mirror of https://github.com/coder/coder.git
84 lines
2.4 KiB
Go
84 lines
2.4 KiB
Go
//go:build !windows
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package pty
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import (
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"context"
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"fmt"
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"runtime"
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"strings"
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"syscall"
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"golang.org/x/xerrors"
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)
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func startPty(cmdPty *Cmd, opt ...StartOption) (retPTY *otherPty, proc Process, err error) {
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var opts startOptions
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for _, o := range opt {
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o(&opts)
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}
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opty, err := newPty(opts.ptyOpts...)
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if err != nil {
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return nil, nil, xerrors.Errorf("newPty failed: %w", err)
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}
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origEnv := cmdPty.Env
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if opty.opts.sshReq != nil {
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cmdPty.Env = append(cmdPty.Env, fmt.Sprintf("SSH_TTY=%s", opty.Name()))
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}
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if opty.opts.setGPGTTY {
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cmdPty.Env = append(cmdPty.Env, fmt.Sprintf("GPG_TTY=%s", opty.Name()))
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}
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if cmdPty.Context == nil {
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cmdPty.Context = context.Background()
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}
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cmdExec := cmdPty.AsExec()
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cmdExec.SysProcAttr = &syscall.SysProcAttr{
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Setsid: true,
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Setctty: true,
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}
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cmdExec.Stdout = opty.tty
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cmdExec.Stderr = opty.tty
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cmdExec.Stdin = opty.tty
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err = cmdExec.Start()
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if err != nil {
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_ = opty.Close()
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if runtime.GOOS == "darwin" && strings.Contains(err.Error(), "bad file descriptor") {
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// macOS has an obscure issue where the PTY occasionally closes
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// before it's used. It's unknown why this is, but creating a new
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// TTY resolves it.
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cmdPty.Env = origEnv
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return startPty(cmdPty, opt...)
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}
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return nil, nil, xerrors.Errorf("start: %w", err)
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}
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if runtime.GOOS == "linux" {
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// Now that we've started the command, and passed the TTY to it, close
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// our file so that the other process has the only open file to the TTY.
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// Once the process closes the TTY (usually on exit), there will be no
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// open references and the OS kernel returns an error when trying to
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// read or write to our PTY end. Without this (on Linux), reading from
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// the process output will block until we close our TTY.
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//
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// Note that on darwin, reads on the PTY don't block even if we keep the
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// TTY file open, and keeping it open seems to prevent race conditions
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// where we lose output. Couldn't find official documentation
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// confirming this, but I did find a thread of someone else's
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// observations: https://developer.apple.com/forums/thread/663632
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if err := opty.tty.Close(); err != nil {
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_ = cmdExec.Process.Kill()
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return nil, nil, xerrors.Errorf("close tty: %w", err)
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}
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opty.tty = nil // remove so we don't attempt to close it again.
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}
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oProcess := &otherProcess{
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pty: opty.pty,
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cmd: cmdExec,
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cmdDone: make(chan any),
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}
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go oProcess.waitInternal()
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return opty, oProcess, nil
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}
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