Linux: refactor zygote support

base/zygote_manager.cc

Index: base/zygote_manager.cc
diff --git a/base/zygote_manager.cc b/base/zygote_manager.cc
deleted file mode 100644
index 7f0043aa6c8ead81dda542dd72ed90a94f8eb3e7..0000000000000000000000000000000000000000
--- a/base/zygote_manager.cc
+++ /dev/null
@@ -1,832 +0,0 @@
-// Copyright (c) 2006-2009 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 "base/zygote_manager.h"
-
-#if defined(OS_LINUX)
-
-#include <errno.h>
-#include <fcntl.h>
-#include <poll.h>
-#include <stdlib.h>
-#include <sys/file.h>     // for flock()
-#include <sys/stat.h>
-#include <sys/uio.h>      // for struct iovec
-#include <sys/wait.h>
-#include <unistd.h>       // for ssize_t
-
-#include <string>
-
-#include "base/eintr_wrapper.h"
-#include "base/file_descriptor_shuffle.h"
-#include "base/file_util.h"
-#include "base/logging.h"
-#include "base/process_util.h"
-#include "base/reserved_file_descriptors.h"
-#include "base/singleton.h"
-
-using file_util::Delete;
-
-// See comment below, where sigaction is called.
-static void SIGCHLDHandler(int signal) {
-}
-
-namespace base {
-
-const char ZygoteManager::kZMagic[] = "zygo";
-
-ZygoteManager::~ZygoteManager() {
-  if (server_fd_ != -1) {
-    close(server_fd_);
-    server_fd_ = -1;
-  }
-  if (client_fd_ != -1) {
-    close(client_fd_);
-    client_fd_ = -1;
-  }
-  if (lockfd_ != -1) {
-    close(lockfd_);
-    lockfd_ = -1;
-  }
-  if (canary_fd_ != -1) {
-    // Wake up the poll() in ReadAndHandleMessage()
-    close(canary_fd_);
-    canary_fd_ = -1;
-  }
-#ifndef OFFICIAL_BUILD
-  // Closing the canary kills the server,
-  // so after this it's ok for e.g. unit tests
-  // to start a new zygote server.
-  (void) unsetenv("ZYGOTE_MANAGER_STARTED");
-#endif
-}
-
-// Runs in client process
-ZygoteManager* ZygoteManager::Get() {
-  static bool checked = false;
-  static bool enabled = false;
-  if (!checked) {
-    enabled = (getenv("DISABLE_ZYGOTE_MANAGER") == NULL);
-    checked = true;
-  }
-  if (!enabled)
-    return NULL;
-  return Singleton<ZygoteManager>::get();
-}
-
-// Runs in zygote manager process
-int ZygoteManager::UnpickleHeader(const Pickle& reply, void** iter) {
-  std::string magic;
-  if (!reply.ReadString(iter, &magic) || magic != std::string(kZMagic)) {
-    LOG(ERROR) << "reply didn't start with " << kZMagic;
-    return ZMBAD;
-  }
-  pid_t clientpid = (pid_t) -1;
-  if (!reply.ReadInt(iter, &clientpid)) {
-    LOG(ERROR) << "Can't read client pid";
-    return ZMBAD;
-  }
-  if (clientpid != getpid()) {
-    LOG(ERROR) << "got client pid " << clientpid << ", expected " << getpid();
-    DCHECK(clientpid == getpid());
-    return ZMBAD;
-  }
-  int kind;
-  if (!reply.ReadInt(iter, &kind)) {
-    LOG(ERROR) << "can't read kind";
-    return ZMBAD;
-  }
-  return kind;
-}
-
-// Runs in client process (only used in unit test)
-bool ZygoteManager::Ping(base::TimeDelta* delta) {
-  if (client_fd_ == -1)
-    return false;
-
-  Pickle pickle;
-  pickle.WriteString(kZMagic);
-  pickle.WriteInt(getpid());
-  pickle.WriteInt(ZMPING);
-
