ROLLOUT 1 · Pylons/waitress
pylons__waitress-249
Not solved
453 stotal time
13tool calls
13model calls
6,764tokens generated
112,783prompt tokens read
Empty agent patch
Turn by turn
Token shading: p ≥ 0.9 0.5 – 0.9 0.2 – 0.5 below 0.2. Hover a token for its id and probability.
System instructions 4,822 characters
You are a principal Python software engineer resolving a repository issue in `/workspace`. Your sole objective is to produce a minimal, root-cause source patch that passes every hidden fail-to-pass and pass-to-pass regression test on the first grading run. ## Critical Environment & Grader Rules 1. **Air-Gapped Sandbox & Available CLI Tools**: No network access. Never run `pip`, `uv`, `conda`, or `git fetch`. Note: `rg` (`ripgrep`) is NOT installed in the container — always use `grep -rn --include="*.py"` for fast exact searches so you never waste a tool call on `command not found`. 2. **Protected Grading Paths**: Before running official verification, the grading harness **strips and reverts all changes** to `tests/`, `test/`, `testing/`, `test_*.py`, `*_test.py`, `conftest.py`, `pyproject.toml`, `setup.cfg`, `pytest.ini`, and `tox.ini`. Every part of your fix MUST reside in non-test production source files. 3. **Untracked File Trap (`git add -N .`)**: `submit_patch` stages ALL untracked files inside `/workspace`! Never leave reproduction or scratch files inside `/workspace` — run reproductions inline via `python3 - <<'PY'` or inside `/tmp/repro.py` in a single `run_command`. 4. **Stdout Truncation Rule**: `run_command` truncates stdout after the first 5,000 characters from the TOP. Always run pytest quietly with short tracebacks: `pytest path/to/test_file.py -k pattern -q --tb=short --no-header` If a test file is large, redirect output to `/tmp/pytest.log` and inspect `tail -n 80 /tmp/pytest.log` so failure tracebacks at the bottom are never cut off. 5. **Strict Pacing Discipline**: `get_status` and `submit_patch` are free and do NOT count toward `max_tool_calls`. Target **16-22 counted tool calls total**, and **begin your first `edit_file` change no later than tool call 15**. Reserve at least 4 calls for verification, `git status --short && git diff`, and submission. ## Execution Protocol ### Phase 1 — Pinpoint Code & Tests Immediately (1-2 tool calls) - The user message already contains `Workspace Layout` — do NOT waste a turn running `ls` on top-level directories. - Run a single compound `run_command` with `grep -rn --include="*.py"` to locate: (a) the exact symbols, error strings, or functions from the problem description, (b) **all parallel or sibling implementations** (for example sync + async variants, `Client` + `AsyncClient`, serializer + deserializer, multiple backends/dialects, base + subclass methods, `__init__.py` / `__all__` exports), and (c) the closest existing unit test files under `tests/`. ### Phase 2 — Deep Read & Spec Anchor (2-5 tool calls) - Use `read_file` with generous `start_line` and `end_line` windows (180-300 lines per call so you read whole modules in fewer calls) on the target function/class, callers, type annotations, and neighboring tests. - Before editing, verify every explicit and implicit requirement from the issue: exact parameter names, defaults, boundary/domain edge cases, exception types/messages, `None` vs empty collection vs falsy (`0`, `False`, `""`) semantics, mutability/copying, and return types. ### Phase 3 — Reproduce Bug in One Call (1 tool call) - Run ONE concise command (`python3 - <<'PY' ... PY` or targeted `pytest ... -q --tb=short --no-header`) via `run_command` to observe the exact pre-fix failure. Do NOT spend multiple tool calls writing separate reproduction scripts. ### Phase 4 — Surgical Implementation Across All Parallel Paths (1-4 tool calls) - Begin editing by tool call 15! Use `edit_file` with 4-6 lines of exact surrounding context copied from `read_file`. - Update ALL parallel codepaths (sync/async, multiple classes/dialects, type hints) consistently so partial fixes do not fail sibling tests. - **2-Strike Edit Rule**: If `edit_file` fails twice on the same block due to whitespace or escaping, do not retry `edit_file` a third time — apply an atomic Python transformation via `run_command` and immediately verify `python3 -m py_compile path/to/file.py`. ### Phase 5 — Edge-Case Verification, Diff Hygiene & Clean Exit (2-4 tool calls) - Run a single compound `run_command` testing both your reproduction + boundary edge cases (`None`, empty input, leading/trailing delimiters, subdomain/prefix boundaries, subclass/async parity) AND the relevant existing `pytest` module(s) with `-q --tb=short --no-header`. - Run `git status --short && git diff` via `run_command`. Confirm: - ZERO untracked (`??`) files in `/workspace` (`rm -f` any untracked workspace files immediately), - ZERO modifications to `tests/` or protected config files (`git checkout -- tests/` if touched), - Minimal, clean diff with valid imports and indentation. - Call `submit_patch` once verification passes, then respond with a brief 2-sentence plain-text summary and make NO further tool calls.
Task prompt 3,378 characters
You are evaluating a software engineering task for repository Pylons/waitress. Problem Statement: ReadOnlyFileBasedBuffer does not work with io.IOBase subclasses ReadOnlyFileBasedBuffer checks if it can detect the file length by using `seek` and `tell` methods. While it checks for the file to be able to provide them at https://github.com/Pylons/waitress/blob/master/waitress/buffers.py#L140 it doesn't actually check if those can be used. In `io.IOBase` subclasses that are not seekable, those two methods exist but raise an `UnsupportedOperation`, in case of io.IOBase instance `.seekable` should probably be checked for `True` or the `UnsupportedOperation` should be trapped. Currently waitress is just crashing if it receives an `io.IOBase` subclasses which is not seekable as the file to serve. ## Task Budget (Session terminates when any budget is exhausted) - Time allowance: 7.5 minutes - Tool calls allowance: 30 calls - Max loop iterations: 40 turns ## Execution Environment Rules - Single command timeout: 90 seconds (commands exceeding this fail without ending the session) - Command output limit: 5000 characters - File view limit: 150 lines per read_file call - File character limit: 10000 characters per read_file call - Environment is offline (no network/PyPI access). All repository and test dependencies are ALREADY pre-installed. Do NOT attempt to run pip install or download packages. ## Instructions: 0. All source code is under `/workspace`. Do NOT search outside `/workspace` (e.g. `/usr/`, `/wheels/`, system site-packages). If imports fail, the issue is in the source code under `/workspace`, not in missing system packages. 1. Analyze the problem statement and any provided hints carefully to identify all requested script paths, CLI subcommands, or Python modules. 2. Inspect existing codebase conventions and test files before making edits. 3. Verify your implementation using targeted tests or inline assertions before submitting. 4. Call submit_patch only after your implementation is complete and verified. 5. As your final action, you must return a text-only response reporting your completion to terminate the session. ## Workspace Layout The repository is located at `/workspace`. Here is the directory tree (up to 3 levels): ``` ./CHANGES.txt ./CONTRIBUTORS.txt ./COPYRIGHT.txt ./HISTORY.txt ./LICENSE.txt ./README.rst ./RELEASING.txt ./TODO.txt ./appveyor.yml ./contributing.md ./docs ./rtd.txt ./setup.cfg ./setup.py ./tox.ini ./waitress ./waitress/__init__.py ./waitress/__main__.py ./waitress/adjustments.py ./waitress/buffers.py ./waitress/channel.py ./waitress/compat.py ./waitress/parser.py ./waitress/receiver.py ./waitress/runner.py ./waitress/server.py ./waitress/task.py ./waitress/tests ./waitress/tests/__init__.py ./waitress/tests/fixtureapps ./waitress/tests/test_adjustments.py ./waitress/tests/test_buffers.py ./waitress/tests/test_channel.py ./waitress/tests/test_compat.py ./waitress/tests/test_functional.py ./waitress/tests/test_init.py ./waitress/tests/test_parser.py ./waitress/tests/test_receiver.py ./waitress/tests/test_regression.py ./waitress/tests/test_runner.py ./waitress/tests/test_server.py ./waitress/tests/test_task.py ./waitress/tests/test_trigger.py ./waitress/tests/test_utilities.py ./waitress/tests/test_wasyncore.py ./waitress/trigger.py ./waitress/utilities.py ./waitress/wasyncore.py ```
Turn 1at 16 s244 tokens out2,978 prompt tokens
The user is reporting a bug in `ReadOnlyFileBasedBuffer` in `waitress/buffers.py`. The issue is that `ReadOnlyFileBasedBuffer` assumes that if `seek` and `tell` methods exist, they are usable. However, for some `io.IOBase` subclasses, these methods exist but raise `UnsupportedOperation` if the stream is not seekable. The suggested fix is to check `.seekable()` or trap `UnsupportedOperation`. Plan: 1. Locate the `ReadOnlyFileBasedBuffer` class in `waitress/buffers.py`. 2. Identify the part where it checks for `seek` and `tell`. 3. Create a reproduction script that uses a non-seekable `io.IOBase` subclass and passes it to `ReadOnlyFileBasedBuffer`. 4. Implement the fix. 5. Verify the fix with the reproduction script and existing tests. Let's start by exploring `waitress/buffers.py`.
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" \"ReadOnlyFileBasedBuffer\" ."
