interface/wx/process.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        process.h
   3 // Purpose:     interface of wxProcess
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows licence
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9
  10 /**
  11     @class wxProcess
  12
  13     The objects of this class are used in conjunction with the ::wxExecute() function.
  14     When a wxProcess object is passed to ::wxExecute(), its OnTerminate() virtual method
  15     is called when the process terminates. This allows the program to be (asynchronously)
  16     notified about the process termination and also retrieve its exit status which is
  17     unavailable from ::wxExecute() in the case of asynchronous execution.
  18
  19     @note
  20         If the @c wxEVT_END_PROCESS event sent after termination is processed by the
  21         parent, then it is responsible for deleting the wxProcess object which sent it.
  22         However, if it is not processed, the object will <b>delete itself</b> and so the
  23         library users should only delete those objects whose notifications have been
  24         processed (and call wxProcess::Detach for others).
  25         This also means that unless you're going to process the @c wxEVT_END_PROCESS event,
  26         you <b>must</b> allocate the wxProcess class on the heap.
  27
  28     wxProcess also supports IO redirection of the child process. For this, you have
  29     to call its Redirect() method before passing it to ::wxExecute().
  30     If the child process was launched successfully, GetInputStream(), GetOutputStream()
  31     and GetErrorStream() can then be used to retrieve the streams corresponding to the
  32     child process standard output, input and error output respectively.
  33
  34     @beginEventEmissionTable{wxProcessEvent}
  35     @event{EVT_END_PROCESS(id, func)}
  36         Process a @c wxEVT_END_PROCESS event, sent by wxProcess::OnTerminate upon
  37         the external process termination.
  38     @endEventTable
  39
  40     @library{wxbase}
  41     @category{appmanagement}
  42
  43     @beginWxPerlOnly
  44     In wxPerl this class has an additional @c Destroy method,
  45     for explicit destruction.
  46     @endWxPerlOnly
  47
  48     @see wxExecute(), @ref page_samples_exec
  49 */
  50 class wxProcess : public wxEvtHandler
  51 {
  52 public:
  53     /**
  54         Constructs a process object. @a id is only used in the case you want to
  55         use wxWidgets events. It identifies this object, or another window that will
  56         receive the event.
  57
  58         If the @a parent parameter is different from @NULL, it will receive
  59         a @c wxEVT_END_PROCESS notification event (you should insert @c EVT_END_PROCESS
  60         macro in the event table of the parent to handle it) with the given @a id.
  61
  62         @param parent
  63             The event handler parent.
  64         @param id
  65             id of an event.
  66     */
  67     wxProcess(wxEvtHandler* parent = NULL, int id = -1);
  68
  69     /**
  70         Creates an object without any associated parent (and hence no id neither)
  71         but allows to specify the @a flags which can have the value of
  72         @c wxPROCESS_DEFAULT or @c wxPROCESS_REDIRECT.
  73
  74         Specifying the former value has no particular effect while using the latter
  75         one is equivalent to calling Redirect().
  76     */
  77     wxProcess(int flags);
  78
  79     /**
  80         Destroys the wxProcess object.
  81     */
  82     virtual ~wxProcess();
  83
  84     /**
  85         Closes the output stream (the one connected to the stdin of the child
  86         process).
  87
  88         This function can be used to indicate to the child process that
  89         there is no more data to be read - usually, a filter program will only
  90         terminate when the input stream is closed.
  91
  92         Notice that GetOutputStream() will return @NULL after the output stream
  93         is closed.
  94     */
  95     void CloseOutput();
  96
  97     /**
  98         Detaches this event handler from the parent specified in the constructor
  99         (see wxEvtHandler::Unlink() for a similar but not identic function).
 100
 101         Normally, a wxProcess object is deleted by its parent when it receives the
 102         notification about the process termination.
 103
 104         However, it might happen that the parent object is destroyed before the external
 105         process is terminated (e.g. a window from which this external process was launched
 106         is closed by the user) and in this case it @b should not delete the wxProcess
 107         object, but @b should call Detach() instead.
 108
 109         After the wxProcess object is detached from its parent, no notification events
 110         will be sent to the parent and the object will delete itself upon reception of
 111         the process termination notification.
 112     */
 113     void Detach();
 114
 115     /**
 116         Returns @true if the given process exists in the system.
 117
 118         @see Kill(), @ref page_samples_exec "Exec sample"
 119     */
 120     static bool Exists(int pid);
 121
 122     /**
 123         Returns an input stream which corresponds to the standard error output (stderr)
 124         of the child process.
 125     */
 126     wxInputStream* GetErrorStream() const;
 127
 128     /**
 129         It returns an input stream corresponding to the standard output stream of the
 130         subprocess. If it is @NULL, you have not turned on the redirection.
 131
 132         @see Redirect().
 133     */
 134     wxInputStream* GetInputStream() const;
 135
 136     /**
 137         It returns an output stream corresponding to the input stream of the subprocess.
 138
 139         If it is @NULL, you have not turned on the redirection or already
 140         called CloseOutput().
