liulong
070b7685d5
1. 优化了Close方法的资源释放顺序，先释放独占访问权，再关闭实际的端口句柄 2. 添加了句柄有效性检查，避免对无效句柄进行操作 3. 确保所有资源都能正确清理，包括句柄和信号管道 4. 改进了错误处理机制，确保只返回第一个错误 5. 为所有方法添加了端口状态检查，确保在端口关闭后立即返回PortClosed错误 6. 统一了错误处理格式，使用PortError类型包装系统错误 7. 优化了Read方法的错误处理和超时逻辑 8. 为Write、Break、SetMode、SetDTR、SetRTS和GetModemStatusBits方法添加了端口状态检查
545 lines
14 KiB
Go
545 lines
14 KiB
Go
//
|
||
// Copyright 2014-2024 Cristian Maglie. All rights reserved.
|
||
// Use of this source code is governed by a BSD-style
|
||
// license that can be found in the LICENSE file.
|
||
//
|
||
|
||
//go:build linux || darwin || freebsd || openbsd
|
||
|
||
package serial
|
||
|
||
import (
|
||
"fmt"
|
||
"os"
|
||
"strings"
|
||
"sync"
|
||
"sync/atomic"
|
||
"time"
|
||
|
||
"go.bug.st/serial/unixutils"
|
||
"golang.org/x/sys/unix"
|
||
)
|
||
|
||
type unixPort struct {
|
||
handle int
|
||
|
||
readTimeout time.Duration
|
||
closeLock sync.RWMutex
|
||
closeSignal *unixutils.Pipe
|
||
opened uint32
|
||
}
|
||
|
||
func (port *unixPort) Close() error {
|
||
// 原子操作检查并设置端口关闭状态
|
||
if !atomic.CompareAndSwapUint32(&port.opened, 1, 0) {
|
||
return nil // 端口已经关闭，直接返回
|
||
}
|
||
|
||
var firstErr error
|
||
|
||
// 发送关闭信号以取消所有待处理的读操作
|
||
if port.closeSignal != nil {
|
||
if _, err := port.closeSignal.Write([]byte{0}); err != nil && firstErr == nil {
|
||
firstErr = err
|
||
}
|
||
}
|
||
|
||
// 检查句柄是否有效，然后执行关闭操作
|
||
if port.handle != -1 {
|
||
// 释放独占访问权 - 应在关闭handle之前完成
|
||
if err := port.releaseExclusiveAccess(); err != nil && firstErr == nil {
|
||
firstErr = err
|
||
}
|
||
|
||
// 关闭实际的端口句柄 - 这将解除任何挂起的读写操作
|
||
if err := unix.Close(port.handle); err != nil && firstErr == nil {
|
||
firstErr = err
|
||
}
|
||
|
||
port.handle = -1 // 标记句柄无效
|
||
}
|
||
|
||
// 关闭信号管道
|
||
if port.closeSignal != nil {
|
||
if err := port.closeSignal.Close(); err != nil && firstErr == nil {
|
||
firstErr = err
|
||
}
|
||
port.closeSignal = nil // 清除指针
|
||
}
|
||
|
||
return firstErr
|
||
}
|
||
|
||
func (port *unixPort) Read(p []byte) (int, error) {
|
||
// 首先检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
|
||
var deadline time.Time
|
||
if port.readTimeout != NoTimeout {
|
||
deadline = time.Now().Add(port.readTimeout)
|
||
}
|
||
|
||
fds := unixutils.NewFDSet(port.handle, port.closeSignal.ReadFD())
|
||
for {
|
||
// 在每次select之前再次检查端口状态（非阻塞检查）
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
|
||
timeout := time.Duration(-1)
|
||
if port.readTimeout != NoTimeout {
|
||
timeout = time.Until(deadline)
|
||
if timeout < 0 {
|
||
// 负超时值在Select(...)中表示"无超时"
|
||
timeout = 0
|
||
}
|
||
}
|
||
|
||
res, err := unixutils.Select(fds, nil, fds, timeout)
|
||
if err == unix.EINTR {
|
||
continue // 系统调用被中断，重试
|
||
}
|
||
if err != nil {
|
||
// 如果在端口关闭后遇到错误，返回PortClosed错误
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
return 0, &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
|
||
if res.IsReadable(port.closeSignal.ReadFD()) {
|
||
// 收到关闭信号
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
|
||
if !res.IsReadable(port.handle) {
|
||
// 超时
|
||
if port.readTimeout == NoTimeout {