}Result of run_command 1,538 characters
{
"status": "ok",
"stdout": "./waitress/buffers.py:132:class ReadOnlyFileBasedBuffer(FileBasedBuffer):\n./waitress/channel.py:21: ReadOnlyFileBasedBuffer,\n./waitress/channel.py:309: if data.__class__ is ReadOnlyFileBasedBuffer:\n./waitress/task.py:21:from .buffers import ReadOnlyFileBasedBuffer\n./waitress/task.py:451: if app_iter.__class__ is ReadOnlyFileBasedBuffer:\n./waitress/task.py:788: 'wsgi.file_wrapper': ReadOnlyFileBasedBuffer,\n./waitress/tests/test_task.py:614: from waitress.buffers import ReadOnlyFileBasedBuffer\n./waitress/tests/test_task.py:616: app_iter = ReadOnlyFileBasedBuffer(f, 8192)\n./waitress/tests/test_task.py:627: from waitress.buffers import ReadOnlyFileBasedBuffer\n./waitress/tests/test_task.py:629: app_iter = ReadOnlyFileBasedBuffer(f, 8192)\n./waitress/tests/test_task.py:641: from waitress.buffers import ReadOnlyFileBasedBuffer\n./waitress/tests/test_task.py:643: app_iter = ReadOnlyFileBasedBuffer(f, 8192)\n./waitress/tests/test_buffers.py:146:class TestReadOnlyFileBasedBuffer(unittest.TestCase):\n./waitress/tests/test_buffers.py:149: from waitress.buffers import ReadOnlyFileBasedBuffer\n./waitress/tests/test_buffers.py:150: return ReadOnlyFileBasedBuffer(file, block_size)\n./waitress/tests/test_channel.py:211: from waitress.buffers import ReadOnlyFileBasedBuffer\n./waitress/tests/test_channel.py:213: wrapper = ReadOnlyFileBasedBuffer(f, 8192)\n",
"stderr": "",
"exit_code": 0
}Generated tokens 244 tokens · stopped: STOP
<|channel>thought
The user is reporting a bug in `ReadOnlyFileBasedBuffer` in `waitress/buffers.py`.
The issue is that `ReadOnlyFileBasedBuffer` assumes that if `seek` and `tell` methods exist, they are usable. However, for some `io.IOBase` subclasses, these methods exist but raise `UnsupportedOperation` if the stream is not seekable.
The suggested fix is to check `.seekable()` or trap `UnsupportedOperation`.
Plan:
1. Locate the `ReadOnlyFileBasedBuffer` class in `waitress/buffers.py`.
2. Identify the part where it checks for `seek` and `tell`.
3. Create a reproduction script that uses a non-seekable `io.IOBase` subclass and passes it to `ReadOnlyFileBasedBuffer`.
4. Implement the fix.
5. Verify the fix with the reproduction script and existing tests.
Let's start by exploring `waitress/buffers.py`.<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" "ReadOnlyFileBasedBuffer" .<|"|>}<tool_call|><|tool_response>
Turn 2at 22 s73 tokens out3,751 prompt tokens
Okay, the target class is in `waitress/buffers.py`. Let's examine the code around line 132 and specifically the part mentioned in the issue (around line 140).
TOOL CALL · read_file
{
"filepath": "waitress/buffers.py",
"start_line": 132
}Result of read_file 4,731 characters
{
"status": "ok",
"filepath": "waitress/buffers.py",
"content": "class ReadOnlyFileBasedBuffer(FileBasedBuffer):\n # used as wsgi.file_wrapper\n\n def __init__(self, file, block_size=32768):\n self.file = file\n self.block_size = block_size # for __iter__\n\n def prepare(self, size=None):\n if hasattr(self.file, 'seek') and hasattr(self.file, 'tell'):\n start_pos = self.file.tell()\n self.file.seek(0, 2)\n end_pos = self.file.tell()\n self.file.seek(start_pos)\n fsize = end_pos - start_pos\n if size is None:\n self.remain = fsize\n else:\n self.remain = min(fsize, size)\n return self.remain\n\n def get(self, numbytes=-1, skip=False):\n # never read more than self.remain (it can be user-specified)\n if numbytes == -1 or numbytes > self.remain:\n numbytes = self.remain\n file = self.file\n if not skip:\n read_pos = file.tell()\n res = file.read(numbytes)\n if skip:\n self.remain -= len(res)\n else:\n file.seek(read_pos)\n return res\n\n def __iter__(self): # called by task if self.filelike has no seek/tell\n return self\n\n def next(self):\n val = self.file.read(self.block_size)\n if not val:\n raise StopIteration\n return val\n\n __next__ = next # py3\n\n def append(self, s):\n raise NotImplementedError\n\nclass OverflowableBuffer(object):\n \"\"\"\n This buffer implementation has four stages:\n - No data\n - Bytes-based buffer\n - BytesIO-based buffer\n - Temporary file storage\n The first two stages are fastest for simple transfers.\n \"\"\"\n\n overflowed = False\n buf = None\n strbuf = b'' # Bytes-based buffer.\n\n def __init__(self, overflow):\n # overflow is the maximum to be stored in a StringIO buffer.\n self.overflow = overflow\n\n def __len__(self):\n buf = self.buf\n if buf is not None:\n # use buf.__len__ rather than len(buf) FBO of not getting\n # OverflowError on Python 2\n return buf.__len__()\n else:\n return self.strbuf.__len__()\n\n def __nonzero__(self):\n # use self.__len__ rather than len(self) FBO of not getting\n # OverflowError on Python 2\n return self.__len__() > 0\n\n __bool__ = __nonzero__ # py3\n\n def _create_buffer(self):\n strbuf = self.strbuf\n if len(strbuf) >= self.overflow:\n self._set_large_buffer()\n else:\n self._set_small_buffer()\n buf = self.buf\n if strbuf:\n buf.append(self.strbuf)\n self.strbuf = b''\n return buf\n\n def _set_small_buffer(self):\n self.buf = BytesIOBasedBuffer(self.buf)\n self.overflowed = False\n\n def _set_large_buffer(self):\n self.buf = TempfileBasedBuffer(self.buf)\n self.overflowed = True\n\n def append(self, s):\n buf = self.buf\n if buf is None:\n strbuf = self.strbuf\n if len(strbuf) + len(s) < STRBUF_LIMIT:\n self.strbuf = strbuf + s\n return\n buf = self._create_buffer()\n buf.append(s)\n # use buf.__len__ rather than len(buf) FBO of not getting\n # OverflowError on Python 2\n sz = buf.__len__()\n if not self.overflowed:\n if sz >= self.overflow:\n self._set_large_buffer()\n\n def get(self, numbytes=-1, skip=False):\n buf = self.buf\n if buf is None:\n strbuf = self.strbuf\n if not skip:\n return strbuf\n buf = self._create_buffer()\n return buf.get(numbytes, skip)\n\n def skip(self, numbytes, allow_prune=False):\n buf = self.buf\n if buf is None:\n if allow_prune and numbytes == len(self.strbuf):\n # We could slice instead of converting to\n # a buffer, but that would eat up memory in\n # large transfers.\n self.strbuf = b''\n return\n buf = self._create_buffer()\n buf.skip(numbytes, allow_prune)\n\n def prune(self):\n \"\"\"\n A potentially expensive operation that removes all data\n already retrieved from the buffer.\n \"\"\"\n buf = self.buf\n if buf is None:\n self.strbuf = b''\n return\n buf.prune()\n if self.overflowed:",
"start_line": 132,
"end_line": 281,
"total_lines": 298,
"is_truncated": true
}Generated tokens 73 tokens · stopped: STOP
Okay, the target class is in `waitress/buffers.py`. Let's examine the code around line 132 and specifically the part mentioned in the issue (around line 140).
<channel|><|tool_call>call:read_file{filepath:<|"|>waitress/buffers.py<|"|>,start_line:132}<tool_call|><|tool_response>
Turn 3at 56 s458 tokens out5,227 prompt tokens
The code in `prepare` is:
```python
def prepare(self, size=None):
if hasattr(self.file, 'seek') and hasattr(self.file, 'tell'):
start_pos = self.file.tell()
self.file.seek(0, 2)
end_pos = self.file.tell()
self.file.seek(start_pos)
fsize = end_pos - start_pos
if size is None:
self.remain = fsize
else:
self.remain = min(fsize, size)
return self.remain
```
The problem is that `hasattr(self.file, 'seek')` is true for all `io.IOBase` objects, but some may not be seekable.
Let's create a reproduction script. I'll use `io.RawIOBase` or `io.BufferedIOBase` and override `seek`/`tell` to raise `io.UnsupportedOperation`. Actually, `io.BufferedReader` would work, or just a custom class that inherits from `io.IOBase`.
Wait, `io.IOBase` already has `seek` and `tell` methods defined, but they raise `io.UnsupportedOperation` by default if not implemented.
Let's try this:
TOOL CALL · run_command
{
"command": "python3 - <<'PY'\nimport io\nfrom waitress.buffers import ReadOnlyFileBasedBuffer\n\nclass NonSeekableIO(io.IOBase):\n def readable(self):\n return True\n def read(self, size=-1):\n return b\"hello world\"\n\nf = NonSeekableIO()\nbuffer = ReadOnlyFileBasedBuffer(f)\ntry:\n buffer.prepare()\n print(\"Success\")\nexcept io.UnsupportedOperation as e:\n print(f\"Caught expected exception: {e}\")\nexcept Exception as e:\n print(f\"Caught unexpected exception: {type(e).__name__}: {e}\")\nPY\n"
}Result of run_command 93 characters
{
"status": "ok",
"stdout": "Caught expected exception: seek\n",
"stderr": "",
"exit_code": 0
}Generated tokens 458 tokens · stopped: STOP
The code in `prepare` is:
```python
def prepare(self, size=None):
if hasattr(self.file, 'seek') and hasattr(self.file, 'tell'):
start_pos = self.file.tell()
self.file.seek(0, 2)
end_pos = self.file.tell()
self.file.seek(start_pos)
fsize = end_pos - start_pos
if size is None:
self.remain = fsize
else:
self.remain = min(fsize, size)
return self.remain
```
The problem is that `hasattr(self.file, 'seek')` is true for all `io.IOBase` objects, but some may not be seekable.
Let's create a reproduction script. I'll use `io.RawIOBase` or `io.BufferedIOBase` and override `seek`/`tell` to raise `io.UnsupportedOperation`. Actually, `io.BufferedReader` would work, or just a custom class that inherits from `io.IOBase`.
Wait, `io.IOBase` already has `seek` and `tell` methods defined, but they raise `io.UnsupportedOperation` by default if not implemented.
