientChannelFd = 3;

 // Used to map a channel name to the equivalent FD # in the client process.

 int ChannelNameToClientFD(const std::string& channel_id) {

   // See the large block comment above PipeMap for the reasoning here.

   const int fd = Singleton<PipeMap>()->Lookup(channel_id);

   if (fd != -1)

     return dup(fd);

   // If we don't find an entry, we assume that the correct value has been

   // inserted in the magic slot.

   return kClientChannelFd;

 }

 //------------------------------------------------------------------------------

 const size_t kMaxPipeNameLength = sizeof(((sockaddr_un*)0)->sun_path);

 // Creates a Fifo with the specified name ready to listen on.

 bool CreateServerFifo(const std::string& pipe_name, int* server_listen_fd) {

   DCHECK(server_listen_fd);

   DCHECK_GT(pipe_name.length(), 0u);

   DCHECK_LT(pipe_name.length(), kMaxPipeNameLength);

   if (pipe_name.length() == 0 || pipe_name.length() >= kMaxPipeNameLength) {

     return false;

   }

   // Create socket.

   int fd = socket(AF_UNIX, SOCK_STREAM, 0);

   if (fd < 0) {

     return false;

   }

   // Make socket non-blocking

   if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) {

     HANDLE_EINTR(close(fd));

     return false;

   }

   // Delete any old FS instances.

   unlink(pipe_name.c_str());

   // Create unix_addr structure

   struct sockaddr_un unix_addr;

   memset(&unix_addr, 0, sizeof(unix_addr));

   unix_addr.sun_family = AF_UNIX;

   snprintf(unix_addr.sun_path, kMaxPipeNameLength, "%s", pipe_name.c_str());

   size_t unix_addr_len = offsetof(struct sockaddr_un, sun_path) +

       strlen(unix_addr.sun_path) + 1;

   // Bind the socket.

   if (bind(fd, reinterpret_cast<const sockaddr*>(&unix_addr),

            unix_addr_len) != 0) {

     HANDLE_EINTR(close(fd));

     return false;

   }

   // Start listening on the socket.

   const int listen_queue_length = 1;

   if (listen(fd, listen_queue_length) != 0) {

     HANDLE_EINTR(close(fd));

     return false;

   }

   *server_listen_fd = fd;

   return true;

 }

 // Accept a connection on a fifo.

 bool ServerAcceptFifoConnection(int server_listen_fd, int* server_socket) {

   DCHECK(server_socket);

   int accept_fd = HANDLE_EINTR(accept(server_listen_fd, NULL, 0));

   if (accept_fd < 0)

     return false;

   if (fcntl(accept_fd, F_SETFL, O_NONBLOCK) == -1) {

     HANDLE_EINTR(close(accept_fd));

     return false;

   }

   *server_socket = accept_fd;

   return true;

 }

 bool ClientConnectToFifo(const std::string &pipe_name, int* client_socket) {

   DCHECK(client_socket);

   DCHECK_LT(pipe_name.length(), kMaxPipeNameLength);

   // Create socket.

   int fd = socket(AF_UNIX, SOCK_STREAM, 0);

   if (fd < 0) {

     CHROMIUM_LOG(ERROR) << "fd is invalid";

     return false;

   }

   // Make socket non-blocking

   if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) {

     CHROMIUM_LOG(ERROR) << "fcntl failed";

     HANDLE_EINTR(close(fd));

     return false;

   }

   // Create server side of socket.

   struct sockaddr_un  server_unix_addr;

   memset(&server_unix_addr, 0, sizeof(server_unix_addr));

   server_unix_addr.sun_family = AF_UNIX;

   snprintf(server_unix_addr.sun_path, kMaxPipeNameLength, "%s",

            pipe_name.c_str());

   size_t server_unix_addr_len = offsetof(struct sockaddr_un, sun_path) +

       strlen(server_unix_addr.sun_path) + 1;

   if (HANDLE_EINTR(connect(fd, reinterpret_cast<sockaddr*>(&server_unix_addr),

                            server_unix_addr_len)) != 0) {

     HANDLE_EINTR(close(fd));

     return false;

   }

   *client_socket = fd;

   return true;

 }

 bool SetCloseOnExec(int fd) {

   int flags = fcntl(fd, F_GETFD);

   if (flags == -1)

     return false;

   flags |= FD_CLOEXEC;

   if (fcntl(fd, F_SETFD, flags) == -1)

     return false;

   return true;

 }

 }  // namespace

 //------------------------------------------------------------------------------

 Channel::ChannelImpl::ChannelImpl(const std::wstring& channel_id, Mode mode,

                                   Listener* listener)

     : factory_(this) {

   Init(mode, listener);

   uses_fifo_ = CommandLine::ForCurrentProcess()->HasSwitch(switches::kIPCUseFIFO);

   if (!CreatePipe(channel_id, mode)) {

     // The pipe may have been closed already.

