chansend() does not always send data to stdin

[haolian9]

Problem

hi, i'm trying to port echo hello | sudo dd of=outfile to lua, the following code is what i got so far, and it works not.
the problem is the data sent by chansend() also goes to tty which should be stdin as it claimed in its doc.

Steps to reproduce

• nvim --clean +'luafile test.lua'
• (test.lua wants to behave like shell echo hello | sudo dd of=/tmp/outfile)
• in the opened terminal, you can see 'hello' be showed in there, and it is a part of the password which is received by sudo, so sudo will ask you to enter password again.

the test.lua:

local uv = vim.loop
local api = vim.api

local bufnr = api.nvim_create_buf(false, true)
-- stylua: ignore
api.nvim_open_win(bufnr, true, {
  relative = "editor", style = "minimal", col = 0, row = 0, width = vim.o.columns, height = vim.o.lines,
})

local term = vim.fn.termopen({ "sudo", "dd", "of=/tmp/outfile" }, {
  stdin = "pipe",
  pty = true,
})
vim.cmd.startinsert()

vim.fn.chansend(term, "hello")

Expected behavior

as i'm carefully using jobstart(pty = true, stdin = 'pipe')， i do think the test.lua should work with no problem, stdin and pty should be different things, thus chansend(job, data) should just send data to stdin rather than pty.

Neovim version (nvim -v)

NVIM v0.8.3

Vim (not Nvim) behaves the same?

N/A

Operating system/version

archlinux

Terminal name/version

st 0.8.5

$TERM environment variable

tmux-256color

Installation

system package manager

[zeertzjq]

I think changing this behavior will breaking existing usage of chansend()

[haolian9]

so this echo hello | sudo dd of=/tmp/outfile is impossible to be implemented in nvim?
oh, good to know that's a document issue.

[bfredl]

stdin="pipe" is a bit misleading, it just means stdin is connected instead of being closed (which is a pipe for a normal job and a tty for a termopen() job).

We will need a separate option for this usecase. I think we should allow to open a PTY without any job running it it, and then run jobstart() with the stdout redirected to the PTY. then you will get two separate channel ids for PTY input and process input.

[haolian9]

allow to open a PTY without any job running it

that would be great! with it i can replace job api with uv.spawn(), the latter is much simpler to use to me personally. ahh, maybe.