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Accept file objects in MODE_AUTO and check the database argument - #471
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Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 36 functions across 7 files. (1 skipped: … | Write docstrings for the functions missing them to satisfy the coverage threshold. |
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Check name Status Explanation Description Check Check skipped - CodeRabbit’s high-level summary is enabled. Title check The title clearly and concisely describes the two main changes: accepting file objects in MODE_AUTO and validating the database argument. Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request.
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Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 36 functions across 7 files. (1 skipped: 1 unsupported.)
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Write docstrings for the functions missing them to satisfy the coverage threshold.
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Actionable comments posted: 1
- 🪄 Fix comments: Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @maxminddb/__init__.py:
- Around line 51-56: Update the ownership wording in the reader documentation to
specify that the reader closes a file descriptor, even when it is not a valid
database, and leaves a caller-provided file object open.
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📒 Files selected for processing: 9
HISTORY.rstREADME.rstmaxminddb/__init__.pymaxminddb/const.pymaxminddb/decoder.pymaxminddb/file.pymaxminddb/reader.pymaxminddb/types.pytests/reader_test.py
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MODE_AUTO passed every database argument to the C extension when it was installed, but the extension accepts only a path. A file object raised TypeError, although the pure Python reader can read it. Without the extension, a file object also raised TypeError. In MODE_AUTO, read a file object as MODE_FD does. A path still opens as a path, even if it also has read(), because some path objects, such as py.path.local, have a text read(). A file descriptor still raises TypeError with the extension, as before. The pure Python path modes close a descriptor, and a caller of the default mode might not expect that. Without the extension, MODE_AUTO still opens a descriptor, as before. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
MODE_FD calls database.read(), so it takes a binary file object, and MODE_AUTO now reads one the same way. The docstrings and the README said that MODE_FD takes a file descriptor. An int file descriptor fails with AttributeError in MODE_FD. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
_load_buffer passed the database argument to open(), FileBuffer and .read() behind 5 type: ignore comments, and it declared -> str although it returns the database argument or a file object name. An Any local hid that mismatch. The ignores hid real mismatches too. MODE_FD with a path raised AttributeError, and a path mode with a file object raised a TypeError from open() that did not name the mode. Check the argument type for the mode and raise TypeError with the fix. The checks narrow the type, so the ignores go away. FileBuffer now takes the path types that open() accepts. The unsupported mode check still comes first. The function returns object, because the caller only formats the name into error messages. One helper decides what is a file descriptor for both open_database and the pure Python reader. Error messages name the module of a type that is not a builtin, so that a zipfile.Path does not show as "Path". A text file that fails to decode in read() raises TypeError. A bytearray from read() stays a bytearray, as before, so the buffer and decoder types now include it. An mmap from read() still works, as in 3.2.0. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The pure Python Reader accepts MODE_MMAP, but the error for an unsupported mode listed only MODE_AUTO, MODE_FILE, MODE_MEMORY and MODE_FD. A caller who passed MODE_MMAP_EXT was told that MODE_MMAP was not supported. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The name for a file object without a name attribute was
f"<{type(database)}>", so error messages showed
"<<class '_io.BytesIO'>>". MODE_AUTO now reads file objects too, so
these messages are more common. Use the type name, as in "<BytesIO>".
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Looks good, with some Claude comments.
| return cast("Reader", _extension.Reader(database, mode)) | ||
| # Leave a bool to the pure Python reader, which refuses it. | ||
| is_descriptor = _is_descriptor(database) | ||
| if mode == MODE_MMAP_EXT or is_descriptor: |
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In MODE_AUTO, a file descriptor works or fails depending on whether the C extension is installed.
- Without the extension,
open_database(os.open(p, os.O_RDONLY))works and the reader closes the fd. - With the extension, it raises
TypeErrorand the fd stays open.
So code that works in one environment fails (and leaks fds) in the other. This PR adds new code that keeps this split. Can we send a descriptor in MODE_AUTO to Reader(database, mode), as we do for a file object? The other option is to refuse a descriptor in both readers.
