fix(sshstdio): keep carriage alive after handshake

commit: 3fedffb524e36334b591afcbd7cbd1256edd92f3
author: brice · 2mo ago · 2026-08-03 14:57 UTC
committer: brice · 2mo ago · 2026-08-04 13:34 UTC
parent: 6e29c9b
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +15 -5

M internal/adapters/sshstdio/transport.go +15 -5


@@ -344,10 +344,11 @@ func DialContextWithRuntimeObserver(ctx context.Context, target, session string,
344	344		return dialContext(ctx, target, session, logger, opts...)
345	345		}
346	346
347		-	// DialContext is like Dial, but the context is propagated to ssh startup so a
348		-	// canceled attach attempt interrupts the local ssh process. Callers may pass a
349		-	// logger to record ssh start failures and non-clean exits without logging the
350		-	// generated command line.
	347	+	// DialContext is like Dial, but the context gates ssh startup. Once the
	348	+	// transport is returned, its Close method owns the subprocess lifetime; the
	349	+	// handshake context must not kill an already-established carriage. Callers may
	350	+	// pass a logger to record ssh start failures and non-clean exits without logging
	351	+	// the generated command line.
351	352		func DialContext(ctx context.Context, target, session string, logger ...*slog.Logger) (ports.Transport, error) {
352	353		var log *slog.Logger
353	354		if len(logger) > 0 {

@@ -361,7 +362,12 @@ func dialContext(ctx context.Context, target, session string, log *slog.Logger,
361	362		return nil, err
362	363		}
363	364		spec := BuildCommand(target, session)
364		-	cmd := exec.CommandContext(ctx, spec.Path, spec.Args...)
	365	+	// The caller's context is also the bounded protocol-handshake context and is
	366	+	// canceled after the first committed publication. Binding it to the command
	367	+	// would kill a healthy long-lived carriage at that boundary. Transport.Close
	368	+	// owns cancellation after Start; the preflight check above keeps canceled
	369	+	// attempts from starting a process.
	370	+	cmd := exec.Command(spec.Path, spec.Args...)
365	371		stdin, err := cmd.StdinPipe()
366	372		if err != nil {
367	373		return nil, fmt.Errorf("sshstdio: stdin pipe: %w", err)

@@ -381,6 +387,10 @@ func dialContext(ctx context.Context, target, session string, log *slog.Logger,
381	387
382	388		waiter := newProcessWaiter(cmd, stdin, &stderr, sshCloseTimeout, log, target, session)
383	389		transport := newTransport(stdout, stdin, waiter.close, waiter.eofErr)
	390	+	if err := ctx.Err(); err != nil {
	391	+	_ = transport.Close()
	392	+	return nil, err
	393	+	}
384	394		for _, opt := range opts {
385	395		if opt != nil {
386	396		opt(transport)

 	return dialContext(ctx, target, session, logger, opts...)
 }
-// DialContext is like Dial, but the context is propagated to ssh startup so a
+// DialContext is like Dial, but the context gates ssh startup. Once the
-// canceled attach attempt interrupts the local ssh process. Callers may pass a
+// transport is returned, its Close method owns the subprocess lifetime; the
-// logger to record ssh start failures and non-clean exits without logging the
+// handshake context must not kill an already-established carriage. Callers may
-// generated command line.
+// pass a logger to record ssh start failures and non-clean exits without logging
+// the generated command line.
 func DialContext(ctx context.Context, target, session string, logger ...*slog.Logger) (ports.Transport, error) {
 	var log *slog.Logger
 	if len(logger) > 0 {
 		return nil, err
 	}
 	spec := BuildCommand(target, session)
-	cmd := exec.CommandContext(ctx, spec.Path, spec.Args...)
+	// The caller's context is also the bounded protocol-handshake context and is
+	// canceled after the first committed publication. Binding it to the command
+	// would kill a healthy long-lived carriage at that boundary. Transport.Close
+	// owns cancellation after Start; the preflight check above keeps canceled
+	// attempts from starting a process.
+	cmd := exec.Command(spec.Path, spec.Args...)
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
 		return nil, fmt.Errorf("sshstdio: stdin pipe: %w", err)
 	waiter := newProcessWaiter(cmd, stdin, &stderr, sshCloseTimeout, log, target, session)
 	transport := newTransport(stdout, stdin, waiter.close, waiter.eofErr)
+	if err := ctx.Err(); err != nil {
+		_ = transport.Close()
+		return nil, err
+	}
 	for _, opt := range opts {
 		if opt != nil {
 			opt(transport)