Function maybeSelfUpdate

cmd/codehamr/main.go:163–200

maybeSelfUpdate runs the pre-launch auto-update. No-op for local builds, an already-current hash, an unsupported platform (see update.assetName), or any network/filesystem refusal. On success it swaps the binary and re-execs via reExec (which only returns on failure). Any failure past "update availa

()

// re-execs via reExec (which only returns on failure). Any failure past
// "update available" prints one stderr line and proceeds with the old binary.
func maybeSelfUpdate() {
	// Skip local builds: hashing a `go run` temp binary against the
	// published checksum would otherwise swap in the last release and hide
	// unreleased work behind an "update applied" banner.
	if isLocalBuild(version) {
		return
	}
	exe, err := os.Executable()
	if err != nil {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), updateBudget)
	defer cancel()
	if !update.Check(ctx, exe) {
		return
	}
	fmt.Fprintln(os.Stderr, "◉ applying codehamr update...")
	if err := update.Apply(ctx, exe); err != nil {
		fmt.Fprintf(os.Stderr, "⚠ update failed: %v\n", err)
		if os.IsPermission(err) {
			fmt.Fprintln(os.Stderr, "  tip: rerun with sudo, or reinstall with PREFIX=$HOME/.local")
		}
		return
	}
	// Re-launch the new binary. reExec is platform-split: unix execve (same
	// PID) vs. Windows spawn-and-wait. CODEHAMR_NO_UPDATE_CHECK=1 stops the
	// replacement run from re-checking its own freshly-written hash. On
	// reExec failure we fall through to the old in-memory binary.
	if err := reExec(exe, os.Args, reexecEnv()); err != nil {
		fmt.Fprintf(os.Stderr, "⚠ re-exec failed: %v (continuing with previous version)\n", err)
	}
}

// reexecEnv arms the update-loop guard and returns the environment for the
// re-exec'd child. os.Setenv overwrites in place so os.Environ() carries
// exactly one entry; append(os.Environ(), …) would leave a pre-existing
// user-set value first, and Unix execve resolves os.Getenv to the FIRST
// match, silently defeating the guard if someone exported
// CODEHAMR_NO_UPDATE_CHECK to a non-"1" value.
func reexecEnv() []string {
	os.Setenv("CODEHAMR_NO_UPDATE_CHECK", "1")