gh-95782: Fix io.BufferedReader.tell etc. being able to return offsets < 0#99709
Merged
serhiy-storchaka merged 2 commits intopython:mainfrom Feb 17, 2024
6t8k:gh-95782
Merged
gh-95782: Fix io.BufferedReader.tell etc. being able to return offsets < 0#99709serhiy-storchaka merged 2 commits intopython:mainfrom 6t8k:gh-95782
io.BufferedReader.tell etc. being able to return offsets < 0#99709serhiy-storchaka merged 2 commits intopython:mainfrom
6t8k:gh-95782
Conversation
|
All commit authors signed the Contributor License Agreement. |
lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests.
serhiy-storchaka
added
needs backport to 3.11
|
Thanks @6t8k for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12. |
miss-islington
pushed a commit
to miss-islington/cpython
that referenced
this pull request
Feb 17, 2024
…n offsets < 0 (pythonGH-99709) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests. (cherry picked from commit 26800cf) Co-authored-by: 6t8k <58048945+6t8k@users.noreply.github.com>
|
GH-115599 is a backport of this pull request to the 3.12 branch. |
miss-islington
pushed a commit
to miss-islington/cpython
that referenced
this pull request
Feb 17, 2024
…n offsets < 0 (pythonGH-99709) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests. (cherry picked from commit 26800cf) Co-authored-by: 6t8k <58048945+6t8k@users.noreply.github.com>
|
GH-115600 is a backport of this pull request to the 3.11 branch. |
serhiy-storchaka
pushed a commit
that referenced
this pull request
Feb 17, 2024
…rn offsets < 0 (GH-99709) (GH-115600) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests. (cherry picked from commit 26800cf) Co-authored-by: 6t8k <58048945+6t8k@users.noreply.github.com>
serhiy-storchaka
pushed a commit
that referenced
this pull request
Feb 17, 2024
…rn offsets < 0 (GH-99709) (GH-115599) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests. (cherry picked from commit 26800cf) Co-authored-by: 6t8k <58048945+6t8k@users.noreply.github.com>
woodruffw
pushed a commit
to woodruffw-forks/cpython
that referenced
this pull request
Mar 4, 2024
…n offsets < 0 (pythonGH-99709) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests.
diegorusso
pushed a commit
to diegorusso/cpython
that referenced
this pull request
Apr 17, 2024
…n offsets < 0 (pythonGH-99709) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests.
LukasWoodtli
pushed a commit
to LukasWoodtli/cpython
that referenced
this pull request
Jan 22, 2025
…n offsets < 0 (pythonGH-99709) lseek() always returns 0 for character pseudo-devices like `/dev/urandom` (for other non-regular files, e.g. `/dev/stdin`, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics. When calling read() on e.g. an instance of `io.BufferedReader` that wraps such a file, `BufferedReader` reads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internal `tell()` always returning 0, which previously resulted in e.g. `BufferedReader.tell()` or `BufferedReader.seek()` being able to return positions < 0 even though these are supposed to be always >= 0. Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
lseek() always returns 0 for character pseudo-devices like
/dev/urandom(for other non-regular files, e.g./dev/stdin, it always returns -1, to which CPython reacts by raising appropriate exceptions). They are thus technically seekable despite not having seek semantics.When calling read() on e.g. an instance of
io.BufferedReaderthat wraps such a file,BufferedReaderreads ahead, filling its buffer, creating a discrepancy between the number of bytes read and the internaltell()always returning 0, which results in e.g.BufferedReader.tell()orBufferedReader.seek()being able to return positions < 0 even though these are supposed to be always >= 0.Invariably keep the return value non-negative by returning max(former_return_value, 0) instead, and add some corresponding tests.
Other possible solutions that I've decided against and why (aside from the aspect that they wouldn't reflect the underlying file's behavior):
io.BufferedWriter.telldoes for bytes written/dev/urandometc. would be detected as unseekable_io.BufferedReader.tell#95782