UnboundLocalError in socket._sendfile_use_sendfile

[berkerpeksag]

BPO	26384
Nosy	@berkerpeksag, @serhiy-storchaka
Files	socket_unboundlocalerror.diff issue26384_v2.diff issue26384_v3.diff

^{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 2016-09-17.20:23:45.805>
created_at = <Date 2016-02-18.15:50:52.431>
labels = ['3.7', 'type-bug', 'library']
title = 'UnboundLocalError in socket._sendfile_use_sendfile'
updated_at = <Date 2016-09-17.20:23:45.804>
user = 'https://github.com/berkerpeksag'

bugs.python.org fields:

activity = <Date 2016-09-17.20:23:45.804>
actor = 'berker.peksag'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-17.20:23:45.805>
closer = 'berker.peksag'
components = ['Library (Lib)']
creation = <Date 2016-02-18.15:50:52.431>
creator = 'berker.peksag'
dependencies = []
files = ['41956', '44720', '44721']
hgrepos = []
issue_num = 26384
keywords = ['patch']
message_count = 5.0
messages = ['260464', '260806', '276822', '276828', '276837']
nosy_count = 3.0
nosy_names = ['python-dev', 'berker.peksag', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26384'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7']

[berkerpeksag]

I noticed this while working on bpo-16915:

Traceback (most recent call last):
  ...
  File "/home/berker/projects/cpython/default/Lib/socket.py", line 262, in _sendfile_use_sendfile
    raise _GiveupOnSendfile(err)  # not a regular file
UnboundLocalError: local variable 'err' referenced before assignment

Here's a patch.

[serhiy-storchaka]

This issue can be tested without moking os.fstat():

        class F:
            def fileno(self):
                return fd
        with socket.socket() as sock:
            fd = os.open(os.curdir, os.O_RDONLY)
            os.close(fd)
            self.assertRaises(socket._GiveupOnSendfile,
                              sock._sendfile_use_sendfile, F())

os.fstat() can raise not only OSError. It may be worth to test also with fd = 2**1000 and fd = None.

[berkerpeksag]

Thanks, Serhiy. Here's an updated patch.

[serhiy-storchaka]

LGTM.

[python-dev]

New changeset 78efbf499611 by Berker Peksag in branch '3.5':
Issue bpo-26384: Fix UnboundLocalError in socket._sendfile_use_sendfile
https://hg.python.org/cpython/rev/78efbf499611

New changeset 2156aa4050c7 by Berker Peksag in branch '3.6':
Issue bpo-26384: Merge from 3.5
https://hg.python.org/cpython/rev/2156aa4050c7

New changeset 0d440fda8604 by Berker Peksag in branch 'default':
Issue bpo-26384: Merge from 3.6
https://hg.python.org/cpython/rev/0d440fda8604