spice: expose the QEMU disable file transfer option

spice-server offers an API to disable file transfer messages
on the agent channel between the client and the guest.
This is supported in qemu through the disable-agent-file-xfer option.

This patch exposes this option to libvirt.
Adds a new element 'filetransfer', with one property,
'enable', which accepts a boolean.
Default is enabled, for backward compatibility.

Depends on the capability exported in the first patch of the series.

Signed-off-by: Francesco Romani <fromani@redhat.com>

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice-agent-file-xfer.args

@@ -0,0 +1,9 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=spice \
+/usr/bin/qemu -S -M pc -m 214 -smp 1 -nodefaults -monitor \
+unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -hda \
+/dev/HostVG/QEMUGuest1 -spice port=5903,tls-port=5904,addr=127.0.0.1,\
+x509-dir=/etc/pki/libvirt-spice,tls-channel=main,plaintext-channel=inputs,\
+disable-agent-file-xfer -vga qxl -global qxl-vga.ram_size=67108864 \
+-global qxl-vga.vram_size=33554432 \
+-device qxl,id=video1,ram_size=67108864,vram_size=67108864,bus=pci.0,addr=0x4 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice-agent-file-xfer.xml

@@ -0,0 +1,40 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <graphics type='spice' port='5903' tlsPort='5904' autoport='no' listen='127.0.0.1'>
+      <listen type='address' address='127.0.0.1'/>
+      <channel name='main' mode='secure'/>
+      <channel name='inputs' mode='insecure'/>
+      <filetransfer enable='no'/>
+    </graphics>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' heads='1'/>
+    </video>
+    <video>
+      <model type='qxl' ram='65536' vram='65536' heads='1'/>
+    </video>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice.args

@@ -6,7 +6,8 @@ x509-dir=/etc/pki/libvirt-spice,tls-channel=default,tls-channel=main,\
 plaintext-channel=inputs,\
 image-compression=auto_glz,jpeg-wan-compression=auto,\
 zlib-glz-wan-compression=auto,\
-playback-compression=on,streaming-video=filter,disable-copy-paste -vga \
-qxl -global qxl.ram_size=67108864 -global qxl.vram_size=18874368 \
+playback-compression=on,streaming-video=filter,disable-copy-paste,\
+disable-agent-file-xfer -vga qxl -global qxl.ram_size=67108864 \
+-global qxl.vram_size=18874368 \
 -device qxl,id=video1,ram_size=67108864,vram_size=33554432,bus=pci.0,addr=0x4 \
 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice.xml

@@ -33,6 +33,7 @@
       <playback compression='on'/>
       <streaming mode='filter'/>
       <clipboard copypaste='no'/>
+      <filetransfer enable='no'/>
     </graphics>
     <video>
       <model type='qxl' ram='65536' vram='18432' heads='1'/>