blob: b1eecd600867dc17b92a804dfd22f5ef2e865ff6 [file] [log] [blame]
// Copyright (c) 2012 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 <stddef.h>
#include <string>
#include <vector>
#include "base/containers/small_map.h"
#include "base/files/scoped_file.h"
#include "base/memory/scoped_vector.h"
#include "base/posix/global_descriptors.h"
#include "base/process/kill.h"
#include "base/process/process.h"
#include "base/process/process_handle.h"
#include "base/time/time.h"
namespace base {
class Pickle;
class PickleIterator;
namespace content {
class ZygoteForkDelegate;
// This is the object which implements the zygote. The ZygoteMain function,
// which is called from ChromeMain, simply constructs one of these objects and
// runs it.
class Zygote {
Zygote(int sandbox_flags, ScopedVector<ZygoteForkDelegate> helpers,
const std::vector<base::ProcessHandle>& extra_children,
const std::vector<int>& extra_fds);
bool ProcessRequests();
struct ZygoteProcessInfo {
// Pid from inside the Zygote's PID namespace.
base::ProcessHandle internal_pid;
// Keeps track of which fork delegate helper the process was started from.
ZygoteForkDelegate* started_from_helper;
// Records when the browser requested the zygote to reap this process.
base::TimeTicks time_of_reap_request;
// Notes whether the zygote has sent SIGKILL to this process.
bool sent_sigkill;
typedef base::SmallMap< std::map<base::ProcessHandle, ZygoteProcessInfo> >
// Retrieve a ZygoteProcessInfo from the process_info_map_.
// Returns true and write to process_info if |pid| can be found, return
// false otherwise.
bool GetProcessInfo(base::ProcessHandle pid,
ZygoteProcessInfo* process_info);
// Returns true if the SUID sandbox is active.
bool UsingSUIDSandbox() const;
// Returns true if the NS sandbox is active.
bool UsingNSSandbox() const;
// ---------------------------------------------------------------------------
// Requests from the browser...
// Read and process a request from the browser. Returns true if we are in a
// new process and thus need to unwind back into ChromeMain.
bool HandleRequestFromBrowser(int fd);
void HandleReapRequest(int fd, base::PickleIterator iter);
// Get the termination status of |real_pid|. |real_pid| is the PID as it
// appears outside of the sandbox.
// Return true if it managed to get the termination status and return the
// status in |status| and the exit code in |exit_code|.
bool GetTerminationStatus(base::ProcessHandle real_pid, bool known_dead,
base::TerminationStatus* status,
int* exit_code);
void HandleGetTerminationStatus(int fd,
base::PickleIterator iter);
// This is equivalent to fork(), except that, when using the SUID sandbox, it
// returns the real PID of the child process as it appears outside the
// sandbox, rather than returning the PID inside the sandbox. The child's
// real PID is determined by having it call content::SendZygoteChildPing(int)
// using the |pid_oracle| descriptor.
// Finally, when using a ZygoteForkDelegate helper, |uma_name|, |uma_sample|,
// and |uma_boundary_value| may be set if the helper wants to make a UMA
int ForkWithRealPid(const std::string& process_type,
const base::GlobalDescriptors::Mapping& fd_mapping,
const std::string& channel_id,
base::ScopedFD pid_oracle,
std::string* uma_name,
int* uma_sample,
int* uma_boundary_value);
// Unpacks process type and arguments from |iter| and forks a new process.
// Returns -1 on error, otherwise returns twice, returning 0 to the child
// process and the child process ID to the parent process, like fork().
base::ProcessId ReadArgsAndFork(base::PickleIterator iter,
std::vector<base::ScopedFD> fds,
std::string* uma_name,
int* uma_sample,
int* uma_boundary_value);
// Handle a 'fork' request from the browser: this means that the browser
// wishes to start a new renderer. Returns true if we are in a new process,
// otherwise writes the child_pid back to the browser via |fd|. Writes a
// child_pid of -1 on error.
bool HandleForkRequest(int fd,
base::PickleIterator iter,
std::vector<base::ScopedFD> fds);
bool HandleGetSandboxStatus(int fd,
base::PickleIterator iter);
// Attempt to reap the child process by calling waitpid, and return
// whether successful. If the process has not terminated within
// 2 seconds of its reap request, send it SIGKILL.
bool ReapChild(const base::TimeTicks& now, ZygoteProcessInfo* child);
// Attempt to reap all outstanding children in |to_reap_|.
void ReapChildren();
// The Zygote needs to keep some information about each process. Most
// notably what the PID of the process is inside the PID namespace of
// the Zygote and whether or not a process was started by the
// ZygoteForkDelegate helper.
ZygoteProcessMap process_info_map_;
const int sandbox_flags_;
ScopedVector<ZygoteForkDelegate> helpers_;
// Count of how many fork delegates for which we've invoked InitialUMA().
size_t initial_uma_index_;
// This vector contains the PIDs of any child processes which have been
// created prior to the construction of the Zygote object, and must be reaped
// before the Zygote exits. The Zygote will perform a blocking wait on these
// children, so they must be guaranteed to be exiting by the time the Zygote
// exits.
std::vector<base::ProcessHandle> extra_children_;
// This vector contains the FDs that must be closed before reaping the extra
// children.
std::vector<int> extra_fds_;
// The vector contains the child processes that need to be reaped.
std::vector<ZygoteProcessInfo> to_reap_;
} // namespace content