Brad Fitzpatrick
efc17c4e50
Tests that exec a fresh CopyTo copy of the tailscale/tailscaled binaries occasionally failed with "text file busy" on GitHub Actions, previously worked around with the retry loop in awaitTailscaledRunnable. The root cause: CopyTo's Linux hardlink fast path only works while the built binary is still linked somewhere. The kernel refuses to hardlink an inode whose link count is zero, even via the still-open FD, so once the building test's TempDir (and every other test's copy) has been cleaned up, later tests silently fall through to the byte-copy path. That path writes the new copy from the test process itself, and if another parallel test forks a child while the write FD is open, the child holds the inherited FD (O_CLOEXEC only closes at exec, not at fork) and a subsequent exec of the fresh copy fails with ETXTBSY. This is golang.org/issue/22315. On macOS and the BSDs, CopyTo always takes the byte-copy path, so every copy races there. Fix it the way the syscall package documents: hold ForkLock for reading across the copy so that no fork overlaps the lifetime of the write FD. A standalone stress program reproduced the race in 86 of 200 execs under a fork storm and in 0 of 200 with the lock held. Updates #15868 Updates #15865 Change-Id: I8a6be72826c9073a9187d7e6c90c8733d2dadb05 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.27. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See commit-messages.md (or skim git log) for our commit message style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.