New NaCl zygote implementation 2

chrome/nacl/nacl_fork_delegate_linux.cc

+// Copyright (c) 2011 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 <signal.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+
+#include "base/basictypes.h"
+#include "base/command_line.h"
+#include "base/eintr_wrapper.h"
+#include "base/logging.h"
+#include "base/file_path.h"
+#include "base/process_util.h"
+#include "content/common/unix_domain_socket_posix.h"
+#include "content/common/zygote_fork_delegate.h"
+#include "chrome/nacl/nacl_fork_delegate_linux.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/nacl_helper_linux.h"
+
+NaClForkDelegate::NaClForkDelegate() : sandboxed_(false),
+                                       fd_(-1),
+                                       pid_(-1) {
+}
+
+void NaClForkDelegate::Init(const bool sandboxed,
+                            const int browserdesc,
+                            const int sandboxdesc) {
+  VLOG(1) << "NaClForkDelegate::Init()";
+  int fds[2];
+
+  sandboxed_ = sandboxed;
+  // Confirm a couple hard-wired assumptions.
+  // The NaCl constants are from chrome/nacl/nacl_linux_helper.h
+  DCHECK(kNaClBrowserDescriptor == browserdesc);
+  DCHECK(kNaClSandboxDescriptor == sandboxdesc);
+
+  CHECK(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fds) == 0);
+  base::file_handle_mapping_vector fds_to_map;
+  fds_to_map.push_back(std::make_pair(fds[1], kNaClZygoteDescriptor));
+  fds_to_map.push_back(std::make_pair(sandboxdesc, kNaClSandboxDescriptor));
+  const char* nacl_zygote_exe = getenv("NACL_NEW_ZYGOTE");

[gregoryd, 2011/06/22 12:46:07]

Will we need to set the environment variable on users machines to make it work?
Maybe a command line flag would be a better option. Also, do you expect the name
of the exe to change?

[Brad Chen, 2011/06/22 16:10:31]

I've added a TODO() comment. Before enabling this by default
it should probably use PathService::Get().
On 2011/06/22 12:46:07, gregoryd wrote:

+  pid_ = -1;
+  if (nacl_zygote_exe) {
+    CommandLine::StringVector argv = CommandLine::ForCurrentProcess()->argv();
+    argv[0] = nacl_zygote_exe;
+    base::LaunchAppWithClone(argv, fds_to_map, false, &pid_,
+                             CLONE_FS | SIGCHLD);
+    // parent and error cases are handled below
+  }
+  HANDLE_EINTR(close(fds[1]));
+  if (pid_ > 0) {
+    const ssize_t kExpectedLength = strlen(kNaClHelperStartupAck);
+    char buf[kExpectedLength];
+
+    // Wait for ack from nacl_helper, indicating it is ready to help
+    const ssize_t nread = read(fds[0], buf, sizeof(buf));
+    if (nread == kExpectedLength &&
+        memcmp(buf, kNaClHelperStartupAck, nread) == 0) {
+      // all is well
+      fd_ = fds[0];
+      return;
+    } else {
+      LOG(ERROR) << "Bad NaCl helper startup ack (" << nread << " bytes";
+    }
+  }
+  // TODO(bradchen): Make this LOG(ERROR) when the NaCl helper
+  // becomes the default.
+  pid_ = -1;
+  fd_ = -1;
+  HANDLE_EINTR(close(fds[0]));
+}
+
+NaClForkDelegate::~NaClForkDelegate() {
+  HANDLE_EINTR(close(fd_));  // side effect: delegate process will terminate
+}
+
+bool NaClForkDelegate::CanHelp(const std::string& process_type) {
+  return (process_type == switches::kNaClLoaderProcess && (Pid() != -1));
+}
+
+pid_t NaClForkDelegate::Fork(const std::vector<int>& fds) {
+  base::ProcessId naclchild;
+  VLOG(1) << "NaClForkDelegate::Fork";
+
+  if (sandboxed_) {
+    DCHECK(fds.size() == kNaClParentFDIndex + 1);
+  } else {
+    DCHECK(fds.size() == kNaClBrowserFDIndex + 1);
+  }
+  if (!UnixDomainSocket::SendMsg(FD(), kNaClForkRequest,
+                                 strlen(kNaClForkRequest), fds)) {
+    LOG(ERROR) << "NaClForkDelegate::Fork: SendMsg failed";
+    return -1;
+  }
+  int nread = read(FD(), &naclchild, sizeof(naclchild));
+  if (nread != sizeof(naclchild)) {
+    LOG(ERROR) << "NaClForkDelegate::Fork: read failed";
+    return -1;
+  }
+  VLOG(1) << "nacl_child is " << naclchild << " (" << nread << " bytes)";
+  return naclchild;
+}