gh-98758: Fix shutil.unpack_archive masking real filesystem errors - #155587
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SomSamantray wants to merge 3 commits into
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gh-98758: Fix shutil.unpack_archive masking real filesystem errors#155587SomSamantray wants to merge 3 commits into
SomSamantray wants to merge 3 commits into
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unpack_archive() raised a generic ReadError("Unknown archive
format") whenever the filename's extension didn't match a
registered format -- including when the real problem was that the
file didn't exist or wasn't readable, masking FileNotFoundError/
PermissionError the way open() would correctly raise them.
When _find_unpack_format() finds no match, stat the path first
(surfaces FileNotFoundError et al.) and, only for regular files,
briefly open() it (surfaces PermissionError) before falling back to
ReadError. Skipping the open() probe for non-regular files avoids
a hang on FIFOs (a blocking read-open with no writer) and preserves
the existing ReadError behavior for directories.
shutil.ReadError has no documented exception entry in the docs (only tarfile.ReadError does), so Sphinx's py:exc cross-reference role can't resolve it, failing the Docs CI check. Use plain code markup instead.
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Fixes gh-98758.
shutil.unpack_archive(filename)with no explicitformatresolves the format purely by pattern-matchingfilename's extension via_find_unpack_format(), which never touches the filesystem. When no extension matches — including the common case of a nonexistent or permission-denied file — it raises a genericshutil.ReadError("Unknown archive format '<filename>'"), masking the real cause:>>> shutil.unpack_archive("./enoent") shutil.ReadError: Unknown archive format './enoent'open()correctly raisesFileNotFoundError/PermissionErrorfor the same inputs; this bringsunpack_archivein line with that.Fix
When
_find_unpack_format()returnsNone:os.stat(filename)first — surfacesFileNotFoundError(and other stat-level errors) for a missing path.open(filename, 'rb')and close it (contents never read) — surfacesPermissionErrorfor a file that exists but isn't readable.ReadErroris still raised — the extension genuinely doesn't match any registered format.The
open()probe is skipped for non-regular files (directories, FIFOs, etc.) so:ReadError(notIsADirectoryError)The explicit
format=...argument path is completely untouched.Testing
check_unpack_archive_with_convertertest helper: a nonexistent path now correctly expectsFileNotFoundErrorinstead of the oldReadError(this assertion previously encoded the bug).ReadError), permission-denied (PermissionError, skipped under root/unsupported-chmod platforms), an unrecognized-extension directory (stillReadError), and an unrecognized-extension FIFO (stillReadError, and confirmed it doesn't hang).test_shutilsuite passes locally (237 tests).