interface/wx/process.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        process.h
   3 // Purpose:     interface of wxProcess
   4 // Author:      wxWidgets team
   5 // Licence:     wxWindows licence
   6 /////////////////////////////////////////////////////////////////////////////
   7
   8
   9 /**
  10     @class wxProcess
  11
  12     The objects of this class are used in conjunction with the ::wxExecute() function.
  13     When a wxProcess object is passed to ::wxExecute(), its OnTerminate() virtual method
  14     is called when the process terminates. This allows the program to be (asynchronously)
  15     notified about the process termination and also retrieve its exit status which is
  16     unavailable from ::wxExecute() in the case of asynchronous execution.
  17
  18     @note
  19         If the @c wxEVT_END_PROCESS event sent after termination is processed by the
  20         parent, then it is responsible for deleting the wxProcess object which sent it.
  21         However, if it is not processed, the object will <b>delete itself</b> and so the
  22         library users should only delete those objects whose notifications have been
  23         processed (and call wxProcess::Detach for others).
  24         This also means that unless you're going to process the @c wxEVT_END_PROCESS event,
  25         you <b>must</b> allocate the wxProcess class on the heap.
  26
  27     wxProcess also supports IO redirection of the child process. For this, you have
  28     to call its Redirect() method before passing it to ::wxExecute().
  29     If the child process was launched successfully, GetInputStream(), GetOutputStream()
  30     and GetErrorStream() can then be used to retrieve the streams corresponding to the
  31     child process standard output, input and error output respectively.
  32
  33     @beginEventEmissionTable{wxProcessEvent}
  34     @event{EVT_END_PROCESS(id, func)}
  35         Process a @c wxEVT_END_PROCESS event, sent by wxProcess::OnTerminate upon
  36         the external process termination.
  37     @endEventTable
  38
  39     @library{wxbase}
  40     @category{appmanagement}
  41
  42     @beginWxPerlOnly
  43     In wxPerl this class has an additional @c Destroy method,
  44     for explicit destruction.
  45     @endWxPerlOnly
  46
  47     @see wxExecute(), @ref page_samples_exec
  48 */
  49 class wxProcess : public wxEvtHandler
  50 {
  51 public:
  52     /**
  53         Constructs a process object. @a id is only used in the case you want to
  54         use wxWidgets events. It identifies this object, or another window that will
  55         receive the event.
  56
  57         If the @a parent parameter is different from @NULL, it will receive
  58         a @c wxEVT_END_PROCESS notification event (you should insert @c EVT_END_PROCESS
  59         macro in the event table of the parent to handle it) with the given @a id.
  60
  61         @param parent
  62             The event handler parent.
  63         @param id
  64             id of an event.
  65     */
  66     wxProcess(wxEvtHandler* parent = NULL, int id = -1);
  67
  68     /**
  69         Creates an object without any associated parent (and hence no id neither)
  70         but allows to specify the @a flags which can have the value of
  71         @c wxPROCESS_DEFAULT or @c wxPROCESS_REDIRECT.
  72
  73         Specifying the former value has no particular effect while using the latter
  74         one is equivalent to calling Redirect().
  75     */
  76     wxProcess(int flags);
  77
  78     /**
  79         Destroys the wxProcess object.
  80     */
  81     virtual ~wxProcess();
  82
  83     /**
  84         Closes the output stream (the one connected to the stdin of the child
  85         process).
  86
  87         This function can be used to indicate to the child process that
  88         there is no more data to be read - usually, a filter program will only
  89         terminate when the input stream is closed.
  90
  91         Notice that GetOutputStream() will return @NULL after the output stream
  92         is closed.
  93     */
  94     void CloseOutput();
  95
  96     /**
  97         Detaches this event handler from the parent specified in the constructor
  98         (see wxEvtHandler::Unlink() for a similar but not identical function).
  99
 100         Normally, a wxProcess object is deleted by its parent when it receives the
 101         notification about the process termination.
 102
 103         However, it might happen that the parent object is destroyed before the external
 104         process is terminated (e.g. a window from which this external process was launched
 105         is closed by the user) and in this case it @b should not delete the wxProcess
 106         object, but @b should call Detach() instead.
 107
 108         After the wxProcess object is detached from its parent, no notification events
 109         will be sent to the parent and the object will delete itself upon reception of
 110         the process termination notification.
 111     */
 112     void Detach();
 113
 114     /**
 115         Returns @true if the given process exists in the system.
 116
 117         @see Kill(), @ref page_samples_exec "Exec sample"
 118     */
 119     static bool Exists(int pid);
 120
 121     /**
 122         Returns an input stream which corresponds to the standard error output (stderr)
 123         of the child process.
 124     */
 125     wxInputStream* GetErrorStream() const;
 126
 127     /**
 128         It returns an input stream corresponding to the standard output stream of the
 129         subprocess. If it is @NULL, you have not turned on the redirection.
 130
 131         @see Redirect().
 132     */
 133     wxInputStream* GetInputStream() const;
 134
 135     /**
 136         It returns an output stream corresponding to the input stream of the subprocess.
 137
 138         If it is @NULL, you have not turned on the redirection or already
 139         called CloseOutput().
 140
 141         @see Redirect().
 142     */
 143     wxOutputStream* GetOutputStream() const;
 144
 145     /**
 146         Returns the process ID of the process launched by Open() or set by
 147         wxExecute() (if you passed this wxProcess as argument).
