From a0352a2accc31efdcc1a9693f6adf761bd635fe0 Mon Sep 17 00:00:00 2001
From: Jeremy Mickelson <jeremy.mickelson@gmail.com>
Date: Sun, 3 Jan 2021 00:07:31 -0800
Subject: [PATCH 1/2] support sending a serial number to hid_open, requires
 support for writing wide strings

---
 hid_api.gemspec            |  1 +
 lib/hid_api.rb             |  7 ++-----
 lib/hid_api/device.rb      | 15 ++++++--------
 lib/hid_api/device_info.rb |  2 +-
 lib/hid_api/util/wchar.rb  | 40 --------------------------------------
 lib/hid_api/wide_string.rb |  7 ++++++-
 6 files changed, 16 insertions(+), 56 deletions(-)
 delete mode 100644 lib/hid_api/util/wchar.rb

diff --git a/hid_api.gemspec b/hid_api.gemspec
index 9cce1d8..b88d5cd 100644
--- a/hid_api.gemspec
+++ b/hid_api.gemspec
@@ -22,6 +22,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency "ffi", "~> 1.9"
+  spec.add_dependency "ffi_wide_char", "~> 1.1"
 
   spec.add_development_dependency "bundler", "~> 1.8"
   spec.add_development_dependency "rake", "~> 10.0"
diff --git a/lib/hid_api.rb b/lib/hid_api.rb
index 5196746..47ecc8e 100644
--- a/lib/hid_api.rb
+++ b/lib/hid_api.rb
@@ -19,7 +19,7 @@ class HidError < StandardError; end
   typedef Device, :device
   typedef :int, :vendor_id
   typedef :int, :product_id
-  typedef :int, :serial_number
+  typedef WideString, :serial_number
   typedef :int, :length
   typedef :int, :timeout
 
@@ -49,7 +49,7 @@ class << self
     alias enumerate hid_enumerate
     alias free_enumeration hid_free_enumeration
     def open(vendor_id, product_id, serial_number = nil)
-      device = hid_open(vendor_id, product_id, serial_number || 0)
+      device = hid_open(vendor_id, product_id, serial_number)
       if device.null?
         error = format(
           "Unable to open %s",
@@ -67,6 +67,3 @@ def open_path(path)
     end
   end
 end
-
-# Attempts to extend some core FFI classes with platform-aware string-handling
-FFI::AbstractMemory.include(HidApi::Util::WCHAR)
diff --git a/lib/hid_api/device.rb b/lib/hid_api/device.rb
index 90a09a5..698ff54 100644
--- a/lib/hid_api/device.rb
+++ b/lib/hid_api/device.rb
@@ -38,7 +38,7 @@ def serial_number_string
     def read(length)
       buffer = clear_buffer length
       with_hid_error_handling do
-        HidApi.hid_read self, buffer, buffer.length
+        HidApi.hid_read self, buffer, buffer.size
       end
       buffer
     end
@@ -46,7 +46,7 @@ def read(length)
     def read_timeout(length, timeout)
       buffer = clear_buffer length
       with_hid_error_handling do
-        HidApi.hid_read_timeout self, buffer, buffer.length, timeout
+        HidApi.hid_read_timeout self, buffer, buffer.size, timeout
       end
       buffer
     end
@@ -59,7 +59,7 @@ def write(data)
       end
 
       with_hid_error_handling do
-        HidApi.hid_write self, buffer, buffer.length
+        HidApi.hid_write self, buffer, buffer.size
       end
     end
 
@@ -80,16 +80,13 @@ def error
     private
 
     def clear_buffer(length)
-      b = FFI::Buffer.new(1, length)
-      # FFI::Buffer doesn't clear the first byte if length < 8
-      b.put_char 0, 0
-      b
+      return FFI::MemoryPointer.new(:char, length)
     end
 
     def get_buffered_string(field)
       buffer = clear_buffer 255
-      HidApi.send "hid_get_#{field}_string", self, buffer, buffer.length
-      buffer.read_wchar_string
+      HidApi.send "hid_get_#{field}_string", self, buffer, buffer.size
+      FfiWideChar.read_wide_string buffer
     end
 
     def with_hid_error_handling
diff --git a/lib/hid_api/device_info.rb b/lib/hid_api/device_info.rb
index 0206ce0..68eb1fa 100644
--- a/lib/hid_api/device_info.rb
+++ b/lib/hid_api/device_info.rb
@@ -28,7 +28,7 @@ def self.release(pointer)
             :next,                DeviceInfo.auto_ptr # struct hid_device_info * next
 