 141
 142         @see Redirect().
 143     */
 144     wxOutputStream* GetOutputStream() const;
 145
 146     /**
 147         Returns the process ID of the process launched by Open() or set by
 148         wxExecute() (if you passed this wxProcess as argument).
 149     */
 150     long GetPid() const;
 151
 152     /**
 153         Returns @true if there is data to be read on the child process standard
 154         error stream.
 155
 156         @see IsInputAvailable()
 157     */
 158     bool IsErrorAvailable() const;
 159
 160     /**
 161         Returns @true if there is data to be read on the child process standard
 162         output stream.
 163
 164         This allows to write simple (and extremely inefficient) polling-based code
 165         waiting for a better mechanism in future wxWidgets versions.
 166         See the @ref page_samples_exec "exec sample" for an example of using this
 167         function.
 168
 169         @see IsInputOpened()
 170     */
 171     bool IsInputAvailable() const;
 172
 173     /**
 174         Returns @true if the child process standard output stream is opened.
 175     */
 176     bool IsInputOpened() const;
 177
 178     /**
 179         Send the specified signal to the given process. Possible signal values
 180         can be one of the ::wxSignal enumeration values.
 181
 182         @c wxSIGNONE, @c wxSIGKILL and @c wxSIGTERM have the same meaning
 183         under both Unix and Windows but all the other signals are equivalent to
 184         @c wxSIGTERM under Windows.
 185
 186         The @a flags parameter can be @c wxKILL_NOCHILDREN (the default),
 187         or @c wxKILL_CHILDREN, in which case the child processes of this
 188         process will be killed too. Note that under Unix, for @c wxKILL_CHILDREN
 189         to work you should have created the process passing @c wxEXEC_MAKE_GROUP_LEADER.
 190
 191         Returns the element of ::wxKillError enum.
 192
 193         @see Exists(), wxKill(), @ref page_samples_exec "Exec sample"
 194     */
 195     static wxKillError Kill(int pid, wxSignal sig = wxSIGTERM,
 196                             int flags = wxKILL_NOCHILDREN);
 197
 198     /**
 199         It is called when the process with the pid @a pid finishes.
 200         It raises a wxWidgets event when it isn't overridden.
 201
 202         Note that this function won't be called if you Kill() the process.
 203
 204         @param pid
 205             The pid of the process which has just terminated.
 206         @param status
 207             The exit code of the process.
 208     */
 209     virtual void OnTerminate(int pid, int status);
 210
 211     /**
 212         This static method replaces the standard @c popen() function: it launches
 213         the process specified by the @a cmd parameter and returns the wxProcess
 214         object which can be used to retrieve the streams connected to the standard
 215         input, output and error output of the child process.
 216
 217         If the process couldn't be launched, @NULL is returned.
 218
 219         @remarks
 220         In any case the returned pointer should @b not be deleted, rather the process
 221         object will be destroyed automatically when the child process terminates. This
 222         does mean that the child process should be told to quit before the main program
 223         exits to avoid memory leaks.
 224
 225         @param cmd
 226             The command to execute, including optional arguments.
 227         @param flags
 228             The flags to pass to ::wxExecute().
 229             Note: @c wxEXEC_SYNC should not be used.
 230
 231         @return A pointer to new wxProcess object or @NULL on error.
 232
 233         @see ::wxExecute()
 234     */
 235     static wxProcess* Open(const wxString& cmd,
 236                            int flags = wxEXEC_ASYNC);
 237
 238     /**
 239         Turns on redirection.
 240
 241         ::wxExecute() will try to open a couple of pipes to catch the subprocess stdio.
 242         The caught input stream is returned by GetOutputStream() as a non-seekable stream.
 243         The caught output stream is returned by GetInputStream() as a non-seekable stream.
 244     */
 245     void Redirect();
 246 };
 247
 248
 249
 250 /**
 251     @class wxProcessEvent
 252
 253     A process event is sent to the wxEvtHandler specified to wxProcess
 254     when a process is terminated.
 255
 256     @beginEventTable{wxProcessEvent}
 257     @event{EVT_END_PROCESS(id, func)}
 258         Process a @c wxEVT_END_PROCESS event. @a id is the identifier of the process
 259         object (the id passed to the wxProcess constructor) or a window to receive
 260         the event.
 261     @endEventTable
 262
 263     @library{wxbase}
 264     @category{events}
 265
 266     @see wxProcess, @ref overview_events
 267 */
 268 class wxProcessEvent : public wxEvent
 269 {
 270 public:
 271     /**
 272         Constructor.
 273
 274         Takes a wxProcessObject or window id, a process id and an exit status.
 275     */
 276     wxProcessEvent(int id = 0, int pid = 0, int exitcode = 0);
 277
 278     /**
 279         Returns the exist status.
 280     */
 281     int GetExitCode();
 282
 283     /**
 284         Returns the process id.
 285     */
 286     int GetPid();
 287 };
 288
 289
 290 wxEventType wxEVT_END_PROCESS;
 291