     CHROMIUM_LOG(WARNING) << "Unable to create pipe named \"" << channel_id <<

                              "\" in " << (mode == MODE_SERVER ? "server" : "client") <<

                              " mode error(" << strerror(errno) << ").";

   }

 }

 Channel::ChannelImpl::ChannelImpl(int fd, Mode mode, Listener* listener)

     : factory_(this) {

   Init(mode, listener);

   pipe_ = fd;

   waiting_connect_ = (MODE_SERVER == mode);

   EnqueueHelloMessage();

 }

 void Channel::ChannelImpl::Init(Mode mode, Listener* listener) {

   mode_ = mode;

   is_blocked_on_write_ = false;

   message_send_bytes_written_ = 0;

   uses_fifo_ = false;

   server_listen_pipe_ = -1;

   pipe_ = -1;

   client_pipe_ = -1;

   listener_ = listener;

   waiting_connect_ = true;

   processing_incoming_ = false;

   closed_ = false;

 #if defined(OS_MACOSX)

   last_pending_fd_id_ = 0;

 #endif

   output_queue_length_ = 0;

 }

 bool Channel::ChannelImpl::CreatePipe(const std::wstring& channel_id,

                                       Mode mode) {

   DCHECK(server_listen_pipe_ == -1 && pipe_ == -1);

   if (uses_fifo_) {

     // This only happens in unit tests; see the comment above PipeMap.

     // TODO(playmobil): We shouldn't need to create fifos on disk.

     // TODO(playmobil): If we do, they should be in the user data directory.

     // TODO(playmobil): Cleanup any stale fifos.

     pipe_name_ = "/var/tmp/chrome_" + WideToASCII(channel_id);

     if (mode == MODE_SERVER) {

       if (!CreateServerFifo(pipe_name_, &server_listen_pipe_)) {

         return false;

       }

     } else {

       if (!ClientConnectToFifo(pipe_name_, &pipe_)) {

         return false;

       }

       waiting_connect_ = false;

     }

   } else {

     // socketpair()

     pipe_name_ = WideToASCII(channel_id);

     if (mode == MODE_SERVER) {

       int pipe_fds[2];

       if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipe_fds) != 0) {

         return false;

       }

       // Set both ends to be non-blocking.

       if (fcntl(pipe_fds[0], F_SETFL, O_NONBLOCK) == -1 ||

           fcntl(pipe_fds[1], F_SETFL, O_NONBLOCK) == -1) {

         HANDLE_EINTR(close(pipe_fds[0]));

         HANDLE_EINTR(close(pipe_fds[1]));

         return false;

       }

       if (!SetCloseOnExec(pipe_fds[0]) ||

           !SetCloseOnExec(pipe_fds[1])) {

         HANDLE_EINTR(close(pipe_fds[0]));

         HANDLE_EINTR(close(pipe_fds[1]));

         return false;

       }

       pipe_ = pipe_fds[0];

       client_pipe_ = pipe_fds[1];

       if (pipe_name_.length()) {

         Singleton<PipeMap>()->Insert(pipe_name_, client_pipe_);

       }

     } else {

       pipe_ = ChannelNameToClientFD(pipe_name_);

       DCHECK(pipe_ > 0);

       waiting_connect_ = false;

     }

   }

   // Create the Hello message to be sent when Connect is called

   return EnqueueHelloMessage();

 }

 /**

  * Reset the file descriptor for communication with the peer.