🤖 Comment by Claude Opus 5.5.
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Agent reply on behalf of @oschwald.
Not changed. 3.2.0 already had both behaviors. With the extension, open_database(fd) raised TypeError. Without it, the pure Python reader opened the fd and closed it. This PR keeps both.
- If we refuse a descriptor in both readers, PyPy and pure Python code that works today breaks.
- If we send it to
Readerwith the extension installed, a call that raised before would now take ownership of the fd and close it, and it would use the slower reader without warning.
The docstrings describe both cases.
| MODE_AUTO, MODE_MMAP, MODE_FILE and MODE_MEMORY also | ||
| accept the file descriptor of a regular file. MODE_MEMORY | ||
| reads it from its current offset, the others from the | ||
| start. The reader closes a file descriptor, even when |
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This says that the reader closes a file descriptor even when the file is not a valid database. Some early errors return before the reader touches the fd, so the fd stays open:
Reader(fd, MODE_MMAP_EXT)raisesValueErrorfrom the mode check.Reader(dir_fd, MODE_MMAP)raisesIsADirectoryError.open()does not close an fd that it did not open.
A caller who trusts this docstring and does not close the fd leaks it in these cases. We can close the fd on every error path, or make the docstring less absolute.
🤖 Comment by Claude Opus 5.5.
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Agent reply on behalf of @oschwald.
Fixed in 54afbd2. Both docstrings now say that the reader closes a descriptor once it opens it, even when the file is not a valid database. If an error comes first, for example for a mode that takes no descriptor or for a directory, the caller still owns it. I confirmed that IsADirectoryError leaves the fd open in MODE_MMAP, MODE_FILE and MODE_MEMORY.
| msg = "The database file object is a text file. Open it in binary mode." | ||
| raise TypeError(msg) from e | ||
| # 3.2.0 also accepted an mmap, such as one that the caller mapped. | ||
| if not isinstance(buf, (bytes, bytearray)) and not ( |
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This now accepts only bytes, bytearray or mmap from read(). In 3.2.0, MODE_FD stored what read() returned and used only rfind, slicing and len. A source that returns another buffer type with those methods worked before. It now raises TypeError: The database file object returned X, not bytes.
If this is intentional, HISTORY should say so. If not, a check for str alone may be enough.
🤖 Comment by Claude Opus 5.5.
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Not changed. We compared buffer sources with v3.2.0. Only bytes, bytearray and mmap worked. A memoryview failed with AttributeError: 'memoryview' object has no attribute 'rfind'. We know of no other type that has rfind, slicing and len and that a read() returns, so the check accepts the same 3 types that worked.
| """Read a binary file object into memory.""" | ||
| try: | ||
| buf = read() | ||
| except UnicodeDecodeError as e: |
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This turns every UnicodeDecodeError from read() into TypeError with the message "is a text file". This causes two problems:
- The exception type changes. A
MODE_FDcaller that caughtValueErrororUnicodeDecodeErrorfor a text-mode file in 3.2.0 no longer catches the error. HISTORY says that the reader now raisesTypeError, but it does not say what it raised before. - A binary stream that raises
UnicodeDecodeErrorfor another reason (for example, a codecs-based reader) gets the wrong message.
We could check isinstance(database, io.TextIOBase) and leave other errors unchanged.
🤖 Comment by Claude Opus 5.5.
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Agent reply on behalf of @oschwald.
Not changed. A text-mode file is a valid database opened in the wrong mode. The problem is the argument type, so TypeError fits:
pickle.load(text_file)also raisesTypeError("a bytes-like object is required, not 'str'").- With the extension, 3.2.0
MODE_AUTOraisedTypeErrorfor every file object. WithTypeError, MODE_AUTO raises the same error type as before. - An
io.TextIOBasecheck would miss wrappers such astempfile.NamedTemporaryFile('r+')andcodecs.open, and theirread()raisesUnicodeDecodeError.
| def _is_descriptor(database: object) -> TypeGuard[SupportsIndex]: | ||
| # open() takes an object with __index__, such as numpy.int64, as a file | ||
| # descriptor. bool is an int, but it is never a file descriptor. | ||
| return not isinstance(database, bool) and hasattr(type(database), "__index__") |
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Any type with __index__ is treated as a file descriptor, and this includes numpy.ndarray and numpy.memmap.