-  int bytes_sent;
-  int bytes_read = -1;
-
-  TimeTicks time_sent = TimeTicks::HighResNow();
-
-  // Lock fork server, send the pickle, wait for the reply, unlock
-  if (flock(lockfd_, LOCK_EX))
-    LOG(ERROR) << "flock failed, errno " << errno;
-  bytes_sent = HANDLE_EINTR(write(client_fd_,
-      const_cast<void *>(pickle.data()), pickle.size()));
-  if (bytes_sent > 0) {
-    bytes_read = HANDLE_EINTR(read(client_fd_, msg_buf_, kMAX_MSG_LEN));
-  }
-  if (flock(lockfd_, LOCK_UN))
-    LOG(ERROR) << "flock failed, errno " << errno;
-
-  TimeTicks time_received = TimeTicks::HighResNow();
-
-  if (bytes_sent < 1) {
-    LOG(ERROR) << "Can't send to zm, errno " << errno;
-    return false;
-  }
-  if (bytes_read < 1) {
-    LOG(ERROR) << "Can't get from zm, errno " << errno;
-    return false;
-  }
-
-  // Unpickle the reply
-  Pickle reply(msg_buf_, bytes_read);
-  void* iter = NULL;
-  int kind = UnpickleHeader(reply, &iter);
-  if (kind != ZMPINGED) {
-    LOG(ERROR) << "reply wrong kind " << kind;
-    return false;
-  }
-  *delta = TimeTicks::HighResNow() - time_sent;
-  LOG(INFO) << "Round trip time in microseconds: " << delta->InMicroseconds();
-  return true;
-}
-
-// Runs in zygote manager process
-void ZygoteManager::PingHandler(const Pickle& request, void* iter,
-    Pickle* reply, std::vector<std::string>** newargv) {
-    reply->WriteInt(ZMPINGED);
-}
-
-// Runs in browser process, called only by base::ForkApp()
-pid_t ZygoteManager::LongFork(const std::vector<std::string>& argv,
-           const file_handle_mapping_vector& fds_to_remap) {
-  if (client_fd_ == -1)
-    return -1;
-
-  Pickle pickle;
-
-  // Encode the arguments and the desired remote fd numbers in the pickle,
-  // and the fds in a separate buffer
-  pickle.WriteString(kZMagic);
-  pickle.WriteInt(getpid());
-  pickle.WriteInt(ZMFORK);
-  pickle.WriteInt(argv.size());
-  std::vector<std::string>::const_iterator argi;
-  for (argi = argv.begin(); argi != argv.end(); ++argi)
-    pickle.WriteString(*argi);
-  pickle.WriteInt(fds_to_remap.size());
-
-  // Wrap the pickle and the fds together in a msghdr
-  ::msghdr msg;
-  memset(&msg, 0, sizeof(msg));
-  struct iovec iov;
-  msg.msg_iov = &iov;
-  msg.msg_iovlen = 1;
-  msg.msg_control = cmsg_buf_;
-  msg.msg_controllen = CMSG_LEN(sizeof(int) * fds_to_remap.size());
-  struct cmsghdr* cmsg;
-  cmsg = CMSG_FIRSTHDR(&msg);
-  cmsg->cmsg_level = SOL_SOCKET;
-  cmsg->cmsg_type = SCM_RIGHTS;
-  cmsg->cmsg_len = msg.msg_controllen;
-  int* wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
-  for (size_t i = 0; i < fds_to_remap.size(); i++) {
-    pickle.WriteInt(fds_to_remap[i].second);
-    wire_fds[i] = fds_to_remap[i].first;
-  }
-  iov.iov_base = const_cast<void *>(pickle.data());
-  iov.iov_len = pickle.size();
-
-  int bytes_sent;
-  int bytes_read = -1;
-
-  // Lock fork server, send the pickle, wait for the reply, unlock
-  if (flock(lockfd_, LOCK_EX))
-    LOG(ERROR) << "flock failed, errno " << errno;
-  bytes_sent = HANDLE_EINTR(sendmsg(client_fd_, &msg, MSG_WAITALL));
-  if (bytes_sent > 0) {
