[pywin32-checkins] pywin32/win32/src win32trace.cpp,1.13,1.14

[Mark H. <mha...@us...>]

Update of /cvsroot/pywin32/pywin32/win32/src
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv15549

Modified Files:
	win32trace.cpp 
Log Message:
Work better on Vista, by dealing with the 'access denied' errors that
are likely when working in the 'Global\\' namespace.


Index: win32trace.cpp
===================================================================
RCS file: /cvsroot/pywin32/pywin32/win32/src/win32trace.cpp,v
retrieving revision 1.13
retrieving revision 1.14
diff -C2 -d -r1.13 -r1.14
*** win32trace.cpp	28 Jan 2005 00:02:23 -0000	1.13
--- win32trace.cpp	18 May 2007 11:22:17 -0000	1.14
***************
*** 46,58 ****
  const char *EVENT_EMPTY_OBJECT_NAME = "Global\\PythonTraceOutputEmptyEvent";
  
! // Function to remove the "Global\\" prefix on NT4/9x
  static const char *FixupObjectName(const char *global_name)
  {
!     OSVERSIONINFO info;
!     info.dwOSVersionInfoSize = sizeof(info);
!     GetVersionEx(&info);
!     if (info.dwMajorVersion <= 4) // NT, 9x
          return strchr(global_name, '\\')+1;
!     // 2000 or later - "Global\\" prefix OK.
      return global_name;
  }
--- 46,80 ----
  const char *EVENT_EMPTY_OBJECT_NAME = "Global\\PythonTraceOutputEmptyEvent";
  
! // Global\\ etc goodness:
! // On NT4/9x, 'Global\\' is not understood and will fail.
! // On 2k/XP, anyone can create 'global' objects.
! // On Vista, you need elavated perms to create global objects - however, once
! // it has been created and permissions adjusted, a user with normal 
! // permissions can open these global objects.
! // As a service generally will be able to create global objects, we want a 
! // non-elevated Python to be capable of automatically using the global space
! // if it exists, but coping when it can't create such an object (a local 
! // one is probably fine in such cases).
! // [Why bother?: without the Global namespace, a 'win32traceutil' running in 
! // a 'Remote Desktop' session would not be able to see output from a 
! // service - they have different local namespaces]
! 
! // This means:
! // * We first check to see if the mutex exists in the local namespace.  If it
! //   does, it we use that namespace for all objects.
! // * We then try and create a mutex in the global namespace - if this works, we also
! //   use the global namespace.
! // * We then create the mutex in our local namespace and use that for everything.
! // (Ack - the above is only true for CreateFileMapping - creating mutexes etc
! // works fine)
! 
! // This behavior is controlled by a global variable set at mutex creation time.
! BOOL use_global_namespace = FALSE;
! 
  static const char *FixupObjectName(const char *global_name)
  {
!     if (!use_global_namespace)
          return strchr(global_name, '\\')+1;
!     // global prefix is ok.
      return global_name;
  }
***************
*** 435,439 ****
      if (!ok)
  	return NULL;
-     // put the new object into sys
      Py_INCREF(Py_None);
      return Py_None;
--- 457,460 ----
***************
*** 448,452 ****
      if (!ok)
  	return NULL;
-     // put the new object into sys
      Py_INCREF(Py_None);
      return Py_None;
--- 469,472 ----
***************
*** 614,617 ****
--- 634,670 ----
  
      assert(hMutex == NULL);
+ 
+     // See comments re global namespace above - the problem child is 
+     // CreateFileMapping - so we temporarily use that just to work out what 
+     // namespace to use for our objects.
+ 
+     // is the "Global\" namespace even possible?
+     OSVERSIONINFO info;
+     info.dwOSVersionInfoSize = sizeof(info);
+     GetVersionEx(&info);
+     BOOL global_ok = info.dwMajorVersion > 4;
+     if (global_ok) {
+         // see comments at top of file - if it exists locally, stick with
+         // local - use_global_namespace is still FALSE now, so that is the 
+         // name we get.
+         HANDLE h = CreateFileMapping((HANDLE)-1, &sa, PAGE_READWRITE, 0, 
+                                      BUFFER_SIZE, 
+                                      FixupObjectName(MAP_OBJECT_NAME));
+         if (GetLastError() != ERROR_ALREADY_EXISTS) {
+             // no local one exists - see if we can create it globally - if
+             // we can, we go global, else we stick with local.
+             HANDLE h2 = CreateFileMapping((HANDLE)-1, &sa, PAGE_READWRITE,
+                                           0, BUFFER_SIZE,
+                                           FixupObjectName(MAP_OBJECT_NAME));
+             use_global_namespace = h2 != NULL && GetLastError() == ERROR_ACCESS_DENIED;
+             if (h2)
+                 CloseHandle(h2);
+         }
+         if (h)
+             CloseHandle(h);
+     }
+     // use_global_namespace is now set and will not change - all objects
+     // we use are in the same namespace.
+ 
      hMutex = CreateMutex(&sa, FALSE, FixupObjectName(MUTEX_OBJECT_NAME));
      if (hMutex==NULL) {