Bug report

Bug description:

netrc.__repr__() says it dumps the data "in the format of a .netrc file", but it writes every value as is with no quoting. So the output only parses back if every value is a single non empty word.

The simplest case is an entry with no login, which is pretty normal for token based logins:

import netrc, tempfile
from pathlib import Path

with tempfile.TemporaryDirectory() as d:
    p = Path(d) / "netrc"
    p.write_text("machine example.com password hunter2\n")
    n = netrc.netrc(p)
    print(n.hosts)      # {'example.com': ('', '', 'hunter2')}
    print(repr(n).splitlines())  # ['machine example.com', '\tlogin ', '\tpassword hunter2']
    p.write_text(repr(n))
    netrc.netrc(p)      # NetrcParseError: bad follower token 'hunter2'

The empty login gets written as login followed by nothing, so the parser takes password as the login and then chokes on hunter2.

Same thing with other values, i tried a few as the password:

"pass word"     -> NetrcParseError: bad follower token 'word'
"pass\tword"    -> NetrcParseError
"pass\nword"    -> NetrcParseError
" pass"         -> reads back as 'pass'
"pass\word"    -> reads back as 'password'

The last two are the worst ones since nothing fails, you just get a different password back.

The reader in the same file already supports quoted values and backslash escapes (_netrclex.get_token), the writer just never uses them. Looks like this goes back to GH-2491 (bpo-30806, #74989). Before that __repr__ used repr() for the values and that fix replaced it with plain f-strings, with the commit message saying "netrc file format doesn't support quotes and escapes". But _netrclex does support both, so the Python quotes got removed and nothing replaced them.

That fix also added a round trip check to the tests:

nrc2 = self.make_nrc(nrc.__repr__())
self.assertEqual(nrc.hosts, nrc2.hosts)

but it was dropped in GH-26330 (15409c7) when test_default was rewritten, and nothing in test_netrc.py calls __repr__ now.

A fix would be to quote a value when its empty or has whitespace, " or \ in it, and escape \ and " inside the quotes the way _netrclex reads them. One thing to keep in mind is #99080 (backslashes outside quotes get dropped by the parser), if that changes how backslashes are read the escaping here would have to match.

I have a patch with a round trip test for all the cases above, happy to open a PR.

CPython versions tested on:

CPython main branch, 3.13

Operating systems tested on:

Windows

Linked PRs

• gh-158560: Quote values in netrc.__repr__() so the output can be parsed back #158561