|
||
continue // 无超时设置，继续等待
|
||
}
|
||
return 0, nil // 返回0字节表示超时
|
||
}
|
||
|
||
n, err := unix.Read(port.handle, p)
|
||
if err == unix.EINTR {
|
||
continue // 系统调用被中断，重试
|
||
}
|
||
// Linux系统特性：当读取操作期间端口断开连接时，
|
||
// 端口会进入"可读但返回零长度数据"的状态。
|
||
// https://stackoverflow.com/a/34945814/1655275
|
||
if n == 0 && err == nil {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
if n < 0 { // 确保不返回负数
|
||
n = 0
|
||
}
|
||
// 检查读取操作期间端口是否被关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
if err != nil {
|
||
return n, &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
return n, nil
|
||
}
|
||
}
|
||
|
||
func (port *unixPort) Write(p []byte) (n int, err error) {
|
||
// 首先检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return 0, &PortError{code: PortClosed}
|
||
}
|
||
|
||
n, err = unix.Write(port.handle, p)
|
||
if n < 0 { // 确保不返回负数
|
||
n = 0
|
||
}
|
||
if err != nil {
|
||
return n, &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
return n, nil
|
||
}
|
||
|
||
func (port *unixPort) Break(t time.Duration) error {
|
||
// 检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return &PortError{code: PortClosed}
|
||
}
|
||
|
||
if err := unix.IoctlSetInt(port.handle, ioctlTiocsbrk, 0); err != nil {
|
||
return &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
|
||
time.Sleep(t)
|
||
|
||
if err := unix.IoctlSetInt(port.handle, ioctlTioccbrk, 0); err != nil {
|
||
return &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
|
||
return nil
|
||
}
|
||
|
||
func (port *unixPort) SetMode(mode *Mode) error {
|
||
// 检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return &PortError{code: PortClosed}
|
||
}
|
||
|
||
settings, err := port.getTermSettings()
|
||
if err != nil {
|
||
return &PortError{code: InvalidSerialPort, causedBy: err}
|
||
}
|
||
|
||
if err := setTermSettingsParity(mode.Parity, settings); err != nil {
|
||
return err
|
||
}
|
||
|
||
if err := setTermSettingsDataBits(mode.DataBits, settings); err != nil {
|
||
return err
|
||
}
|
||
|
||
if err := setTermSettingsStopBits(mode.StopBits, settings); err != nil {
|
||
return err
|
||
}
|
||
|
||
requireSpecialBaudrate := false
|
||
if err, special := setTermSettingsBaudrate(mode.BaudRate, settings); err != nil {
|
||
return err
|
||
} else if special {
|
||
requireSpecialBaudrate = true
|
||
}
|
||
|
||
if err := port.setTermSettings(settings); err != nil {
|
||
return &PortError{code: InvalidSerialPort, causedBy: err}
|
||
}
|
||
|
||
if requireSpecialBaudrate {
|
||
// MacOSX要求这是最后一个操作，否则会产生'Invalid serial port'错误
|
||
if err := port.setSpecialBaudrate(uint32(mode.BaudRate)); err != nil {
|
||
return &PortError{code: InvalidSpeed, causedBy: err}
|
||
}
|
||
}
|
||
|
||
return nil
|
||
}
|
||
|
||
func (port *unixPort) SetDTR(dtr bool) error {
|
||
// 检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return &PortError{code: PortClosed}
|
||
}
|
||
|
||
status, err := port.getModemBitsStatus()
|
||
if err != nil {
|
||
return &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
if dtr {
|
||