-    bytes_read = HANDLE_EINTR(read(client_fd_, msg_buf_, kMAX_MSG_LEN));
-  }
-  if (flock(lockfd_, LOCK_UN))
-    LOG(ERROR) << "flock failed, errno " << errno;
-
-  if (bytes_sent < 1) {
-    LOG(ERROR) << "Can't send to zm, errno " << errno << ", fd " << client_fd_;
-    return (pid_t) -1;
-  }
-  if (bytes_read < 1) {
-    LOG(ERROR) << "Can't get from zm, errno " << errno;
-    return (pid_t) -1;
-  }
-
-  // Unpickle the reply
-  Pickle reply(msg_buf_, bytes_read);
-  void* iter = NULL;
-  int kind = UnpickleHeader(reply, &iter);
-  if (kind != ZMFORKED) {
-    LOG(ERROR) << "reply wrong kind " << kind;
-    return (pid_t) -1;
-  }
-  pid_t newpid = (pid_t) -1;
-  int pid_errno;
-  if (!reply.ReadInt(&iter, &newpid) || !reply.ReadInt(&iter, &pid_errno)) {
-    LOG(ERROR) << "fork failed, can't read pid/errno";
-    return (pid_t) -1;
-  }
-  if ((newpid == (pid_t) -1) || pid_errno != 0) {
-    LOG(ERROR) << "fork failed, pid " << newpid << ", errno " << pid_errno;
-    return (pid_t) -1;
-  }
-  return newpid;
-}
-
-// Runs in zygote manager process
-bool ZygoteManager::LongForkHandler(const Pickle& request, void* iter,
-    Pickle* reply, std::vector<std::string>** newargv,
-    const int wire_fds[], int num_wire_fds) {
-  file_handle_mapping_vector fds_to_remap;
-  pid_t childpid;
-
-  reply->WriteInt(ZMFORKED);
-
-  // Unpickle commandline for new child
-  std::vector<std::string>* argv = new std::vector<std::string>;
-  int argc;
-  request.ReadInt(&iter, &argc);
-  for (int i = 0; i < argc; i++) {
-    std::string arg;
-    if (!request.ReadString(&iter, &arg)) {
-      LOG(ERROR) << "can't read arg?";
-      goto error_reply;
-    }
-    argv->push_back(arg);
-  }
-  // Unpickle file descriptor map for new child
-  int numfds;
-  request.ReadInt(&iter, &numfds);
-  DCHECK(numfds == num_wire_fds);
-  if (numfds != num_wire_fds) {
-    LOG(ERROR) << "numfds " << numfds << " != num_wire_fds " << num_wire_fds;
-    goto error_reply;
-  }
-  for (int i = 0; i < numfds; i++) {
-    int fd;
-    if (!request.ReadInt(&iter, &fd)) {
-      LOG(ERROR) << "can't read fd?";
-      goto error_reply;
-    }
-    fds_to_remap.push_back(std::pair<int, int>(wire_fds[i], fd));
-  }
-
-  // Mitosis!
-  childpid = fork();
-
-  if (childpid != 0) {
-    // parent
-    // first off, close our copy of the child's file descriptors
-    for (file_handle_mapping_vector::const_iterator
-        it = fds_to_remap.begin(); it != fds_to_remap.end(); ++it) {
-      close(it->first);
-    }
-
-    // Finish formatting the reply
-    reply->WriteInt(childpid);
-    if (childpid == (pid_t) -1) {
-      reply->WriteInt(errno);
-      return false;
-    } else {
-      reply->WriteInt(0);
-    }
-  } else {
-    // child
-    // Apply file descriptor map
-    InjectiveMultimap fd_shuffle;
-    for (file_handle_mapping_vector::const_iterator
-        it = fds_to_remap.begin(); it != fds_to_remap.end(); ++it) {
-      fd_shuffle.push_back(InjectionArc(it->first, it->second, false));
-    }
-
-    // Avoid closing descriptor children will need to contact fork server.