Let's try this:
<channel|><|tool_call>call:run_command{command:<|"|>python3 - <<'PY'
import io
from waitress.buffers import ReadOnlyFileBasedBuffer
class NonSeekableIO(io.IOBase):
def readable(self):
return True
def read(self, size=-1):
return b"hello world"
f = NonSeekableIO()
buffer = ReadOnlyFileBasedBuffer(f)
try:
buffer.prepare()
print("Success")
except io.UnsupportedOperation as e:
print(f"Caught expected exception: {e}")
except Exception as e:
print(f"Caught unexpected exception: {type(e).__name__}: {e}")
PY
<|"|>}<tool_call|><|tool_response>
Turn 4at 79 s448 tokens out5,730 prompt tokens
Confirmed. The code crashes with `io.UnsupportedOperation` when `seek` or `tell` is called on a non-seekable `io.IOBase` subclass, even though the methods exist.
Also, I should check `get` method in `ReadOnlyFileBasedBuffer`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
file = self.file
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
```
Wait, the `get` method also uses `tell` and `seek`!
```python
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
```
If `skip` is `False`, it does `file.tell()` and `file.seek(read_pos)`. Why?
Ah, I see. It's trying to read `numbytes` but then seek back to `read_pos` if `skip` is `False`.
Wait, if `skip` is `False`, it reads and then seeks back? That seems weird for a buffer's `get` method.
Let's look at `FileBasedBuffer` if it exists. `ReadOnlyFileBasedBuffer` inherits from `FileBasedBuffer`.
Let's read `waitress/buffers.py` from the beginning to see `FileBasedBuffer`.
TOOL CALL · read_file
{
"end_line": 131,
"filepath": "waitress/buffers.py",
"start_line": 1
}Result of read_file 3,972 characters
{
"status": "ok",
"filepath": "waitress/buffers.py",
"content": "##############################################################################\n#\n# Copyright (c) 2001-2004 Zope Foundation and Contributors.\n# All Rights Reserved.\n#\n# This software is subject to the provisions of the Zope Public License,\n# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.\n# THIS SOFTWARE IS PROVIDED \"AS IS\" AND ANY AND ALL EXPRESS OR IMPLIED\n# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED\n# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS\n# FOR A PARTICULAR PURPOSE.\n#\n##############################################################################\n\"\"\"Buffers\n\"\"\"\nfrom io import BytesIO\n\n# copy_bytes controls the size of temp. strings for shuffling data around.\nCOPY_BYTES = 1 << 18 # 256K\n\n# The maximum number of bytes to buffer in a simple string.\nSTRBUF_LIMIT = 8192\n\nclass FileBasedBuffer(object):\n\n remain = 0\n\n def __init__(self, file, from_buffer=None):\n self.file = file\n if from_buffer is not None:\n from_file = from_buffer.getfile()\n read_pos = from_file.tell()\n from_file.seek(0)\n while True:\n data = from_file.read(COPY_BYTES)\n if not data:\n break\n file.write(data)\n self.remain = int(file.tell() - read_pos)\n from_file.seek(read_pos)\n file.seek(read_pos)\n\n def __len__(self):\n return self.remain\n\n def __nonzero__(self):\n return True\n\n __bool__ = __nonzero__ # py3\n\n def append(self, s):\n file = self.file\n read_pos = file.tell()\n file.seek(0, 2)\n file.write(s)\n file.seek(read_pos)\n self.remain = self.remain + len(s)\n\n def get(self, numbytes=-1, skip=False):\n file = self.file\n if not skip:\n read_pos = file.tell()\n if numbytes < 0:\n # Read all\n res = file.read()\n else:\n res = file.read(numbytes)\n if skip:\n self.remain -= len(res)\n else:\n file.seek(read_pos)\n return res\n\n def skip(self, numbytes, allow_prune=0):\n if self.remain < numbytes:\n raise ValueError(\"Can't skip %d bytes in buffer of %d bytes\" % (\n numbytes, self.remain)\n )\n self.file.seek(numbytes, 1)\n self.remain = self.remain - numbytes\n\n def newfile(self):\n raise NotImplementedError()\n\n def prune(self):\n file = self.file\n if self.remain == 0:\n read_pos = file.tell()\n file.seek(0, 2)\n sz = file.tell()\n file.seek(read_pos)\n if sz == 0:\n # Nothing to prune.\n return\n nf = self.newfile()\n while True:\n data = file.read(COPY_BYTES)\n if not data:\n break\n nf.write(data)\n self.file = nf\n\n def getfile(self):\n return self.file\n\n def close(self):\n if hasattr(self.file, 'close'):\n self.file.close()\n self.remain = 0\n\nclass TempfileBasedBuffer(FileBasedBuffer):\n\n def __init__(self, from_buffer=None):\n FileBasedBuffer.__init__(self, self.newfile(), from_buffer)\n\n def newfile(self):\n from tempfile import TemporaryFile\n return TemporaryFile('w+b')\n\nclass BytesIOBasedBuffer(FileBasedBuffer):\n\n def __init__(self, from_buffer=None):\n if from_buffer is not None:\n FileBasedBuffer.__init__(self, BytesIO(), from_buffer)\n else:\n # Shortcut. :-)\n self.file = BytesIO()\n\n def newfile(self):\n return BytesIO()\n",
"start_line": 1,
"end_line": 131,
"total_lines": 298,
"is_truncated": false
}Generated tokens 448 tokens · stopped: STOP
Confirmed. The code crashes with `io.UnsupportedOperation` when `seek` or `tell` is called on a non-seekable `io.IOBase` subclass, even though the methods exist.
Also, I should check `get` method in `ReadOnlyFileBasedBuffer`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
file = self.file
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
```
Wait, the `get` method also uses `tell` and `seek`!
```python
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
```
If `skip` is `False`, it does `file.tell()` and `file.seek(read_pos)`. Why?
Ah, I see. It's trying to read `numbytes` but then seek back to `read_pos` if `skip` is `False`.
Wait, if `skip` is `False`, it reads and then seeks back? That seems weird for a buffer's `get` method.
Let's look at `FileBasedBuffer` if it exists. `ReadOnlyFileBasedBuffer` inherits from `FileBasedBuffer`.
Let's read `waitress/buffers.py` from the beginning to see `FileBasedBuffer`.<channel|><|tool_call>call:read_file{filepath:<|"|>waitress/buffers.py<|"|>,start_line:1,end_line:131}<tool_call|><|tool_response>
Turn 5at 113 s490 tokens out7,347 prompt tokens
The `ReadOnlyFileBasedBuffer.get` method is almost identical to `FileBasedBuffer.get`. Both of them seem to do something strange:
```python
def get(self, numbytes=-1, skip=False):
# ...
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
```
Wait, if `skip` is `False`, it returns the data but *seeks back* to where it was?
Looking at this again:
1. `read_pos = file.tell()`
2. `res = file.read(numbytes)`
3. `file.seek(read_pos)`
4. `return res`
Yes, if `skip=False`, the file pointer is NOT advanced.
Wait, if the file pointer is not advanced, and `get` is called again with `skip=False`, it will return the same data again?
Wait, `ReadOnlyFileBasedBuffer` is used as `wsgi.file_wrapper`. WSGI servers usually call `read()` on the returned iterator (or call `__next__` on it).
`ReadOnlyFileBasedBuffer` has `__iter__` and `next`:
```python
def __iter__(self): # called by task if self.filelike has no seek/tell
return self
def next(self):
val = self.file.read(self.block_size)
if not val:
raise StopIteration
return val
__next__ = next # py3
```
If it's used as an iterator (which is standard for `wsgi.file_wrapper`), `next()` is called, which just calls `file.read(self.block_size)`. This advances the file pointer.
But there is also a `get` method. Who calls `get`?
Let's search for calls to `get` on `ReadOnlyFileBasedBuffer`.
TOOL CALL · run_command
{
"command": "grep -rn \".get(\" . | grep -v \"test_\""
}Result of run_command 2,009 characters
{
"status": "ok",
"stdout": "./waitress/parser.py:210: connection = headers.get('CONNECTION', '')\n./waitress/parser.py:226: expect = headers.get('EXPECT', '').lower()\n./waitress/parser.py:233: cl = int(headers.get('CONTENT_LENGTH', 0))\n./waitress/adjustments.py:466: kw['listen'] = '{} {}'.format(kw.get('listen', ''), value)\n./waitress/wasyncore.py:160: obj = map.get(fd)\n./waitress/wasyncore.py:166: obj = map.get(fd)\n./waitress/wasyncore.py:172: obj = map.get(fd)\n./waitress/wasyncore.py:204: obj = map.get(fd)\n./waitress/wasyncore.py:455: self.logger.log(severity.get(type, logging.INFO), message)\n./waitress/buffers.py:59: def get(self, numbytes=-1, skip=False):\n./waitress/buffers.py:152: def get(self, numbytes=-1, skip=False):\n./waitress/buffers.py:250: def get(self, numbytes=-1, skip=False):\n./waitress/buffers.py:257: return buf.get(numbytes, skip)\n./waitress/channel.py:228: chunk = outbuf.get(self.sendbuf_len)\n./waitress/task.py:195: connection = self.request.headers.get('CONNECTION', '').lower()\n./waitress/task.py:369: connection = self.request.headers.get('CONNECTION', '').lower()\n./waitress/task.py:563: forwarded_proto = undquote(headers.get(\"X_FORWARDED_PROTO\", \"\"))\n./waitress/task.py:571: forwarded_port = undquote(headers.get(\"X_FORWARDED_PORT\", \"\"))\n./waitress/task.py:584: forwarded = headers.get(\"FORWARDED\", None)\n./waitress/task.py:825: mykey = rename_headers.get(key, None)\n./waitress/tests/fixtureapps/nocl.py:12: cl = environ.get('CONTENT_LENGTH', None)\n./waitress/tests/fixtureapps/echo.py:2: cl = environ.get('CONTENT_LENGTH', None)\n./waitress/tests/fixtureapps/error.py:2: cl = environ.get('CONTENT_LENGTH', None)\n./docs/socket-activation.rst:18: content_length = environ.get('CONTENT_LENGTH', None)\n",
"stderr": "",
"exit_code": 0
}Generated tokens 490 tokens · stopped: STOP
The `ReadOnlyFileBasedBuffer.get` method is almost identical to `FileBasedBuffer.get`. Both of them seem to do something strange:
```python
def get(self, numbytes=-1, skip=False):
# ...
if not skip:
read_pos = file.tell()
res = file.read(numbytes)
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
```
Wait, if `skip` is `False`, it returns the data but *seeks back* to where it was?
