Re: [libvirt-users] Where does "cmd" initailize in qemu_command.c?
On 08/16/2012 10:52 AM, He Xin wrote:
In qemu_command.c, there is a function call "cmd =
virCommandNewArgList(emulator, "-S", NULL);", which initializes pointer
"cmd". However, I don't find the initial value of "cmd->args",
which
represents the input of virFindFileInPath in Util.c. Through
virFindFileInPath, one could find a requested executable file in the PATH
env to start specified hypervisors.
So could you please tell me what the value of args[0] is? Or where does
cmd->args initialize?
cmd->args is initialized by the constructor - in this case, you are
using the virCommandNewArgList constructor, so cmd->args[0] will be a
copy of your 'emulator' parameter. So, you merely need trace back up
the call stack to see where 'emulator' was first determined (hint: it
came from virDomainDefPtr def->emulator, which was populated during
virDomainDefParseXML to either match the explicit <emulator> tag in your
XML or fall back to the default stored in the virCapsPtr caps structure).
In qemu_driver.c, there is a function call "vm =
virDomainFindByUUID(&driver->domains, dom->uuid);", whose returned value
"vm" is important in the next functions. Then we could get the
"vm"'s value
in hash.c which is the end part to lookup domains saved in hashtable.
May I know where does HashTable initialize? I mean where can I set the
hashtable's values in detail, if I want to modify some values?
The &driver->domains hash table is manipulated via functions in
src/conf/domain_conf.c.
3.
This might be the same as question 1.
In command.c, "execve(cmd->args[0], cmd->args, cmd->env)" is
a way
to exec command. About qemu_driver, what is the value of those three inputs?
Yes, this is the same as question 1 - these values are determined by all
the calls to the virCommand* functions acting on the cmd structure.
Your questions seem to be more of a development nature about the libvirt
source code, and less of a user nature about how to use the API in using
the libvirt as a library in your own code. As such, you should probably
take future questions of this nature to libvir-lists(a)redhat.com.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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