Linux系统下串口Close相关实现的深度优化
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
This commit is contained in:
159
serial_unix.go
159
serial_unix.go
@@ -30,35 +30,48 @@ type unixPort struct {
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}
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func (port *unixPort) Close() error {
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// 原子操作检查并设置端口关闭状态
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if !atomic.CompareAndSwapUint32(&port.opened, 1, 0) {
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return nil
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return nil // 端口已经关闭，直接返回
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}
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// Close port
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port.releaseExclusiveAccess()
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if err := unix.Close(port.handle); err != nil {
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return err
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}
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var firstErr error
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// 发送关闭信号以取消所有待处理的读操作
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if port.closeSignal != nil {
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// Send close signal to all pending reads (if any)
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port.closeSignal.Write([]byte{0})
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// Wait for all readers to complete
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port.closeLock.Lock()
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defer port.closeLock.Unlock()
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// Close signaling pipe
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if err := port.closeSignal.Close(); err != nil {
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return err
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if _, err := port.closeSignal.Write([]byte{0}); err != nil && firstErr == nil {
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firstErr = err
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}
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}
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return nil
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// 检查句柄是否有效，然后执行关闭操作
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if port.handle != -1 {
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// 释放独占访问权 - 应在关闭handle之前完成
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if err := port.releaseExclusiveAccess(); err != nil && firstErr == nil {
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firstErr = err
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}
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// 关闭实际的端口句柄 - 这将解除任何挂起的读写操作
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if err := unix.Close(port.handle); err != nil && firstErr == nil {
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firstErr = err
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}
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port.handle = -1 // 标记句柄无效
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}
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// 关闭信号管道
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if port.closeSignal != nil {
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if err := port.closeSignal.Close(); err != nil && firstErr == nil {
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firstErr = err
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}
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port.closeSignal = nil // 清除指针
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}
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return firstErr
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}
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func (port *unixPort) Read(p []byte) (int, error) {
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port.closeLock.RLock()
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defer port.closeLock.RUnlock()
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// 首先检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return 0, &PortError{code: PortClosed}
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}
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@@ -70,104 +83,157 @@ func (port *unixPort) Read(p []byte) (int, error) {
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fds := unixutils.NewFDSet(port.handle, port.closeSignal.ReadFD())
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for {
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// 在每次select之前再次检查端口状态（非阻塞检查）
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if atomic.LoadUint32(&port.opened) != 1 {
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return 0, &PortError{code: PortClosed}
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}
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timeout := time.Duration(-1)
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if port.readTimeout != NoTimeout {
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timeout = time.Until(deadline)
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if timeout < 0 {
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// a negative timeout means "no-timeout" in Select(...)
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// 负超时值在Select(...)中表示"无超时"
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timeout = 0
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}
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}
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res, err := unixutils.Select(fds, nil, fds, timeout)
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if err == unix.EINTR {
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continue
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continue // 系统调用被中断，重试
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}
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if err != nil {
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return 0, err
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// 如果在端口关闭后遇到错误，返回PortClosed错误
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if atomic.LoadUint32(&port.opened) != 1 {
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return 0, &PortError{code: PortClosed}
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}
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return 0, &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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if res.IsReadable(port.closeSignal.ReadFD()) {
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// 收到关闭信号
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return 0, &PortError{code: PortClosed}
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}
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if !res.IsReadable(port.handle) {
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// Timeout happened
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return 0, nil
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// 超时
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if port.readTimeout == NoTimeout {
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continue // 无超时设置，继续等待
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}
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return 0, nil // 返回0字节表示超时
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}
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n, err := unix.Read(port.handle, p)
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if err == unix.EINTR {
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continue
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continue // 系统调用被中断，重试
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}
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// Linux: when the port is disconnected during a read operation
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// the port is left in a "readable with zero-length-data" state.
