[libvirt] [PATCH] Win32 compatibility for 0.9.11
Hello everyone, I tried to build libvirt-0.9.11 for Windows using the MSYS Build Script provided by Matthias Bolte and noticed that there were two problems which made libvirt unusable. 1) Whenever a TCP Connection is opened, libvirt will fail with failed to set close-on-exec (Im using xen+tcp here). 2) The lib will crash most of the time, because it tries to access a null pointer. I fixed both issues with a little patch: 1) On Win32 platforms virSetInherit always returns -1, therefore failing any call which tries to set close-on-exec. I dont know if theres a Win32 equivalent of close-on-exec, so I just set this to return 0 instead. 2) Libvirt crashes, because TlsGetValue seems to return a NULL value sometimes. Not sure right now, if this is ok in a way or if it indicates another problem somewhere... (This might be the case, as Im experience crashes as soon as libvirt is used in a multithreading application, though I had this with an old version as well. Will discuss that in another mail). As this is my first mail to a mailing list, please dont hesitate to tell me, what I did wrong! By the way, should I attach the binaries for 0.9.11 in case anyone is looking for those without the need to compile them? Best Regards, Marcel
Am 7. April 2012 20:23 schrieb Marcel Müller <marcel-mueller@gmx.de>:
Hello everyone,
I tried to build libvirt-0.9.11 for Windows using the MSYS Build Script provided by Matthias Bolte and noticed that there were two problems which made libvirt unusable.
1) Whenever a TCP Connection is opened, libvirt will fail with “failed to set close-on-exec” (I’m using “xen+tcp” here).
2) The lib will crash most of the time, because it tries to access a null pointer.
I fixed both issues with a little patch:
1) On Win32 platforms virSetInherit always returns -1, therefore failing any call which tries to set “close-on-exec”. I don’t know if there’s a Win32 equivalent of “close-on-exec”, so I just set this to return 0 instead.
2) Libvirt crashes, because TlsGetValue seems to return a NULL value sometimes. Not sure right now, if this is ok in a way or if it indicates another problem somewhere... (This might be the case, as I’m experience crashes as soon as libvirt is used in a multithreading application, though I had this with an old version as well. Will discuss that in another mail).
Okay, I looked into the TlsGetValue problem and I can reproduce it. In my case it happened because virThreadIsSelf was called on the thread that was not create via virThreadCreate and has no data set in the TLS slot for the virThreadPtr. Because of this TlsGetValue returns NULL. In contrast the pthread version is safe because pthread_self works also on threads not created by virThreadCreate. But your fix for this is incomplete, you need to set virThreadPtr properly in all cases, including TlsGetValue returning NULL. I've posted an improved version: https://www.redhat.com/archives/libvir-list/2012-April/msg01206.html I didn't have time to look into the virSetInherit problem. -- Matthias Bolte http://photron.blogspot.com
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Marcel Müller -
Matthias Bolte