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// Copyright 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.
#ifndef BASE_PROCESS_PROCESS_H_
#define BASE_PROCESS_PROCESS_H_
#include "base/base_export.h"
#include "base/macros.h"
#include "base/process/process_handle.h"
#include "base/time/time.h"
#include "build/build_config.h"
#if defined(OS_WIN)
#include "base/win/scoped_handle.h"
#endif
#if defined(OS_FUCHSIA)
#include <lib/zx/process.h>
#endif
#if defined(OS_MACOSX)
#include "base/feature_list.h"
#include "base/process/port_provider_mac.h"
#endif
namespace base {
#if defined(OS_MACOSX)
extern const Feature kMacAllowBackgroundingProcesses;
#endif
// Provides a move-only encapsulation of a process.
//
// This object is not tied to the lifetime of the underlying process: the
// process may be killed and this object may still around, and it will still
// claim to be valid. The actual behavior in that case is OS dependent like so:
//
// Windows: The underlying ProcessHandle will be valid after the process dies
// and can be used to gather some information about that process, but most
// methods will obviously fail.
//
// POSIX: The underlying ProcessHandle is not guaranteed to remain valid after
// the process dies, and it may be reused by the system, which means that it may
// end up pointing to the wrong process.
class BASE_EXPORT Process {
public:
// On Windows, this takes ownership of |handle|. On POSIX, this does not take
// ownership of |handle|.
explicit Process(ProcessHandle handle = kNullProcessHandle);
Process(Process&& other);
// The destructor does not terminate the process.
~Process();
Process& operator=(Process&& other);
// Returns an object for the current process.
static Process Current();
// Returns a Process for the given |pid|.
static Process Open(ProcessId pid);
// Returns a Process for the given |pid|. On Windows the handle is opened
// with more access rights and must only be used by trusted code (can read the
// address space and duplicate handles).
static Process OpenWithExtraPrivileges(ProcessId pid);
#if defined(OS_WIN)
// Returns a Process for the given |pid|, using some |desired_access|.
// See ::OpenProcess documentation for valid |desired_access|.
static Process OpenWithAccess(ProcessId pid, DWORD desired_access);
#endif
// Creates an object from a |handle| owned by someone else.
// Don't use this for new code. It is only intended to ease the migration to
// a strict ownership model.
// TODO(rvargas) crbug.com/417532: Remove this code.
static Process DeprecatedGetProcessFromHandle(ProcessHandle handle);
// Returns true if processes can be backgrounded.
static bool CanBackgroundProcesses();
// Terminates the current process immediately with |exit_code|.
[[noreturn]] static void TerminateCurrentProcessImmediately(int exit_code);
// Returns true if this objects represents a valid process.
bool IsValid() const;
// Returns a handle for this process. There is no guarantee about when that
// handle becomes invalid because this object retains ownership.
ProcessHandle Handle() const;
// Returns a second object that represents this process.
Process Duplicate() const;
// Get the PID for this process.
ProcessId Pid() const;
#if !defined(OS_ANDROID)
// Get the creation time for this process. Since the Pid can be reused after a
// process dies, it is useful to use both the Pid and the creation time to
// uniquely identify a process.
//
// Not available on Android because /proc/stat/ cannot be accessed on O+.
Time CreationTime() const;
#endif // !defined(OS_ANDROID)
// Returns true if this process is the current process.
bool is_current() const;
// Close the process handle. This will not terminate the process.
void Close();
// Returns true if this process is still running. This is only safe on Windows
// (and maybe Fuchsia?), because the ProcessHandle will keep the zombie
// process information available until itself has been released. But on Posix,
// the OS may reuse the ProcessId.
#if defined(OS_WIN)
bool IsRunning() const {
return !WaitForExitWithTimeout(base::TimeDelta(), nullptr);
}
#endif
// Terminates the process with extreme prejudice. The given |exit_code| will
// be the exit code of the process. If |wait| is true, this method will wait
// for up to one minute for the process to actually terminate.
// Returns true if the process terminates within the allowed time.
// NOTE: On POSIX |exit_code| is ignored.
bool Terminate(int exit_code, bool wait) const;
// Waits for the process to exit. Returns true on success.
// On POSIX, if the process has been signaled then |exit_code| is set to -1.
// On Linux this must be a child process, however on Mac and Windows it can be
// any process.
// NOTE: |exit_code| is optional, nullptr can be passed if the exit code is
// not required.
bool WaitForExit(int* exit_code) const;
// Same as WaitForExit() but only waits for up to |timeout|.
// NOTE: |exit_code| is optional, nullptr can be passed if the exit code
// is not required.
bool WaitForExitWithTimeout(TimeDelta timeout, int* exit_code) const;
// Indicates that the process has exited with the specified |exit_code|.
// This should be called if process exit is observed outside of this class.
// (i.e. Not because Terminate or WaitForExit, above, was called.)
// Note that nothing prevents this being called multiple times for a dead
// process though that should be avoided.
void Exited(int exit_code) const;
#if defined(OS_MACOSX)
// The Mac needs a Mach port in order to manipulate a process's priority,
// and there's no good way to get that from base given the pid. These Mac
// variants of the IsProcessBackgrounded and SetProcessBackgrounded API take
// a port provider for this reason. See crbug.com/460102
//
// A process is backgrounded when its task priority is
// |TASK_BACKGROUND_APPLICATION|.
//
// Returns true if the port_provider can locate a task port for the process
// and it is backgrounded. If port_provider is null, returns false.
bool IsProcessBackgrounded(PortProvider* port_provider) const;
// Set the process as backgrounded. If value is
// true, the priority of the associated task will be set to
// TASK_BACKGROUND_APPLICATION. If value is false, the
// priority of the process will be set to TASK_FOREGROUND_APPLICATION.
//
// Returns true if the priority was changed, false otherwise. If
// |port_provider| is null, this is a no-op and it returns false.
bool SetProcessBackgrounded(PortProvider* port_provider, bool value);
#else
// A process is backgrounded when it's priority is lower than normal.
// Return true if this process is backgrounded, false otherwise.
bool IsProcessBackgrounded() const;
// Set a process as backgrounded. If value is true, the priority of the
// process will be lowered. If value is false, the priority of the process
// will be made "normal" - equivalent to default process priority.
// Returns true if the priority was changed, false otherwise.
bool SetProcessBackgrounded(bool value);
#endif // defined(OS_MACOSX)
// Returns an integer representing the priority of a process. The meaning
// of this value is OS dependent.
int GetPriority() const;
#if defined(OS_CHROMEOS)
// Get the PID in its PID namespace.
// If the process is not in a PID namespace or /proc/<pid>/status does not
// report NSpid, kNullProcessId is returned.
ProcessId GetPidInNamespace() const;
#endif
private:
#if defined(OS_WIN)
win::ScopedHandle process_;
#elif defined(OS_FUCHSIA)
zx::process process_;
#else
ProcessHandle process_;
#endif
#if defined(OS_WIN) || defined(OS_FUCHSIA)
bool is_current_process_;
#endif
DISALLOW_COPY_AND_ASSIGN(Process);
};
#if defined(OS_CHROMEOS)
// Exposed for testing.
// Given the contents of the /proc/<pid>/cgroup file, determine whether the
// process is backgrounded or not.
BASE_EXPORT bool IsProcessBackgroundedCGroup(
const StringPiece& cgroup_contents);
#endif // defined(OS_CHROMEOS)
} // namespace base
#endif // BASE_PROCESS_PROCESS_H_