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 license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     Signal constants used by wxProcess.
  11 */
  12 enum wxSignal
  13 {
  14     wxSIGNONE = 0,  //!< verify if the process exists under Unix
  15     wxSIGHUP,
  16     wxSIGINT,
  17     wxSIGQUIT,
  18     wxSIGILL,
  19     wxSIGTRAP,
  20     wxSIGABRT,
  21     wxSIGEMT,
  22     wxSIGFPE,
  23     wxSIGKILL,      //!< forcefully kill, dangerous!
  24     wxSIGBUS,
  25     wxSIGSEGV,
  26     wxSIGSYS,
  27     wxSIGPIPE,
  28     wxSIGALRM,
  29     wxSIGTERM       //!< terminate the process gently
  30 };
  31
  32 /**
  33     Return values for wxProcess::Kill.
  34 */
  35 enum wxKillError
  36 {
  37     wxKILL_OK,              //!< no error
  38     wxKILL_BAD_SIGNAL,      //!< no such signal
  39     wxKILL_ACCESS_DENIED,   //!< permission denied
  40     wxKILL_NO_PROCESS,      //!< no such process
  41     wxKILL_ERROR            //!< another, unspecified error
  42 };
  43
  44
  45 /**
  46     @class wxProcess
  47
  48     The objects of this class are used in conjunction with the ::wxExecute() function.
  49     When a wxProcess object is passed to ::wxExecute(), its OnTerminate() virtual method
  50     is called when the process terminates. This allows the program to be (asynchronously)
  51     notified about the process termination and also retrieve its exit status which is
  52     unavailable from ::wxExecute() in the case of asynchronous execution.
  53
  54     @note
  55         If the @c wxEVT_END_PROCESS event sent after termination is processed by the
  56         parent, then it is responsible for deleting the wxProcess object which sent it.
  57         However, if it is not processed, the object will <b>delete itself</b> and so the
  58         library users should only delete those objects whose notifications have been
  59         processed (and call wxProcess::Detach for others).
  60         This also means that unless you're going to process the @c wxEVT_END_PROCESS event,
  61         you <b>must</b> allocate the wxProcess class on the heap.
  62
  63     wxProcess also supports IO redirection of the child process. For this, you have
  64     to call its Redirect() method before passing it to ::wxExecute().
  65     If the child process was launched successfully, GetInputStream(), GetOutputStream()
  66     and GetErrorStream() can then be used to retrieve the streams corresponding to the
  67     child process standard output, input and error output respectively.
  68
  69     @beginEventEmissionTable{wxProcessEvent}
  70     @event{EVT_END_PROCESS(id, func)}
  71         Process a @c wxEVT_END_PROCESS event, sent by wxProcess::OnTerminate upon
  72         the external process termination.
  73     @endEventTable
  74
  75     @library{wxbase}
  76     @category{appmanagement}
  77
  78     @beginWxPerlOnly
  79     In wxPerl this class has an additional @c Destroy method,
  80     for explicit destruction.
  81     @endWxPerlOnly
  82
  83     @see wxExecute(), @ref page_samples_exec
  84 */
  85 class wxProcess : public wxEvtHandler
  86 {
  87 public:
  88     /**
  89         Constructs a process object. @a id is only used in the case you want to
  90         use wxWidgets events. It identifies this object, or another window that will
  91         receive the event.
  92
  93         If the @a parent parameter is different from @NULL, it will receive
  94         a @c wxEVT_END_PROCESS notification event (you should insert @c EVT_END_PROCESS
  95         macro in the event table of the parent to handle it) with the given @a id.
  96
  97         @param parent
  98             The event handler parent.
  99         @param id
 100             id of an event.
 101     */
 102     wxProcess(wxEvtHandler* parent = NULL, int id = -1);
 103
 104     /**
 105         Creates an object without any associated parent (and hence no id neither)
 106         but allows to specify the @a flags which can have the value of
 107         @c wxPROCESS_DEFAULT or @c wxPROCESS_REDIRECT.
 108
 109         Specifying the former value has no particular effect while using the latter
 110         one is equivalent to calling Redirect().
 111     */
 112     wxProcess(int flags);
 113
 114     /**
 115         Destroys the wxProcess object.
 116     */
 117     virtual ~wxProcess();
 118
 119     /**
 120         Closes the output stream (the one connected to the stdin of the child
 121         process).
 122
 123         This function can be used to indicate to the child process that
 124         there is no more data to be read - usually, a filter program will only
 125         terminate when the input stream is closed.
 126     */
 127     void CloseOutput();
 128
 129     /**
 130         Detaches this event handler from the parent specified in the constructor
 131         (see wxEvtHandler::Unlink() for a similar but not identic function).
 132
 133         Normally, a wxProcess object is deleted by its parent when it receives the
 134         notification about the process termination.
 135
 136         However, it might happen that the parent object is destroyed before the external
 137         process is terminated (e.g. a window from which this external process was launched
 138         is closed by the user) and in this case it @b should not delete the wxProcess
 139         object, but @b should call Detach() instead.
 140
 141         After the wxProcess object is detached from its parent, no notification events
 142         will be sent to the parent and the object will delete itself upon reception of
 143         the process termination notification.
 144     */
 145     void Detach();
 146
 147     /**
 148         Returns @true if the given process exists in the system.
 149
 150         @see Kill(), @ref page_samples_exec "Exec sample"
 151     */
 152     static bool Exists(int pid);
 153
 154     /**
 155         Returns an input stream which corresponds to the standard error output (stderr)
 156         of the child process.
