Channels opened by sockconnect() does not close automatically on EOF

[alaviss]

• nvim --version:

  NVIM v0.4.2
  Build type: Release
  LuaJIT 2.0.5
  Compilation: /usr/bin/x86_64-pc-linux-gnu-gcc -O3 -march=native -pipe -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -DMIN_LOG_LEVEL=3 -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fdiagnostics-color=always -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/tmp/portage/app-editors/neovim-0.4.2/work/neovim-0.4.2_build/config -I/tmp/portage/app-editors/neovim-0.4.2/work/neovim-0.4.2/src -I/usr/include -I/tmp/portage/app-editors/neovim-0.4.2/work/neovim-0.4.2_build/src/nvim/auto -I/tmp/portage/app-editors/neovim-0.4.2/work/neovim-0.4.2_build/include
  Compiled by portage@workstation
  
  Features: +acl +iconv +tui
  See ":help feature-compile"
  
     system vimrc file: "/etc/vim/sysinit.vim"
    fall-back for $VIM: "/usr/share/nvim"
  
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• Operating system/version: Gentoo

• Terminal name/version: alacritty 0.3.3

• $TERM: alacritty

Steps to reproduce using nvim -u NORC

1. Make an auto-disconnecting TCP server:

import net

var server = newSocket()
server.bindAddr 8000.Port, "localhost"
server.listen()

var client: Socket
while true:
  server.accept client
  close client

2. Reproduce the problem

nvim -u NORC
:echo sockconnect('tcp', 'localhost:8000', {})
<returns channel id>
:echo nvim_list_chans()

Actual behaviour

The returned channel is still in the list. lsof will report that the socket held by nvim is in CLOSE_WAIT state.

A walkaround is to close the channel manually via the handler on EOF.

Expected behaviour

The channel should be closed.

[justinmk]

Still present on b7084fe

Python version:

import socket

serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serversocket.bind(('localhost', 8000))
serversocket.listen(5)

while True:
    (clientsocket, address) = serversocket.accept()
    serversocket.close()

[tmccombs]

FWIW, I don't think this happens if you include an on_data function in the third argument to sockconnect.

[alaviss]

After a while, I think this behavior is correct. It prevents a class of bug where the channel id is reused but a stale one is held elsewhere before cleanup occurs (ie. in a dict).

There should probably be documentation to remind users that they have to close the channel once they're done with it. I believe I got the assumption that the channel auto closes from :h channel_buffered.

channel-buffered The callback is invoked immediately as data is available, where a single-item list [''] indicates EOF (stream closed).