request-usb: init; ugly helper for attaching usb to crosvm

pkgs/request-usb/package.nix

@@ -0,0 +1,63 @@
+{ writeShellScriptBin }:
+
+writeShellScriptBin "request-usb" ''
+  set -euo pipefail
+
+  parseArgs() {
+    N_CONSTRAINTS=0
+    while [[ -n "''${1:-}" ]]; do
+        local x=
+        case "$1" in
+          "--manufacturer" )
+              N_CONSTRAINTS=$(( $N_CONSTRAINTS + 1 ))
+              MANUFACTURER="$2"
+              shift 2
+              ;;
+          "--manufacturer="* )
+              N_CONSTRAINTS=$(( $N_CONSTRAINTS + 1 ))
+              MANUFACTURER=''${1#--manufacturer=}
+              shift 1
+              ;;
+          "--" )
+              break
+              ;;
+          *)
+              printUsage
+              ;;
+        esac
+    done
+  }
+  printUsage() {
+      echo "$(caller)" >&2
+      echo "Usage: request-usb [--manufacturer=MANUFACTURER]" >&2
+      exit 1
+  }
+
+  findFirst() {
+    local d=
+
+    [[ ''${N_CONSTRAINTS:-0} != 0 ]] || printUsage
+    for d in /sys/bus/usb/devices/* ; do
+        [[ -e "$d/manufacturer" ]] || continue
+        [[ -e "$d/uevent" ]] || continue
+
+        read -r x < "$d/manufacturer"
+        if ! [[ -z "''${MANUFACTURER:-}" || "$MANUFACTURER" =  "$x" ]] ; then
+            continue
+        fi
+
+        # NOTE: Other predicates here
+        # ...
+
+        echo -n "$d"
+        return
+    done
+    return 1
+  }
+
+  parseArgs $@
+  d=$(findFirst)
+  export $( cat "$d/uevent" )
+  sudo chown "$USER" /dev/bus/usb/"$BUSNUM"/"$DEVNUM"
+  echo -n /dev/bus/usb/"$BUSNUM"/"$DEVNUM"
+''