115 lines
3.2 KiB
Go
115 lines
3.2 KiB
Go
// Copyright 2013 Google Inc. All rights reserved.
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// Copyright 2016 the gousb Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package gousb provides an low-level interface to attached USB devices.
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//
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// A Context represents a new
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package gousb
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// Context manages all resources related to USB device handling.
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type Context struct {
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ctx *libusbContext
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done chan struct{}
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}
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// Debug changes the debug level. Level 0 means no debug, higher levels
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// will print out more debugging information.
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func (c *Context) Debug(level int) {
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libusb.setDebug(c.ctx, level)
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}
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// NewContext returns a new Context instance.
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func NewContext() *Context {
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c, err := libusb.init()
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if err != nil {
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panic(err)
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}
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ctx := &Context{
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ctx: c,
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done: make(chan struct{}),
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}
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go libusb.handleEvents(ctx.ctx, ctx.done)
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return ctx
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}
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// ListDevices calls each with each enumerated device.
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// If the function returns true, the device is opened and a Device is returned if the operation succeeds.
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// Every Device returned (whether an error is also returned or not) must be closed.
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// If there are any errors enumerating the devices,
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// the final one is returned along with any successfully opened devices.
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func (c *Context) ListDevices(each func(desc *Descriptor) bool) ([]*Device, error) {
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list, err := libusb.getDevices(c.ctx)
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if err != nil {
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return nil, err
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}
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var reterr error
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var ret []*Device
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for _, dev := range list {
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desc, err := libusb.getDeviceDesc(dev)
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if err != nil {
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libusb.dereference(dev)
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reterr = err
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continue
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}
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if each(desc) {
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handle, err := libusb.open(dev)
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if err != nil {
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reterr = err
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continue
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}
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ret = append(ret, &Device{handle: handle, Descriptor: desc})
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} else {
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libusb.dereference(dev)
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}
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}
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return ret, reterr
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}
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// OpenDeviceWithVIDPID opens Device from specific VendorId and ProductId.
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// If none is found, it returns nil and nil error. If there are multiple devices
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// with the same VID/PID, it will return one of them, picked arbitrarily.
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// If there were any errors during device list traversal, it is possible
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// it will return a non-nil device and non-nil error. A Device.Close() must
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// be called to release the device if the returned device wasn't nil.
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func (c *Context) OpenDeviceWithVIDPID(vid, pid ID) (*Device, error) {
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var found bool
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devs, err := c.ListDevices(func(desc *Descriptor) bool {
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if found {
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return false
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}
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if desc.Vendor == ID(vid) && desc.Product == ID(pid) {
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found = true
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return true
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}
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return false
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})
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if len(devs) == 0 {
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return nil, err
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}
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return devs[0], nil
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}
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// Close releases the Context and all associated resources.
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func (c *Context) Close() error {
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c.done <- struct{}{}
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if c.ctx != nil {
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libusb.exit(c.ctx)
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}
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c.ctx = nil
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return nil
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}
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