Consider FileResponse.chunk_size when handling multiple ranges (#2703)

* Take in consideration the `FileResponse.chunk_size` on multiple ranges

* Update starlette/responses.py

* Update starlette/responses.py

* Update starlette/responses.py

Co-authored-by: Frost Ming <mianghong@gmail.com>

---------

Co-authored-by: Frost Ming <mianghong@gmail.com>

pyproject.toml

@@ -103,4 +103,5 @@ exclude_lines = [
  "pragma: nocover",
  "if typing.TYPE_CHECKING:",
  "@typing.overload",
+ "raise NotImplementedError",
 ]

starlette/responses.py

@@ -374,13 +374,7 @@ async def _handle_simple(self, send: Send, send_header_only: bool) -> None:
  while more_body:
  chunk = await file.read(self.chunk_size)
  more_body = len(chunk) == self.chunk_size
- await send(
- {
- "type": "http.response.body",
- "body": chunk,
- "more_body": more_body,
- }
- )
+ await send({"type": "http.response.body", "body": chunk, "more_body": more_body})
 
  async def _handle_single_range(
  self, send: Send, start: int, end: int, file_size: int, send_header_only: bool
@@ -419,10 +413,12 @@ async def _handle_multiple_ranges(
  else:
  async with await anyio.open_file(self.path, mode="rb") as file:
  for start, end in ranges:
- await file.seek(start)
- chunk = await file.read(min(self.chunk_size, end - start))
  await send({"type": "http.response.body", "body": header_generator(start, end), "more_body": True})
- await send({"type": "http.response.body", "body": chunk, "more_body": True})
+ await file.seek(start)
+ while start < end:
+ chunk = await file.read(min(self.chunk_size, end - start))
+ start += len(chunk)
+ await send({"type": "http.response.body", "body": chunk, "more_body": True})
  await send({"type": "http.response.body", "body": b"\n", "more_body": True})
  await send(
  {

tests/middleware/test_base.py

@@ -289,7 +289,7 @@ async def passthrough(
  }
 
  async def receive() -> Message:
- raise NotImplementedError("Should not be called!") # pragma: no cover
+ raise NotImplementedError("Should not be called!")
 
  async def send(message: Message) -> None:
  if message["type"] == "http.response.body":
@@ -330,7 +330,7 @@ async def passthrough(request: Request, call_next: RequestResponseEndpoint) -> R
  }
 
  async def receive() -> Message:
- raise NotImplementedError("Should not be called!") # pragma: no cover
+ raise NotImplementedError("Should not be called!")
 
  async def send(message: Message) -> None:
  if message["type"] == "http.response.body":
@@ -403,7 +403,7 @@ async def passthrough(
  }
 
  async def receive() -> Message:
- raise NotImplementedError("Should not be called!") # pragma: no cover
+ raise NotImplementedError("Should not be called!")
 
  async def send(message: Message) -> None:
  if message["type"] == "http.response.body":

tests/test_responses.py

@@ -4,7 +4,7 @@
 import time
 from http.cookies import SimpleCookie
 from pathlib import Path
-from typing import AsyncIterator, Iterator
+from typing import Any, AsyncIterator, Iterator
 
 import anyio
 import pytest
@@ -682,3 +682,58 @@ def test_file_response_insert_ranges(file_response_client: TestClient) -> None:
  "",
  f"--{boundary}--",
  ]
+
+
+@pytest.mark.anyio
+async def test_file_response_multi_small_chunk_size(readme_file: Path) -> None:
+ class SmallChunkSizeFileResponse(FileResponse):
+ chunk_size = 10
+
+ app = SmallChunkSizeFileResponse(path=str(readme_file))
+
+ received_chunks: list[bytes] = []
+ start_message: dict[str, Any] = {}
+
+ async def receive() -> Message:
+ raise NotImplementedError("Should not be called!")
+
+ async def send(message: Message) -> None:
+ if message["type"] == "http.response.start":
+ start_message.update(message)
+ elif message["type"] == "http.response.body":
+ received_chunks.append(message["body"])
+
+ await app({"type": "http", "method": "get", "headers": [(b"range", b"bytes=0-15,20-35,35-50")]}, receive, send)
+ assert start_message["status"] == 206
+
+ headers = Headers(raw=start_message["headers"])
+ assert headers.get("content-type") == "text/plain; charset=utf-8"
+ assert headers.get("accept-ranges") == "bytes"
+ assert "content-length" in headers
+ assert "last-modified" in headers
+ assert "etag" in headers
+ assert headers["content-range"].startswith("multipart/byteranges; boundary=")
+ boundary = headers["content-range"].split("boundary=")[1]
+
+ assert received_chunks == [
+ # Send the part headers.
+ f"--{boundary}\nContent-Type: text/plain; charset=utf-8\nContent-Range: bytes 0-15/526\n\n".encode(),
+ # Send the first chunk (10 bytes).
+ b"# B\xc3\xa1iZ\xc3\xa9\n",
+ # Send the second chunk (6 bytes).
+ b"\nPower",
+ # Send the new line to separate the parts.
+ b"\n",
+ # Send the part headers. We merge the ranges 20-35 and 35-50 into a single part.
+ f"--{boundary}\nContent-Type: text/plain; charset=utf-8\nContent-Range: bytes 20-50/526\n\n".encode(),
+ # Send the first chunk (10 bytes).
+ b"and exquis",
+ # Send the second chunk (10 bytes).
+ b"ite WSGI/A",
+ # Send the third chunk (10 bytes).
+ b"SGI framew",
+ # Send the last chunk (1 byte).
+ b"o",
+ b"\n",
+ f"\n--{boundary}--\n".encode(),
+ ]