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     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         Notice that GetOutputStream() will return @NULL after the output stream
 128         is closed.
 129     */
 130     void CloseOutput();
 131
 132     /**
 133         Detaches this event handler from the parent specified in the constructor
 134         (see wxEvtHandler::Unlink() for a similar but not identic function).
 135
 136         Normally, a wxProcess object is deleted by its parent when it receives the
 137         notification about the process termination.
 138
 139         However, it might happen that the parent object is destroyed before the external
 140         process is terminated (e.g. a window from which this external process was launched
 141         is closed by the user) and in this case it @b should not delete the wxProcess
 142         object, but @b should call Detach() instead.
 143
 144         After the wxProcess object is detached from its parent, no notification events
 145         will be sent to the parent and the object will delete itself upon reception of
 146         the process termination notification.
 147     */
 148     void Detach();
 149
 150     /**
 151         Returns @true if the given process exists in the system.
 152
 153         @see Kill(), @ref page_samples_exec "Exec sample"
 154     */
 155     static bool Exists(int pid);
 156
 157     /**
 158         Returns an input stream which corresponds to the standard error output (stderr)
 159         of the child process.
 160     */
 161     wxInputStream* GetErrorStream() const;
 162
 163     /**
 164         It returns an input stream corresponding to the standard output stream of the
 165         subprocess. If it is @NULL, you have not turned on the redirection.
 166
 167         @see Redirect().
 168     */
 169     wxInputStream* GetInputStream() const;
 170
 171     /**
 172         It returns an output stream corresponding to the input stream of the subprocess.
 173
 174         If it is @NULL, you have not turned on the redirection or already
 175         called CloseOutput().
 176
 177         @see Redirect().
 178     */
 179     wxOutputStream* GetOutputStream() const;
 180
 181     /**
 182         Returns the process ID of the process launched by Open() or set by
 183         wxExecute() (if you passed this wxProcess as argument).
 184     */
 185     long GetPid() const;
 186
 187     /**
 188         Returns @true if there is data to be read on the child process standard
 189         error stream.
 190
 191         @see IsInputAvailable()
 192     */
 193     bool IsErrorAvailable() const;
 194
 195     /**
 196         Returns @true if there is data to be read on the child process standard
 197         output stream.
 198
 199         This allows to write simple (and extremely inefficient) polling-based code
 200         waiting for a better mechanism in future wxWidgets versions.
 201         See the @ref page_samples_exec "exec sample" for an example of using this
 202         function.
 203
 204         @see IsInputOpened()
 205     */
 206     bool IsInputAvailable() const;
 207
 208     /**
 209         Returns @true if the child process standard output stream is opened.
 210     */
 211     bool IsInputOpened() const;
 212
 213     /**
 214         Send the specified signal to the given process. Possible signal values
 215         can be one of the ::wxSignal enumeration values.
 216
 217         @c wxSIGNONE, @c wxSIGKILL and @c wxSIGTERM have the same meaning
 218         under both Unix and Windows but all the other signals are equivalent to
 219         @c wxSIGTERM under Windows.
 220
 221         The @a flags parameter can be @c wxKILL_NOCHILDREN (the default),
 222         or @c wxKILL_CHILDREN, in which case the child processes of this
 223         process will be killed too. Note that under Unix, for @c wxKILL_CHILDREN
 224         to work you should have created the process passing @c wxEXEC_MAKE_GROUP_LEADER.
 225
 226         Returns the element of ::wxKillError enum.
 227
 228         @see Exists(), wxKill(), @ref page_samples_exec "Exec sample"
 229     */
 230     static wxKillError Kill(int pid, wxSignal sig = wxSIGTERM,
 231                             int flags = wxKILL_NOCHILDREN);
 232
 233     /**
 234         It is called when the process with the pid @a pid finishes.
 235         It raises a wxWidgets event when it isn't overridden.
 236
 237         Note that this function won't be called if you Kill() the process.
 238
 239         @param pid
 240             The pid of the process which has just terminated.
 241         @param status
 242             The exit code of the process.
 243     */
 244     virtual void OnTerminate(int pid, int status);
 245
 246     /**
 247         This static method replaces the standard @c popen() function: it launches
 248         the process specified by the @a cmd parameter and returns the wxProcess
 249         object which can be used to retrieve the streams connected to the standard
 250         input, output and error output of the child process.
 251
 252         If the process couldn't be launched, @NULL is returned.
 253
 254         @remarks
 255         In any case the returned pointer should @b not be deleted, rather the process
 256         object will be destroyed automatically when the child process terminates. This
 257         does mean that the child process should be told to quit before the main program
 258         exits to avoid memory leaks.
 259
 260         @param cmd
 261             The command to execute, including optional arguments.
 262         @param flags
 263             The flags to pass to ::wxExecute().
 264             Note: @c wxEXEC_SYNC should not be used.
 265
 266         @return A pointer to new wxProcess object or @NULL on error.
 267
 268         @see ::wxExecute()
 269     */
 270     static wxProcess* Open(const wxString& cmd,
 271                            int flags = wxEXEC_ASYNC);
 272
 273     /**
 274         Turns on redirection.
 275
 276         ::wxExecute() will try to open a couple of pipes to catch the subprocess stdio.
 277         The caught input stream is returned by GetOutputStream() as a non-seekable stream.
 278         The caught output stream is returned by GetInputStream() as a non-seekable stream.
 279     */
 280     void Redirect();
 281 };
 282
 283
 284
 285 /**
 286     @class wxProcessEvent
 287
 288     A process event is sent to the wxEvtHandler specified to wxProcess
 289     when a process is terminated.
 290
 291     @beginEventTable{wxProcessEvent}
 292     @event{EVT_END_PROCESS(id, func)}
 293         Process a @c wxEVT_END_PROCESS event. @a id is the identifier of the process
 294         object (the id passed to the wxProcess constructor) or a window to receive
 295         the event.
 296     @endEventTable
 297
 298     @library{wxbase}
 299     @category{events}
 300
 301     @see wxProcess, @ref overview_events
 302 */
 303 class wxProcessEvent : public wxEvent
 304 {
 305 public:
 306     /**
 307         Constructor.
 308
 309         Takes a wxProcessObject or window id, a process id and an exit status.
 310     */
 311     wxProcessEvent(int id = 0, int pid = 0, int exitcode = 0);
 312
 313     /**
 314         Returns the exist status.
 315     */
 316     int GetExitCode();
 317
 318     /**
 319         Returns the process id.
 320     */
 321     int GetPid();
 322 };
 323