Looking at this again:
1. `read_pos = file.tell()`
2. `res = file.read(numbytes)`
3. `file.seek(read_pos)`
4. `return res`
Yes, if `skip=False`, the file pointer is NOT advanced.
Wait, if the file pointer is not advanced, and `get` is called again with `skip=False`, it will return the same data again?
Wait, `ReadOnlyFileBasedBuffer` is used as `wsgi.file_wrapper`. WSGI servers usually call `read()` on the returned iterator (or call `__next__` on it).
`ReadOnlyFileBasedBuffer` has `__iter__` and `next`:
```python
def __iter__(self): # called by task if self.filelike has no seek/tell
return self
def next(self):
val = self.file.read(self.block_size)
if not val:
raise StopIteration
return val
__next__ = next # py3
```
If it's used as an iterator (which is standard for `wsgi.file_wrapper`), `next()` is called, which just calls `file.read(self.block_size)`. This advances the file pointer.
But there is also a `get` method. Who calls `get`?
Let's search for calls to `get` on `ReadOnlyFileBasedBuffer`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn ".get(" . | grep -v "test_"<|"|>}<tool_call|><|tool_response>
Turn 6at 118 s87 tokens out8,555 prompt tokens
In `waitress/channel.py:228`: `chunk = outbuf.get(self.sendbuf_len)`. Let's see what `outbuf` is in `waitress/channel.py`.
TOOL CALL · read_file
{
"end_line": 250,
"filepath": "waitress/channel.py",
"start_line": 200
}Result of read_file 2,050 characters
{
"status": "ok",
"filepath": "waitress/channel.py",
"content": " self.server.add_task(self)\n\n return True\n\n def _flush_some_if_lockable(self):\n # Since our task may be appending to the outbuf, we try to acquire\n # the lock, but we don't block if we can't.\n if self.outbuf_lock.acquire(False):\n try:\n self._flush_some()\n\n if self.total_outbufs_len < self.adj.outbuf_high_watermark:\n self.outbuf_lock.notify()\n finally:\n self.outbuf_lock.release()\n\n def _flush_some(self):\n # Send as much data as possible to our client\n\n sent = 0\n dobreak = False\n\n while True:\n outbuf = self.outbufs[0]\n # use outbuf.__len__ rather than len(outbuf) FBO of not getting\n # OverflowError on 32-bit Python\n outbuflen = outbuf.__len__()\n while outbuflen > 0:\n chunk = outbuf.get(self.sendbuf_len)\n num_sent = self.send(chunk)\n if num_sent:\n outbuf.skip(num_sent, True)\n outbuflen -= num_sent\n sent += num_sent\n self.total_outbufs_len -= num_sent\n else:\n # failed to write anything, break out entirely\n dobreak = True\n break\n else:\n # self.outbufs[-1] must always be a writable outbuf\n if len(self.outbufs) > 1:\n toclose = self.outbufs.pop(0)\n try:\n toclose.close()\n except Exception:\n self.logger.exception(\n 'Unexpected error when closing an outbuf')\n else:\n # caught up, done flushing for now\n dobreak = True",
"start_line": 200,
"end_line": 250,
"total_lines": 415,
"is_truncated": false
}Generated tokens 87 tokens · stopped: STOP
In `waitress/channel.py:228`: `chunk = outbuf.get(self.sendbuf_len)`.
Let's see what `outbuf` is in `waitress/channel.py`.
<channel|><|tool_call>call:read_file{filepath:<|"|>waitress/channel.py<|"|>,start_line:200,end_line:250}<tool_call|><|tool_response>
Turn 7at 152 s484 tokens out9,204 prompt tokens
OK, so in `_flush_some`:
```python
chunk = outbuf.get(self.sendbuf_len)
num_sent = self.send(chunk)
if num_sent:
outbuf.skip(num_sent, True)
outbuflen -= num_sent
sent += num_sent
self.total_outbufs_len -= num_sent
```
When `outbuf.get(self.sendbuf_len)` is called, `skip` defaults to `False`. So it reads `self.sendbuf_len` bytes, but then seeks back. Then `outbuf.skip(num_sent, True)` is called, which actually advances the file pointer by `num_sent` bytes.
Since `num_sent` might be less than `len(chunk)`, this pattern allows it to handle partial sends.
But the point is, if `outbuf` is a `ReadOnlyFileBasedBuffer` wrapping a non-seekable file, `get(..., skip=False)` will call `tell()` and `seek()`, which will raise `UnsupportedOperation`. And `skip(...)` will call `seek(numbytes, 1)`, which will also raise `UnsupportedOperation`.
So the fix needs to address both `prepare`, `get` and `skip`.
Wait, if the file is not seekable, can we even use `ReadOnlyFileBasedBuffer`?
If it's not seekable, we can't use `prepare` to find the size, and we can't use `get(..., skip=False)` or `skip()`.
However, the `ReadOnlyFileBasedBuffer` is also an iterator (`__next__`).
If the WSGI server uses it as an iterator and just calls `next()`, it stays in `next()` and doesn't use `get` or `skip`.
But `waitress` seems to use `get` and `skip` in `_flush_some`.
Let's see where `outbufs` are populated. In `waitress/task.py`.
TOOL CALL · run_command
{
"command": "grep -rn \"self.channel.outbufs.append\" waitress/task.py"
}Result of run_command 127 characters
{
"status": "error",
"error_type": "CommandError",
"error_message": "",
"details": {
"stdout": "",
"stderr": "",
"exit_code": 1
}
}Generated tokens 484 tokens · stopped: STOP
OK, so in `_flush_some`:
```python
chunk = outbuf.get(self.sendbuf_len)
num_sent = self.send(chunk)
if num_sent:
outbuf.skip(num_sent, True)
outbuflen -= num_sent
sent += num_sent
self.total_outbufs_len -= num_sent
```
When `outbuf.get(self.sendbuf_len)` is called, `skip` defaults to `False`. So it reads `self.sendbuf_len` bytes, but then seeks back. Then `outbuf.skip(num_sent, True)` is called, which actually advances the file pointer by `num_sent` bytes.
Since `num_sent` might be less than `len(chunk)`, this pattern allows it to handle partial sends.
But the point is, if `outbuf` is a `ReadOnlyFileBasedBuffer` wrapping a non-seekable file, `get(..., skip=False)` will call `tell()` and `seek()`, which will raise `UnsupportedOperation`. And `skip(...)` will call `seek(numbytes, 1)`, which will also raise `UnsupportedOperation`.
So the fix needs to address both `prepare`, `get` and `skip`.
Wait, if the file is not seekable, can we even use `ReadOnlyFileBasedBuffer`?
If it's not seekable, we can't use `prepare` to find the size, and we can't use `get(..., skip=False)` or `skip()`.
However, the `ReadOnlyFileBasedBuffer` is also an iterator (`__next__`).
If the WSGI server uses it as an iterator and just calls `next()`, it stays in `next()` and doesn't use `get` or `skip`.
But `waitress` seems to use `get` and `skip` in `_flush_some`.
Let's see where `outbufs` are populated. In `waitress/task.py`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn "self.channel.outbufs.append" waitress/task.py<|"|>}<tool_call|><|tool_response>
Turn 8at 154 s38 tokens out9,743 prompt tokens
Maybe just `outbufs.append`.
TOOL CALL · run_command
{
"command": "grep -rn \"outbufs.append\" waitress/task.py"
}Result of run_command 127 characters
{
"status": "error",
"error_type": "CommandError",
"error_message": "",
"details": {
"stdout": "",
"stderr": "",
"exit_code": 1
}
}Generated tokens 38 tokens · stopped: STOP
Maybe just `outbufs.append`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn "outbufs.append" waitress/task.py<|"|>}<tool_call|><|tool_response>
Turn 9at 155 s46 tokens out9,836 prompt tokens
Let's search for `outbufs` in `waitress/task.py`.
TOOL CALL · run_command
{
"command": "grep -rn \"outbufs\" waitress/task.py"
}Result of run_command 127 characters
{
"status": "error",
"error_type": "CommandError",
"error_message": "",
"details": {
"stdout": "",
"stderr": "",
"exit_code": 1
}
}Generated tokens 46 tokens · stopped: STOP
Let's search for `outbufs` in `waitress/task.py`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn "outbufs" waitress/task.py<|"|>}<tool_call|><|tool_response>
Turn 10at 164 s107 tokens out9,937 prompt tokens
Strange. Let me check `waitress/channel.py` again. It has `self.outbufs`. Maybe it's `server.outbufs`? No, `channel.py` says `self.outbufs`. Wait, `channel.py` is probably where `outbufs` list is managed. Let's search for `outbufs` in the whole project.
TOOL CALL · run_command
{
"command": "grep -rn \"outbufs\" ."