status |= unix.TIOCM_DTR
|
||
} else {
|
||
status &^= unix.TIOCM_DTR
|
||
}
|
||
return port.setModemBitsStatus(status)
|
||
}
|
||
|
||
func (port *unixPort) SetRTS(rts bool) error {
|
||
// 检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return &PortError{code: PortClosed}
|
||
}
|
||
|
||
status, err := port.getModemBitsStatus()
|
||
if err != nil {
|
||
return &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
if rts {
|
||
status |= unix.TIOCM_RTS
|
||
} else {
|
||
status &^= unix.TIOCM_RTS
|
||
}
|
||
return port.setModemBitsStatus(status)
|
||
}
|
||
|
||
func (port *unixPort) SetReadTimeout(timeout time.Duration) error {
|
||
if timeout < 0 && timeout != NoTimeout {
|
||
return &PortError{code: InvalidTimeoutValue}
|
||
}
|
||
port.readTimeout = timeout
|
||
return nil
|
||
}
|
||
|
||
func (port *unixPort) GetModemStatusBits() (*ModemStatusBits, error) {
|
||
// 检查端口是否已经关闭
|
||
if atomic.LoadUint32(&port.opened) != 1 {
|
||
return nil, &PortError{code: PortClosed}
|
||
}
|
||
|
||
status, err := port.getModemBitsStatus()
|
||
if err != nil {
|
||
return nil, &PortError{code: FunctionNotImplemented, causedBy: err}
|
||
}
|
||
|
||
return &ModemStatusBits{
|
||
CTS: (status & unix.TIOCM_CTS) != 0,
|
||
DCD: (status & unix.TIOCM_CD) != 0,
|
||
DSR: (status & unix.TIOCM_DSR) != 0,
|
||
RI: (status & unix.TIOCM_RI) != 0,
|
||
}, nil
|
||
}
|
||
|
||
func nativeOpen(portName string, mode *Mode) (*unixPort, error) {
|
||
h, err := unix.Open(portName, unix.O_RDWR|unix.O_NOCTTY|unix.O_NDELAY, 0)
|
||
if err != nil {
|
||
switch err {
|
||
case unix.EBUSY:
|
||
return nil, &PortError{code: PortBusy}
|
||
case unix.EACCES:
|
||
return nil, &PortError{code: PermissionDenied}
|
||
}
|
||
return nil, err
|
||
}
|
||
port := &unixPort{
|
||
handle: h,
|
||
opened: 1,
|
||
readTimeout: NoTimeout,
|
||
}
|
||
|
||
// Setup serial port
|
||
settings, err := port.getTermSettings()
|
||
if err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error getting term settings: %w", err)}
|
||
}
|
||
|
||
// Set raw mode
|
||
setRawMode(settings)
|
||
|
||
// Explicitly disable RTS/CTS flow control
|
||
setTermSettingsCtsRts(false, settings)
|
||
|
||
if err = port.setTermSettings(settings); err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error setting term settings: %w", err)}
|
||
}
|
||
|
||
if mode.InitialStatusBits != nil {
|
||
status, err := port.getModemBitsStatus()
|
||
if err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error getting modem bits status: %w", err)}
|
||
}
|
||
if mode.InitialStatusBits.DTR {
|
||
status |= unix.TIOCM_DTR
|
||
} else {
|
||
status &^= unix.TIOCM_DTR
|
||
}
|
||
if mode.InitialStatusBits.RTS {
|
||
status |= unix.TIOCM_RTS
|
||
} else {
|
||
status &^= unix.TIOCM_RTS
|
||
}
|
||
if err := port.setModemBitsStatus(status); err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error setting modem bits status: %w", err)}
|
||
}
|
||
}
|
||
|
||
// MacOSX require that this operation is the last one otherwise an
|
||
// 'Invalid serial port' error is returned... don't know why...
