On 3/15/2011 3:07 PM, Christopher Faylor wrote: > On Tue, Mar 15, 2011 at 06:34:27PM +0000, Jon TURNEY wrote: >> >> I've come across a problem whilst trying to run the twisted test suite, where >> some tests just cause python to segfault. It seems to be the same issue with >> libcrypto as reported in [2],[3]
> Actually you aren't supposed to be able to call anything you like here and > it isn't clear why a POSIX/UNIX/Linux program would be relying on DllMain. There are cases where cygwin-ish code does win32-ish things, like login.exe, or the PyWin32 extensions for Python-on-Windows(and cygwin). Maybe twisty uses PyWin32? However, it does seem that python (or one of its extensions) is doing something it shouldn't. >From http://msdn.microsoft.com/en-us/library/ms682583%28v=vs.85%29.aspx > The entry-point function should perform only simple initialization > or termination tasks. It must not call the LoadLibrary or LoadLibraryEx > function (or a function that calls these functions), because this may > create dependency loops in the DLL load order. This can result in a DLL > being used before the system has executed its initialization code. > Similarly, the entry-point function must not call the FreeLibrary > function (or a function that calls FreeLibrary) during process > termination, because this can result in a DLL being used after the > system has executed its termination code. > > Because Kernel32.dll is guaranteed to be loaded in the process > space when the entry-point function is called, calling functions in > Kernel32.dll does not result in the DLL being used before its > initialization code has been executed. Therefore, the entry-point > function can call functions in Kernel32.dll that do not load other DLLs. > For example, DllMain can create synchronization objects such as critical > sections and mutexes, and use TLS. Unfortunately, there is not a > comprehensive list of safe functions in Kernel32.dll. > > Windows 2000: Do not create a named synchronization object in > DllMain because the system will then load an additional DLL. > > Calling functions that require DLLs other than Kernel32.dll may > result in problems that are difficult to diagnose. For example, > calling User, Shell, and COM functions can cause access violation > errors, because some functions load other system components. > Conversely, calling functions such as these during termination can > cause access violation errors because the corresponding component may > already have been unloaded or uninitialized. > > Because DLL notifications are serialized, entry-point functions > should not attempt to communicate with other threads or processes. > Deadlocks may occur as a result. -- Chuck -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