  */

 void Channel::ChannelImpl::ResetFileDescriptor(int fd) {

   NS_ASSERTION(fd > 0 && fd == pipe_, "Invalid file descriptor");

   EnqueueHelloMessage();

 }

 bool Channel::ChannelImpl::EnqueueHelloMessage() {

   scoped_ptr<Message> msg(new Message(MSG_ROUTING_NONE,

                                       HELLO_MESSAGE_TYPE,

                                       IPC::Message::PRIORITY_NORMAL));

   if (!msg->WriteInt(base::GetCurrentProcId())) {

     Close();

     return false;

   }

   OutputQueuePush(msg.release());

   return true;

 }

 static void

 ClearAndShrink(std::string& s, size_t capacity)

 {

   // This swap trick is the closest thing C++ has to a guaranteed way to

   // shrink the capacity of a string.

   std::string tmp;

   tmp.reserve(capacity);

   s.swap(tmp);

 }

 bool Channel::ChannelImpl::Connect() {

   if (mode_ == MODE_SERVER && uses_fifo_) {

     if (server_listen_pipe_ == -1) {

       return false;

     }

     MessageLoopForIO::current()->WatchFileDescriptor(

         server_listen_pipe_,

         true,

         MessageLoopForIO::WATCH_READ,

         &server_listen_connection_watcher_,

         this);

   } else {

     if (pipe_ == -1) {

       return false;

     }

     MessageLoopForIO::current()->WatchFileDescriptor(

         pipe_,

         true,

         MessageLoopForIO::WATCH_READ,

         &read_watcher_,

         this);

     waiting_connect_ = false;

   }

   if (!waiting_connect_)

     return ProcessOutgoingMessages();

   return true;

 }

 bool Channel::ChannelImpl::ProcessIncomingMessages() {

   ssize_t bytes_read = 0;

   struct msghdr msg = {0};

   struct iovec iov = {input_buf_, Channel::kReadBufferSize};

   msg.msg_iov = &iov;

   msg.msg_iovlen = 1;

   msg.msg_control = input_cmsg_buf_;

   for (;;) {

     msg.msg_controllen = sizeof(input_cmsg_buf_);

     if (bytes_read == 0) {

       if (pipe_ == -1)

         return false;

       // Read from pipe.

       // recvmsg() returns 0 if the connection has closed or EAGAIN if no data

       // is waiting on the pipe.

       bytes_read = HANDLE_EINTR(recvmsg(pipe_, &msg, MSG_DONTWAIT));

       if (bytes_read < 0) {

         if (errno == EAGAIN) {

           return true;

         } else {

           CHROMIUM_LOG(ERROR) << "pipe error (" << pipe_ << "): " << strerror(errno);

           return false;

         }

       } else if (bytes_read == 0) {

         // The pipe has closed...

         Close();

         return false;

       }

     }

     DCHECK(bytes_read);

     if (client_pipe_ != -1) {

       Singleton<PipeMap>()->Remove(pipe_name_);

       HANDLE_EINTR(close(client_pipe_));

       client_pipe_ = -1;

     }

     // a pointer to an array of |num_wire_fds| file descriptors from the read

     const int* wire_fds = NULL;

     unsigned num_wire_fds = 0;

     // walk the list of control messages and, if we find an array of file

     // descriptors, save a pointer to the array

     // This next if statement is to work around an OSX issue where

     // CMSG_FIRSTHDR will return non-NULL in the case that controllen == 0.

     // Here's a test case:

     //

     // int main() {

     // struct msghdr msg;

     //   msg.msg_control = &msg;

     //   msg.msg_controllen = 0;

     //   if (CMSG_FIRSTHDR(&msg))

     //     printf("Bug found!\n");

     // }

     if (msg.msg_controllen > 0) {

       // On OSX, CMSG_FIRSTHDR doesn't handle the case where controllen is 0

       // and will return a pointer into nowhere.

       for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg;

            cmsg = CMSG_NXTHDR(&msg, cmsg)) {

         if (cmsg->cmsg_level == SOL_SOCKET &&

             cmsg->cmsg_type == SCM_RIGHTS) {

           const unsigned payload_len = cmsg->cmsg_len - CMSG_LEN(0);

           DCHECK(payload_len % sizeof(int) == 0);

           wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));

           num_wire_fds = payload_len / 4;

           if (msg.msg_flags & MSG_CTRUNC) {

             CHROMIUM_LOG(ERROR) << "SCM_RIGHTS message was truncated"

                                 << " cmsg_len:" << cmsg->cmsg_len

                                 << " fd:" << pipe_;

             for (unsigned i = 0; i < num_wire_fds; ++i)