}Result of run_command 5,193 characters
{
"status": "ok",
"stdout": "./waitress/channel.py:56: total_outbufs_len = 0 # total bytes ready to send\n./waitress/channel.py:73: self.outbufs = [OverflowableBuffer(adj.outbuf_overflow)]\n./waitress/channel.py:91: return self.total_outbufs_len or self.will_close\n./waitress/channel.py:108: elif self.total_outbufs_len >= self.adj.send_bytes:\n./waitress/channel.py:130: if self.close_when_flushed and not self.total_outbufs_len:\n./waitress/channel.py:143: return not (self.will_close or self.requests or self.total_outbufs_len)\n./waitress/channel.py:180: self.outbufs[-1].append(outbuf_payload)\n./waitress/channel.py:182: self.total_outbufs_len += len(outbuf_payload)\n./waitress/channel.py:211: if self.total_outbufs_len < self.adj.outbuf_high_watermark:\n./waitress/channel.py:223: outbuf = self.outbufs[0]\n./waitress/channel.py:234: self.total_outbufs_len -= num_sent\n./waitress/channel.py:240: # self.outbufs[-1] must always be a writable outbuf\n./waitress/channel.py:241: if len(self.outbufs) > 1:\n./waitress/channel.py:242: toclose = self.outbufs.pop(0)\n./waitress/channel.py:263: for outbuf in self.outbufs:\n./waitress/channel.py:269: self.total_outbufs_len = 0\n./waitress/channel.py:306: self._flush_outbufs_below_high_watermark()\n./waitress/channel.py:311: self.outbufs.append(data)\n./waitress/channel.py:313: self.outbufs.append(nextbuf)\n./waitress/channel.py:320: self.outbufs.append(nextbuf)\n./waitress/channel.py:322: self.outbufs[-1].append(data)\n./waitress/channel.py:325: self.total_outbufs_len += num_bytes\n./waitress/channel.py:333: def _flush_outbufs_below_high_watermark(self):\n./waitress/channel.py:335: if self.total_outbufs_len > self.adj.outbuf_high_watermark:\n./waitress/channel.py:339: self.total_outbufs_len > self.adj.outbuf_high_watermark\n./waitress/channel.py:395: # much data in the outbufs waiting to be flushed\n./waitress/channel.py:402: self._flush_outbufs_below_high_watermark()\n./waitress/tests/test_channel.py:26: def test_total_outbufs_len_an_outbuf_size_gt_sys_maxint(self):\n./waitress/tests/test_channel.py:36: inst.total_outbufs_len = 1\n./waitress/tests/test_channel.py:37: inst.outbufs = [DummyBuffer()]\n./waitress/tests/test_channel.py:41: self.assertEqual(inst.total_outbufs_len, MAXINT+1)\n./waitress/tests/test_channel.py:45: inst.total_outbufs_len = 3\n./waitress/tests/test_channel.py:73: inst.outbufs = [DummyBuffer(b'abc')]\n./waitress/tests/test_channel.py:74: inst.total_outbufs_len = len(inst.outbufs[0])\n./waitress/tests/test_channel.py:86: inst.outbufs = [outbuf]\n./waitress/tests/test_channel.py:87: inst.total_outbufs_len = len(outbuf)\n./waitress/tests/test_channel.py:101: inst.outbufs = [outbuf]\n./waitress/tests/test_channel.py:102: inst.total_outbufs_len = len(outbuf)\n./waitress/tests/test_channel.py:116: inst.outbufs = [outbuf]\n./waitress/tests/test_channel.py:129: inst.outbufs = [DummyBuffer(b'abc')]\n./waitress/tests/test_channel.py:130: inst.total_outbufs_len = len(inst.outbufs[0])\n./waitress/tests/test_channel.py:143: inst.outbufs = [outbuf]\n./waitress/tests/test_channel.py:144: inst.total_outbufs_len = len(outbuf)\n./waitress/tests/test_channel.py:202: self.assertEqual(len(inst.outbufs[0]), 0)\n./waitress/tests/test_channel.py:208: self.assertEqual(len(inst.outbufs[0]), 1)\n./waitress/tests/test_channel.py:216: outbufs = inst.outbufs\n./waitress/tests/test_channel.py:217: orig_outbuf = outbufs[0]\n./waitress/tests/test_channel.py:220: self.assertEqual(len(outbufs), 3)\n./waitress/tests/test_channel.py:221: self.assertEqual(outbufs[0], orig_outbuf)\n./waitress/tests/test_channel.py:222: self.assertEqual(outbufs[1], wrapper)\n./waitress/tests/test_channel.py:223: self.assertEqual(outbufs[2].__class__.__name__, 'OverflowableBuffer')\n./waitress/tests/test_channel.py:236: inst._flush_outbufs_below_high_watermark = dummy_flush\n./waitress/tests/test_channel.py:245: self.assertEqual(len(inst.outbufs), 2)\n./waitress/tests/test_channel.py:246: self.assertEqual(inst.outbufs[0].get(), b'')\n./waitress/tests/test_channel.py:247: self.assertEqual(inst.outbufs[1].get(), b'xyz')\n./waitress/tests/test_channel.py:252: inst.total_outbufs_len = 4\n./waitress/tests/test_channel.py:256: inst.total_outbufs_len = 0\n./waitress/tests/test_channel.py:261: self.assertEqual(len(inst.outbufs), 2)\n./waitress/tests/test_channel.py:262: self.assertEqual(inst.outbufs[0].get(), b'')\n./waitress/tests/test_channel.py:263: self.assertEqual(inst.outbufs[1].get(), b'xyz",
"stderr": "grep: ./waitress/__pycache__/channel.cpython-37.pyc: binary file matches\n",
"exit_code": 0
}Generated tokens 107 tokens · stopped: STOP
Strange. Let me check `waitress/channel.py` again. It has `self.outbufs`.
Maybe it's `server.outbufs`? No, `channel.py` says `self.outbufs`.
Wait, `channel.py` is probably where `outbufs` list is managed.
Let's search for `outbufs` in the whole project.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn "outbufs" .<|"|>}<tool_call|><|tool_response>
Turn 11at 297 s2,088 tokens out11,930 prompt tokens
In `waitress/channel.py:311`, `self.outbufs.append(data)` where `data` might be a `ReadOnlyFileBasedBuffer`.
If we have a `ReadOnlyFileBasedBuffer` wrapping a non-seekable file, and it's added to `outbufs`, then `_flush_some` will call `get` and `skip`, which will both fail with `UnsupportedOperation`.
So, the solution should be:
In `ReadOnlyFileBasedBuffer`, check if the file is seekable. If it's not, we should probably avoid using `seek` and `tell`.
In `prepare`:
If not seekable, we can't know the file size. We can set `self.remain` to something that indicates unknown size, or maybe just 0 and hope `get` handles it?
Wait, `get` uses `self.remain`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is 0, `get` will read 0 bytes. This is not good.
But if it's not seekable, we can just read until EOF.
Wait, if the file is not seekable, maybe we shouldn't be using `ReadOnlyFileBasedBuffer` at all? But the user is reporting that it crashes when it *is* used.
Actually, if it's not seekable, `ReadOnlyFileBasedBuffer` should behave as a simple stream.
Let's see how to check if it's seekable. `io.IOBase` objects have a `seekable()` method.
```python
def prepare(self, size=None):
if hasattr(self.file, 'seekable') and self.file.seekable():
# ... current seek/tell logic ...
else:
# what to do if not seekable?
# we can't know the size.
# Maybe set self.remain to a very large number?
# Or maybe use some other mechanism.
```
Wait, if `self.remain` is used to limit reading, and we don't know the size, we might as well set it to something that doesn't limit reading.
But look at `get`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is, say, `float('inf')`, then `numbytes` will be `self.sendbuf_len` (if `numbytes` was `-1` or `> self.remain`).
What about `skip`?
```python
def skip(self, numbytes, allow_prune=False):
# (Wait, ReadOnlyFileBasedBuffer does not have skip method, it inherits from FileBasedBuffer)
```
Let's check `FileBasedBuffer.skip`:
```python
def skip(self, numbytes, allow_prune=0):
if self.remain < numbytes:
raise ValueError("Can't skip %d bytes in buffer of %d bytes" % (
numbytes, self.remain)
)
self.file.seek(numbytes, 1)
self.remain = self.remain - numbytes
```
If `ReadOnlyFileBasedBuffer` doesn't override `skip`, it uses `FileBasedBuffer.skip`, which calls `self.file.seek(numbytes, 1)`. This will fail on non-seekable files.
Wait, `ReadOnlyFileBasedBuffer` probably *should* override `skip` too if we want to support non-seekable files. But how do you skip in a non-seekable file? You have to read and discard.
Similarly, `get(..., skip=False)` does a `seek(read_pos)`. If not seekable, it can't do that.
If the file is not seekable, `ReadOnlyFileBasedBuffer` cannot support `get(..., skip=False)` and `skip()`.
But these are used by `waitress/channel.py` for handling partial sends.
If the file is not seekable, we can't "peek" at the data using `get(..., skip=False)` and then "skip" it. We must read it and store it in a buffer.
Wait! If the file is not seekable, we can't use it as a `FileBasedBuffer` in the way `waitress` expects. We should probably read it into an `OverflowableBuffer`.
However, the issue is specifically about `ReadOnlyFileBasedBuffer`.
If `ReadOnlyFileBasedBuffer` is wrapping a non-seekable file, the only way to support `get` and `skip` is to read the data and keep it. But then it's not a "file based buffer" anymore, it's just a buffer.
Let's re-read the problem statement:
"In `io.IOBase` subclasses that are not seekable, those two methods exist but raise an `UnsupportedOperation`, in case of io.IOBase instance `.seekable` should probably be checked for `True` or the `UnsupportedOperation` should be trapped."
This suggests that we should just avoid calling `seek` and `tell` if the file is not seekable.
But if we don't call them in `prepare`, we don't know `self.remain`.
If we don't call them in `get(..., skip=False)`, we can't seek back.
If we don't call them in `skip()`, we can't skip.
Wait, is `ReadOnlyFileBasedBuffer` intended only for seekable files?
The `prepare` method tries to find the size using `seek(0, 2)`. This is a classic way to find the size of a seekable file.
If the file is not seekable, `prepare` should probably not set `self.remain` based on file size.
But if `self.remain` is not set, `get` is broken.
Maybe the intended behavior for non-seekable files is to just let them fail or to handle them differently?
The problem says "currently waitress is just crashing".
If we trap `UnsupportedOperation` in `prepare`, then `self.remain` remains 0 (from the base class).
Then `get` will read 0 bytes.
This still seems broken.
Wait, let's look at `ReadOnlyFileBasedBuffer` again.
```python
class ReadOnlyFileBasedBuffer(FileBasedBuffer):
# used as wsgi.file_wrapper
def __init__(self, file, block_size=32768):
self.file = file
self.block_size = block_size # for __iter__
def prepare(self, size=None):
if hasattr(self.file, 'seek') and hasattr(self.file, 'tell'):
# ...
```
Actually, the `FileBasedBuffer` (the base class) also uses `seek` and `tell` in `__init__`, `append`, `get`, `skip`, and `prune`.
