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device.go
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device.go
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package crawler
import (
"bufio"
"bytes"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"github.com/snapcore/snapd/osutil/udev/netlink"
)
const (
BASE_DEVPATH = "/sys/devices"
)
type Device struct {
KObj string
Env map[string]string
}
// ExistingDevices return all plugged devices matched by the matcher
// All uevent files inside /sys/devices is crawled to match right env values
func ExistingDevices(queue chan Device, errors chan error, matcher netlink.Matcher) chan struct{} {
quit := make(chan struct{}, 1)
if matcher != nil {
if err := matcher.Compile(); err != nil {
errors <- fmt.Errorf("Wrong matcher, err: %v", err)
quit <- struct{}{}
return quit
}
}
go func() {
err := filepath.Walk(BASE_DEVPATH, func(path string, info os.FileInfo, err error) error {
select {
case <-quit:
return fmt.Errorf("abort signal receive")
default:
if err != nil {
return err
}
if info.IsDir() || info.Name() != "uevent" {
return nil
}
env, err := getEventFromUEventFile(path)
if err != nil {
return err
}
kObj := filepath.Dir(path)
// Append to env subsystem if existing
if link, err := os.Readlink(kObj + "/subsystem"); err == nil {
env["SUBSYSTEM"] = filepath.Base(link)
}
if matcher == nil || matcher.EvaluateEnv(env) {
queue <- Device{
KObj: kObj,
Env: env,
}
}
return nil
}
})
if err != nil {
errors <- err
}
close(queue)
}()
return quit
}
// getEventFromUEventFile return all env var define in file
// syntax: name=value for each line
// Fonction use for /sys/.../uevent files
func getEventFromUEventFile(path string) (rv map[string]string, err error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
data, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
rv = make(map[string]string, 0)
buf := bufio.NewScanner(bytes.NewBuffer(data))
var line string
for buf.Scan() {
line = buf.Text()
field := strings.SplitN(line, "=", 2)
if len(field) != 2 {
return
}
rv[field[0]] = field[1]
}
return
}