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Misleading error message upon dependent DLL resolution failure #83574

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plimkilde mannequin opened this issue Jan 20, 2020 · 5 comments
Closed

Misleading error message upon dependent DLL resolution failure #83574

plimkilde mannequin opened this issue Jan 20, 2020 · 5 comments
Labels
3.8 only security fixes 3.9 only security fixes easy extension-modules C modules in the Modules dir OS-windows topic-ctypes type-bug An unexpected behavior, bug, or error

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@plimkilde
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plimkilde mannequin commented Jan 20, 2020

BPO 39393
Nosy @pfmoore, @tjguk, @zware, @eryksun, @zooba, @miss-islington, @plimkilde
PRs
  • bpo-39393: Misleading error message on dependent DLL resolution failure #18093
  • [3.8] bpo-39393: Misleading error message on dependent DLL resolution failure (GH-18093) #18230
    		•

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

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    GitHub fields:

    assignee = None
closed_at = <Date 2020-01-28.09:58:31.572>
created_at = <Date 2020-01-20.09:27:30.061>
labels = ['easy', 'type-bug', '3.8', '3.9', 'extension-modules', 'ctypes', 'OS-windows']
title = 'Misleading error message upon dependent DLL resolution failure'
updated_at = <Date 2020-01-28.10:00:20.458>
user = 'https://github.com/plimkilde'

    bugs.python.org fields:

    activity = <Date 2020-01-28.10:00:20.458>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2020-01-28.09:58:31.572>
closer = 'steve.dower'
components = ['Extension Modules', 'Windows', 'ctypes']
creation = <Date 2020-01-20.09:27:30.061>
creator = 'plimkilde'
dependencies = []
files = []
hgrepos = []
issue_num = 39393
keywords = ['patch', 'easy (C)']
message_count = 5.0
messages = ['360305', '360323', '360848', '360851', '360855']
nosy_count = 7.0
nosy_names = ['paul.moore', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'miss-islington', 'plimkilde']
pr_nums = ['18093', '18230']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39393'
versions = ['Python 3.8', 'Python 3.9']
    @plimkilde
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    plimkilde mannequin commented Jan 20, 2020

    Under Windows with Python 3.8+, trying to load a DLL whose dependencies cannot be resolved may produce a misleading error message.

    For example, if we are trying to load a library foo.dll that depends on bar.dll, and bar.dll cannot be resolved while foo.dll itself can, Python gives this error message:
    "FileNotFoundError: Could not find module 'foo.dll'. Try using the full path with constructor syntax."
    (behavior introduced with PR bpo-12302)

    Personally, I'd be happy to see a fix that simply adds " (or one of its dependencies)" to the error message.

    @plimkilde plimkilde mannequin added 3.8 only security fixes 3.9 only security fixes OS-windows topic-ctypes type-bug An unexpected behavior, bug, or error labels Jan 20, 2020
    @eryksun
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    eryksun commented Jan 20, 2020

    That clarification seems okay to me. The error message is in load_library in Modules/_ctypes/callproc.c.

    The underlying problem is that the directory of the DLL is only added to the search path (in CDLL.__init__ in Lib/ctypes/init.py) if the caller uses a qualified path. This is an OS limit that we can't avoid.

    Also note that the suggestion to use a qualified path won't necessarily resolve the problem, in which case scripts will have to use os.add_dll_directory, and find a reliable way to identify the required directories.

    @eryksun eryksun added easy extension-modules C modules in the Modules dir labels Jan 20, 2020
    @zooba
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    zooba commented Jan 28, 2020

    New changeset 13c1c35 by Steve Dower (Zackery Spytz) in branch 'master':
    bpo-39393: Misleading error message on dependent DLL resolution failure (GH-18093)
    13c1c35

    @zooba
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    zooba commented Jan 28, 2020

    Thanks, Zackery!

    @zooba zooba closed this as completed Jan 28, 2020
    @zooba zooba closed this as completed Jan 28, 2020
    @miss-islington
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    New changeset 46735c7 by Miss Islington (bot) in branch '3.8':
    bpo-39393: Misleading error message on dependent DLL resolution failure (GH-18093)
    46735c7

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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