               HANDLE_EINTR(close(wire_fds[i]));

             return false;

           }

           break;

         }

       }

     }

     // Process messages from input buffer.

     const char *p;

     const char *overflowp;

     const char *end;

     if (input_overflow_buf_.empty()) {

       overflowp = NULL;

       p = input_buf_;

       end = p + bytes_read;

     } else {

       if (input_overflow_buf_.size() >

          static_cast<size_t>(kMaximumMessageSize - bytes_read)) {

         ClearAndShrink(input_overflow_buf_, Channel::kReadBufferSize);

         CHROMIUM_LOG(ERROR) << "IPC message is too big";

         return false;

       }

       input_overflow_buf_.append(input_buf_, bytes_read);

       overflowp = p = input_overflow_buf_.data();

       end = p + input_overflow_buf_.size();

     }

     // A pointer to an array of |num_fds| file descriptors which includes any

     // fds that have spilled over from a previous read.

     const int* fds;

     unsigned num_fds;

     unsigned fds_i = 0;  // the index of the first unused descriptor

     if (input_overflow_fds_.empty()) {

       fds = wire_fds;

       num_fds = num_wire_fds;

     } else {

       const size_t prev_size = input_overflow_fds_.size();

       input_overflow_fds_.resize(prev_size + num_wire_fds);

       memcpy(&input_overflow_fds_[prev_size], wire_fds,

              num_wire_fds * sizeof(int));

       fds = &input_overflow_fds_[0];

       num_fds = input_overflow_fds_.size();

     }

     while (p < end) {

       const char* message_tail = Message::FindNext(p, end);

       if (message_tail) {

         int len = static_cast<int>(message_tail - p);

         Message m(p, len);

         if (m.header()->num_fds) {

           // the message has file descriptors

           const char* error = NULL;

           if (m.header()->num_fds > num_fds - fds_i) {

             // the message has been completely received, but we didn't get

             // enough file descriptors.

             error = "Message needs unreceived descriptors";

           }

           if (m.header()->num_fds >

               FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE) {

             // There are too many descriptors in this message

             error = "Message requires an excessive number of descriptors";

           }

           if (error) {

             CHROMIUM_LOG(WARNING) << error

                                   << " channel:" << this

                                   << " message-type:" << m.type()

                                   << " header()->num_fds:" << m.header()->num_fds

                                   << " num_fds:" << num_fds

                                   << " fds_i:" << fds_i;

             // close the existing file descriptors so that we don't leak them

             for (unsigned i = fds_i; i < num_fds; ++i)

               HANDLE_EINTR(close(fds[i]));

             input_overflow_fds_.clear();

             // abort the connection

             return false;

           }

 #if defined(OS_MACOSX)

           // Send a message to the other side, indicating that we are now

           // responsible for closing the descriptor.

           Message *fdAck = new Message(MSG_ROUTING_NONE,

                                        RECEIVED_FDS_MESSAGE_TYPE,

                                        IPC::Message::PRIORITY_NORMAL);

           DCHECK(m.fd_cookie() != 0);

           fdAck->set_fd_cookie(m.fd_cookie());

           OutputQueuePush(fdAck);

 #endif

           m.file_descriptor_set()->SetDescriptors(

               &fds[fds_i], m.header()->num_fds);

           fds_i += m.header()->num_fds;

         }

 #ifdef IPC_MESSAGE_DEBUG_EXTRA

         DLOG(INFO) << "received message on channel @" << this <<

                       " with type " << m.type();

 #endif

 #ifdef MOZ_TASK_TRACER

         AutoSaveCurTraceInfo saveCurTraceInfo;

         SetCurTraceInfo(m.header()->source_event_id,

                         m.header()->parent_task_id,

                         m.header()->source_event_type);

 #endif

         if (m.routing_id() == MSG_ROUTING_NONE &&

             m.type() == HELLO_MESSAGE_TYPE) {

           // The Hello message contains only the process id.

           listener_->OnChannelConnected(MessageIterator(m).NextInt());

 #if defined(OS_MACOSX)

         } else if (m.routing_id() == MSG_ROUTING_NONE &&

                    m.type() == RECEIVED_FDS_MESSAGE_TYPE) {

           DCHECK(m.fd_cookie() != 0);

           CloseDescriptors(m.fd_cookie());

