Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Support libffi implementations that cannot support invocations with 1024 arguments #91364

Open
hoodmane mannequin opened this issue Apr 4, 2022 · 5 comments
Open

Support libffi implementations that cannot support invocations with 1024 arguments #91364

hoodmane mannequin opened this issue Apr 4, 2022 · 5 comments
Labels
3.11 only security fixes tests Tests in the Lib/test dir topic-ctypes type-bug An unexpected behavior, bug, or error

Comments

@hoodmane
Copy link
Mannequin

hoodmane mannequin commented Apr 4, 2022

BPO 47208
Nosy @amauryfa, @abalkin, @tiran, @meadori, @hoodmane
PRs
  • bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT (GH-32297) #32297
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

    Show more details

    GitHub fields:

    assignee = None
closed_at = None
created_at = <Date 2022-04-04.00:27:44.616>
labels = ['ctypes', 'type-bug', 'tests', '3.11']
title = 'Support libffi implementations that cannot support invocations with 1024 arguments'
updated_at = <Date 2022-04-04.19:07:48.227>
user = 'https://github.com/hoodmane'

    bugs.python.org fields:

    activity = <Date 2022-04-04.19:07:48.227>
actor = 'hoodchatham'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Tests', 'ctypes']
creation = <Date 2022-04-04.00:27:44.616>
creator = 'hoodchatham'
dependencies = []
files = []
hgrepos = []
issue_num = 47208
keywords = ['patch']
message_count = 4.0
messages = ['416646', '416677', '416678', '416692']
nosy_count = 5.0
nosy_names = ['amaury.forgeotdarc', 'belopolsky', 'christian.heimes', 'meador.inge', 'hoodchatham']
pr_nums = ['32297']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue47208'
versions = ['Python 3.11']
    @hoodmane
    Copy link
    Mannequin Author

    hoodmane mannequin commented Apr 4, 2022

    ctypes defines CTYPES_MAX_ARGCOUNT to be 1024:

    cpython/Modules/_ctypes/ctypes.h

    Line 21 in 6db2db9

    #define CTYPES_MAX_ARGCOUNT 1024

    If a function call is attempted with more than 1024 arguments, it will fail. The libffi emscripten port github.com/hoodmane/libffi-emscripten can only support function calls with at most 122 arguments due to limitations in Emscripten / Wasm:
    emscripten-core/emscripten#16653

    I propose to allow the libffi port to define FFI_MAX_CLOSURE_ARGS and if this is defined then use this number instead for CTYPES_MAX_ARGCOUNT.
    libffi/libffi#703

    The test test_callback_too_many_args should also be updated to respect the value of CTYPES_MAX_ARGCOUNT rather than hardcoding 1024 into the test.

    @hoodmane hoodmane mannequin added topic-ctypes labels Apr 4, 2022
    @tiran
    Copy link
    Member

    tiran commented Apr 4, 2022

    New changeset d1b1c88 by Christian Heimes in branch 'main':
    bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT (GH-32297)
    d1b1c88

    @tiran
    Copy link
    Member

    tiran commented Apr 4, 2022

    #76478 adds #ifndef CTYPES_MAX_ARGCOUNT and exposes the constant in the _ctypes extension module, so the test case can use the constant. It allows you to override CTYPES_MAX_ARGCOUNT until libffi upstream agrees on FFI_MAX_CLOSURE_ARGS.

    @tiran tiran added tests Tests in the Lib/test dir 3.11 only security fixes type-bug An unexpected behavior, bug, or error labels Apr 4, 2022
    @hoodmane
    Copy link
    Mannequin Author

    hoodmane mannequin commented Apr 4, 2022

    Ideally the library should be able to define a different macro, e.g., CTYPES_CUSTOM_MAX_ARGCOUNT. This way the libffi port can define CTYPES_CUSTOM_MAX_ARGCOUNT and it will be compatible with older Python versions without causing Warning: "CTYPES_MAX_ARGCOUNT redefined`.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @furkanonder
    Copy link
    Sponsor Contributor

    The issue seems to be solved, I think we can close it. @tiran

    Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
    Assignees
    No one assigned
    Labels
    3.11 only security fixes tests Tests in the Lib/test dir topic-ctypes type-bug An unexpected behavior, bug, or error
    Projects
    None yet
    Milestone
    No milestone
    Development

    No branches or pull requests
    2 participants
    @tiran @furkanonder