Add range support

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/filemanager/s3.go

@@ -31,17 +31,21 @@ import (
 )
 
 type FileObject struct {
-	Body          io.ReadCloser
-	ContentType   string
-	ContentLength int64
-	ETag          string
-	LastModified  time.Time
-	NotModified   bool
+	Body                io.ReadCloser
+	ContentType         string
+	ContentLength       int64
+	ContentRange        string
+	ETag                string
+	LastModified        time.Time
+	NotModified         bool
+	PartialContent      bool
+	RangeNotSatisfiable bool
 }
 
 type FileConditions struct {
 	IfNoneMatch     string
 	IfModifiedSince time.Time
+	Range           string
 }
 
 func (s *Service) GetFileBase64(
@@ -111,11 +115,21 @@ func (s *Service) OpenFile(
 		input.IfModifiedSince = &conds.IfModifiedSince
 	}
 
+	if conds.Range != "" {
+		input.Range = &conds.Range
+	}
+
 	result, err := s.s3Client.GetObject(ctx, input)
 	if err != nil {
 		if respErr, ok := errors.AsType[*smithyhttp.ResponseError](err); ok {
-			if respErr.HTTPStatusCode() == http.StatusNotModified {
+			switch respErr.HTTPStatusCode() {
+			case http.StatusNotModified:
 				return &FileObject{NotModified: true}, nil
+			case http.StatusRequestedRangeNotSatisfiable:
+				return &FileObject{
+					RangeNotSatisfiable: true,
+					ContentLength:       file.FileSize,
+				}, nil
 			}
 		}
 
@@ -136,6 +150,19 @@ func (s *Service) OpenFile(
 		obj.LastModified = *result.LastModified
 	}
 
+	// A Range request that S3 honors comes back as 206 Partial Content with a
+	// Content-Range header and a ContentLength scoped to the returned slice. An
+	// If-Range mismatch (or no Range) yields a normal 200 with the full object,
+	// so we only override the length/status when Content-Range is present.
+	if result.ContentRange != nil {
+		obj.ContentRange = *result.ContentRange
+		obj.PartialContent = true
+	}
+
+	if result.ContentLength != nil {
+		obj.ContentLength = *result.ContentLength
+	}
+
 	return obj, nil
 }
 

pkg/filemanager/s3_test.go

@@ -91,6 +91,87 @@ func TestOpenFile_StreamsBody(t *testing.T) {
 	assert.Equal(t, content, string(body))
 }
 
+func TestOpenFile_RangeRequestReturnsPartialContent(t *testing.T) {
+	t.Parallel()
+
+	const (
+		etag    = `"abc123"`
+		content = "hello world"
+	)
+
+	svc := newTestS3Service(
+		t,
+		func(w http.ResponseWriter, r *http.Request) {
+			assert.Equal(t, "bytes=0-4", r.Header.Get("Range"))
+
+			w.Header().Set("ETag", etag)
+			w.Header().Set("Content-Range", "bytes 0-4/11")
+			w.Header().Set("Content-Length", "5")
+			w.WriteHeader(http.StatusPartialContent)
+			_, _ = io.WriteString(w, content[:5])
+		},
+	)
+
+	file := &coredata.File{
+		BucketName: "uploads",
+		FileKey:    "tenant/file",
+		MimeType:   "text/plain",
+		FileSize:   int64(len(content)),
+	}
+
+	obj, err := svc.OpenFile(
+		context.Background(),
+		file,
+		filemanager.FileConditions{Range: "bytes=0-4"},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, obj)
+
+	defer func() { _ = obj.Body.Close() }()
+
+	assert.True(t, obj.PartialContent)
+	assert.False(t, obj.NotModified)
+	assert.Equal(t, "bytes 0-4/11", obj.ContentRange)
+	assert.Equal(t, int64(5), obj.ContentLength)
+
+	body, err := io.ReadAll(obj.Body)
+	require.NoError(t, err)
+	assert.Equal(t, content[:5], string(body))
+}
+
+func TestOpenFile_RangeNotSatisfiable(t *testing.T) {
+	t.Parallel()
+
+	const content = "hello world"
+
+	svc := newTestS3Service(
+		t,
+		func(w http.ResponseWriter, _ *http.Request) {
+			w.Header().Set("Content-Range", "bytes */11")
+			w.WriteHeader(http.StatusRequestedRangeNotSatisfiable)
+		},
+	)
+
+	file := &coredata.File{
+		BucketName: "uploads",
+		FileKey:    "tenant/file",
+		MimeType:   "text/plain",
+		FileSize:   int64(len(content)),
+	}
+
+	obj, err := svc.OpenFile(
+		context.Background(),
+		file,
+		filemanager.FileConditions{Range: "bytes=999-1000"},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, obj)
+	assert.True(t, obj.RangeNotSatisfiable)
+	assert.False(t, obj.PartialContent)
+	assert.Nil(t, obj.Body)
+	assert.Equal(t, int64(len(content)), obj.ContentLength)
+}
+
 func TestOpenFile_NotModifiedByETag(t *testing.T) {
 	t.Parallel()