`http.client.HTTPResponse.read1` does not close response after reading all data

[illia-v]

Bug report

Bug description:

While trying to use read1 in urllib3, we discovered that read1 unlike read never closes the response after reading all data when the content length is known (urllib3/urllib3#3235).

---

import http.client

conn = http.client.HTTPSConnection("www.python.org")
conn.request("GET", "/")
response = conn.getresponse()

This runs successfully:

response.read()
assert response.isclosed()

This fails:

while response.read1():
    pass
assert response.isclosed()

CPython versions tested on:

3.8, 3.9, 3.10, 3.11, 3.12, 3.13, CPython main branch

Operating systems tested on:

Linux, macOS, Windows

Linked PRs

• gh-113199: Make read1 and readline of HTTPResponse close IO after reading all data #113200
• [3.12] gh-113199: Make read1() and readline() of HTTPResponse close IO after reading all data (GH-113200) #113259
• [3.11] gh-113199: Make read1() and readline() of HTTPResponse close IO after reading all data (GH-113200) #113260

[serhiy-storchaka]

Is it a bug? The next reading operation will return an empty bytes and close the connection. So it may be just an optimization.

The read1() method was added in 8e5d0ca (bpo-19009/#63209), several years after adding autoclose when read all data in 7066590 (bpo-1580738/#44147). Why this was not added in read1() and readline()? @kristjanvalur, @pitrou, was it just an oversight or were there reasons for it?

[pitrou]

This was probably an oversight and I think this should be fixed.

[illia-v]

Is it a bug? The next reading operation will return an empty bytes and close the connection.

Closing won't happen when the content length is known.

cpython/Lib/http/client.py

Lines 661 to 665 in 21d5299

	if self.length is not None and (n < 0 or n > self.length):
	n = self.length
	result = self.fp.read1(n)
	if not result and n:
	self._close_conn()

After it has read all data, any subsequent call will reset n to self.length equal to 0 on line 662. Because of this closing will be skipped.

[kristjanvalur]

Nice necro. Yes, probably an oversight. The original impetus was to read from streams that didn't close.