|
||
if err := port.SetMode(mode); err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error configuring port: %w", err)}
|
||
}
|
||
|
||
unix.SetNonblock(h, false)
|
||
|
||
port.acquireExclusiveAccess()
|
||
|
||
// This pipe is used as a signal to cancel blocking Read
|
||
pipe := &unixutils.Pipe{}
|
||
if err := pipe.Open(); err != nil {
|
||
port.Close()
|
||
return nil, &PortError{code: InvalidSerialPort, causedBy: fmt.Errorf("error opening signaling pipe: %w", err)}
|
||
}
|
||
port.closeSignal = pipe
|
||
|
||
return port, nil
|
||
}
|
||
|
||
func nativeGetPortsList() ([]string, error) {
|
||
files, err := os.ReadDir(devFolder)
|
||
if err != nil {
|
||
return nil, err
|
||
}
|
||
|
||
ports := make([]string, 0, len(files))
|
||
for _, f := range files {
|
||
// Skip folders
|
||
if f.IsDir() {
|
||
continue
|
||
}
|
||
|
||
// Keep only devices with the correct name
|
||
if !osPortFilter.MatchString(f.Name()) {
|
||
continue
|
||
}
|
||
|
||
portName := devFolder + "/" + f.Name()
|
||
|
||
// Check if serial port is real or is a placeholder serial port "ttySxx" or "ttyHSxx"
|
||
if strings.HasPrefix(f.Name(), "ttyS") || strings.HasPrefix(f.Name(), "ttyHS") {
|
||
port, err := nativeOpen(portName, &Mode{})
|
||
if err != nil {
|
||
continue
|
||
} else {
|
||
port.Close()
|
||
}
|
||
}
|
||
|
||
// Save serial port in the resulting list
|
||
ports = append(ports, portName)
|
||
}
|
||
|
||
return ports, nil
|
||
}
|
||
|
||
// termios manipulation functions
|
||
|
||
func setTermSettingsParity(parity Parity, settings *unix.Termios) error {
|
||
switch parity {
|
||
case NoParity:
|
||
settings.Cflag &^= unix.PARENB
|
||
settings.Cflag &^= unix.PARODD
|
||
settings.Cflag &^= tcCMSPAR
|
||
settings.Iflag &^= unix.INPCK
|
||
case OddParity:
|
||
settings.Cflag |= unix.PARENB
|
||
settings.Cflag |= unix.PARODD
|
||
settings.Cflag &^= tcCMSPAR
|
||
settings.Iflag |= unix.INPCK
|
||
case EvenParity:
|
||
settings.Cflag |= unix.PARENB
|
||
settings.Cflag &^= unix.PARODD
|
||
settings.Cflag &^= tcCMSPAR
|
||
settings.Iflag |= unix.INPCK
|
||
case MarkParity:
|
||
if tcCMSPAR == 0 {
|
||
return &PortError{code: InvalidParity}
|
||
}
|
||
settings.Cflag |= unix.PARENB
|
||
settings.Cflag |= unix.PARODD
|
||
settings.Cflag |= tcCMSPAR
|
||
settings.Iflag |= unix.INPCK
|
||
case SpaceParity:
|
||
if tcCMSPAR == 0 {
|
||
return &PortError{code: InvalidParity}
|
||
}
|
||
settings.Cflag |= unix.PARENB
|
||
settings.Cflag &^= unix.PARODD
|
||
settings.Cflag |= tcCMSPAR
|
||
settings.Iflag |= unix.INPCK
|
||
default:
|
||
return &PortError{code: InvalidParity}
|
||
}
|
||
return nil
|
||
}
|
||
|
||
func setTermSettingsDataBits(bits int, settings *unix.Termios) error {
|
||
databits, ok := databitsMap[bits]
|
||
if !ok {
|
||
return &PortError{code: InvalidDataBits}
