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