```python
def __init__(self, file, from_buffer=None):
self.file = file
if from_buffer is not None:
from_file = from_buffer.getfile()
read_pos = from_file.tell()
from_file.seek(0)
# ...
from_file.seek(read_pos)
file.seek(read_pos)
def append(self, s):
file = self.file
read_pos = file.tell()
file.seek(0, 2)
file.write(s)
file.seek(read_pos)
self.remain = self.remain + len(s)
def get(self, numbytes=-1, skip=False):
file = self.file
if not skip:
read_pos = file.tell()
# ...
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
def skip(self, numbytes, allow_prune=0):
# ...
self.file.seek(numbytes, 1)
self.remain = self.remain - numbytes
```
It seems `FileBasedBuffer` is fundamentally designed for seekable files.
`ReadOnlyFileBasedBuffer` is a subclass that is intended to be used as a `wsgi.file_wrapper`.
If a non-seekable file is passed as a `wsgi.file_wrapper`, it should probably be handled as a stream.
In `waitress/task.py`, `wsgi.file_wrapper` is used.
Let's see how `ReadOnlyFileBasedBuffer` is used in `task.py`.
TOOL CALL · run_command
{
"command": "grep -n \"ReadOnlyFileBasedBuffer\" waitress/task.py"
}Result of run_command 239 characters
{
"status": "ok",
"stdout": "21:from .buffers import ReadOnlyFileBasedBuffer\n451: if app_iter.__class__ is ReadOnlyFileBasedBuffer:\n788: 'wsgi.file_wrapper': ReadOnlyFileBasedBuffer,\n",
"stderr": "",
"exit_code": 0
}Generated tokens 2,088 tokens · stopped: STOP
In `waitress/channel.py:311`, `self.outbufs.append(data)` where `data` might be a `ReadOnlyFileBasedBuffer`.
If we have a `ReadOnlyFileBasedBuffer` wrapping a non-seekable file, and it's added to `outbufs`, then `_flush_some` will call `get` and `skip`, which will both fail with `UnsupportedOperation`.
So, the solution should be:
In `ReadOnlyFileBasedBuffer`, check if the file is seekable. If it's not, we should probably avoid using `seek` and `tell`.
In `prepare`:
If not seekable, we can't know the file size. We can set `self.remain` to something that indicates unknown size, or maybe just 0 and hope `get` handles it?
Wait, `get` uses `self.remain`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is 0, `get` will read 0 bytes. This is not good.
But if it's not seekable, we can just read until EOF.
Wait, if the file is not seekable, maybe we shouldn't be using `ReadOnlyFileBasedBuffer` at all? But the user is reporting that it crashes when it *is* used.
Actually, if it's not seekable, `ReadOnlyFileBasedBuffer` should behave as a simple stream.
Let's see how to check if it's seekable. `io.IOBase` objects have a `seekable()` method.
```python
def prepare(self, size=None):
if hasattr(self.file, 'seekable') and self.file.seekable():
# ... current seek/tell logic ...
else:
# what to do if not seekable?
# we can't know the size.
# Maybe set self.remain to a very large number?
# Or maybe use some other mechanism.
```
Wait, if `self.remain` is used to limit reading, and we don't know the size, we might as well set it to something that doesn't limit reading.
But look at `get`:
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is, say, `float('inf')`, then `numbytes` will be `self.sendbuf_len` (if `numbytes` was `-1` or `> self.remain`).
What about `skip`?
```python
def skip(self, numbytes, allow_prune=False):
# (Wait, ReadOnlyFileBasedBuffer does not have skip method, it inherits from FileBasedBuffer)
```
Let's check `FileBasedBuffer.skip`:
```python
def skip(self, numbytes, allow_prune=0):
if self.remain < numbytes:
raise ValueError("Can't skip %d bytes in buffer of %d bytes" % (
numbytes, self.remain)
)
self.file.seek(numbytes, 1)
self.remain = self.remain - numbytes
```
If `ReadOnlyFileBasedBuffer` doesn't override `skip`, it uses `FileBasedBuffer.skip`, which calls `self.file.seek(numbytes, 1)`. This will fail on non-seekable files.
Wait, `ReadOnlyFileBasedBuffer` probably *should* override `skip` too if we want to support non-seekable files. But how do you skip in a non-seekable file? You have to read and discard.
Similarly, `get(..., skip=False)` does a `seek(read_pos)`. If not seekable, it can't do that.
If the file is not seekable, `ReadOnlyFileBasedBuffer` cannot support `get(..., skip=False)` and `skip()`.
But these are used by `waitress/channel.py` for handling partial sends.
If the file is not seekable, we can't "peek" at the data using `get(..., skip=False)` and then "skip" it. We must read it and store it in a buffer.
Wait! If the file is not seekable, we can't use it as a `FileBasedBuffer` in the way `waitress` expects. We should probably read it into an `OverflowableBuffer`.
However, the issue is specifically about `ReadOnlyFileBasedBuffer`.
If `ReadOnlyFileBasedBuffer` is wrapping a non-seekable file, the only way to support `get` and `skip` is to read the data and keep it. But then it's not a "file based buffer" anymore, it's just a buffer.
Let's re-read the problem statement:
"In `io.IOBase` subclasses that are not seekable, those two methods exist but raise an `UnsupportedOperation`, in case of io.IOBase instance `.seekable` should probably be checked for `True` or the `UnsupportedOperation` should be trapped."
This suggests that we should just avoid calling `seek` and `tell` if the file is not seekable.
But if we don't call them in `prepare`, we don't know `self.remain`.
If we don't call them in `get(..., skip=False)`, we can't seek back.
If we don't call them in `skip()`, we can't skip.
Wait, is `ReadOnlyFileBasedBuffer` intended only for seekable files?
The `prepare` method tries to find the size using `seek(0, 2)`. This is a classic way to find the size of a seekable file.
If the file is not seekable, `prepare` should probably not set `self.remain` based on file size.
But if `self.remain` is not set, `get` is broken.
Maybe the intended behavior for non-seekable files is to just let them fail or to handle them differently?
The problem says "currently waitress is just crashing".
If we trap `UnsupportedOperation` in `prepare`, then `self.remain` remains 0 (from the base class).
Then `get` will read 0 bytes.
This still seems broken.
Wait, let's look at `ReadOnlyFileBasedBuffer` again.
```python
class ReadOnlyFileBasedBuffer(FileBasedBuffer):
# used as wsgi.file_wrapper
def __init__(self, file, block_size=32768):
self.file = file
self.block_size = block_size # for __iter__
def prepare(self, size=None):
if hasattr(self.file, 'seek') and hasattr(self.file, 'tell'):
# ...
```
Actually, the `FileBasedBuffer` (the base class) also uses `seek` and `tell` in `__init__`, `append`, `get`, `skip`, and `prune`.
```python
def __init__(self, file, from_buffer=None):
self.file = file
if from_buffer is not None:
from_file = from_buffer.getfile()
read_pos = from_file.tell()
from_file.seek(0)
# ...
from_file.seek(read_pos)
file.seek(read_pos)
def append(self, s):
file = self.file
read_pos = file.tell()
file.seek(0, 2)
file.write(s)
file.seek(read_pos)
self.remain = self.remain + len(s)
def get(self, numbytes=-1, skip=False):
file = self.file
if not skip:
read_pos = file.tell()
# ...
if skip:
self.remain -= len(res)
else:
file.seek(read_pos)
return res
def skip(self, numbytes, allow_prune=0):
# ...
self.file.seek(numbytes, 1)
self.remain = self.remain - numbytes
```
It seems `FileBasedBuffer` is fundamentally designed for seekable files.
`ReadOnlyFileBasedBuffer` is a subclass that is intended to be used as a `wsgi.file_wrapper`.
If a non-seekable file is passed as a `wsgi.file_wrapper`, it should probably be handled as a stream.
In `waitress/task.py`, `wsgi.file_wrapper` is used.
Let's see how `ReadOnlyFileBasedBuffer` is used in `task.py`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -n "ReadOnlyFileBasedBuffer" waitress/task.py<|"|>}<tool_call|><|tool_response>
Turn 12at 300 s58 tokens out14,109 prompt tokens
Let's look at `waitress/task.py` around line 451.
TOOL CALL · read_file
{
"end_line": 460,
"filepath": "waitress/task.py",
"start_line": 440
}Result of read_file 998 characters
{
"status": "ok",
"filepath": "waitress/task.py",
"content": "\n self.response_headers.extend(headers)\n\n # Return a method used to write the response data.\n return self.write\n\n # Call the application to handle the request and write a response\n app_iter = self.channel.server.application(env, start_response)\n\n can_close_app_iter = True\n try:\n if app_iter.__class__ is ReadOnlyFileBasedBuffer:\n cl = self.content_length\n size = app_iter.prepare(cl)\n if size:\n if cl != size:\n if cl is not None:\n self.remove_content_length_header()\n self.content_length = size\n self.write(b'') # generate headers\n # if the write_soon below succeeds then the channel will",
"start_line": 440,
"end_line": 460,
"total_lines": 833,
"is_truncated": false
}Generated tokens 58 tokens · stopped: STOP
Let's look at `waitress/task.py` around line 451.
<channel|><|tool_call>call:read_file{end_line:460,filepath:<|"|>waitress/task.py<|"|>,start_line:440}<tool_call|><|tool_response>
Turn 13at 433 s2,143 tokens out14,436 prompt tokens
And line 788:
```python
'wsgi.file_wrapper': ReadOnlyFileBasedBuffer,
```
When `asgi.file_wrapper` is provided, the application can use it to return a file-like object.
The issue is that `ReadOnlyFileBasedBuffer` tries to use `seek` and `tell` in `prepare` to determine the file size, and then `waitress` uses it in `_flush_some` with `get` and `skip`.
If the file is not seekable, we can't use `seek` and `tell`.
The suggested fix is:
"In `io.IOBase` subclasses that are not seekable, those two methods exist but raise an `UnsupportedOperation`, in case of io.IOBase instance `.seekable` should probably be checked for `True` or the `UnsupportedOperation` should be trapped."
Let's try implementing this in `ReadOnlyFileBasedBuffer.prepare`.
What about `get` and `skip`?
