Rewrite wxExecute() implementation under Unix.

This commit changes wxExecute() to handle SIGCHLD to be notified about the
child process termination instead of detecting when the file descriptor
corresponding to the other end of a pipe opened in the parent process was
closed in the child as this was not reliable and could (and did) result in not
detecting the termination of the child processes that closed all their file
descriptors before exiting.

This commit also removes a lot of platform-specific code duplicating the
generic event loop sources support and reuses it for wxExecute() purposes too.

Final big change is that wxEndProcessData was merged into wxExecuteData and we
don't have two similar but quite different classes any more but just one,
which is used both to pass the information from wxExecute() to wxAppTraits
methods and to store this information until the child termination.

Closes #10258.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74350 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/apptbase.h

@@ -12,8 +12,10 @@
 #ifndef _WX_UNIX_APPTBASE_H_
 #define _WX_UNIX_APPTBASE_H_
 
-struct wxEndProcessData;
-struct wxExecuteData;
+#include "wx/evtloop.h"
+#include "wx/evtloopsrc.h"
+
+class wxExecuteData;
 class wxFDIOManager;
 class wxEventLoopSourcesManagerBase;
 
@@ -27,23 +29,13 @@ public:
     // wxExecute() support methods
     // ---------------------------
 
-    // wait for the process termination, return whatever wxExecute() must
-    // return
+    // Wait for the process termination and return its exit code or -1 on error.
     //
-    // base class implementation handles all cases except wxEXEC_SYNC without
-    // wxEXEC_NOEVENTS one which is implemented at the GUI level
+    // Notice that this is only used when execData.flags contains wxEXEC_SYNC
+    // and does not contain wxEXEC_NOEVENTS, i.e. when we need to really wait
+    // until the child process exit and dispatch the events while doing it.
     virtual int WaitForChild(wxExecuteData& execData);
 
-    // integrate the monitoring of the given fd with the port-specific event
-    // loop: when this fd, which corresponds to a dummy pipe opened between the
-    // parent and child processes, is closed by the child, the parent is
-    // notified about this via a call to wxHandleProcessTermination() function
-    //
-    // the default implementation uses wxFDIODispatcher and so is suitable for
-    // the console applications or ports which don't have any specific event
-    // loop
-    virtual int AddProcessCallback(wxEndProcessData *data, int fd);
-
 #if wxUSE_SOCKETS
     // return a pointer to the object which should be used to integrate
     // monitoring of the file descriptors to the event loop (currently this is
@@ -62,10 +54,12 @@ public:
     virtual wxEventLoopSourcesManagerBase* GetEventLoopSourcesManager();
 
 protected:
-    // a helper for the implementation of WaitForChild() in wxGUIAppTraits:
-    // checks the streams used for redirected IO in execData and returns true
-    // if there is any activity in them
-    bool CheckForRedirectedIO(wxExecuteData& execData);
+    // Wait for the process termination by running the given event loop until
+    // this happens.
+    //
+    // This is used by the public WaitForChild() after creating the event loop
+    // of the appropriate kind.
+    int RunLoopUntilChildExit(wxExecuteData& execData, wxEventLoopBase& loop);
 };
 
 #endif // _WX_UNIX_APPTBASE_H_