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- // Copyright 2021 Jeffrey H. Johnson <trnsz@pobox.com>
- // Copyright 2018 psgo authors
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
- package dev
- import (
- "os"
- "strings"
- "syscall"
- )
- // TTY represents a tty including its minor and major device number and the
- // path to the tty.
- type TTY struct {
- // Minor device number.
- Minor uint64
- // Major device number.
- Major uint64
- // Path to the tty device.
- Path string
- }
- // FindTTY return the corresponding TTY to the ttyNr or nil of non could be
- // found.
- func FindTTY(ttyNr uint64, devices *[]TTY) (*TTY, error) {
- // (man 5 proc) The minor device number is contained in the combination
- // of bits 31 to 20 and 7 to 0; the major device number is in bits 15
- // to 8.
- maj := (ttyNr >> 8) & 0xFF
- min := (ttyNr & 0xFF) | ((ttyNr >> 20) & 0xFFF)
- if devices == nil {
- devs, err := TTYs()
- if err != nil {
- return nil, err
- }
- devices = devs
- }
- for _, t := range *devices {
- if t.Minor == min && t.Major == maj {
- return &t, nil
- }
- }
- return nil, nil
- }
- // majDevNum returns the major device number of rdev (see stat_t.Rdev).
- func majDevNum(rdev uint64) uint64 {
- return (rdev >> 8) & 0xFFF
- }
- // minDevNum returns the minor device number of rdev (see stat_t.Rdev).
- func minDevNum(rdev uint64) uint64 {
- return (rdev & 0xFF) | ((rdev >> 12) & 0xFFF00)
- }
- // TTYs parses /dev for tty and pts devices.
- func TTYs() (*[]TTY, error) {
- devDir, err := os.Open("/dev/")
- if err != nil {
- return nil, err
- }
- defer devDir.Close()
- devices := []string{}
- devTTYs, err := devDir.Readdirnames(0)
- if err != nil {
- return nil, err
- }
- for _, d := range devTTYs {
- if !strings.HasPrefix(d, "tty") {
- continue
- }
- devices = append(devices, "/dev/"+d)
- }
- devPTSDir, err := os.Open("/dev/pts/")
- if err != nil {
- return nil, err
- }
- defer devPTSDir.Close()
- devPTSs, err := devPTSDir.Readdirnames(0)
- if err != nil {
- return nil, err
- }
- for _, d := range devPTSs {
- devices = append(devices, "/dev/pts/"+d)
- }
- ttys := []TTY{}
- for _, dev := range devices {
- fi, err := os.Stat(dev)
- if err != nil {
- if os.IsNotExist(err) {
- // catch race conditions
- continue
- }
- return nil, err
- }
- s := fi.Sys().(*syscall.Stat_t)
- t := TTY{
- // Rdev is type uint32 on mips arch so we have to cast to uint64
- Minor: minDevNum(uint64(s.Rdev)),
- Major: majDevNum(uint64(s.Rdev)),
- Path: dev,
- }
- ttys = append(ttys, t)
- }
- return &ttys, nil
- }
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