Bound remote control object reads

internal/adapters/storage/bounded_read_test.go

@@ -0,0 +1,135 @@
+package storage
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"testing"
+)
+
+func TestReadObjectBoundedAcceptsExactLimitWithAbsentSizeMetadata(t *testing.T) {
+	body := &trackingReadCloser{reader: bytes.NewReader([]byte("12345678")), chunkSize: 2}
+	store := &boundedReadStore{read: func(context.Context, string) (ObjectInfo, io.ReadCloser, error) {
+		return ObjectInfo{Key: "control.json", ETag: "generation"}, body, nil
+	}}
+
+	info, data, err := ReadObjectBounded(context.Background(), store, "control.json", 8)
+	if err != nil {
+		t.Fatalf("ReadObjectBounded() error = %v", err)
+	}
+	if string(data) != "12345678" || info.ETag != "generation" {
+		t.Fatalf("ReadObjectBounded() = (%#v, %q), want opened object metadata and bytes", info, data)
+	}
+	if !body.closed {
+		t.Fatal("object body was not closed")
+	}
+}
+
+func TestReadObjectBoundedRejectsLimitPlusOneDespiteMissingOrInaccurateMetadata(t *testing.T) {
+	tests := []struct {
+		name         string
+		metadataSize int64
+	}{
+		{name: "missing", metadataSize: 0},
+		{name: "inaccurate", metadataSize: 2},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			body := &trackingReadCloser{reader: bytes.NewReader([]byte("123456789")), chunkSize: 1}
+			store := &boundedReadStore{read: func(context.Context, string) (ObjectInfo, io.ReadCloser, error) {
+				return ObjectInfo{Key: "control.json", Size: test.metadataSize}, body, nil
+			}}
+
+			_, data, err := ReadObjectBounded(context.Background(), store, "control.json", 8)
+			var limitErr *ReadLimitError
+			if !errors.As(err, &limitErr) {
+				t.Fatalf("ReadObjectBounded() error = %v, want ReadLimitError", err)
+			}
+			if data != nil || body.bytesRead != 9 || !body.closed {
+				t.Fatalf("data=%q bytes read=%d closed=%t, want nil, 9, true", data, body.bytesRead, body.closed)
+			}
+		})
+	}
+}
+
+func TestReadObjectBoundedRejectsOversizedMetadataBeforeTransfer(t *testing.T) {
+	body := &trackingReadCloser{reader: bytes.NewReader([]byte("small"))}
+	store := &boundedReadStore{read: func(context.Context, string) (ObjectInfo, io.ReadCloser, error) {
+		return ObjectInfo{Key: "control.json", Size: 9}, body, nil
+	}}
+
+	_, _, err := ReadObjectBounded(context.Background(), store, "control.json", 8)
+	var limitErr *ReadLimitError
+	if !errors.As(err, &limitErr) {
+		t.Fatalf("ReadObjectBounded() error = %v, want ReadLimitError", err)
+	}
+	if body.bytesRead != 0 || !body.closed {
+		t.Fatalf("bytes read=%d closed=%t, want zero-byte transfer and closed body", body.bytesRead, body.closed)
+	}
+}
+
+func TestReadObjectBoundedPropagatesCancellationAndClosesBody(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	body := &trackingReadCloser{reader: bytes.NewReader([]byte("12345678")), chunkSize: 1, afterRead: cancel}
+	store := &boundedReadStore{read: func(context.Context, string) (ObjectInfo, io.ReadCloser, error) {
+		return ObjectInfo{Key: "control.json"}, body, nil
+	}}
+
+	_, data, err := ReadObjectBounded(ctx, store, "control.json", 8)
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("ReadObjectBounded() error = %v, want context cancellation", err)
+	}
+	if data != nil || body.bytesRead != 1 || !body.closed {
+		t.Fatalf("data=%q bytes read=%d closed=%t, want nil, 1, true", data, body.bytesRead, body.closed)
+	}
+}
+
+func TestReadObjectBoundedReturnsCloseFailure(t *testing.T) {
+	closeErr := errors.New("close failed")
+	body := &trackingReadCloser{reader: bytes.NewReader([]byte("ok")), closeErr: closeErr}
+	store := &boundedReadStore{read: func(context.Context, string) (ObjectInfo, io.ReadCloser, error) {
+		return ObjectInfo{Key: "control.json", Size: 2}, body, nil
+	}}
+
+	_, data, err := ReadObjectBounded(context.Background(), store, "control.json", 8)
+	if !errors.Is(err, closeErr) || data != nil || !body.closed {
+		t.Fatalf("data=%q error=%v closed=%t, want close failure and no retained data", data, err, body.closed)
+	}
+}
+
+type boundedReadStore struct {
+	ObjectStore
+	read func(context.Context, string) (ObjectInfo, io.ReadCloser, error)
+}
+
+func (s *boundedReadStore) Read(ctx context.Context, key string) (ObjectInfo, io.ReadCloser, error) {
+	return s.read(ctx, key)
+}
+
+type trackingReadCloser struct {
+	reader    io.Reader
+	chunkSize int
+	afterRead func()
+	closeErr  error
+	bytesRead int
+	closed    bool
+}
+
+func (r *trackingReadCloser) Read(p []byte) (int, error) {
+	if r.chunkSize > 0 && len(p) > r.chunkSize {
+		p = p[:r.chunkSize]
+	}
+	n, err := r.reader.Read(p)
+	r.bytesRead += n
+	if n > 0 && r.afterRead != nil {
+		r.afterRead()
+		r.afterRead = nil
+	}
+	return n, err
+}
+
+func (r *trackingReadCloser) Close() error {
+	r.closed = true
+	return r.closeErr
+}