https://github.com/python/cpython/commit/cdabbc126fb16420903166ad788d39e01230c966
commit: cdabbc126fb16420903166ad788d39e01230c966
branch: 3.13
author: Gregory P. Smith <g...@krypto.org>
committer: gpshead <g...@krypto.org>
date: 2025-04-21T21:55:57Z
summary:
[3.13] gh-122179: Fix hashlib.file_digest and non-blocking I/O (GH-132787)
gh-122179: Fix hashlib.file_digest and non-blocking I/O (GH-122183)
* Fix hashlib.file_digest and non-blocking I/O
* Add documentation around this behavior
* Add versionchanged
(cherry picked from commit 2b47f46d7dc30d27b2486991fea4acd83553294b)
Co-authored-by: Sebastian Rittau <srit...@rittau.biz>
files:
A Misc/NEWS.d/next/Library/2024-07-23-17-08-41.gh-issue-122179.0jZm9h.rst
M Doc/library/hashlib.rst
M Lib/hashlib.py
M Lib/test/test_hashlib.py
diff --git a/Doc/library/hashlib.rst b/Doc/library/hashlib.rst
index 7bf6152311f058..ff15a08a792ed2 100644
--- a/Doc/library/hashlib.rst
+++ b/Doc/library/hashlib.rst
@@ -270,7 +270,10 @@ a file or file-like object.
*fileobj* must be a file-like object opened for reading in binary mode.
It accepts file objects from builtin :func:`open`, :class:`~io.BytesIO`
instances, SocketIO objects from :meth:`socket.socket.makefile`, and
- similar. The function may bypass Python's I/O and use the file descriptor
+ similar. *fileobj* must be opened in blocking mode, otherwise a
+ :exc:`BlockingIOError` may be raised.
+
+ The function may bypass Python's I/O and use the file descriptor
from :meth:`~io.IOBase.fileno` directly. *fileobj* must be assumed to be
in an unknown state after this function returns or raises. It is up to
the caller to close *fileobj*.
@@ -299,6 +302,10 @@ a file or file-like object.
.. versionadded:: 3.11
+ .. versionchanged:: next
+ Now raises a :exc:`BlockingIOError` if the file is opened in blocking
+ mode. Previously, spurious null bytes were added to the digest.
+
Key derivation
--------------
diff --git a/Lib/hashlib.py b/Lib/hashlib.py
index 1b16441cb60ba7..296210e5d30d1d 100644
--- a/Lib/hashlib.py
+++ b/Lib/hashlib.py
@@ -231,6 +231,8 @@ def file_digest(fileobj, digest, /, *, _bufsize=2**18):
view = memoryview(buf)
while True:
size = fileobj.readinto(buf)
+ if size is None:
+ raise BlockingIOError("I/O operation would block.")
if size == 0:
break # EOF
digestobj.update(view[:size])
diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index a3693f5b8934f7..48621f47af038b 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -1190,6 +1190,15 @@ def test_file_digest(self):
with open(os_helper.TESTFN, "wb") as f:
hashlib.file_digest(f, "sha256")
+ class NonBlocking:
+ def readinto(self, buf):
+ return None
+ def readable(self):
+ return True
+
+ with self.assertRaises(BlockingIOError):
+ hashlib.file_digest(NonBlocking(), hashlib.sha256)
+
if __name__ == "__main__":
unittest.main()
diff --git
a/Misc/NEWS.d/next/Library/2024-07-23-17-08-41.gh-issue-122179.0jZm9h.rst
b/Misc/NEWS.d/next/Library/2024-07-23-17-08-41.gh-issue-122179.0jZm9h.rst
new file mode 100644
index 00000000000000..2b0678f31e8ef6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-07-23-17-08-41.gh-issue-122179.0jZm9h.rst
@@ -0,0 +1,3 @@
+:func:`hashlib.file_digest` now raises :exc:`BlockingIOError` when no data
+is available during non-blocking I/O. Before, it added spurious null bytes
+to the digest.
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