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This is an automatically generated e-mail. To reply, visit:
http://codereview.secondlife.com/r/272/
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(Updated April 18, 2011, 6:04 a.m.)
Review request for Viewer.
Changes
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linking jira issue
Summary
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STORM-1088: bundled winmm.dll shim crashes on start-up on some systems.
This patch tests the theory that according to MSDN, calls to LoadLibrary,
GetProcAddress in DllMain are likely to create a race condition.
This addresses bug storm-1088.
http://jira.secondlife.com/browse/storm-1088
Diffs
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doc/contributions.txt f632f87bb71b
indra/media_plugins/winmmshim/forwarding_api.h f632f87bb71b
indra/media_plugins/winmmshim/forwarding_api.cpp f632f87bb71b
indra/media_plugins/winmmshim/winmm_shim.cpp f632f87bb71b
Diff: http://codereview.secondlife.com/r/272/diff
Testing
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winmm.dll from Second Life 2.6.3 (226640) Apr 14 2011 12:32:01 (Second Life
Beta Viewer) causes this viewer, and a number of prior versions, to crash at
startup for me.
winmm.dll built by me from viewer-development source code also does, tested
against the same viewer binary.
The version of winmm.dll with my patch, built by me and substituted into the
installed viewer, causes the above mentioned viewer to start up without issue
and function apparently properly - sound works (FMOD), media_plugin_webkit
works, voice is audible, windows_volume_catcher of llqtwebkit is functional.
Same applies to Second Life 2.6.3 (226792) Apr 17 2011 07:01:06 (Second Life
Developer), built by Oz Linden with a prior version of my patch.
media_plugin_quicktime functionality untested, voice capture untested.
The patch contains debug output, which causes the following messages in
debugger:
INFO: LLAudioEngine::init: LLAudioEngine::init() AudioEngine successfully
initialized
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\winmm.dll', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\myokent.dll', Cannot find
or open the PDB file
WINMM_SHIM.DLL: real winmm.dll initialized successfully
WINMM_SHIM.DLL: real winmm.dll initialized successfully
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Unloaded 'C:\WINXP\system32\wdmaud.drv'
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Unloaded 'C:\WINXP\system32\wdmaud.drv'
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Unloaded 'C:\WINXP\system32\wdmaud.drv'
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Unloaded 'C:\WINXP\system32\wdmaud.drv'
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Unloaded 'C:\WINXP\system32\wdmaud.drv'
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\wdmaud.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\msacm32.drv', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\midimap.dll', Cannot find
or open the PDB file
'SecondLifeBetaViewer.exe': Loaded 'C:\WINXP\system32\ksuser.dll', Cannot find
or open the PDB file
INFO: idle_startup: Audio Engine Initialized.
This is very puzzling to me, why the success message is being output twice.
Perhaps if the reason of that is found, the real reason for the failure of
failure of upstream winmm shim would become evident, or perhaps it's a bug in
my patch. I'd like everyone to check whether they see the same thing.
...
After some testing, it turns out myokent.dll (MIDI Yoke, a software loop-back
cable for musicians) seems to be the culprit on my system, causing a trivial
circular dependency, not a race condition. It tries to use a number of
winmm.dll functions (first of them being GetDriverModuleHandle) right from its
DllMain, which is invoked by LoadLibrary. Now it turns out, that if we try to
load real winmm.dll from DllMain, which in turn loads myokent.dll from its
DllMain, which in turn from its DllMain uses winmm.dll's functions, calling the
ones in OUR winmm.dll, which simply aren't initialized at that point yet
because we need LoadLibrary (and DllMains of used DLLs) to complete, then we
can populate the function pointers. My patch apparently sidesteps this trivial
problem, but this doesn't give an insight on why, on systems with UAC, for some
people, winmm.dll shim would cause a problem when run as a normal user, and not
cause a problem when run with admin rights.
Still, if we assume the other problems on affected systems are similar in
nature (circular dependency), then it appears we still need to move loading and
initialization outside of DllMain to resolve them. Scratch that, if the problem
is only this, it would be sufficient to first call LoadLibraryEx with
DONT_RESOLVE_DLL_REFERENCES, then call init_function_pointers, then have a
normal LoadLibrary call to kick off the rest of the chain.
Thanks,
Siana
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