github.com/sk3wlabs/go-serial

First off, kudos to the original package maintainers for, in my opinion, the best, cross-platform serial library for Go. Cheers.

This repo was forked from <github.com/bugst/go-serial> on 2023-04-26 to address a complication resulting from how the nativeGetPortsList() function (in UNIX) determines whether a ttyS... serial port is actually a device, or just a placeholder. It follows the pattern used in setserial:

• In setserial, the file descriptor is opened with O_RDWR|O_NONBLOCK, and then an ioctl is performed to query the device's current state. If it errors, it's not a [usable] serial device.
• In this library, the same thing is done, but the fd is opened with O_RDWR|O_NOCTTY|O_NDELAY. The documentation out there re: O_NDELAY and O_NONBLOCK can be contradictory, but generally either O_NONBLOCK is preferred for a more consistent experience across file descriptor types, or that there is no logical difference between the two.

On a server with an active serial console, when we're looking for a different serial device, the instant the port enumeration touches the active serial console, the active serial console locks, and a reboot is required to regain use serial console.

In an attempt to write a fix that would be no-touch in terms of overall implementation, and low-touch in terms of implementation on unix (from the Go perspective) devices, I simply added a UnixFdNonBlock bool to the Mode struct that would |= O_NONBLOCK to the unix.Open() mode. However, the unix library reports that both O_NDELAY and O_NONBLOCK evaluate to the same 0x4 value.

Unfortunately, I'll need to write a heavier-handed fix, after which I'll speak with the original package maintainers on how best to contribute back a fix that doesn't make a breaking change.

Changelog

• Functional Things:
  • Added a boolean field to the Mode struct called UnixFdNonBlock to control whether the filemode used with unix.Open() should be or-equalled with O_NONBLOCK.
• The Usual Fork Changes:
  • All (or most) url package references have been switched from the original repo to this repo.
  • Go version from 1.17 to 1.19
    • ioutil.ReadDir() -> os.ReadDir()

Original Readme:

go.bug.st/serial

A cross-platform serial library for go-lang.

Documentation and examples

See the godoc here: https://godoc.org/go.bug.st/serial

go.mod transition

This library now support go.mod with the import go.bug.st/serial.

If you came from the pre-go.mod era please update your import paths from go.bug.st/serial.v1 to go.bug.st/serial to receive new updates. Anyway, the latest v1 release should still be avaiable using the old import.

Credits

:sparkles: Thanks to all awesome contributors! :sparkles:

License

The software is release under a BSD 3-clause license