libvirt/src/vbox
Daniel P. Berrange 707781fe12 Only add the timer when a callback is registered
The lifetime of the virDomainEventState object is tied to
the lifetime of the driver, which in stateless drivers is
tied to the lifetime of the virConnectPtr.

If we add & remove a timer when allocating/freeing the
virDomainEventState object, we can get a situation where
the timer still triggers once after virDomainEventState
has been freed. The timeout callback can't keep a ref
on the event state though, since that would be a circular
reference.

The trick is to only register the timer when a callback
is registered with the event state & remove the timer
when the callback is unregistered.

The demo for the bug is to run

  while true ; do date ; ../tools/virsh -q -c test:///default 'shutdown test; undefine test; dominfo test' ; done

prior to this fix, it will frequently hang and / or
crash, or corrupt memory
2011-12-19 11:08:25 +00:00
..
README integration of the VirtualBox support 2009-04-17 16:09:07 +00:00
vbox_CAPI_v2_2.h vbox: Handle different IID representation in Version 2.2 on Windows 2010-12-27 23:53:39 +01:00
vbox_CAPI_v3_0.h vbox: Match struct layout of the MSCOM implementation on Windows 2010-12-17 22:15:24 +01:00
vbox_CAPI_v3_1.h vbox: Match struct layout of the MSCOM implementation on Windows 2010-12-17 22:15:24 +01:00
vbox_CAPI_v3_2.h vbox: Match struct layout of the MSCOM implementation on Windows 2010-12-17 22:15:24 +01:00
vbox_CAPI_v4_0.h vbox: Add support for VirtualBox 4.0 2010-12-28 00:18:46 +01:00
vbox_CAPI_v4_1.h vbox: Add support for VirtualBox 4.1 2011-10-29 21:26:57 +02:00
vbox_driver.c vbox: Add support for VirtualBox 4.1 2011-10-29 21:26:57 +02:00
vbox_driver.h build: consistently indent preprocessor directives 2010-03-09 19:22:28 +01:00
vbox_glue.c vbox: Add glue layer for MSCOM on Windows 2010-12-17 22:51:33 +01:00
vbox_glue.h vbox: Add glue layer for MSCOM on Windows 2010-12-17 22:51:33 +01:00
vbox_MSCOMGlue.c util: choose whether to require micro in version strings 2011-07-01 11:22:11 -06:00
vbox_MSCOMGlue.h vbox: Add support for VirtualBox 4.0 2010-12-28 00:18:46 +01:00
vbox_tmpl.c Only add the timer when a callback is registered 2011-12-19 11:08:25 +00:00
vbox_V2_2.c integration of the VirtualBox support 2009-04-17 16:09:07 +00:00
vbox_V3_0.c Add support for VBox 3 and event callbacks on vbox 2009-07-24 18:12:16 +02:00
vbox_V3_1.c vbox: Add support for version 3.1 2009-12-04 14:49:45 +01:00
vbox_V3_2.c Support for VirtualBox version 3.2 2010-05-27 01:28:21 +02:00
vbox_V4_0.c vbox: Add support for VirtualBox 4.0 2010-12-28 00:18:46 +01:00
vbox_V4_1.c vbox: Add support for VirtualBox 4.1 2011-10-29 21:26:57 +02:00
vbox_XPCOMCGlue.c vbox: Fix typo in error message 2011-06-04 22:41:49 +02:00
vbox_XPCOMCGlue.h vbox: Add support for VirtualBox 4.0 2010-12-28 00:18:46 +01:00

    Explanation about the how multi-version support
    for VirtualBox libvirt driver is implemented.

Since VirtualBox adds multiple new features for each release, it is but
natural that the C API which VirtualBox exposes is volatile across
versions and thus needs a good mechanism to handle multiple versions
during runtime. The solution was something like this:

Firstly the file structure is as below:

vbox_CAPI_v2_2.h
vbox_XPCOMCGlue.h
vbox_XPCOMCGlue.c
These files are C API/glue code files directly taken from the
VirtualBox OSE source and is needed for C API to work as expected.

vbox_driver.h
vbox_driver.c
These files have the main logic for registering the virtualbox driver
with libvirt.

vbox_V2_2.c
The file which has version dependent changes and includes the template
file for given below for all of its functionality.

vbox_tmpl.c
The file where all the real driver implementation code exists.

Now there would be a vbox_V*.c file (for eg: vbox_V2_2.c for V2.2) for
each major virtualbox version which would do some preprocessor magic
and include the template file (vbox_tmpl.c) in it for the functionality
it offers.