- With the extension,
open_database(np.memmap(path))raises "The C extension requires a path (numpy.memmap given). Use MODE_MMAP for a file descriptor." That advice is wrong. Reader(np_array, MODE_AUTO)gets numpy's "only integer scalar arrays can be converted to a scalar index" fromoperator.index, not the "Unsupported database type" message.
Calling operator.index() in a try and catching TypeError would be a stricter check.
🤖 Comment by Claude Opus 5.5.
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Fixed in b8ca09a. _is_descriptor now calls operator.index and treats TypeError as "not a descriptor". With the extension, a numpy array gets "The C extension requires a path", without the MODE_MMAP advice. The pure Python reader gives "Unsupported database type". A test uses a class whose __index__ raises, as numpy does.
| except UnicodeDecodeError as e: | ||
| msg = "The database file object is a text file. Open it in binary mode." | ||
| raise TypeError(msg) from e | ||
| # 3.2.0 also accepted an mmap, such as one that the caller mapped. |
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This comment says that the reader supports an mmap from read() that the caller mapped. But close() and a failed _load both call _close_buffer, which closes that mmap. The docs say that the reader does not close the caller's file object.
MODE_AUTO now accepts this case too. If the database is not valid, or after reader.close(), the caller's next access to its mmap raises ValueError: mmap closed or invalid.
🤖 Comment by Claude Opus 5.5.
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Fixed in f996560. 3.2.0's close() also closed the buffer that read() returned, so the code stays the same. The docstrings now say that the reader closes a buffer from read() that has close(), such as an mmap. The comment no longer suggests that the caller can keep using it.
| return self._load_path(operator.index(database), mode) | ||
| # MODE_AUTO reads a file object into memory, as MODE_FD does. | ||
| read = getattr(database, "read", None) | ||
| if mode in (MODE_AUTO, MODE_FD) and callable(read): |
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In MODE_AUTO, a regular file such as open(path, "rb") is read whole into memory and uses the pure Python reader. This happens even when the C extension is installed and fileno() is available.
For a 100+ MB City database, this copies the whole file into each process, and lookups are about 10x slower. A memory map would share pages across processes. One option is to memory-map fileno() when it is available, and to keep the "reads from the current position" rule only for streams. HISTORY already notes that lookups are slower, so this may be an accepted trade-off.
🤖 Comment by Claude Opus 5.5.
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Not changed. fileno() is not always the file that read() reads. GzipFile.fileno() is the compressed file, and io.BufferedReader(gzip.GzipFile(...)) also has fileno(). The test suite passes that wrapper to MODE_AUTO. A list of the types that are safe to map would be fragile. HISTORY and the README say that a path is faster, and a caller who wants the C extension can pass the path.
| **NOTE**: When using a file object, it is the *caller's* responsibility to be | ||
| sure that the file object gets closed properly. The caller may close the | ||
| file object immediately after the ``Reader`` object is created. A reader | ||
| closes a file descriptor that you pass to ``Mode.MMAP``, ``Mode.FILE`` or |
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This says that the reader closes a file descriptor only in Mode.MMAP, Mode.FILE and Mode.MEMORY. But Mode.AUTO without the C extension, and the pure Python Reader in MODE_AUTO, also take the fd and close it.
A user who reads this calls open_database(fd) on an install without the extension and then calls os.close(fd). That is a double close. The second close raises EBADF, or it closes an unrelated fd that reused the number.