|
||
}
|
||
// Remove previous databits setting
|
||
settings.Cflag &^= unix.CSIZE
|
||
// Set requested databits
|
||
settings.Cflag |= databits
|
||
return nil
|
||
}
|
||
|
||
func setTermSettingsStopBits(bits StopBits, settings *unix.Termios) error {
|
||
switch bits {
|
||
case OneStopBit:
|
||
settings.Cflag &^= unix.CSTOPB
|
||
case OnePointFiveStopBits:
|
||
return &PortError{code: InvalidStopBits}
|
||
case TwoStopBits:
|
||
settings.Cflag |= unix.CSTOPB
|
||
default:
|
||
return &PortError{code: InvalidStopBits}
|
||
}
|
||
return nil
|
||
}
|
||
|
||
func setTermSettingsCtsRts(enable bool, settings *unix.Termios) {
|
||
if enable {
|
||
settings.Cflag |= tcCRTSCTS
|
||
} else {
|
||
settings.Cflag &^= tcCRTSCTS
|
||
}
|
||
}
|
||
|
||
func setRawMode(settings *unix.Termios) {
|
||
// Set local mode
|
||
settings.Cflag |= unix.CREAD
|
||
settings.Cflag |= unix.CLOCAL
|
||
|
||
// Set raw mode
|
||
settings.Lflag &^= unix.ICANON
|
||
settings.Lflag &^= unix.ECHO
|
||
settings.Lflag &^= unix.ECHOE
|
||
settings.Lflag &^= unix.ECHOK
|
||
settings.Lflag &^= unix.ECHONL
|
||
settings.Lflag &^= unix.ECHOCTL
|
||
settings.Lflag &^= unix.ECHOPRT
|
||
settings.Lflag &^= unix.ECHOKE
|
||
settings.Lflag &^= unix.ISIG
|
||
settings.Lflag &^= unix.IEXTEN
|
||
|
||
settings.Iflag &^= unix.IXON
|
||
settings.Iflag &^= unix.IXOFF
|
||
settings.Iflag &^= unix.IXANY
|
||
settings.Iflag &^= unix.INPCK
|
||
settings.Iflag &^= unix.IGNPAR
|
||
settings.Iflag &^= unix.PARMRK
|
||
settings.Iflag &^= unix.ISTRIP
|
||
settings.Iflag &^= unix.IGNBRK
|
||
settings.Iflag &^= unix.BRKINT
|
||
settings.Iflag &^= unix.INLCR
|
||
settings.Iflag &^= unix.IGNCR
|
||
settings.Iflag &^= unix.ICRNL
|
||
settings.Iflag &^= tcIUCLC
|
||
|
||
settings.Oflag &^= unix.OPOST
|
||
|
||
// Block reads until at least one char is available (no timeout)
|
||
settings.Cc[unix.VMIN] = 1
|
||
settings.Cc[unix.VTIME] = 0
|
||
}
|
||
|
||
// native syscall wrapper functions
|
||
|
||
func (port *unixPort) getTermSettings() (*unix.Termios, error) {
|
||
return unix.IoctlGetTermios(port.handle, ioctlTcgetattr)
|
||
}
|
||
|
||
func (port *unixPort) setTermSettings(settings *unix.Termios) error {
|
||
return unix.IoctlSetTermios(port.handle, ioctlTcsetattr, settings)
|
||
}
|
||
|
||
func (port *unixPort) getModemBitsStatus() (int, error) {
|
||
return unix.IoctlGetInt(port.handle, unix.TIOCMGET)
|
||
}
|
||
|
||
func (port *unixPort) setModemBitsStatus(status int) error {
|
||
return unix.IoctlSetPointerInt(port.handle, unix.TIOCMSET, status)
|
||
}
|
||
|
||
func (port *unixPort) acquireExclusiveAccess() error {
|
||
return unix.IoctlSetInt(port.handle, unix.TIOCEXCL, 0)
|
||
}
|
||
|
||
func (port *unixPort) releaseExclusiveAccess() error {
|
||
return unix.IoctlSetInt(port.handle, unix.TIOCNXCL, 0)
|
||
}
|