Add a "native_support" service.

services/native_support/process_impl.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/process_impl.h"
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <algorithm>
+#include <limits>
+#include <utility>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/environment.h"
+#include "base/files/scoped_file.h"
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/process/launch.h"
+#include "base/process/process.h"
+#include "build/build_config.h"
+#include "mojo/services/files/public/interfaces/types.mojom.h"
+#include "services/native_support/make_pty_pair.h"
+#include "services/native_support/process_controller_impl.h"
+#include "services/native_support/process_io_redirection.h"
+
+namespace native_support {
+
+namespace {
+
+class SetsidPreExecDelegate : public base::LaunchOptions::PreExecDelegate {
+ public:
+  SetsidPreExecDelegate() {}
+  ~SetsidPreExecDelegate() override {}
+
+  void RunAsyncSafe() override {
+    static const char kErrorMessage[] = "setsid() failed";
+
+    // Note: |setsid()| and |write()| are both async-signal-safe.
+    if (setsid() == static_cast<pid_t>(-1))
+      write(STDERR_FILENO, kErrorMessage, sizeof(kErrorMessage) - 1);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SetsidPreExecDelegate);
+};
+
+}  // namespace
+
+ProcessImpl::ProcessImpl(scoped_refptr<base::TaskRunner> worker_runner,
+                         mojo::ApplicationConnection* connection,
+                         mojo::InterfaceRequest<Process> request)
+    : worker_runner_(worker_runner.Pass()), binding_(this, request.Pass()) {}
+
+ProcessImpl::~ProcessImpl() {}
+
+void ProcessImpl::Spawn(
+    const mojo::String& path,
+    mojo::Array<mojo::String> argv,
+    mojo::Array<mojo::String> envp,
+    mojo::files::FilePtr stdin_file,
+    mojo::files::FilePtr stdout_file,
+    mojo::files::FilePtr stderr_file,
+    mojo::InterfaceRequest<ProcessController> process_controller,
+    const SpawnCallback& callback) {
+  std::vector<int> fds_to_inherit(3, -1);
+
+  // stdin:
+  base::ScopedFD stdin_fd;
+  base::ScopedFD stdin_parent_fd;
+  if (stdin_file) {
+    int stdin_pipe_fds[2] = {-1, -1};
+    CHECK_EQ(pipe(stdin_pipe_fds), 0);
+    stdin_fd.reset(stdin_pipe_fds[0]);
+    stdin_parent_fd.reset(stdin_pipe_fds[1]);
+  } else {
+    stdin_fd.reset(HANDLE_EINTR(open("/dev/null", O_RDONLY)));
+  }
+  fds_to_inherit[STDIN_FILENO] = stdin_fd.get();
+
+  // stdout:
+  base::ScopedFD stdout_fd;
+  base::ScopedFD stdout_parent_fd;
+  if (stdout_file) {
+    int stdout_pipe_fds[2] = {-1, -1};
+    CHECK_EQ(pipe(stdout_pipe_fds), 0);
+    stdout_fd.reset(stdout_pipe_fds[1]);
+    stdout_parent_fd.reset(stdout_pipe_fds[0]);
+  } else {
+    stdout_fd.reset(HANDLE_EINTR(open("/dev/null", O_WRONLY)));
+  }
+  fds_to_inherit[STDOUT_FILENO] = stdout_fd.get();
+
+  // stderr:
+  base::ScopedFD stderr_fd;
+  base::ScopedFD stderr_parent_fd;
+  if (stderr_file) {
+    int stderr_pipe_fds[2] = {-1, -1};
+    CHECK_EQ(pipe(stderr_pipe_fds), 0);
+    stderr_fd.reset(stderr_pipe_fds[1]);
+    stderr_parent_fd.reset(stderr_pipe_fds[0]);
+  } else {
+    stderr_fd.reset(HANDLE_EINTR(open("/dev/null", O_WRONLY)));
+  }
+  fds_to_inherit[STDERR_FILENO] = stderr_fd.get();
+
+  std::unique_ptr<ProcessIORedirection> process_io_redirection(
+      new ProcessIORedirectionForStdIO(
+          stdin_file.Pass(), stdout_file.Pass(), stderr_file.Pass(),
+          stdin_parent_fd.Pass(), stdout_parent_fd.Pass(),
+          stderr_parent_fd.Pass()));
+
+  SpawnImpl(path, argv.Pass(), envp.Pass(), std::move(process_io_redirection),
+            fds_to_inherit, process_controller.Pass(), callback);
+}
+
+void ProcessImpl::SpawnWithTerminal(
+    const mojo::String& path,
+    mojo::Array<mojo::String> argv,
+    mojo::Array<mojo::String> envp,
+    mojo::files::FilePtr terminal_file,
+    mojo::InterfaceRequest<ProcessController> process_controller,
+    const SpawnWithTerminalCallback& callback) {
+  DCHECK(terminal_file);
+
+  std::vector<int> fds_to_inherit(3, -1);
+
+  base::ScopedFD master_fd;
+  base::ScopedFD slave_fd;
+  int errno_value = 0;
+  if (!MakePtyPair(&master_fd, &slave_fd, &errno_value)) {
+    // TODO(vtl): Well, this is dumb (we should use errno_value).