-    fd_shuffle.push_back(InjectionArc(client_fd_, client_fd_, false));
-    // Avoid closing log descriptor we're using
-    int logfd = logging::GetLoggingFileDescriptor();
-    if (logfd != -1)
-      fd_shuffle.push_back(InjectionArc(logfd, logfd, false));
-    // And of course avoid closing the cached fds.
-    std::map<std::string, int>::iterator i;
-    for (i = cached_fds_.begin(); i != cached_fds_.end(); ++i) {
-      fd_shuffle.push_back(InjectionArc(i->second, i->second, false));
-    }
-
-    // If there is any clash in the mapping, this function will DCHECK.
-    if (!ShuffleFileDescriptors(fd_shuffle))
-      exit(127);
-
-    // Open this after shuffle to avoid using reserved slots.
-    lockfd_ = open(lockfile_.c_str(), O_RDWR, 0);
-    if (lockfd_ == -1) {
-      // TODO(dkegel): real error handling
-      exit(126);
-    }
-    // Mark it as not to be closed.
-    fd_shuffle.push_back(InjectionArc(lockfd_, lockfd_, false));
-
-    // Also closes reserved fds.
-    CloseSuperfluousFds(fd_shuffle);
-
-    *newargv = argv;
-    // Because *newargv is set, we will return to main instead of looping
-  }
-  return true;
-
- error_reply:
-  reply->WriteInt(-1);
-  reply->WriteInt(-1);
-  for (int i=0; i<num_wire_fds; i++)
-    close(wire_fds[i]);
-  return false;
-}
-
-// Runs in browser process, called by ProcessWatcher::EnsureProcessTerminated().
-void ZygoteManager::EnsureProcessTerminated(pid_t childpid) {
-  if (client_fd_ == -1)
-    return;
-
-  Pickle pickle;
-
-  pickle.WriteString(kZMagic);
-  pickle.WriteInt(getpid());
-  pickle.WriteInt(ZMREAP);
-  pickle.WriteInt(childpid);
-
-  int bytes_sent = HANDLE_EINTR(
-      write(client_fd_, const_cast<void*>(pickle.data()), pickle.size()));
-
-  if (bytes_sent < 1) {
-    LOG(ERROR) << "Can't send to zm, errno " << errno << ", fd " << client_fd_;
-  }
-}
-
-// Runs in zygote manager process
-void ZygoteManager::EnsureProcessTerminatedHandler(const Pickle& request,
-    void* iter) {
-  pid_t childpid;
-  request.ReadInt(&iter, &childpid);
-  NOTIMPLEMENTED();
-  // TODO(dkegel): put childpid on a watch list, and terminate it
-  // after a while as chrome/common/process_watcher does.
-}
-
-static bool ValidateFilename(const std::string& filename) {
-  // We only have to open one kind of file, but we don't know
-  // the directory it's in, so be as restrictive as we can within
-  // those bounds.
-
-  static const char* allowed_prefix = "/";
-  if (filename.compare(0, strlen(allowed_prefix), allowed_prefix) != 0) {
-    LOG(ERROR) << "filename did not start with " << allowed_prefix;
-    return false;
-  }
-  static const char* allowed_suffix = ".pak";
-  if ((filename.length() <= strlen(allowed_suffix)) ||
-      (filename.compare(filename.length() - strlen(allowed_suffix),
-                       strlen(allowed_suffix), allowed_suffix) != 0)) {
-    LOG(ERROR) << "filename did not end in " << allowed_suffix;
-    return false;
-  }
-  if (filename.find("../") != std::string::npos) {
-    LOG(ERROR) << "filename contained relative component";
-    return false;
-  }
-  static const char* forbidden_prefixes[] = {
-    "/var/", "/tmp/", "/etc/", "/dev/", "/proc/", 0 };
-  for (const char** p = forbidden_prefixes;
-       *p; p++) {
-    if (filename.compare(0, strlen(*p), *p) == 0) {
-      LOG(ERROR) << "filename began with " << *p;
-      return false;
-    }
-  }
-  return true;
-}
-
-// Runs in browser process
-int ZygoteManager::OpenFile(const std::string& filename) {
-  // For security reasons, we only support .pak files,
-  // and only in certain locations.
