4:26 a.m.
Hi,
I am little confused about these api's such as
virConnCopyLastError and virCopyLastError. Please correct my
understanding.
1. virConnCopyLastError expects 2 parameter connection and virErrorPtr,
This is used only after getting successful connection, If i call this
without connection say it is NULL, I hope it will return -1 if no what
will it return?
2. virCopyLastError expects on 1 parameter virErrorPtr, this can be used
any time, even before getting connection, If it is No. Then when will i
use virCopyLastError api?
3. If virConnectOpen/virConnectOpenReadOnly fails which api should be
called to know the error code?
Thanks & Regards
--Ajish
6:49 a.m.
New subject: [Libvir] What is the Difference Between virConnCopyLastError and virCopyLastError?
On Thu, Apr 10, 2008 at 02:56:36PM +0530, ajishrao wrote:
Hi,
I am little confused about these api's such as
virConnCopyLastError and virCopyLastError. Please correct my
understanding.
1. virConnCopyLastError expects 2 parameter connection and virErrorPtr,
This is used only after getting successful connection, If i call this
without connection say it is NULL, I hope it will return -1 if no what
will it return?
yes, see the code
...
virConnCopyLastError(virConnectPtr conn, virErrorPtr to)
{
if (conn == NULL)
return (-1);
...
2. virCopyLastError expects on 1 parameter virErrorPtr, this can be
used
any time, even before getting connection, If it is No. Then when will i
use virCopyLastError api?
Also some errors may happen at a place where we don't have a connection
pointer handy to report them, in that case the data is still saved but in a
global variable. It's not just if a connection was successful or not.
3. If virConnectOpen/virConnectOpenReadOnly fails which api should
be
called to know the error code?
virCopyLastError
Note that you don't have to do things asynchronously like this, see
http://libvirt.org/html/libvirt-virterror.html#virSetErrorFunc
allowing to provide a callback called on error if no connection
is available and
http://libvirt.org/html/libvirt-virterror.html#virConnSetErrorFunc
to set such callback in a context with a connection
i have tried to detail all this in the documentation at
http://libvirt.org/errors.html
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
10:39 a.m.
New subject: [Libvir] What is the Difference Between virConnCopyLastError and virCopyLastError?
On Thu, Apr 10, 2008 at 02:56:36PM +0530, ajishrao wrote:
3. If virConnectOpen/virConnectOpenReadOnly fails which api should
be
called to know the error code?
You might find some example code useful. Look at the definition of
CHECK_ERROR macro, used here:
http://hg.et.redhat.com/applications/virt/applications/virt-top--devel?f=...
(eg line 63)
and defined here:
http://hg.et.redhat.com/applications/virt/applications/virt-top--devel?f=...
(line 45)
and the _raise_virterror function which gets the virterror defined
here:
http://hg.et.redhat.com/applications/virt/applications/virt-top--devel?f=...
(line 66)
errp = conn ? virConnGetLastError (conn) : virGetLastError ();
Note that actually copying the virterror may not be such a good idea.
The lifetime of that structure and the strings / pointers contained
within it is a little bit undefined, and the virCopy* functions don't
do a deep copy IIRC. So you should take copies of anything you need
yourself, and make sure you don't refer to the conn/dom/net structure
fields if you can possibly avoid it.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
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2 comments
3 participants
participants (3)
-
ajishrao -
Daniel Veillard -
Richard W.M. Jones