 148     */
 149     long GetPid() const;
 150
 151     /**
 152         Returns @true if there is data to be read on the child process standard
 153         error stream.
 154
 155         @see IsInputAvailable()
 156     */
 157     bool IsErrorAvailable() const;
 158
 159     /**
 160         Returns @true if there is data to be read on the child process standard
 161         output stream.
 162
 163         This allows to write simple (and extremely inefficient) polling-based code
 164         waiting for a better mechanism in future wxWidgets versions.
 165         See the @ref page_samples_exec "exec sample" for an example of using this
 166         function.
 167
 168         @see IsInputOpened()
 169     */
 170     bool IsInputAvailable() const;
 171
 172     /**
 173         Returns @true if the child process standard output stream is opened.
 174     */
 175     bool IsInputOpened() const;
 176
 177     /**
 178         Send the specified signal to the given process. Possible signal values
 179         can be one of the ::wxSignal enumeration values.
 180
 181         @c wxSIGNONE, @c wxSIGKILL and @c wxSIGTERM have the same meaning
 182         under both Unix and Windows but all the other signals are equivalent to
 183         @c wxSIGTERM under Windows.
 184
 185         The @a flags parameter can be @c wxKILL_NOCHILDREN (the default),
 186         or @c wxKILL_CHILDREN, in which case the child processes of this
 187         process will be killed too. Note that under Unix, for @c wxKILL_CHILDREN
 188         to work you should have created the process passing @c wxEXEC_MAKE_GROUP_LEADER.
 189
 190         Returns the element of ::wxKillError enum.
 191
 192         @see Exists(), wxKill(), @ref page_samples_exec "Exec sample"
 193     */
 194     static wxKillError Kill(int pid, wxSignal sig = wxSIGTERM,
 195                             int flags = wxKILL_NOCHILDREN);
 196
 197     /**
 198         It is called when the process with the pid @a pid finishes.
 199         It raises a wxWidgets event when it isn't overridden.
 200
 201         Note that this function won't be called if you Kill() the process.
 202
 203         @param pid
 204             The pid of the process which has just terminated.
 205         @param status
 206             The exit code of the process.
 207     */
 208     virtual void OnTerminate(int pid, int status);
 209
 210     /**
 211         This static method replaces the standard @c popen() function: it launches
 212         the process specified by the @a cmd parameter and returns the wxProcess
 213         object which can be used to retrieve the streams connected to the standard
 214         input, output and error output of the child process.
 215
 216         If the process couldn't be launched, @NULL is returned.
 217
 218         @remarks
 219         In any case the returned pointer should @b not be deleted, rather the process
 220         object will be destroyed automatically when the child process terminates. This
 221         does mean that the child process should be told to quit before the main program
 222         exits to avoid memory leaks.
 223
 224         @param cmd
 225             The command to execute, including optional arguments.
 226         @param flags
 227             The flags to pass to ::wxExecute().
 228             Note: @c wxEXEC_SYNC should not be used.
 229
 230         @return A pointer to new wxProcess object or @NULL on error.
 231
 232         @see ::wxExecute()
 233     */
 234     static wxProcess* Open(const wxString& cmd,
 235                            int flags = wxEXEC_ASYNC);
 236
 237     /**
 238         Turns on redirection.
 239
 240         ::wxExecute() will try to open a couple of pipes to catch the subprocess stdio.
 241         The caught input stream is returned by GetOutputStream() as a non-seekable stream.
 242         The caught output stream is returned by GetInputStream() as a non-seekable stream.
 243     */
 244     void Redirect();
 245
 246     /**
 247         Sets the priority of the process, between 0 (lowest) and 100 (highest).
 248         It can only be set before the process is created.
 249
 250         The following symbolic constants can be used in addition to raw
 251         values in 0..100 range:
 252           - @b wxPRIORITY_MIN: 0
 253           - @b wxPRIORITY_DEFAULT: 50
 254           - @b wxPRIORITY_MAX: 100
 255
 256         @since 2.9.5
 257     */
 258     void SetPriority(unsigned priority);
 259 };
 260
 261
 262
 263 /**
 264     @class wxProcessEvent
 265
 266     A process event is sent to the wxEvtHandler specified to wxProcess
 267     when a process is terminated.
 268
 269     @beginEventTable{wxProcessEvent}
 270     @event{EVT_END_PROCESS(id, func)}
 271         Process a @c wxEVT_END_PROCESS event. @a id is the identifier of the process
 272         object (the id passed to the wxProcess constructor) or a window to receive
 273         the event.
 274     @endEventTable
 275
 276     @library{wxbase}
 277     @category{events}
 278
 279     @see wxProcess, @ref overview_events
 280 */
 281 class wxProcessEvent : public wxEvent
 282 {
 283 public:
 284     /**
 285         Constructor.
 286
 287         Takes a wxProcessObject or window id, a process id and an exit status.
 288     */
 289     wxProcessEvent(int id = 0, int pid = 0, int exitcode = 0);
 290
 291     /**
 292         Returns the exist status.
 293     */
 294     int GetExitCode();
 295
 296     /**
 297         Returns the process id.
 298     */
 299     int GetPid();
 300 };
 301
 302
 303 wxEventType wxEVT_END_PROCESS;
 304