-  if (!ValidateFilename(filename)) {
-    LOG(INFO) << "ZygoteManager: filename " << filename << " disallowed.";
-    return -1;
-  }
-
-  std::map<std::string, int>::iterator mapiter = cached_fds_.find(filename);
-  if (mapiter != cached_fds_.end())
-    return mapiter->second;
-
-  if (client_fd_ == -1)
-    return -1;
-
-  Pickle pickle;
-
-  pickle.WriteString(kZMagic);
-  pickle.WriteInt(getpid());
-  pickle.WriteInt(ZMOPEN);
-  pickle.WriteString(filename);
-
-  // Get ready to receive fds
-  ::msghdr msg = {0};
-  struct iovec iov = {msg_buf_, kMAX_MSG_LEN};
-  msg.msg_iov = &iov;
-  msg.msg_iovlen = 1;
-  msg.msg_control = cmsg_buf_;
-  msg.msg_controllen = kMAX_CMSG_LEN;
-
-  ssize_t bytes_sent;
-  ssize_t bytes_read = 0;
-
-  if (flock(lockfd_, LOCK_EX))
-    LOG(ERROR) << "flock failed, errno " << errno;
-  bytes_sent = HANDLE_EINTR(
-      write(client_fd_, const_cast<void *>(pickle.data()), pickle.size()));
-  if (bytes_sent > 0) {
-    bytes_read = HANDLE_EINTR(recvmsg(client_fd_, &msg, MSG_WAITALL));
-  }
-  if (flock(lockfd_, LOCK_UN))
-    LOG(ERROR) << "flock failed, errno " << errno;
-
-  if (bytes_sent < 1) {
-    LOG(ERROR) << "Can't send to zm, errno " << errno << ", fd " << client_fd_;
-    return -1;
-  }
-  if (bytes_read < 1) {
-    LOG(ERROR) << "Can't get from zm, errno " << errno;
-    return -1;
-  }
-
-  // Locate the sole block of sent file descriptors within the list of
-  // control messages
-  const int* wire_fds = NULL;
-  unsigned num_wire_fds = 0;
-  if (msg.msg_controllen > 0) {
-    struct cmsghdr* cmsg;
-    for (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);
-        assert(payload_len % sizeof(int) == 0);
-        wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
-        num_wire_fds = payload_len / sizeof(int);
-        break;
-      }
-    }
-  }
-  DCHECK(!(msg.msg_flags & MSG_CTRUNC));
-
-  // Unpickle the reply
-  Pickle reply(msg_buf_, bytes_read);
-  void* iter = NULL;
-  int kind = UnpickleHeader(reply, &iter);
-  if (kind != ZMOPENED) {
-    LOG(ERROR) << "reply wrong kind " << kind;
-    goto error_close;
-  }
-  int newfd_errno;
-  if (!reply.ReadInt(&iter, &newfd_errno)) {
-    LOG(ERROR) << "open failed, can't read errno";
-    goto error_close;
-  }
-  if (newfd_errno != 0) {
-    LOG(ERROR) << "open failed, errno " << newfd_errno;
-    goto error_close;
-  }
-  if (num_wire_fds != 1) {
-    LOG(ERROR) << "open failed, reply wrong number fds " << num_wire_fds;
-    goto error_close;
-  }
-  if (wire_fds[0] == -1) {
-    LOG(ERROR) << "open failed, fd -1";
-    NOTREACHED();
-    return -1;
-  }
-  return wire_fds[0];
-
- error_close:
-  for (unsigned i=0; i<num_wire_fds; i++)
-    close(wire_fds[i]);
-  return -1;
-}
-
-// Runs in zygote manager process
-bool ZygoteManager::OpenFileHandler(const Pickle& request, void* iter,
-    Pickle* reply, ::msghdr* msg) {
