feat(quickemu): add support for passing extra arguments to the SPICE viewer

docs/quickemu_conf.5.md

@@ -46,6 +46,7 @@ secureboot="off"
 tpm="off"
 usb_devices=()
 viewer="spicy"
+viewer_extra_args=""
 ssh_port=""
 spice_port=""
 public_dir=""
@@ -273,6 +274,18 @@ device selection*) support this feature.
 To ensure that this functionality works as expected, make sure that you
 have installed the necessary SPICE Guest Tools on the virtual machine.
 
+Automatic redirection of specific devices can be configured in the
+configuration file by setting the `viewer_extra_args` variable.
+
+For example (in the configuration file):
+
+    viewer_extra_args="--spice-usbredir-redirect-on-connect=-1,0x1234,0x5678,-1,1"
+
+Where `0x1234` and `0x5678` are example USB VID and PID, respectively.
+
+The string format is described at:
+<https://www.spice-space.org/usbredir.html#filter-string-format>.
+
 ##### Enabling SPICE redirection on NixOS
 
 On NixOS, if you encounter this error:

quickemu

@@ -2243,6 +2243,12 @@ function start_viewer {
         viewer_args+=("${viewer_uri}")
     fi
 
+    # Add extra arguments
+    if [ -n "${viewer_extra_args}" ]; then
+        # shellcheck disable=SC2206
+        viewer_args+=(${viewer_extra_args})
+    fi
+
     # Launch the viewer
     echo " - Viewer:   ${viewer} ${viewer_args[*]} >/dev/null 2>&1 &"
     "${viewer}" "${viewer_args[@]}" >/dev/null 2>&1 &
@@ -2550,6 +2556,7 @@ secureboot="off"
 tpm="off"
 usb_devices=()
 viewer="${viewer:-spicy}"
+viewer_extra_args="${viewer_extra_args:-}"
 width="${width:-}"
 height="${height:-}"
 ssh_port="${ssh_port:-}"