+    callback.Run(mojo::files::ERROR_UNKNOWN);
+    return;
+  }
+
+  // stdin:
+  base::ScopedFD stdin_fd(slave_fd.Pass());
+  fds_to_inherit[STDIN_FILENO] = stdin_fd.get();
+
+  // stdout:
+  base::ScopedFD stdout_fd(HANDLE_EINTR(dup(stdin_fd.get())));
+  fds_to_inherit[STDOUT_FILENO] = stdout_fd.get();
+
+  // stderr:
+  base::ScopedFD stderr_fd(HANDLE_EINTR(dup(stdin_fd.get())));
+  fds_to_inherit[STDERR_FILENO] = stderr_fd.get();
+
+  std::unique_ptr<ProcessIORedirection> process_io_redirection(
+      new ProcessIORedirectionForTerminal(terminal_file.Pass(),
+                                          master_fd.Pass()));
+
+  SpawnImpl(path, argv.Pass(), envp.Pass(), std::move(process_io_redirection),
+            fds_to_inherit, process_controller.Pass(), callback);
+}
+
+void ProcessImpl::SpawnImpl(
+    const mojo::String& path,
+    mojo::Array<mojo::String> argv,
+    mojo::Array<mojo::String> envp,
+    std::unique_ptr<ProcessIORedirection> process_io_redirection,
+    const std::vector<int>& fds_to_inherit,
+    mojo::InterfaceRequest<ProcessController> process_controller,
+    const SpawnCallback& callback) {
+  DCHECK(!path.is_null());
+  DCHECK(process_controller.is_pending());
+
+  size_t argc = std::max(argv.size(), static_cast<size_t>(1));
+  std::vector<const char*> argv_ptrs(argc);
+  if (argv.is_null()) {
+    argv_ptrs[0] = path.data();
+  } else {
+    if (!argv.size() ||
+        argv.size() > static_cast<size_t>(std::numeric_limits<int>::max())) {
+      callback.Run(mojo::files::ERROR_INVALID_ARGUMENT);
+      return;
+    }
+    // TODO(vtl): Currently, we don't support setting argv[0], due to
+    // |base::CommandLine| limitations.
+    argv_ptrs[0] = path.data();
+    for (size_t i = 1; i < argv.size(); i++)
+      argv_ptrs[i] = argv[i].data();
+  }
+  base::CommandLine command_line(static_cast<int>(argc), argv_ptrs.data());
+
+  bool inherit_environment = true;
+  base::EnvironmentMap environment_map;
+  if (!envp.is_null()) {
+    inherit_environment = false;
+    for (size_t i = 0; i < envp.size(); i++) {
+      std::string s(envp[i].data());
+      size_t equals_pos = s.find_first_of('=');
+      environment_map[s.substr(0, equals_pos)] =
+          (equals_pos == std::string::npos) ? std::string()
+                                            : s.substr(equals_pos + 1);
+    }
+  }
+
+  base::FileHandleMappingVector fd_mapping;
+  DCHECK(fds_to_inherit.size() >= 3);
+  for (size_t i = 0; i < fds_to_inherit.size(); i++) {
+    DCHECK_GE(fds_to_inherit[i], 0);
+    fd_mapping.push_back(
+        std::make_pair(fds_to_inherit[i], static_cast<int>(i)));
+  }
+
+  SetsidPreExecDelegate pre_exec_delegate;
+  base::LaunchOptions launch_options;
+  launch_options.wait = false;
+  launch_options.environ.swap(environment_map);
+  launch_options.clear_environ = !inherit_environment;
+  launch_options.fds_to_remap = &fd_mapping;
+  // launch_options.maximize_rlimits
+  launch_options.new_process_group = false;
+  // launch_options.clone_flags = 0;
+#if defined(OS_LINUX)
+  launch_options.allow_new_privs = true;
+#endif
+  // launch_options.kill_on_parent_death = true;
+  // launch_options.current_directory
+  launch_options.pre_exec_delegate = &pre_exec_delegate;
+
+  base::Process process = LaunchProcess(command_line, launch_options);
+  // Note: Failure is extremely unusual. E.g., it won't fail even if |path|
+  // doesn't exist (since fork succeeds; it's the exec that fails).
+  if (!process.IsValid()) {
+    // TODO(vtl): Well, this is dumb (can we check errno?).
+    callback.Run(mojo::files::ERROR_UNKNOWN);
+    return;
+  }
+
+  new ProcessControllerImpl(worker_runner_, process_controller.Pass(),
+                            process.Pass(), std::move(process_io_redirection));
+  callback.Run(mojo::files::ERROR_OK);
+}
+
+}  // namespace native_support