From f3df7da4f93d56f579eb5826cf518d515a80840a Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <infinisil@icloud.com>
Date: Tue, 17 Oct 2017 18:55:57 +0200
Subject: [PATCH 1/2] usbmuxd service: init

---
 nixos/modules/module-list.nix               |  1 +
 nixos/modules/services/hardware/usbmuxd.nix | 25 +++++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 nixos/modules/services/hardware/usbmuxd.nix

diff --git a/nixos/modules/module-list.nix b/nixos/modules/module-list.nix
index a8cb957ffe21..16af3200a4be 100644
--- a/nixos/modules/module-list.nix
+++ b/nixos/modules/module-list.nix
@@ -237,6 +237,7 @@
   ./services/hardware/udev.nix
   ./services/hardware/udisks2.nix
   ./services/hardware/upower.nix
+  ./services/hardware/usbmuxd.nix
   ./services/hardware/thermald.nix
   ./services/logging/SystemdJournal2Gelf.nix
   ./services/logging/awstats.nix
diff --git a/nixos/modules/services/hardware/usbmuxd.nix b/nixos/modules/services/hardware/usbmuxd.nix
new file mode 100644
index 000000000000..4d7320953f07
--- /dev/null
+++ b/nixos/modules/services/hardware/usbmuxd.nix
@@ -0,0 +1,25 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  options.services.usbmuxd.enable = mkOption {
+    type = types.bool;
+    default = false;
+    description = ''
+      Enable the usbmuxd ("USB multiplexing daemon") service. This daemon is in
+      charge of multiplexing connections over USB to an iOS device. This is
+      needed for transferring data from and to iOS devices (see ifuse). Also
+      this may enable plug-n-play tethering for iPhones.
+    '';
+  };
+
+  config = mkIf config.services.usbmuxd.enable {
+    systemd.services.usbmuxd = {
+      description = "usbmuxd";
+      wantedBy = [ "multi-user.target" ];
+      unitConfig.Documentation = "man:usbmuxd(8)";
+      serviceConfig.ExecStart = "${pkgs.usbmuxd}/bin/usbmuxd -f";
+    };
+  };
+}

From 2d019b3de374f4888e3ca57ef262b4e8bcf35849 Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <infinisil@icloud.com>
Date: Wed, 18 Oct 2017 22:21:29 +0200
Subject: [PATCH 2/2] usbmuxd service: user and group options

---
 nixos/modules/services/hardware/usbmuxd.nix | 71 +++++++++++++++++----
 1 file changed, 60 insertions(+), 11 deletions(-)

diff --git a/nixos/modules/services/hardware/usbmuxd.nix b/nixos/modules/services/hardware/usbmuxd.nix
index 4d7320953f07..7ebd49fa01c2 100644
--- a/nixos/modules/services/hardware/usbmuxd.nix
+++ b/nixos/modules/services/hardware/usbmuxd.nix
@@ -2,24 +2,73 @@
 
 with lib;
 
+let
+
+  defaultUserGroup = "usbmux";
+  apple = "05ac";
+
+  cfg = config.services.usbmuxd;
+
+in
+
 {
-  options.services.usbmuxd.enable = mkOption {
-    type = types.bool;
-    default = false;
-    description = ''
-      Enable the usbmuxd ("USB multiplexing daemon") service. This daemon is in
-      charge of multiplexing connections over USB to an iOS device. This is
-      needed for transferring data from and to iOS devices (see ifuse). Also
-      this may enable plug-n-play tethering for iPhones.
-    '';
+  options.services.usbmuxd = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Enable the usbmuxd ("USB multiplexing daemon") service. This daemon is
+        in charge of multiplexing connections over USB to an iOS device. This is
+        needed for transferring data from and to iOS devices (see ifuse). Also
+        this may enable plug-n-play tethering for iPhones.
+      '';
+    };
+
+    user = mkOption {
+      type = types.str;
+      default = defaultUserGroup;
+      description = ''
+        The user usbmuxd should use to run after startup.
+      '';
+    };
+
+    group = mkOption {
+      type = types.str;
+      default = defaultUserGroup;
+      description = ''
+        The group usbmuxd should use to run after startup.
+      '';
+    };
   };
 
-  config = mkIf config.services.usbmuxd.enable {
+  config = mkIf cfg.enable {
+
+    users.extraUsers = optional (cfg.user == defaultUserGroup) {
+      name = cfg.user;
+      description = "usbmuxd user";
+      group = cfg.group;
+    };
+
+    users.extraGroups = optional (cfg.group == defaultUserGroup) {
+      name = cfg.group;
+    };
+
+    # Give usbmuxd permission for Apple devices
+    services.udev.extraRules = ''
+      SUBSYSTEM=="usb", ATTR{idVendor}=="${apple}", GROUP="${cfg.group}"
+    '';
+
     systemd.services.usbmuxd = {
       description = "usbmuxd";
       wantedBy = [ "multi-user.target" ];
       unitConfig.Documentation = "man:usbmuxd(8)";
-      serviceConfig.ExecStart = "${pkgs.usbmuxd}/bin/usbmuxd -f";
+      serviceConfig = {
+        # Trigger the udev rule manually. This doesn't require replugging the
+        # device when first enabling the option to get it to work
+        ExecStartPre = "${pkgs.libudev}/bin/udevadm trigger -s usb -a idVendor=${apple}";
+        ExecStart = "${pkgs.usbmuxd}/bin/usbmuxd -U ${cfg.user} -f";
+      };
     };
+
   };
 }