[libvirt] QEMU/KVM auto-detection bug

All, Even with Guido/Pritesh's recent changes to the vbox open routine, the auto-detection in libvirt is currently broken. What happens is that in src/libvirt.c:do_open(), at the start of the loop to auto-detect drivers, ret->uri is NULL. As each driver declines, it remains NULL. However, the very first thing the vboxOpen() routine does is: if (conn->uri == NULL) { conn->uri = xmlParseURI(uid ? "vbox:///session" : "vbox:///system"); if (conn->uri == NULL) { return VIR_DRV_OPEN_ERROR; } So, any driver that is trying to auto-probe after vboxOpen sees a conn->uri with a scheme of vbox and a path of system/session, and they all fail (including Qemu, which is what I'm mostly concerned with at the moment). In point of fact, this whole auto-detection thing is fragile. We got away with it before because the qemuOpen() routine bombs out before doing the whole conn->uri == NULL check, but in general, it's very easy for one buggy driver to mess up auto-detection for all drivers. Any thoughts about where to go here? We should obviously fix the vboxOpen() routine to not mess with the URI if it's going to fail. Additionally, I was thinking that maybe we should reset conn->uri to NULL in each iteration of the auto-detection loop. While that might leak memory for buggy drivers, it should at least make this whole thing less fragile. Thoughts? -- Chris Lalancette