78 lines
1.9 KiB
Go
78 lines
1.9 KiB
Go
// Package privilege manages sudo timestamp acquisition and keepalive so
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// a long-running installer only prompts once.
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package privilege
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import (
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"context"
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"fmt"
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"os/exec"
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"time"
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)
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// Keepalive holds the lifetime of a background sudo-refresh goroutine.
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type Keepalive struct {
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cancel context.CancelFunc
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done chan struct{}
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}
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// Stop terminates the keepalive goroutine. Safe to call multiple times.
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func (k *Keepalive) Stop() {
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if k == nil || k.cancel == nil {
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return
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}
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k.cancel()
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<-k.done
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k.cancel = nil
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}
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// Acquirer abstracts the `sudo` binary so tests can inject a fake.
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type Acquirer interface {
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Validate(ctx context.Context) error // sudo -v (may prompt)
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ValidateNonInteractive(ctx context.Context) error // sudo -n -v
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}
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// ExecSudo is the production Acquirer.
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type ExecSudo struct{}
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func (ExecSudo) Validate(ctx context.Context) error {
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cmd := exec.CommandContext(ctx, "sudo", "-v")
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cmd.Stdin = nil // inherit terminal stdin
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return cmd.Run()
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}
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func (ExecSudo) ValidateNonInteractive(ctx context.Context) error {
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return exec.CommandContext(ctx, "sudo", "-n", "-v").Run()
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}
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// Acquire runs `sudo -v` once (prompting if needed) and returns a Keepalive
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// that refreshes the timestamp every `interval` using ValidateNonInteractive.
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// If the initial Validate fails, no goroutine is started and the error is returned.
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func Acquire(ctx context.Context, a Acquirer, interval time.Duration) (*Keepalive, error) {
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if a == nil {
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a = ExecSudo{}
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}
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if interval <= 0 {
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interval = 50 * time.Second
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}
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if err := a.Validate(ctx); err != nil {
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return nil, fmt.Errorf("sudo -v failed: %w", err)
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}
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kCtx, cancel := context.WithCancel(ctx)
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k := &Keepalive{cancel: cancel, done: make(chan struct{})}
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go func() {
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defer close(k.done)
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t := time.NewTicker(interval)
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defer t.Stop()
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for {
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select {
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case <-kCtx.Done():
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return
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case <-t.C:
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_ = a.ValidateNonInteractive(kCtx) // best-effort
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}
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}
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}()
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return k, nil
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}
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