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// Linux系统特性：当读取操作期间端口断开连接时，
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// 端口会进入"可读但返回零长度数据"的状态。
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// https://stackoverflow.com/a/34945814/1655275
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if n == 0 && err == nil {
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return 0, &PortError{code: PortClosed}
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}
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if n < 0 { // Do not return -1 unix errors
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if n < 0 { // 确保不返回负数
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n = 0
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}
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return n, err
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// 检查读取操作期间端口是否被关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return 0, &PortError{code: PortClosed}
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}
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if err != nil {
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return n, &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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return n, nil
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}
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}
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func (port *unixPort) Write(p []byte) (n int, err error) {
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// 首先检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return 0, &PortError{code: PortClosed}
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}
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n, err = unix.Write(port.handle, p)
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if n < 0 { // Do not return -1 unix errors
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if n < 0 { // 确保不返回负数
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n = 0
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}
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return
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if err != nil {
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return n, &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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return n, nil
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}
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func (port *unixPort) Break(t time.Duration) error {
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// 检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return &PortError{code: PortClosed}
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}
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if err := unix.IoctlSetInt(port.handle, ioctlTiocsbrk, 0); err != nil {
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return err
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return &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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time.Sleep(t)
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if err := unix.IoctlSetInt(port.handle, ioctlTioccbrk, 0); err != nil {
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return err
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return &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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return nil
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}
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func (port *unixPort) SetMode(mode *Mode) error {
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// 检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return &PortError{code: PortClosed}
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}
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settings, err := port.getTermSettings()
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if err != nil {
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return err
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return &PortError{code: InvalidSerialPort, causedBy: err}
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}
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if err := setTermSettingsParity(mode.Parity, settings); err != nil {
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return err
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}
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if err := setTermSettingsDataBits(mode.DataBits, settings); err != nil {
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return err
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}
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if err := setTermSettingsStopBits(mode.StopBits, settings); err != nil {
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return err
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}
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requireSpecialBaudrate := false
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if err, special := setTermSettingsBaudrate(mode.BaudRate, settings); err != nil {
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return err
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} else if special {
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requireSpecialBaudrate = true
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}
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if err := port.setTermSettings(settings); err != nil {
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return err
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return &PortError{code: InvalidSerialPort, causedBy: err}
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}
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if requireSpecialBaudrate {
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// MacOSX require this one to be the last operation otherwise an
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// 'Invalid serial port' error is produced.
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// MacOSX要求这是最后一个操作，否则会产生'Invalid serial port'错误
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if err := port.setSpecialBaudrate(uint32(mode.BaudRate)); err != nil {
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return err
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return &PortError{code: InvalidSpeed, causedBy: err}
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}
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}
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return nil
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}
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func (port *unixPort) SetDTR(dtr bool) error {
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// 检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return &PortError{code: PortClosed}
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}
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status, err := port.getModemBitsStatus()
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if err != nil {
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return err
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return &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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if dtr {
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status |= unix.TIOCM_DTR
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@@ -178,9 +244,14 @@ func (port *unixPort) SetDTR(dtr bool) error {
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}
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func (port *unixPort) SetRTS(rts bool) error {
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// 检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return &PortError{code: PortClosed}
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}
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status, err := port.getModemBitsStatus()
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if err != nil {
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return err
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return &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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if rts {
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status |= unix.TIOCM_RTS
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@@ -199,10 +270,16 @@ func (port *unixPort) SetReadTimeout(timeout time.Duration) error {
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}
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func (port *unixPort) GetModemStatusBits() (*ModemStatusBits, error) {
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// 检查端口是否已经关闭
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if atomic.LoadUint32(&port.opened) != 1 {
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return nil, &PortError{code: PortClosed}
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}
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status, err := port.getModemBitsStatus()
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if err != nil {
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return nil, err
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return nil, &PortError{code: FunctionNotImplemented, causedBy: err}
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}
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return &ModemStatusBits{
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CTS: (status & unix.TIOCM_CTS) != 0,
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DCD: (status & unix.TIOCM_CD) != 0,
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