     # Makes the struct members available as methods
-    layout.members.each do |f|
+    members.each do |f|
       define_method(f) do
         self[f]
       end
diff --git a/lib/hid_api/util/wchar.rb b/lib/hid_api/util/wchar.rb
deleted file mode 100644
index 51415f9..0000000
--- a/lib/hid_api/util/wchar.rb
+++ /dev/null
@@ -1,40 +0,0 @@
-module HidApi
-  module Util
-    # A utility module that provides simple (maybe naive) platform-dependent
-    # support for wide characters
-    module WCHAR
-      WCHAR_T_WIDTH = ::RUBY_PLATFORM =~ /mswin/i ? 2 : 4
-
-      # Maps a WCHAR_T_WIDTH to the corresponding Array#pack character width
-      FORMATS = {
-        2 => "S",
-        4 => "L"
-      }.freeze
-
-      # The platform-specific Array#pack format for wide characters
-      FORMAT = FORMATS[WCHAR_T_WIDTH].freeze
-
-      # Maps a WCHAR_T_WIDTH to the corresponding string encoding
-      ENCODINGS = {
-        2 => "utf-16le",
-        4 => "utf-32le"
-      }.freeze
-
-      # The platform-specific String encoding that can handle wide characters
-      ENCODING = ENCODINGS[WCHAR_T_WIDTH].freeze
-
-      def read_wchar_string(_max_chars = nil)
-        buffer = []
-        offset = 0
-        loop do
-          pointer = self + (offset * WCHAR_T_WIDTH)
-          char = pointer.send("read_uint#{WCHAR_T_WIDTH * 8}")
-          break if char.zero?
-          buffer << char
-          offset += 1
-        end
-        buffer.pack("#{FORMAT}*").force_encoding(ENCODING).encode("utf-8")
-      end
-    end
-  end
-end
diff --git a/lib/hid_api/wide_string.rb b/lib/hid_api/wide_string.rb
index d7739b8..b8c0016 100644
--- a/lib/hid_api/wide_string.rb
+++ b/lib/hid_api/wide_string.rb
@@ -1,4 +1,5 @@
 require "ffi"
+require 'ffi_wide_char'
 
 module HidApi
   # An FFI data converter that marshalls data from specific device fields via
@@ -10,7 +11,11 @@ class WideString
     class << self
       def from_native(value, _context)
         return nil if value.null?
-        value.read_wchar_string
+        FfiWideChar.read_wide_string value
+      end
+
+      def to_native(value, _ctx)
+        FfiWideChar.to_wide_string value
       end
     end
   end

From a6147baceef520f3e22ef4402c14f2a7e1b86790 Mon Sep 17 00:00:00 2001
From: Jeremy Mickelson <jeremy.mickelson@gmail.com>
Date: Sun, 3 Jan 2021 01:23:55 -0800
Subject: [PATCH 2/2] re-encode wide string to utf-8 before returning

---
 lib/hid_api/device.rb      | 2 +-
 lib/hid_api/util.rb        | 5 -----
 lib/hid_api/wide_string.rb | 6 +++---
 3 files changed, 4 insertions(+), 9 deletions(-)
 delete mode 100644 lib/hid_api/util.rb

diff --git a/lib/hid_api/device.rb b/lib/hid_api/device.rb
index 698ff54..e17e669 100644
--- a/lib/hid_api/device.rb
+++ b/lib/hid_api/device.rb
@@ -86,7 +86,7 @@ def clear_buffer(length)
     def get_buffered_string(field)
       buffer = clear_buffer 255
       HidApi.send "hid_get_#{field}_string", self, buffer, buffer.size
-      FfiWideChar.read_wide_string buffer
+      WideString.from_native(buffer)
     end
 
     def with_hid_error_handling
diff --git a/lib/hid_api/util.rb b/lib/hid_api/util.rb
deleted file mode 100644
index 8ac764c..0000000
--- a/lib/hid_api/util.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-module HidApi
-  module Util # :nodoc:
-    autoload :WCHAR, "hid_api/util/wchar"
-  end
-end
diff --git a/lib/hid_api/wide_string.rb b/lib/hid_api/wide_string.rb
index b8c0016..7a8f148 100644
--- a/lib/hid_api/wide_string.rb
+++ b/lib/hid_api/wide_string.rb
@@ -9,12 +9,12 @@ class WideString
     native_type FFI::Type::POINTER
 
     class << self
-      def from_native(value, _context)
+      def from_native(value, _ctx = nil)
         return nil if value.null?
-        FfiWideChar.read_wide_string value
+        FfiWideChar.read_wide_string(value).encode('utf-8')
       end
 
-      def to_native(value, _ctx)
+      def to_native(value, _ctx = nil)
         FfiWideChar.to_wide_string value
       end
     end