-  reply->WriteInt(ZMOPENED);
-
-  std::string filename;
-  if (!request.ReadString(&iter, &filename)) {
-    LOG(ERROR) << "no filename?";
-    return false;
-  }
-  if (!ValidateFilename(filename)) {
-    // Fake a unix error code
-    reply->WriteInt(EPERM);
-    return false;
-  }
-
-  std::map<std::string, int>::iterator i;
-  int newfd;
-  std::map<std::string, int>::iterator mapiter = cached_fds_.find(filename);
-  if (mapiter == cached_fds_.end()) {
-    // Verify that file is a plain file
-    struct stat statbuf;
-    if (lstat(filename.c_str(), &statbuf) != 0) {
-      LOG(ERROR) << "can't stat " << filename << ", errno " << errno;
-      return false;
-    }
-    if (!S_ISREG(statbuf.st_mode)) {
-      LOG(ERROR) << "not regular file " << filename;
-      // Fake a unix error code
-      reply->WriteInt(EISDIR);
-      return false;
-    }
-    newfd = open(filename.c_str(), O_RDONLY, 0);
-    if (newfd != -1) {
-      cached_fds_[filename] = newfd;
-    } else {
-      LOG(ERROR) << "can't open " << filename << ", errno " << errno;
-    }
-  } else {
-    newfd = mapiter->second;
-  }
-  if (newfd == -1) {
-    reply->WriteInt(errno);
-  } else {
-    reply->WriteInt(0);
-    msg->msg_control = cmsg_buf_;
-    msg->msg_controllen = CMSG_LEN(sizeof(int));
-    struct cmsghdr* cmsg;
-    cmsg = CMSG_FIRSTHDR(msg);
-    cmsg->cmsg_level = SOL_SOCKET;
-    cmsg->cmsg_type = SCM_RIGHTS;
-    cmsg->cmsg_len = msg->msg_controllen;
-    int* wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
-    wire_fds[0] = newfd;
-  }
-
-  return true;
-}
-
-// Runs in zygote manager process
-bool ZygoteManager::ReadAndHandleMessage(std::vector<std::string>** newargv) {
-  // Wait for activity either on canary fd or main fd.
-  struct pollfd watcher[2];
-  memset(watcher, 0, sizeof(watcher));
-  watcher[0].fd = canary_fd_;
-  watcher[0].events = POLLIN|POLLHUP;
-  watcher[1].fd = server_fd_;
-  watcher[1].events = POLLIN;
-  // Wait at most one minute.  This lets us detect case where
-  // canary socket is closed abruptly because the main client aborted.
-  // Also lets us reap dead children once a minute even if we don't get SIGCHLD.
-  // We'd like to wait less time, but that's hard on battery life.
-  // Note: handle EINTR manually here, not with wrapper, as we need
-  // to return when we're interrupted so caller can reap promptly.
-  int nactive = poll(watcher, 2, 60*1000);
-
-  if (nactive == -1) {
-    if (errno == EINTR) {
-      // Probably SIGCHLD.  Return to main loop so it can reap.
-      return true;
-    }
-    LOG(ERROR) << "poll failed, errno " << errno << ", aborting";
-    return false;
-  }
-
-  // If it was the canary, exit
-  if (watcher[0].revents != 0) {
-    LOG(INFO) << "notified of peer destruction, exiting";
-    return false;
-  }
-  if ((watcher[1].revents & POLLIN) != POLLIN) {
-    // spurious wakeup?
