base/process/process.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_PROCESS_PROCESS_PROCESS_H_
   6 #define BASE_PROCESS_PROCESS_PROCESS_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/basictypes.h"
  10 #include "base/move.h"
  11 #include "base/process/process_handle.h"
  12 #include "base/time/time.h"
  13 #include "build/build_config.h"
  14
  15 #if defined(OS_WIN)
  16 #include "base/win/scoped_handle.h"
  17 #endif
  18
  19 namespace base {
  20
  21 // Provides a move-only encapsulation of a process.
  22 //
  23 // This object is not tied to the lifetime of the underlying process: the
  24 // process may be killed and this object may still around, and it will still
  25 // claim to be valid. The actual behavior in that case is OS dependent like so:
  26 //
  27 // Windows: The underlying ProcessHandle will be valid after the process dies
  28 // and can be used to gather some information about that process, but most
  29 // methods will obviously fail.
  30 //
  31 // POSIX: The underlying PorcessHandle is not guaranteed to remain valid after
  32 // the process dies, and it may be reused by the system, which means that it may
  33 // end up pointing to the wrong process.
  34 class BASE_EXPORT Process {
  35   MOVE_ONLY_TYPE_FOR_CPP_03(Process, RValue)
  36
  37  public:
  38   explicit Process(ProcessHandle handle = kNullProcessHandle);
  39
  40   // Move constructor for C++03 move emulation of this type.
  41   Process(RValue other);
  42
  43   // The destructor does not terminate the process.
  44   ~Process() {}
  45
  46   // Move operator= for C++03 move emulation of this type.
  47   Process& operator=(RValue other);
  48
  49   // Returns an object for the current process.
  50   static Process Current();
  51
  52   // Returns a Process for the given |pid|.
  53   static Process Open(ProcessId pid);
  54
  55   // Returns a Process for the given |pid|. On Windows the handle is opened
  56   // with more access rights and must only be used by trusted code (can read the
  57   // address space and duplicate handles).
  58   static Process OpenWithExtraPriviles(ProcessId pid);
  59
  60 #if defined(OS_WIN)
  61   // Returns a Process for the given |pid|, using some |desired_access|.
  62   // See ::OpenProcess documentation for valid |desired_access|.
  63   static Process OpenWithAccess(ProcessId pid, DWORD desired_access);
  64 #endif
  65
  66   // Creates an object from a |handle| owned by someone else.
  67   // Don't use this for new code. It is only intended to ease the migration to
  68   // a strict ownership model.
  69   // TODO(rvargas) crbug.com/417532: Remove this code.
  70   static Process DeprecatedGetProcessFromHandle(ProcessHandle handle);
  71
  72   // Returns true if processes can be backgrounded.
  73   static bool CanBackgroundProcesses();
  74
  75   // Returns true if this objects represents a valid process.
  76   bool IsValid() const;
  77
  78   // Returns a handle for this process. There is no guarantee about when that
  79   // handle becomes invalid because this object retains ownership.
  80   ProcessHandle Handle() const;
  81
  82   // Returns a second object that represents this process.
  83   Process Duplicate() const;
  84
  85   // Get the PID for this process.
  86   ProcessId Pid() const;
  87
  88   // Returns true if this process is the current process.
  89   bool is_current() const;
  90
  91   // Close the process handle. This will not terminate the process.
  92   void Close();
  93
  94   // Terminates the process with extreme prejudice. The given |result_code| will
  95   // be the exit code of the process.
  96   // NOTE: On POSIX |result_code| is ignored.
  97   void Terminate(int result_code);
  98
  99   // Waits for the process to exit. Returns true on success.
 100   // On POSIX, if the process has been signaled then |exit_code| is set to -1.
 101   bool WaitForExit(int* exit_code);
 102
 103   // Same as WaitForExit() but only waits for up to |timeout|.
 104   bool WaitForExitWithTimeout(TimeDelta timeout, int* exit_code);
 105
 106   // A process is backgrounded when it's priority is lower than normal.
 107   // Return true if this process is backgrounded, false otherwise.
 108   bool IsProcessBackgrounded() const;
 109
 110   // Set a process as backgrounded. If value is true, the priority of the
 111   // process will be lowered. If value is false, the priority of the process
 112   // will be made "normal" - equivalent to default process priority.
 113   // Returns true if the priority was changed, false otherwise.
 114   bool SetProcessBackgrounded(bool value);
 115
 116   // Returns an integer representing the priority of a process. The meaning
 117   // of this value is OS dependent.
 118   int GetPriority() const;
 119
 120  private:
 121 #if defined(OS_WIN)
 122   bool is_current_process_;
 123   win::ScopedHandle process_;
 124 #else
 125   ProcessHandle process_;
 126 #endif
 127 };
 128
 129 }  // namespace base
 130
 131 #endif  // BASE_PROCESS_PROCESS_PROCESS_H_