banger/internal/daemon/fcproc/fcproc_test.go

package fcproc

import (
	"context"
	"errors"
	"log/slog"
	"os"
	"path/filepath"
	"testing"
	"time"
)

// scriptedRunner is a minimal Runner that records every call and
// plays back a pre-scripted sequence of (name, args, out, err)
// steps. Failing to match or running past the script fails the
// test. Mirrors the pattern from internal/daemon/snapshot_test.go
// but lives here because fcproc is a leaf package — it can't import
// its parent's test helpers.
type scriptedRunner struct {
	t     *testing.T
	runs  []scriptedCall
	sudos []scriptedCall
}

type scriptedCall struct {
	matchName string   // empty for RunSudo (sudo has no distinct name arg)
	matchArgs []string // nil means "don't care"
	out       []byte
	err       error
}

func (r *scriptedRunner) Run(_ context.Context, name string, args ...string) ([]byte, error) {
	r.t.Helper()
	if len(r.runs) == 0 {
		r.t.Fatalf("unexpected Run(%q, %v)", name, args)
	}
	step := r.runs[0]
	r.runs = r.runs[1:]
	if step.matchName != "" && step.matchName != name {
		r.t.Fatalf("Run name = %q, want %q", name, step.matchName)
	}
	return step.out, step.err
}

func (r *scriptedRunner) RunSudo(_ context.Context, args ...string) ([]byte, error) {
	r.t.Helper()
	if len(r.sudos) == 0 {
		r.t.Fatalf("unexpected RunSudo(%v)", args)
	}
	step := r.sudos[0]
	r.sudos = r.sudos[1:]
	return step.out, step.err
}

// TestWaitForPathReturnsDeadlineExceededWhenSocketNeverAppears pins
// the timeout branch of waitForPath. If this drifts, every callsite
// that wraps it (EnsureSocketAccess on the firecracker API +
// vsock sockets) loses its bounded wait.
func TestWaitForPathReturnsDeadlineExceededWhenSocketNeverAppears(t *testing.T) {
	missing := filepath.Join(t.TempDir(), "never-created.sock")
	start := time.Now()
	err := waitForPath(context.Background(), missing, 150*time.Millisecond, "api socket")
	elapsed := time.Since(start)

	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("err = %v, want wrapped context.DeadlineExceeded", err)
	}
	if !contains(err.Error(), "api socket") {
		t.Fatalf("err = %v, want label 'api socket' in message", err)
	}
	// Timeout should fire close to the configured budget, not zero
	// (tight-loop regression) and not way over (missing select
	// regression). The 100ms poll tick plus the initial stat makes
	// the lower bound noisy; check we at least waited a tick.
	if elapsed < 90*time.Millisecond {
		t.Fatalf("returned after %s; waitForPath exited before its timeout budget", elapsed)
	}
}

// TestWaitForPathReturnsOnceSocketAppears pins the happy path:
// when the file materialises mid-wait, the function returns nil
// without having to walk to its deadline.
func TestWaitForPathReturnsOnceSocketAppears(t *testing.T) {
	socketPath := filepath.Join(t.TempDir(), "will-appear.sock")
	go func() {
		time.Sleep(50 * time.Millisecond)
		_ = os.WriteFile(socketPath, []byte{}, 0o600)
	}()
	if err := waitForPath(context.Background(), socketPath, 2*time.Second, "api socket"); err != nil {
		t.Fatalf("waitForPath: %v", err)
	}
}

// TestWaitForPathRespectsContextCancellation pins the ctx.Done()
// branch — a canceled request must not be blocked by the poll
// interval.
func TestWaitForPathRespectsContextCancellation(t *testing.T) {
	missing := filepath.Join(t.TempDir(), "never.sock")
	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		time.Sleep(30 * time.Millisecond)
		cancel()
	}()
	err := waitForPath(ctx, missing, 5*time.Second, "api socket")
	if !errors.Is(err, context.Canceled) {
		t.Fatalf("err = %v, want context.Canceled when ctx is cancelled mid-wait", err)
	}
}

// TestEnsureSocketAccessChmodFailureBubbles verifies the chmod step
// fails fast before any ownership handoff. Once chown runs, the
// bounded helper no longer owns the socket and can't tighten its mode
// without CAP_FOWNER, so the order matters.
func TestEnsureSocketAccessChmodFailureBubbles(t *testing.T) {
	socketPath := filepath.Join(t.TempDir(), "present.sock")
	if err := os.WriteFile(socketPath, []byte{}, 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	chmodErr := errors.New("sudo chmod failed")
	runner := &scriptedRunner{
		t:     t,
		sudos: []scriptedCall{{err: chmodErr}},
	}
	mgr := New(runner, Config{}, slog.Default())

	err := mgr.EnsureSocketAccess(context.Background(), socketPath, "api socket")
	if !errors.Is(err, chmodErr) {
		t.Fatalf("err = %v, want chmod error", err)
	}
	// chown must not have been attempted.
	if len(runner.sudos) != 0 {
		t.Fatalf("chown was attempted after chmod failed: %d sudo calls left", len(runner.sudos))
	}
}

// TestEnsureSocketAccessChownFailureBubbles verifies the ownership
// handoff still surfaces errors after chmod succeeds.
func TestEnsureSocketAccessChownFailureBubbles(t *testing.T) {
	socketPath := filepath.Join(t.TempDir(), "present.sock")
	if err := os.WriteFile(socketPath, []byte{}, 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}

	chownErr := errors.New("sudo chown failed")
	runner := &scriptedRunner{
		t: t,
		sudos: []scriptedCall{
			{},              // chmod succeeds
			{err: chownErr}, // chown fails
		},
	}
	mgr := New(runner, Config{}, slog.Default())

	err := mgr.EnsureSocketAccess(context.Background(), socketPath, "api socket")
	if !errors.Is(err, chownErr) {
		t.Fatalf("err = %v, want chown error", err)
	}
}

// TestEnsureSocketAccessTimesOutBeforeTouchingRunner pins the
// ordering contract: if waitForPath never sees the socket, the
// sudo commands must not run. Running chown/chmod against a
// non-existent path would just noise the logs.
func TestEnsureSocketAccessTimesOutBeforeTouchingRunner(t *testing.T) {
	missing := filepath.Join(t.TempDir(), "never.sock")
	runner := &scriptedRunner{t: t} // no scripted calls — any runner invocation fails the test
	mgr := New(runner, Config{}, slog.Default())

	// EnsureSocketAccess's waitForPath has a hardcoded 5s timeout,
	// and we can't inject a shorter one without widening the API.
	// Use a short context instead — cancellation short-circuits
	// waitForPath via the ctx.Done() branch.
	ctx, cancel := context.WithTimeout(context.Background(), 150*time.Millisecond)
	defer cancel()

	err := mgr.EnsureSocketAccess(ctx, missing, "api socket")
	if err == nil {
		t.Fatal("EnsureSocketAccess: want error when socket never appears")
	}
}

func contains(s, sub string) bool {
	for i := 0; i+len(sub) <= len(s); i++ {
		if s[i:i+len(sub)] == sub {
			return true
		}
	}
	return false
}