 #endif

         } else {

           listener_->OnMessageReceived(m);

         }

         p = message_tail;

       } else {

         // Last message is partial.

         break;

       }

     }

     if (end == p) {

       ClearAndShrink(input_overflow_buf_, Channel::kReadBufferSize);

     } else if (!overflowp) {

       // p is from input_buf_

       input_overflow_buf_.assign(p, end - p);

     } else if (p > overflowp) {

       // p is from input_overflow_buf_

       input_overflow_buf_.erase(0, p - overflowp);

     }

     input_overflow_fds_ = std::vector<int>(&fds[fds_i], &fds[num_fds]);

     // When the input data buffer is empty, the overflow fds should be too. If

     // this is not the case, we probably have a rogue renderer which is trying

     // to fill our descriptor table.

     if (input_overflow_buf_.empty() && !input_overflow_fds_.empty()) {

       // We close these descriptors in Close()

       return false;

     }

     bytes_read = 0;  // Get more data.

   }

   return true;

 }

 bool Channel::ChannelImpl::ProcessOutgoingMessages() {

   DCHECK(!waiting_connect_);  // Why are we trying to send messages if there's

                               // no connection?

   is_blocked_on_write_ = false;

   if (output_queue_.empty())

     return true;

   if (pipe_ == -1)

     return false;

   // Write out all the messages we can till the write blocks or there are no

   // more outgoing messages.

   while (!output_queue_.empty()) {

     Message* msg = output_queue_.front();

     struct msghdr msgh = {0};

     static const int tmp = CMSG_SPACE(sizeof(

         int[FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE]));

     char buf[tmp];

     if (message_send_bytes_written_ == 0 &&

         !msg->file_descriptor_set()->empty()) {

       // This is the first chunk of a message which has descriptors to send

       struct cmsghdr *cmsg;

       const unsigned num_fds = msg->file_descriptor_set()->size();

       if (num_fds > FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE) {

         CHROMIUM_LOG(FATAL) << "Too many file descriptors!";

         // This should not be reached.

         return false;

       }

       msgh.msg_control = buf;

       msgh.msg_controllen = CMSG_SPACE(sizeof(int) * num_fds);

       cmsg = CMSG_FIRSTHDR(&msgh);

       cmsg->cmsg_level = SOL_SOCKET;

       cmsg->cmsg_type = SCM_RIGHTS;

       cmsg->cmsg_len = CMSG_LEN(sizeof(int) * num_fds);

       msg->file_descriptor_set()->GetDescriptors(

           reinterpret_cast<int*>(CMSG_DATA(cmsg)));

       msgh.msg_controllen = cmsg->cmsg_len;

       msg->header()->num_fds = num_fds;

 #if defined(OS_MACOSX)

       msg->set_fd_cookie(++last_pending_fd_id_);

 #endif

     }

 #ifdef MOZ_TASK_TRACER

     GetCurTraceInfo(&msg->header()->source_event_id,

                     &msg->header()->parent_task_id,

                     &msg->header()->source_event_type);

 #endif

     size_t amt_to_write = msg->size() - message_send_bytes_written_;

     DCHECK(amt_to_write != 0);

     const char *out_bytes = reinterpret_cast<const char*>(msg->data()) +

         message_send_bytes_written_;

     struct iovec iov = {const_cast<char*>(out_bytes), amt_to_write};

     msgh.msg_iov = &iov;

     msgh.msg_iovlen = 1;

     ssize_t bytes_written = HANDLE_EINTR(sendmsg(pipe_, &msgh, MSG_DONTWAIT));

 #if !defined(OS_MACOSX)

     // On OSX CommitAll gets called later, once we get the RECEIVED_FDS_MESSAGE_TYPE

     // message.

     if (bytes_written > 0)

       msg->file_descriptor_set()->CommitAll();

 #endif

     if (bytes_written < 0 && errno != EAGAIN) {

       CHROMIUM_LOG(ERROR) << "pipe error: " << strerror(errno);

       return false;

     }

     if (static_cast<size_t>(bytes_written) != amt_to_write) {

       if (bytes_written > 0) {

         // If write() fails with EAGAIN then bytes_written will be -1.

         message_send_bytes_written_ += bytes_written;

       }

       // Tell libevent to call us back once things are unblocked.

       is_blocked_on_write_ = true;

       MessageLoopForIO::current()->WatchFileDescriptor(

           pipe_,

           false,  // One shot

           MessageLoopForIO::WATCH_WRITE,

           &write_watcher_,

           this);

       return true;

     } else {

       message_send_bytes_written_ = 0;

 #if defined(OS_MACOSX)

       if (!msg->file_descriptor_set()->empty())

         pending_fds_.push_back(PendingDescriptors(msg->fd_cookie(),

                                                   msg->file_descriptor_set()));

 #endif

       // Message sent OK!

