use libusb 1.0.27 as backend on linux

README.md

@@ -22,18 +22,9 @@ and go-gettable.
 Supported platforms at the moment are Linux, macOS and Windows (exclude constraints are also specified
 for Android and iOS to allow smoother vendoring into cross platform projects).
 
-## Dependencies 
-
-On linux, the 'libudev' package is required for building. 
-
-On Ubuntu:
-
-	apt install libudev-dev
-
-
-On Fedora:
-
-	dnf install systemd-devel
+The `hidapi` on linux unfortunately requires `libuddev` (`libudev-dev` on ubuntu, `systemd-devel` on fedora). Therefore, 
+this library includes [`libusb`](https://github.com/libusb/libusb) which we use as a backend on `linux`, and thus avoid 
+runtime dependencies.
 
 
 ## Cross-compiling
@@ -58,6 +49,7 @@ such, `gowchar` was also vendored in inline (copyright headers and origins prese
 The components of `hid` are licensed as such:
 
  * `hidapi` is released under the [three licenses](https://github.com/libusb/hidapi/blob/master/LICENSE.txt): [GPL-V3](https://github.com/libusb/hidapi/blob/master/LICENSE-gpl3.txt), [3-clause BSD](https://github.com/libusb/hidapi/blob/master/LICENSE-bsd.txt) and [original HIDAPI](https://github.com/libusb/hidapi/blob/master/LICENSE-orig.txt) license.
+ * `libusb` is released under [GPLv2.1](https://github.com/libusb/libusb/blob/master/COPYING)
  * `go.hid` was released under the [2-clause BSD](https://github.com/GeertJohan/go.hid/blob/master/LICENSE) license.
  * `gowchar` is released under the [3-clause BSD](https://github.com/orofarne/gowchar/blob/master/LICENSE) license.
 

appveyor.yml

@@ -17,13 +17,10 @@ install:
   - go version
 
 for:
-  # Linux has its own script without -arch and -cc.
-  # The linux builder also runs lint.
   - matrix:
       only:
         - image: Ubuntu
     build_script:
-      - sudo apt-get -qy --no-install-recommends install libudev-dev
       - gcc --version
       - go build ./...
       - CGO_ENABLED=0 go build ./...
@@ -33,12 +30,6 @@ for:
       - go test -v ./...
       - CGO_ENABLED=0 go test -v ./...
 
-  # linux/386 is disabled.
-  - matrix:
-      exclude:
-        - image: Ubuntu
-          GETH_ARCH: 386
-
   # Windows builds for amd64 + 386.
   - matrix:
       only:

hid_enabled.go

@@ -11,40 +11,54 @@
 package hid
 
 /*
-Linux uses the 'libudev' package.
-
-On Fedora:
-
-	dnf install systemd-devel
-
-On Ubuntu:
-
-	apt install libhidapi-dev
-
+Linux/hidapi requires the 'libudev' package. Fedora:`dnf install systemd-devel`, Ubuntu `apt install libhidapi-dev`.
+However, we prefer to not require libudev, which is why `libusb` is included, and enabled
+specifically for the linux platform, below.
 */
 
 /*
-
 #cgo CFLAGS: -I./hidapi/hidapi
 #cgo CFLAGS: -DDEFAULT_VISIBILITY=""
 #cgo CFLAGS: -DPOLL_NFDS_TYPE=int
 
-#cgo linux CFLAGS: -DOS_LINUX -D_GNU_SOURCE -DHAVE_SYS_TIME_H
-#cgo linux,!android LDFLAGS: -lrt -ludev
+#cgo linux CFLAGS: -I./libusb/libusb -DOS_LINUX -D_GNU_SOURCE -DHAVE_SYS_TIME_H -DHAVE_CLOCK_GETTIME
+#cgo linux,!android LDFLAGS: -lrt
+
 #cgo darwin CFLAGS: -DOS_DARWIN -DHAVE_SYS_TIME_H
 #cgo darwin LDFLAGS: -framework CoreFoundation -framework IOKit -lobjc
+
 #cgo windows CFLAGS: -DOS_WINDOWS
 #cgo windows LDFLAGS: -lsetupapi
+
 #cgo freebsd CFLAGS: -DOS_FREEBSD
 #cgo freebsd LDFLAGS: -lusb
+
 #cgo openbsd CFLAGS: -DOS_OPENBSD
 
 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(DOS_FREEBSD) || defined(OS_OPENBSD)
 	#include <poll.h>
 #endif
 
 #ifdef OS_LINUX
-	#include "hidapi/linux/hid.c"
+	#include "os/events_posix.h"
+	#include "os/threads_posix.h"
+
+	#include "os/events_posix.c"
+	#include "os/threads_posix.c"
+
+	#include "os/linux_usbfs.c"
+	#include "os/linux_netlink.c"
+
+	#include "core.c"
+	#include "descriptor.c"
+	#include "hotplug.c"
+
+	#include "io.c"
+	#include "strerror.c"
+	#include "sync.c"
+
+   #include "hidapi/libusb/hid.c"
+
 #elif OS_DARWIN
 	#include "hidapi/mac/hid.c"
 #elif OS_WINDOWS

hidapi/libusb/hid.c

@@ -20,7 +20,9 @@
         https://github.com/libusb/hidapi .
 ********************************************************/
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE /* needed for wcsdup() before glibc 2.10 */
+#endif
 
 /* C */
 #include <stdio.h>

libusb/dummy.go

@@ -0,0 +1,7 @@
+//go:build dummy
+
+// Package c contains only a C file.
+//
+// This Go file is part of a workaround for `go mod vendor`.
+// Please see the file dummy.go at the root of the module for more information.
+package libusb

libusb/libusb/config.h

@@ -0,0 +1,3 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+#endif