base/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_H_
   6 #define BASE_PROCESS_H_
   7 #pragma once
   8
   9 #include "base/base_export.h"
  10 #include "base/basictypes.h"
  11 #include "build/build_config.h"
  12
  13 #include <sys/types.h>
  14 #if defined(OS_WIN)
  15 #include <windows.h>
  16 #endif
  17
  18 namespace base {
  19
  20 // ProcessHandle is a platform specific type which represents the underlying OS
  21 // handle to a process.
  22 // ProcessId is a number which identifies the process in the OS.
  23 #if defined(OS_WIN)
  24 typedef HANDLE ProcessHandle;
  25 typedef DWORD ProcessId;
  26 typedef HANDLE UserTokenHandle;
  27 const ProcessHandle kNullProcessHandle = NULL;
  28 const ProcessId kNullProcessId = 0;
  29 #elif defined(OS_POSIX)
  30 // On POSIX, our ProcessHandle will just be the PID.
  31 typedef pid_t ProcessHandle;
  32 typedef pid_t ProcessId;
  33 const ProcessHandle kNullProcessHandle = 0;
  34 const ProcessId kNullProcessId = 0;
  35 #endif  // defined(OS_WIN)
  36
  37 #if defined(OS_POSIX) && !defined(OS_MACOSX)
  38 // saved_priority_ will be set to this to indicate that it's not holding
  39 // a valid value. -20 to 19 are valid process priorities.
  40 const int kUnsetProcessPriority = 256;
  41 #endif
  42
  43 class BASE_EXPORT Process {
  44  public:
  45   Process() : process_(kNullProcessHandle) {
  46 #if defined(OS_POSIX) && !defined(OS_MACOSX)
  47     saved_priority_ = kUnsetProcessPriority;
  48 #endif
  49   }
  50
  51   explicit Process(ProcessHandle handle) : process_(handle) {
  52 #if defined(OS_POSIX) && !defined(OS_MACOSX)
  53     saved_priority_ = kUnsetProcessPriority;
  54 #endif
  55   }
  56
  57   // A handle to the current process.
  58   static Process Current();
  59
  60   // Get/Set the handle for this process. The handle will be 0 if the process
  61   // is no longer running.
  62   ProcessHandle handle() const { return process_; }
  63   void set_handle(ProcessHandle handle) {
  64     process_ = handle;
  65 #if defined(OS_POSIX) && !defined(OS_MACOSX)
  66     saved_priority_ = kUnsetProcessPriority;
  67 #endif
  68   }
  69
  70   // Get the PID for this process.
  71   ProcessId pid() const;
  72
  73   // Is the this process the current process.
  74   bool is_current() const;
  75
  76   // Close the process handle. This will not terminate the process.
  77   void Close();
  78
  79   // Terminates the process with extreme prejudice. The given result code will
  80   // be the exit code of the process. If the process has already exited, this
  81   // will do nothing.
  82   void Terminate(int result_code);
  83
  84   // A process is backgrounded when it's priority is lower than normal.
  85   // Return true if this process is backgrounded, false otherwise.
  86   bool IsProcessBackgrounded() const;
  87
  88   // Set a process as backgrounded. If value is true, the priority
  89   // of the process will be lowered. If value is false, the priority
  90   // of the process will be made "normal" - equivalent to default
  91   // process priority.
  92   // Returns true if the priority was changed, false otherwise.
  93   bool SetProcessBackgrounded(bool value);
  94
  95   // Returns an integer representing the priority of a process. The meaning
  96   // of this value is OS dependent.
  97   int GetPriority() const;
  98
  99  private:
 100   ProcessHandle process_;
 101 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 102   // Holds the priority that the process was set to when it was backgrounded.
 103   // If the process wasn't backgrounded it will be kUnsetProcessPriority.
 104   int saved_priority_;
 105 #endif
 106 };
 107
 108 }  // namespace base
 109
 110 #endif  // BASE_PROCESS_H_