-    return true;
-  }
-
-  ssize_t bytes_read = 0;
-  struct msghdr msg = {0};
-  struct iovec iov = {msg_buf_, kMAX_MSG_LEN};
-  msg.msg_iov = &iov;
-  msg.msg_iovlen = 1;
-  msg.msg_control = cmsg_buf_;
-  msg.msg_controllen = kMAX_CMSG_LEN;
-  bytes_read = HANDLE_EINTR(recvmsg(server_fd_, &msg, MSG_WAITALL));
-  if (bytes_read == 0) {
-    LOG(ERROR) << "got EOF, aborting";
-    return false;
-  }
-  if (bytes_read == -1) {
-    LOG(ERROR) << "got errno " << errno << ", aborting";
-    return false;
-  }
-
-  // Locate the sole block of sent file descriptors within the list of
-  // control messages
-  const int* wire_fds = NULL;
-  unsigned num_wire_fds = 0;
-  if (msg.msg_controllen > 0) {
-    struct cmsghdr* cmsg;
-    for (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);
-        assert(payload_len % sizeof(int) == 0);
-        wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
-        num_wire_fds = payload_len / sizeof(int);
-        break;
-      }
-    }
-  }
-  DCHECK(!(msg.msg_flags & MSG_CTRUNC));
-
-  // Unpickle/parse message
-  Pickle pickle(msg_buf_, bytes_read);
-  void* iter = NULL;
-  std::string magic;
-  if (!pickle.ReadString(&iter, &magic) || magic != std::string(kZMagic)) {
-    LOG(ERROR) << "msg didn't start with " << kZMagic << ", got " << magic;
-    for (unsigned i=0; i<num_wire_fds; i++)
-      close(wire_fds[i]);
-    return true;
-  }
-  pid_t clientpid = (pid_t) -1;
-  pickle.ReadInt(&iter, &clientpid);
-  int kind;
-  pickle.ReadInt(&iter, &kind);
-
-  Pickle reply;
-  reply.WriteString(kZMagic);
-  reply.WriteInt(clientpid);
-
-  struct msghdr replymsg = {0};
-  memset(&replymsg, 0, sizeof(replymsg));
-
-  switch (kind) {
-  case ZMPING:
-    DCHECK_EQ(0U, num_wire_fds);
-    PingHandler(pickle, iter, &reply, newargv);
-    break;
-  case ZMFORK:
-    // TODO(dkegel): real error handling
-    (void) LongForkHandler(pickle, iter, &reply, newargv, wire_fds,
-                           num_wire_fds);
-    if (*newargv != NULL) {
-      // Child.  Just return to caller, who will return from SetLongFork.
-      return true;
-    }
-    break;
-  case ZMREAP:
-    DCHECK_EQ(0U, num_wire_fds);
-    EnsureProcessTerminatedHandler(pickle, iter);
-    // no reply to this message
-    return true;
-  case ZMOPEN:
-    DCHECK_EQ(0U, num_wire_fds);
-    // TODO(dkegel): real error handling
-    (void) OpenFileHandler(pickle, iter, &reply, &replymsg);
-    break;
-  default:
-    // TODO(dkegel): real error handling
-    LOG(ERROR) << "Unknown message kind " << kind;
-    DCHECK_EQ(0U, num_wire_fds);
-    break;
-  }
-
-  struct iovec riov = {const_cast<void *>(reply.data()), reply.size()};
-  replymsg.msg_iov = &riov;
-  replymsg.msg_iovlen = 1;
-
-  int bytes_sent;
-  bytes_sent = HANDLE_EINTR(sendmsg(server_fd_, &replymsg, MSG_WAITALL));
-  if (bytes_sent != static_cast<int>(riov.iov_len)) {
-    // TODO(dkegel): real error handling
-    LOG(ERROR) << "Can't send reply.";
-    return false;
-  }
-  return true;
-}
-
-// Called only by ChromeMain(), forks the zygote manager process.