If we only fix `prepare`, `_flush_some` will still call `get(..., skip=False)` and `skip()`, which will call `tell()` and `seek()`.
Wait, if `ReadOnlyFileBasedBuffer` is used, it means the user specifically wanted to use a file-based buffer. If they provide a non-seekable file, they should expect it to behave like a stream.
If we want to support non-seekable files in `ReadOnlyFileBasedBuffer`, we must also fix `get` and `skip`.
But `get(..., skip=False)`'s purpose is to peek at the data. If the file is not seekable, you can't peek. You have to read and then store the data in a buffer.
Actually, if the file is not seekable, we can't use it as a `FileBasedBuffer`. Maybe we should just fallback to `OverflowableBuffer`? But `ReadOnlyFileBasedBuffer` is just a wrapper around the file.
Let's see if `ReadOnlyFileBasedBuffer` SHOULD support non-seekable files. The problem statement says "currently waitress is just crashing if it receives an `io.IOBase` subclasses which is not seekable as the file to serve." This implies it SHOULD support them.
If it's not seekable, `prepare` should not try to seek. `remain` should stay 0 (or some value that indicates unknown size).
Actually, if we don't know the size, and we can't seek, we can't use the `get`/`skip` mechanism in `_flush_some` as it is.
Wait! If `self.remain` is 0, does `get` still work?
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is 0, `numbytes` becomes 0, and `get` returns `b''`.
So `_flush_some` will think the buffer is empty.
This means that for a non-seekable file, `ReadOnlyFileBasedBuffer` is essentially useless with the current `get` implementation.
Maybe the fix is simpler: just wrap the calls to `seek` and `tell` in `try...except UnsupportedOperation` and if they fail, we treat the file as a simple stream?
But if we treat it as a simple stream, we can't support `get(..., skip=False)` and `skip()`.
Wait, look at `ReadOnlyFileBasedBuffer` again. It's an iterator!
```python
def __iter__(self): # called by task if self.filelike has no seek/tell
return self
def next(self):
val = self.file.read(self.block_size)
if not val:
raise StopIteration
return val
```
If the buffer is used as an iterator, it works perfectly fine with non-seekable files.
The problem is when `waitress` decides to use `get()` and `skip()` instead of just iterating over the buffer.
When does that happen?
In `waitress/channel.py`, `outbufs` is a list of buffers.
If `ReadOnlyFileBasedBuffer` is in `outbufs`, then `_flush_some` uses `get()` and `skip()`.
Wait, I suspect the fix should be to make `ReadOnlyFileBasedBuffer` behave properly when not seekable.
If it's not seekable, we can't use `get` and `skip`. But we can still implement `__len__` (maybe return some large value or handle it) and `__iter__`.
Actually, if we can't seek, we can't support the "peek" and "skip" pattern.
But maybe we can just make `get` and `skip` raise some error? No, that would just crash elsewhere.
Let's think about what `get(..., skip=False)` does. It peeks at the data.
If we can't peek, we have to read the data and keep it in a buffer.
But `ReadOnlyFileBasedBuffer` is intended to AVOID keeping data in memory.
If we have a non-seekable file, we can't avoid keeping data in memory if we want to support peeking and skipping.
However, the problem statement specifically points to the `prepare` method and the check for `seek` and `tell`.
"ReadOnlyFileBasedBuffer checks if it can detect the file length by using seek and tell methods. While it checks for the file to be able to provide them ..., it doesn't actually check if those can be used. ... in case of io.IOBase instance .seekable should probably be checked for True or the UnsupportedOperation should be trapped."
This specifically refers to the `prepare` method. Maybe the `get` and `skip` methods are not the primary concern, or they are handled elsewhere?
But I saw that `get` uses `tell` and `seek` too.
If I fix `prepare`, then `self.remain` will be 0.
If `self.remain` is 0, `get` will return `b''`.
If `get` returns `b''`, `_flush_some` will think there is no more data.
This seems like it would still be broken.
Unless... `self.remain` is NOT used if the file is not seekable?
But `get` starts with:
```python
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
```
If `self.remain` is 0, `numbytes` is 0.
Maybe `self.remain` should be set to a very large number if not seekable?
Like `sys.maxsize`.
Let's try it.
But wait, if we set `self.remain = sys.maxsize`, then `get(..., skip=False)` will still call `tell()` and `seek()`, which will crash.
So we MUST also fix `get` and `skip`.
For `get(..., skip=False)`:
If the file is not seekable, we can't seek back.
So if `skip=False`, we can't peek.
But wait, the `_flush_some` logic is:
```python
chunk = outbuf.get(self.sendbuf_len)
num_sent = self.send(chunk)
if num_sent:
outbuf.skip(num_sent, True)
```
If `skip=False` (default), `get` reads and then seeks back. Then `skip(num_sent, True)` is called, which seeks forward by `num_sent`.
Net result: the file pointer is advanced by `num_sent`.
If the file is NOT seekable, we can just read `self.sendbuf_len` bytes. But if `num_sent < len(chunk)`, we have to keep the remaining bytes of `chunk` for the next call, because we can't seek back.
This means that if the file is not seekable, `ReadOnlyFileBasedBuffer` MUST maintain its own internal buffer for the partially sent chunks.
This is exactly what `OverflowableBuffer` does!
So, if a file is not seekable, maybe `ReadOnlyFileBasedBuffer` should just read from the file and put it into an internal buffer?
But that's getting complicated. Let's look at the problem statement again. It's very focused on `prepare` and `seek`/`tell`.
Maybe I should just implement the suggested change in `prepare` and see what happens.
If I trap `UnsupportedOperation` in `prepare`, `self.remain` remains 0.
Wait, `self.remain` is defined in `FileBasedBuffer` as 0.
If `self.remain` is 0, then `get` returns `b''`.
TOOL CALL · run_command
{
"command": "python3 - <<'PY'\nimport io\nfrom waitress.buffers import ReadOnlyFileBasedBuffer\n\nclass NonSeekableIO(io.IOBase):\n def readable(self):\n return True\n def read(self, size=-1):\n return b\"hello world\"\n\nf = NonSeekableIO()\nbuffer = ReadOnlyFileBasedBuffer(f)\n# Assume prepare is fixed and doesn't crash, but leaves self.remain = 0\nbuffer.remain = 0 \nprint(f\"get(10): {buffer.get(10)}\")\nPY\n"
}Result of run_command 523 characters
{
"status": "error",
"error_type": "CommandError",
"error_message": "Traceback (most recent call last):\n File \"<stdin>\", line 14, in <module>\n File \"/workspace/waitress/buffers.py\", line 158, in get\n read_pos = file.tell()\nio.UnsupportedOperation: seek\n",
"details": {
"stdout": "",
"stderr": "Traceback (most recent call last):\n File \"<stdin>\", line 14, in <module>\n File \"/workspace/waitress/buffers.py\", line 158, in get\n read_pos = file.tell()\nio.UnsupportedOperation: seek\n",
"exit_code": 1
}
}Generated tokens 2,143 tokens · stopped: STOP
And line 788:
```python
'wsgi.file_wrapper': ReadOnlyFileBasedBuffer,
```
When `asgi.file_wrapper` is provided, the application can use it to return a file-like object.
The issue is that `ReadOnlyFileBasedBuffer` tries to use `seek` and `tell` in `prepare` to determine the file size, and then `waitress` uses it in `_flush_some` with `get` and `skip`.
If the file is not seekable, we can't use `seek` and `tell`.
The suggested fix is:
"In `io.IOBase` subclasses that are not seekable, those two methods exist but raise an `UnsupportedOperation`, in case of io.IOBase instance `.seekable` should probably be checked for `True` or the `UnsupportedOperation` should be trapped."
Let's try implementing this in `ReadOnlyFileBasedBuffer.prepare`.
What about `get` and `skip`?
If we only fix `prepare`, `_flush_some` will still call `get(..., skip=False)` and `skip()`, which will call `tell()` and `seek()`.
Wait, if `ReadOnlyFileBasedBuffer` is used, it means the user specifically wanted to use a file-based buffer. If they provide a non-seekable file, they should expect it to behave like a stream.
If we want to support non-seekable files in `ReadOnlyFileBasedBuffer`, we must also fix `get` and `skip`.
But `get(..., skip=False)`'s purpose is to peek at the data. If the file is not seekable, you can't peek. You have to read and then store the data in a buffer.
Actually, if the file is not seekable, we can't use it as a `FileBasedBuffer`. Maybe we should just fallback to `OverflowableBuffer`? But `ReadOnlyFileBasedBuffer` is just a wrapper around the file.
Let's see if `ReadOnlyFileBasedBuffer` SHOULD support non-seekable files. The problem statement says "currently waitress is just crashing if it receives an `io.IOBase` subclasses which is not seekable as the file to serve." This implies it SHOULD support them.
If it's not seekable, `prepare` should not try to seek. `remain` should stay 0 (or some value that indicates unknown size).
Actually, if we don't know the size, and we can't seek, we can't use the `get`/`skip` mechanism in `_flush_some` as it is.
Wait! If `self.remain` is 0, does `get` still work?
```python
def get(self, numbytes=-1, skip=False):
# never read more than self.remain (it can be user-specified)
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
# ...
```
If `self.remain` is 0, `numbytes` becomes 0, and `get` returns `b''`.
So `_flush_some` will think the buffer is empty.
This means that for a non-seekable file, `ReadOnlyFileBasedBuffer` is essentially useless with the current `get` implementation.
Maybe the fix is simpler: just wrap the calls to `seek` and `tell` in `try...except UnsupportedOperation` and if they fail, we treat the file as a simple stream?
But if we treat it as a simple stream, we can't support `get(..., skip=False)` and `skip()`.
Wait, look at `ReadOnlyFileBasedBuffer` again. It's an iterator!
```python
def __iter__(self): # called by task if self.filelike has no seek/tell
return self
def next(self):
val = self.file.read(self.block_size)
if not val:
raise StopIteration
return val
```
If the buffer is used as an iterator, it works perfectly fine with non-seekable files.
The problem is when `waitress` decides to use `get()` and `skip()` instead of just iterating over the buffer.
When does that happen?
