never enable lchmod on Linux

[benjaminp]

BPO	34652
Nosy	@benjaminp, @jmroot, @asottile, @miss-islington
PRs	closes bpo-34652: Always disable lchmod on Linux. #9234 [3.7] closes bpo-34652: Always disable lchmod on Linux. (GH-9234) #9239 [3.6] closes bpo-34652: Always disable lchmod on Linux. (GH-9234) #9240 Revert "closes bpo-34652: Always disable lchmod on Linux." #9241 [2.7] closes bpo-34652: Always disable lchmod on Linux. #9242 [3.7] closes bpo-34652: Always disable lchmod on Linux. (GH-9234) #9243 [3.6] closes bpo-34652: Always disable lchmod on Linux. (GH-9234) #9244 bpo-34652: Remove lchmod from the big func checking block. #9247 [3.7] bpo-34652: Remove lchmod from the big func checking block. (GH-9247) #9249 [3.6] bpo-34652: Remove lchmod from the big func checking block. #9250 [2.7] bpo-34652: Remove lchmod from the big func checking block. (GH-9247) #12799 bpo-34652 again: Remove lchmod from the default AC_CHECK_FUNCS list. #15758 [3.8] bpo-34652 again: Remove lchmod from the default AC_CHECK_FUNCS list. (GH-15758) #15763

^{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 2018-09-12.22:52:43.508>
created_at = <Date 2018-09-12.21:43:38.114>
labels = ['3.8', 'build', '3.7']
title = 'never enable lchmod on Linux'
updated_at = <Date 2019-09-09.13:01:50.789>
user = 'https://github.com/benjaminp'

bugs.python.org fields:

activity = <Date 2019-09-09.13:01:50.789>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2018-09-12.22:52:43.508>
closer = 'benjamin.peterson'
components = ['Build']
creation = <Date 2018-09-12.21:43:38.114>
creator = 'benjamin.peterson'
dependencies = []
files = []
hgrepos = []
issue_num = 34652
keywords = ['patch']
message_count = 14.0
messages = ['325185', '325204', '325210', '325212', '325213', '325220', '325223', '325233', '335177', '339968', '340004', '340073', '351436', '351449']
nosy_count = 4.0
nosy_names = ['benjamin.peterson', 'jmr', 'Anthony Sottile', 'miss-islington']
pr_nums = ['9234', '9239', '9240', '9241', '9242', '9243', '9244', '9247', '9249', '9250', '12799', '15758', '15763']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue34652'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']

[benjaminp]

You can't modify the mode of symbolic links on Linux. Thus, lchmod is a useless function. libc may, however, define a lchmod stub that always returns an error. autoconf has a check that detects the dummy stub for glibc, but it detects lchmod as working on musl. I propose we simply always disable lchmod if the target system is Linux.

[benjaminp]

New changeset 40caa05 by Benjamin Peterson in branch 'master':
closes bpo-34652: Always disable lchmod on Linux. (GH-9234)
40caa05

[benjaminp]

New changeset 69e9691 by Benjamin Peterson in branch '2.7':
[2.7] closes bpo-34652: Always disable lchmod on Linux. (GH-9242)
69e9691

[miss-islington]

New changeset 98344a4 by Miss Islington (bot) in branch '3.7':
closes bpo-34652: Always disable lchmod on Linux. (GH-9234)
98344a4

[miss-islington]

New changeset bdace2e by Miss Islington (bot) in branch '3.6':
closes bpo-34652: Always disable lchmod on Linux. (GH-9234)
bdace2e

[benjaminp]

New changeset ed709d5 by Benjamin Peterson in branch 'master':
bpo-34652: Remove lchmod from the big func checking block. (GH-9247)
ed709d5

[benjaminp]

New changeset 2184fe5 by Benjamin Peterson in branch '3.6':
[3.6] bpo-34652: Remove lchmod from the big func checking block. (GH-9250)
2184fe5

[miss-islington]

New changeset 35c94c7 by Miss Islington (bot) in branch '3.7':
bpo-34652: Remove lchmod from the big func checking block. (GH-9247)
35c94c7

[asottile]

I believe this also closes https://bugs.python.org/issue31940 and https://bugs.python.org/issue28627

[jmroot]

The follow-up fix (AC_CHECK_FUNC -> AC_CHECK_FUNCS) still needs to be backported to 2.7. Currently the lack of it causes lchmod to be disabled on all platforms, not just Linux.

[benjaminp]

We can take a PR to fix that.

On Thu, Apr 11, 2019, at 04:42, Joshua Root wrote:

Joshua Root <josh+python@root.id.au> added the comment:

The follow-up fix (AC_CHECK_FUNC -> AC_CHECK_FUNCS) still needs to be
backported to 2.7. Currently the lack of it causes lchmod to be
disabled on all platforms, not just Linux.

----------
nosy: +jmr

---

Python tracker <report@bugs.python.org>
<https://bugs.python.org/issue34652\>

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[benjaminp]

New changeset 0fd5a73 by Benjamin Peterson (Joshua Root) in branch '2.7':
bpo-34652: Use AC_CHECK_FUNCS for lchmod. (GH-12799)
0fd5a73

[benjaminp]

New changeset bed04b6 by Benjamin Peterson in branch 'master':
bpo-34652 again: Remove lchmod from the default AC_CHECK_FUNCS list. (GH-15758)
bed04b6

[miss-islington]

New changeset 12acb5b by Miss Islington (bot) in branch '3.8':
bpo-34652 again: Remove lchmod from the default AC_CHECK_FUNCS list. (GH-15758)
12acb5b