-std::vector<std::string>* ZygoteManager::Start() {
-  DCHECK(lockfd_ == -1);
-  DCHECK(canary_fd_ == -1);
-  DCHECK(server_fd_ == -1);
-  DCHECK(client_fd_ == -1);
-
-#ifndef OFFICIAL_BUILD
-  // Disallow nested ZygoteManager servers
-  CHECK(getenv("ZYGOTE_MANAGER_STARTED") == NULL) << "already started?!";
-  (void) setenv("ZYGOTE_MANAGER_STARTED", "1", 1);
-#endif
-
-  int pipe_fds[2];
-
-  // Avoid using the reserved fd slots.
-  int reserved_fds[kReservedFds];
-  for (int i=0; i < kReservedFds; i++)
-    reserved_fds[i] = open("/dev/null", O_RDONLY, 0);
-
-  // Create the main communications pipe.
-  int err = HANDLE_EINTR(socketpair(AF_UNIX, SOCK_DGRAM, 0, pipe_fds));
-  if (err != 0) {
-    // TODO(dkegel): real error handling
-    exit(99);
-  }
-  server_fd_ = pipe_fds[1];
-  client_fd_ = pipe_fds[0];
-
-  // Create the pipe used only to relay destruction event server.
-  // Must be SOCK_STREAM so close() is sensed by poll().
-  err = HANDLE_EINTR(socketpair(AF_UNIX, SOCK_STREAM, 0, pipe_fds));
-  if (err != 0) {
-    // TODO(dkegel): real error handling
-    exit(99);
-  }
-
-  // Create lock file.
-  // TODO(dkegel): get rid of this
-  char lockfile[256];
-  strcpy(lockfile, "/tmp/zygote_manager_lock.XXXXXX");
-  lockfd_ = mkstemp(lockfile);
-  if (lockfd_ == -1) {
-    // TODO(dkegel): real error handling
-    exit(99);
-  }
-  lockfile_.assign(lockfile);
-
-  // Fork a fork server.
-  pid_t childpid = fork();
-
-  if (!childpid) {
-    for (int i=0; i < kReservedFds; i++)
-      close(reserved_fds[i]);
-
-    // Original child.  Continues on with the main program
-    // and becomes the first client.
-    close(server_fd_);
-    server_fd_ = -1;
-
-    close(pipe_fds[1]);
-    canary_fd_ = pipe_fds[0];
-
-    // Return now to indicate this is the original process.
-    return NULL;
-  } else {
-    close(lockfd_);
-
-    close(pipe_fds[0]);
-    canary_fd_ = pipe_fds[1];
-
-    // We need to accept SIGCHLD, even though our handler is a no-op because
-    // otherwise we cannot wait on children. (According to POSIX 2001.)
-    // (And otherwise poll() might not wake up on SIGCHLD.)
-    struct sigaction action;
-    memset(&action, 0, sizeof(action));
-    action.sa_handler = SIGCHLDHandler;
-    CHECK(sigaction(SIGCHLD, &action, NULL) == 0);
-
-    // Original process.  Acts as the server.
-    while (true) {
-      std::vector<std::string>* newargv = NULL;
-      if (!ReadAndHandleMessage(&newargv))
-        break;
-      if (newargv) {
-        // Return new commandline to show caller this is a new child process.
-        return newargv;
-      }
-      // Server process continues around loop.
-
-      // Reap children.
-      while (true) {
-        int status = -1;
-        pid_t reaped = waitpid(-1, &status, WNOHANG);
-        if (reaped != -1 && reaped != 0) {
-          LOG(INFO) << "Reaped pid " << reaped;
-          continue;
-        }
-        break;
-      }
-    }
-    // Server cleanup after EOF or error reading from the socket.
-    Delete(FilePath(lockfile_), false);
-    // TODO(dkegel): real error handling
-    LOG(INFO) << "exiting.  " << cached_fds_.size() << " cached fds.";
-    std::map<std::string, int>::iterator i;
-    for (i = cached_fds_.begin(); i != cached_fds_.end(); ++i) {
-      LOG(INFO) << "Closing fd " << i->second << " filename " << i->first;
-      close(i->second);
-    }
-    exit(0);
-  }
-}
-}
-#endif  // defined(OS_LINUX)