 #ifdef IPC_MESSAGE_DEBUG_EXTRA

       DLOG(INFO) << "sent message @" << msg << " on channel @" << this <<

                     " with type " << msg->type();

 #endif

       OutputQueuePop();

       delete msg;

     }

   }

   return true;

 }

 bool Channel::ChannelImpl::Send(Message* message) {

 #ifdef IPC_MESSAGE_DEBUG_EXTRA

   DLOG(INFO) << "sending message @" << message << " on channel @" << this

              << " with type " << message->type()

              << " (" << output_queue_.size() << " in queue)";

 #endif

 #ifdef IPC_MESSAGE_LOG_ENABLED

   Logging::current()->OnSendMessage(message, L"");

 #endif

   // If the channel has been closed, ProcessOutgoingMessages() is never going

   // to pop anything off output_queue; output_queue will only get emptied when

   // the channel is destructed.  We might as well delete message now, instead

   // of waiting for the channel to be destructed.

   if (closed_) {

     if (mozilla::ipc::LoggingEnabled()) {

       fprintf(stderr, "Can't send message %s, because this channel is closed.\n",

               message->name());

     }

     delete message;

     return false;

   }

   OutputQueuePush(message);

   if (!waiting_connect_) {

     if (!is_blocked_on_write_) {

       if (!ProcessOutgoingMessages())

         return false;

     }

   }

   return true;

 }

 void Channel::ChannelImpl::GetClientFileDescriptorMapping(int *src_fd,

                                                           int *dest_fd) const {

   DCHECK(mode_ == MODE_SERVER);

   *src_fd = client_pipe_;

   *dest_fd = kClientChannelFd;

 }

 void Channel::ChannelImpl::CloseClientFileDescriptor() {

   if (client_pipe_ != -1) {

     Singleton<PipeMap>()->Remove(pipe_name_);

     HANDLE_EINTR(close(client_pipe_));

     client_pipe_ = -1;

   }

 }

 // Called by libevent when we can read from th pipe without blocking.

 void Channel::ChannelImpl::OnFileCanReadWithoutBlocking(int fd) {

   bool send_server_hello_msg = false;

   if (waiting_connect_ && mode_ == MODE_SERVER) {

     // In the case of a socketpair() the server starts listening on its end

     // of the pipe in Connect().

     DCHECK(uses_fifo_);

     if (!ServerAcceptFifoConnection(server_listen_pipe_, &pipe_)) {

       Close();

     }

     // No need to watch the listening socket any longer since only one client

     // can connect.  So unregister with libevent.

     server_listen_connection_watcher_.StopWatchingFileDescriptor();

     // Start watching our end of the socket.

     MessageLoopForIO::current()->WatchFileDescriptor(

         pipe_,

         true,

         MessageLoopForIO::WATCH_READ,

         &read_watcher_,

         this);

     waiting_connect_ = false;

     send_server_hello_msg = true;

   }

   if (!waiting_connect_ && fd == pipe_) {

     if (!ProcessIncomingMessages()) {

       Close();

       listener_->OnChannelError();

     }

   }

   // If we're a server and handshaking, then we want to make sure that we

   // only send our handshake message after we've processed the client's.

   // This gives us a chance to kill the client if the incoming handshake

   // is invalid.

   if (send_server_hello_msg) {

     // This should be our first write so there's no chance we can block here...