 157     */
 158     wxInputStream* GetErrorStream() const;
 159
 160     /**
 161         It returns an input stream corresponding to the standard output stream of the
 162         subprocess. If it is @NULL, you have not turned on the redirection.
 163
 164         @see Redirect().
 165     */
 166     wxInputStream* GetInputStream() const;
 167
 168     /**
 169         It returns an output stream correspoding to the input stream of the subprocess.
 170         If it is @NULL, you have not turned on the redirection.
 171
 172         @see Redirect().
 173     */
 174     wxOutputStream* GetOutputStream() const;
 175
 176     /**
 177         Returns the process ID of the process launched by Open() or set by
 178         wxExecute() (if you passed this wxProcess as argument).
 179     */
 180     long GetPid() const;
 181
 182     /**
 183         Returns @true if there is data to be read on the child process standard
 184         error stream.
 185
 186         @see IsInputAvailable()
 187     */
 188     bool IsErrorAvailable() const;
 189
 190     /**
 191         Returns @true if there is data to be read on the child process standard
 192         output stream.
 193
 194         This allows to write simple (and extremely inefficient) polling-based code
 195         waiting for a better mechanism in future wxWidgets versions.
 196         See the @ref page_samples_exec "exec sample" for an example of using this
 197         function.
 198
 199         @see IsInputOpened()
 200     */
 201     bool IsInputAvailable() const;
 202
 203     /**
 204         Returns @true if the child process standard output stream is opened.
 205     */
 206     bool IsInputOpened() const;
 207
 208     /**
 209         Send the specified signal to the given process. Possible signal values
 210         can be one of the ::wxSignal enumeration values.
 211
 212         @c wxSIGNONE, @c wxSIGKILL and @c wxSIGTERM have the same meaning
 213         under both Unix and Windows but all the other signals are equivalent to
 214         @c wxSIGTERM under Windows.
 215
 216         The @a flags parameter can be @c wxKILL_NOCHILDREN (the default),
 217         or @c wxKILL_CHILDREN, in which case the child processes of this
 218         process will be killed too. Note that under Unix, for @c wxKILL_CHILDREN
 219         to work you should have created the process passing @c wxEXEC_MAKE_GROUP_LEADER.
 220
 221         Returns the element of ::wxKillError enum.
 222
 223         @see Exists(), wxKill(), @ref page_samples_exec "Exec sample"
 224     */
 225     static wxKillError Kill(int pid, wxSignal sig = wxSIGTERM,
 226                             int flags = wxKILL_NOCHILDREN);
 227
 228     /**
 229         It is called when the process with the pid @a pid finishes.
 230         It raises a wxWidgets event when it isn't overridden.
 231
 232         Note that this function won't be called if you Kill() the process.
 233
 234         @param pid
 235             The pid of the process which has just terminated.
 236         @param status
 237             The exit code of the process.
 238     */
 239     virtual void OnTerminate(int pid, int status);
 240
 241     /**
 242         This static method replaces the standard @c popen() function: it launches
 243         the process specified by the @a cmd parameter and returns the wxProcess
 244         object which can be used to retrieve the streams connected to the standard
 245         input, output and error output of the child process.
 246
 247         If the process couldn't be launched, @NULL is returned.
 248
 249         @remarks
 250         In any case the returned pointer should @b not be deleted, rather the process
 251         object will be destroyed automatically when the child process terminates. This
 252         does mean that the child process should be told to quit before the main program
 253         exits to avoid memory leaks.
 254
 255         @param cmd
 256             The command to execute, including optional arguments.
 257         @param flags
 258             The flags to pass to ::wxExecute().
 259             Note: @c wxEXEC_SYNC should not be used.
 260
 261         @return A pointer to new wxProcess object or @NULL on error.
 262
 263         @see ::wxExecute()
 264     */
 265     static wxProcess* Open(const wxString& cmd,
 266                            int flags = wxEXEC_ASYNC);
 267
 268     /**
 269         Turns on redirection.
 270
 271         ::wxExecute() will try to open a couple of pipes to catch the subprocess stdio.
 272         The caught input stream is returned by GetOutputStream() as a non-seekable stream.
 273         The caught output stream is returned by GetInputStream() as a non-seekable stream.
 274     */
 275     void Redirect();
 276 };
 277
 278
 279
 280 /**
 281     @class wxProcessEvent
 282
 283     A process event is sent to the wxEvtHandler specified to wxProcess
 284     when a process is terminated.
 285
 286     @beginEventTable{wxProcessEvent}
 287     @event{EVT_END_PROCESS(id, func)}
 288         Process a @c wxEVT_END_PROCESS event. @a id is the identifier of the process
 289         object (the id passed to the wxProcess constructor) or a window to receive
 290         the event.
 291     @endEventTable
 292
 293     @library{wxbase}
 294     @category{events}
 295
 296     @see wxProcess, @ref overview_events
 297 */
 298 class wxProcessEvent : public wxEvent
 299 {
 300 public:
 301     /**
 302         Constructor.
 303
 304         Takes a wxProcessObject or window id, a process id and an exit status.
 305     */
 306     wxProcessEvent(int id = 0, int pid = 0, int exitcode = 0);
 307
 308     /**
 309         Returns the exist status.
 310     */
 311     int GetExitCode();
 312
 313     /**
 314         Returns the process id.
 315     */
 316     int GetPid();
 317 };
 318