🤖 Comment by Claude Opus 5.5.
| # io buffers are not guaranteed to have a name attribute | ||
| if hasattr(database, "name"): | ||
| return database.name | ||
| return f"<{type(database).__name__}>" |
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This uses f"<{type(database).__name__}>" and not the _type_name() helper that this PR adds. The same object then shows as _io.BytesIO in one error ("The C extension requires a path (_io.BytesIO given)") and as <BytesIO> in another ("Error opening database file ()"). This also drops the module, which _type_name adds for the zipfile.Path case.
Suggest return f"<{_type_name(database)}>".
🤖 Comment by Claude Opus 5.5.
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Not changed. File objects from open() and io.BytesIO are in the _io module, so _type_name gives <_io.BytesIO> and <_io.BufferedReader>. These are the most common sources, and the short form reads better. The module helps in a TypeError, where a caller must find the wrong type, such as a zipfile.Path. An InvalidDatabaseError only needs a label for the source.
| # the pure Python reader. It still refuses a file descriptor, as before. | ||
| # The cast pretends the C reader is the pure Python Reader, which has the | ||
| # same API. | ||
| if mode in (MODE_AUTO, MODE_MMAP_EXT) and has_extension: |
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The code checks the database type in two places. open_database and Reader._load_buffer each test isinstance(database, _PATH_TYPES), _is_descriptor() and callable(getattr(database, "read", None)), and each builds its own hints.
The messages already differ: one says "(X given). Use MODE_FD for a file object." and the other says "Unsupported database type (X). ...". One shared helper that returns the kind (path, descriptor, file object or other) would remove the repeated checks and keep the messages the same.
🤖 Comment by Claude Opus 5.5.
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Not changed. _is_descriptor is the one shared check, and both places use it. Each place sorts the argument for its own reader. The extension takes only a path, but the pure Python reader also takes a descriptor or a file object. So each one gives the hint that fits its own reader.
_is_descriptor treated any type with __index__ as a file descriptor. A numpy.ndarray or numpy.memmap of many values has __index__, but it raises TypeError. With the extension, open_database then told the caller to use MODE_MMAP for a file descriptor. The pure Python reader raised numpy's error from operator.index, not "Unsupported database type". Call operator.index and treat a TypeError as "not a descriptor". Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Before _load_path existed, the MODE_MEMORY branch was an explicit elif, and a final branch raised ValueError. In _load_path, MODE_MEMORY was the plain else, so any other mode was read into memory. Only the MODE_FD guard in _load_buffer kept MODE_FD out. Check MODE_MEMORY by name and raise ValueError for any other mode. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The docstrings said that the reader closes a file descriptor, even when the file is not a valid database. An error before open() leaves the descriptor open. Examples are a mode that takes no descriptor, such as MODE_FD or MODE_MMAP_EXT, and a descriptor for a directory, which open() refuses without closing it. The README said that the reader closes a descriptor only in MODE_MMAP, MODE_FILE and MODE_MEMORY. Without the C extension, MODE_AUTO also closes it, so a caller who follows the README could close it twice. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The docstrings said that the reader does not close a file object. But close() and a failed open close the buffer that read() returned, such as an mmap, as close() did in 3.2.0. A comment also suggested that the caller could keep using an mmap that it mapped. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Lets
MODE_AUTOread a file object and gives clear errors for a database argument that does not suit the mode.MODE_AUTO. With the extension installed,MODE_AUTOpassed every argument to the extension, which accepts only a path, so a file object raisedTypeError.MODE_AUTOnow reads a file object into memory with the pure Python reader, asMODE_FDdoes. A path object that also has a textread(), such aspy.path.local, still opens as a path. A file descriptor still raisesTypeErrorwith the extension, as before.TypeErrorwith the fix for a path withMODE_FD, a file object with a path mode, a text-mode file, aread()that returns neither bytes nor an mmap, and abool. Before, some of these raisedAttributeErroror an unrelated error. A descriptor object with__index__, such asnumpy.int64, still works in the path modes.MODE_FDas taking a file descriptor. They now say it takes a binary file object, and they note that a file object inMODE_AUTOuses the slower pure Python reader.STF-1961
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