     DCHECK(is_blocked_on_write_ == false);

     ProcessOutgoingMessages();

   }

 }

 #if defined(OS_MACOSX)

 void Channel::ChannelImpl::CloseDescriptors(uint32_t pending_fd_id)

 {

   DCHECK(pending_fd_id != 0);

   for (std::list<PendingDescriptors>::iterator i = pending_fds_.begin();

        i != pending_fds_.end();

        i++) {

     if ((*i).id == pending_fd_id) {

       (*i).fds->CommitAll();

       pending_fds_.erase(i);

       return;

     }

   }

   DCHECK(false) << "pending_fd_id not in our list!";

 }

 #endif

 void Channel::ChannelImpl::OutputQueuePush(Message* msg)

 {

   output_queue_.push(msg);

   output_queue_length_++;

 }

 void Channel::ChannelImpl::OutputQueuePop()

 {

   output_queue_.pop();

   output_queue_length_--;

 }

 // Called by libevent when we can write to the pipe without blocking.

 void Channel::ChannelImpl::OnFileCanWriteWithoutBlocking(int fd) {

   if (!ProcessOutgoingMessages()) {

     Close();

     listener_->OnChannelError();

   }

 }

 void Channel::ChannelImpl::Close() {

   // Close can be called multiple times, so we need to make sure we're

   // idempotent.

   // Unregister libevent for the listening socket and close it.

   server_listen_connection_watcher_.StopWatchingFileDescriptor();

   if (server_listen_pipe_ != -1) {

     HANDLE_EINTR(close(server_listen_pipe_));

     server_listen_pipe_ = -1;

   }

   // Unregister libevent for the FIFO and close it.

   read_watcher_.StopWatchingFileDescriptor();

   write_watcher_.StopWatchingFileDescriptor();

   if (pipe_ != -1) {

     HANDLE_EINTR(close(pipe_));

     pipe_ = -1;

   }

   if (client_pipe_ != -1) {

     Singleton<PipeMap>()->Remove(pipe_name_);

     HANDLE_EINTR(close(client_pipe_));

     client_pipe_ = -1;

   }

   if (uses_fifo_) {

     // Unlink the FIFO

     unlink(pipe_name_.c_str());

   }

   while (!output_queue_.empty()) {

     Message* m = output_queue_.front();

     OutputQueuePop();

     delete m;

   }

   // Close any outstanding, received file descriptors

   for (std::vector<int>::iterator

        i = input_overflow_fds_.begin(); i != input_overflow_fds_.end(); ++i) {

     HANDLE_EINTR(close(*i));

   }

   input_overflow_fds_.clear();

 #if defined(OS_MACOSX)

   for (std::list<PendingDescriptors>::iterator i = pending_fds_.begin();

        i != pending_fds_.end();

        i++) {

     (*i).fds->CommitAll();

   }

   pending_fds_.clear();

 #endif

   closed_ = true;

 }

 bool Channel::ChannelImpl::Unsound_IsClosed() const

 {

   return closed_;

 }

 uint32_t Channel::ChannelImpl::Unsound_NumQueuedMessages() const

 {

   return output_queue_length_;

 }

 //------------------------------------------------------------------------------

 // Channel's methods simply call through to ChannelImpl.

 Channel::Channel(const std::wstring& channel_id, Mode mode,

                  Listener* listener)

     : channel_impl_(new ChannelImpl(channel_id, mode, listener)) {

 }

 Channel::Channel(int fd, Mode mode, Listener* listener)

     : channel_impl_(new ChannelImpl(fd, mode, listener)) {

 }

 Channel::~Channel() {

   delete channel_impl_;

 }

 bool Channel::Connect() {

   return channel_impl_->Connect();

 }

 void Channel::Close() {

   channel_impl_->Close();

 }

 Channel::Listener* Channel::set_listener(Listener* listener) {

   return channel_impl_->set_listener(listener);

 }

 bool Channel::Send(Message* message) {

   return channel_impl_->Send(message);

 }

 void Channel::GetClientFileDescriptorMapping(int *src_fd, int *dest_fd) const {

   return channel_impl_->GetClientFileDescriptorMapping(src_fd, dest_fd);

 }

 void Channel::ResetFileDescriptor(int fd) {

   channel_impl_->ResetFileDescriptor(fd);

 }

 int Channel::GetFileDescriptor() const {

     return channel_impl_->GetFileDescriptor();

 }

 void Channel::CloseClientFileDescriptor() {

   channel_impl_->CloseClientFileDescriptor();

 }

 bool Channel::Unsound_IsClosed() const {

   return channel_impl_->Unsound_IsClosed();

 }

 uint32_t Channel::Unsound_NumQueuedMessages() const {

   return channel_impl_->Unsound_NumQueuedMessages();

 }

 }  // namespace IPC