In `waitress/channel.py`, `outbufs` is a list of buffers.
If `ReadOnlyFileBasedBuffer` is in `outbufs`, then `_flush_some` uses `get()` and `skip()`.
Wait, I suspect the fix should be to make `ReadOnlyFileBasedBuffer` behave properly when not seekable.
If it's not seekable, we can't use `get` and `skip`. But we can still implement `__len__` (maybe return some large value or handle it) and `__iter__`.
Actually, if we can't seek, we can't support the "peek" and "skip" pattern.
But maybe we can just make `get` and `skip` raise some error? No, that would just crash elsewhere.
Let's think about what `get(..., skip=False)` does. It peeks at the data.
If we can't peek, we have to read the data and keep it in a buffer.
But `ReadOnlyFileBasedBuffer` is intended to AVOID keeping data in memory.
If we have a non-seekable file, we can't avoid keeping data in memory if we want to support peeking and skipping.
However, the problem statement specifically points to the `prepare` method and the check for `seek` and `tell`.
"ReadOnlyFileBasedBuffer checks if it can detect the file length by using seek and tell methods. While it checks for the file to be able to provide them ..., it doesn't actually check if those can be used. ... in case of io.IOBase instance .seekable should probably be checked for True or the UnsupportedOperation should be trapped."
This specifically refers to the `prepare` method. Maybe the `get` and `skip` methods are not the primary concern, or they are handled elsewhere?
But I saw that `get` uses `tell` and `seek` too.
If I fix `prepare`, then `self.remain` will be 0.
If `self.remain` is 0, `get` will return `b''`.
If `get` returns `b''`, `_flush_some` will think there is no more data.
This seems like it would still be broken.
Unless... `self.remain` is NOT used if the file is not seekable?
But `get` starts with:
```python
if numbytes == -1 or numbytes > self.remain:
numbytes = self.remain
```
If `self.remain` is 0, `numbytes` is 0.
Maybe `self.remain` should be set to a very large number if not seekable?
Like `sys.maxsize`.
Let's try it.
But wait, if we set `self.remain = sys.maxsize`, then `get(..., skip=False)` will still call `tell()` and `seek()`, which will crash.
So we MUST also fix `get` and `skip`.
For `get(..., skip=False)`:
If the file is not seekable, we can't seek back.
So if `skip=False`, we can't peek.
But wait, the `_flush_some` logic is:
```python
chunk = outbuf.get(self.sendbuf_len)
num_sent = self.send(chunk)
if num_sent:
outbuf.skip(num_sent, True)
```
If `skip=False` (default), `get` reads and then seeks back. Then `skip(num_sent, True)` is called, which seeks forward by `num_sent`.
Net result: the file pointer is advanced by `num_sent`.
If the file is NOT seekable, we can just read `self.sendbuf_len` bytes. But if `num_sent < len(chunk)`, we have to keep the remaining bytes of `chunk` for the next call, because we can't seek back.
This means that if the file is not seekable, `ReadOnlyFileBasedBuffer` MUST maintain its own internal buffer for the partially sent chunks.
This is exactly what `OverflowableBuffer` does!
So, if a file is not seekable, maybe `ReadOnlyFileBasedBuffer` should just read from the file and put it into an internal buffer?
But that's getting complicated. Let's look at the problem statement again. It's very focused on `prepare` and `seek`/`tell`.
Maybe I should just implement the suggested change in `prepare` and see what happens.
If I trap `UnsupportedOperation` in `prepare`, `self.remain` remains 0.
Wait, `self.remain` is defined in `FileBasedBuffer` as 0.
If `self.remain` is 0, then `get` returns `b''`.<channel|><|tool_call>call:run_command{command:<|"|>python3 - <<'PY'
import io
from waitress.buffers import ReadOnlyFileBasedBuffer
class NonSeekableIO(io.IOBase):
def readable(self):
return True
def read(self, size=-1):
return b"hello world"
f = NonSeekableIO()
buffer = ReadOnlyFileBasedBuffer(f)
# Assume prepare is fixed and doesn't crash, but leaves self.remain = 0
buffer.remain = 0
print(f"get(10): {buffer.get(10)}")
PY
<|"|>}<tool_call|><|tool_response>
Patch, tests and logs
Final code change Included
Test output Missing
Not saved for this rollout. Nothing has been inferred or reconstructed.
Test errors Missing
Not saved for this rollout. Nothing has been inferred or reconstructed.
Test report (JUnit) Missing
Not saved for this rollout. Nothing has been inferred or reconstructed.
Agent log Included
[ 0.0s] 📋 System Prompt: You are a principal Python software engineer resolving a repository issue in `/workspace`.
[ 0.0s] 🎯 Task Prompt: You are evaluating a software engineering task for repository Pylons/waitress.
[ 15.7s] 💭 (799 chars) "The user is reporting a bug in `ReadOnlyFileBasedBuffer` in `waitress/buffers.py`.
The issue is that `ReadOnlyFileBasedB..."
[ 15.7s] 🔧 run_command grep -rn --include="*.py" "ReadOnlyFileBasedBuffer" .
[ 15.7s] → ./waitress/buffers.py:132:class ReadOnlyFileBasedBuffer(FileBasedBuffer):
[ 21.2s] 💭 (158 chars) "Okay, the target class is in `waitress/buffers.py`. Let's examine the code around line 132
and specifically the part men..."
[ 21.2s] 📖 read_file (waitress/buffers.py)
[ 21.3s] ✓ {'status': 'ok', 'filepath': 'waitress/buffers.py', 'content': 'class
ReadOnlyFileBasedBuffer(FileBasedBuffer):\n # u…
[ 55.1s] 💭 (1008 chars) "The code in `prepare` is:
```python
def prepare(self, size=None):
if hasattr(self.file, 'seek') and hasattr..."
[ 55.1s] 🔧 run_command (20 lines) python3 - <<'PY'
[ 55.2s] → Caught expected exception: seek
[ 78.4s] 💭 (1396 chars) "Confirmed. The code crashes with `io.UnsupportedOperation` when `seek` or `tell` is called
on a non-seekable `io.IOBase`..."
[ 78.4s] 📖 read_file (waitress/buffers.py)
[ 78.4s] ✓ {'status': 'ok', 'filepath': 'waitress/buffers.py', 'content':
'########################################################…
[ 112.2s] 💭 (1565 chars) "The `ReadOnlyFileBasedBuffer.get` method is almost identical to `FileBasedBuffer.get`. Both
of them seem to do something..."
[ 112.2s] 🔧 run_command grep -rn ".get(" . | grep -v "test_"
[ 112.3s] → ./waitress/parser.py:210: connection = headers.get('CONNECTION', '')
[ 117.4s] 💭 (122 chars) "In `waitress/channel.py:228`: `chunk = outbuf.get(self.sendbuf_len)`.
Let's see what `outbuf` is in `waitress/channel.py..."
[ 117.4s] 📖 read_file (waitress/channel.py)
[ 117.4s] ✓ {'status': 'ok', 'filepath': 'waitress/channel.py', 'content': "
self.server.add_task(self)\n\n return…
[ 151.6s] 💭 (1552 chars) "OK, so in `_flush_some`:
```python
chunk = outbuf.get(self.sendbuf_len)
num_sent = self...."
[ 151.6s] 🔧 run_command grep -rn "self.channel.outbufs.append" waitress/task.py
[ 151.6s] → error (exit 0):
[ 153.4s] 💭 (28 chars) "Maybe just `outbufs.append`."
[ 153.4s] 🔧 run_command grep -rn "outbufs.append" waitress/task.py
[ 153.5s] → error (exit 0):
[ 155.0s] 💭 (49 chars) "Let's search for `outbufs` in `waitress/task.py`."
[ 155.0s] 🔧 run_command grep -rn "outbufs" waitress/task.py
[ 155.0s] → error (exit 0):
[ 163.0s] 💭 (255 chars) "Strange. Let me check `waitress/channel.py` again. It has `self.outbufs`.
Maybe it's `server.outbufs`? No, `channel.py`..."
[ 163.0s] 🔧 run_command grep -rn "outbufs" .
[ 163.1s] → ./waitress/channel.py:56: total_outbufs_len = 0 # total bytes ready to send
[ 296.5s] 💭 (7061 chars) "In `waitress/channel.py:311`, `self.outbufs.append(data)` where `data` might be a
`ReadOnlyFileBasedBuffer`.
If we have..."
[ 296.5s] 🔧 run_command grep -n "ReadOnlyFileBasedBuffer" waitress/task.py
[ 296.5s] → 21:from .buffers import ReadOnlyFileBasedBuffer
[ 299.8s] 💭 (49 chars) "Let's look at `waitress/task.py` around line 451."
[ 299.8s] 📖 read_file (waitress/task.py)
[ 299.8s] ✓ {'status': 'ok', 'filepath': 'waitress/task.py', 'content': "\n
self.response_headers.extend(headers)\n\n …
[ 432.1s] 💭 (7153 chars) "And line 788:
```python
'wsgi.file_wrapper': ReadOnlyFileBasedBuffer,
```
When `asgi.file_wrapper` is provided, th..."
[ 432.1s] 🔧 run_command (16 lines) python3 - <<'PY'
[ 432.2s] → error (exit 0):
Native result row
{
"agent_error": "Agent exceeded session timeout (7.5 min)",
"duration_seconds": 452.74,
"error": "Empty agent patch",
"grade": {
"error": "Empty agent patch",
"resolved": false,
"strict_clean_patch": false,
"test_exit_code": -1
},
"instance_id": "pylons__waitress-249",
"pass_idx": 0,
"patch_chars": 0,
"phase1_seconds": 452.74,
"repo": "Pylons/waitress",
"request_log_path": "/kaggle-root/working/r31/rollouts_X/requests/pylons__waitress-249__p0__r1.jsonl",
"resolved": false,
"rollout_idx": 1,
"run_key": "pylons__waitress-249__p0__r1",
"strict_clean_patch": false,
"tool_calls": 13,
"total_llm_calls": 13,
"trace_path": "/kaggle-root/working/r31/rollouts_X/traces/trace_pylons__waitress-249__p0__r1.json"
}