Cannot create temp file for executing external commands over a range when shell is set to powershell

[3N4N]

Neovim version (nvim -v)

NVIM v0.5.1

Vim (not Nvim) behaves the same?

Can't say. Do not have vim installed.

Operating system/version

Windows 10 21H1

Terminal name/version

Windows Terminal, Conhost

$TERM environment variable

Nil

Installation

Put the zip folder from release page and added the location in Windows path variable

How to reproduce the issue

nvim -u NONE
:let &shell = 'pwsh'
:let &shellcmdflag = '-NoLogo -NoProfile -ExecutionPolicy RemoteSigned -Command [Console]::InputEncoding=[Console]::OutputEncoding=[System.Text.Encoding]::UTF8;'
:let &shellredir = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
:let &shellpipe = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
:set shellquote= shellxquote=
:e random-nonempty.file
:1,5!sort

Expected behavior

The lines from 1 to 5 should be sorted with the external sort command (which exists in my path).

Actual behavior

I get the following error.

E485: Can't read file C:\Users\ACER\AppData\Local\Temp\nvim6UJx04\7

I checked with Process Monitor and saw that neovim is failing to create the file/subdirectory ...\nvim6UJx04\7 when the :h 'shell' is set to pwsh (PowerShell Core). With shell set to cmd, it works alright. Note that in my full config, I set up the shell according to :h 'shell-powershell' but the same issue persists.

[3N4N]

Here is a snap of the process with shell=cmd:

And here is one with shell=pwsh:

[justinmk]

:let &shell = 'pwsh'

There are many shell-related options in vim, it is not a simple matter of setting 'shell' only. See :help shell-powershell for the correct settings (which is a section of :help 'shell'... read the help before opening issues).

[justinmk]

Note that in my full config, I set up the shell according to :h 'shell-powershell' but the same issue persists.

Wait, why isn't that part of the repro steps?

[3N4N]

@justinmk I will update now. Thought I should reduce the steps as much as possible.

Edit: Issue updated.

[justinmk]

Thought I should reduce the steps as much as possible.

Yes :) But in this case setting only 'shell' is incorrect so it is not a sufficient repro.

BTW, latest stable release is Nvim 0.5.1

[3N4N]

Just checked with the newest release (0.5.1) and the issue remains.

[3N4N]

I checked with Ubuntu 20.04 in WSL. Using powershell as shell produces the same bug in Linux as well.

[3N4N]

@justinmk, the problem may be because of permissions. I was debugging with gdb. It says the perm (of the temp files) with powershell is -2 while with cmd it's 33188. I would guess it's because the spawned powershell process doesn't have the required permission. But then how does cmd/bash spawned processes get the permission? Dunno.

Also, the do_filter function reads/writes two files. One for storing the original text, and another I guess for storing the processed text. Powershell can write the infile, but not the outfile. That seems weird.

By the way, the source of problem, the source inside nvim, is this call to uv_fs_stat(...). Looks like a call do libuv. I couldn't go deeper than that.

Any thoughts?

EDIT: The stack of function calls:

[#0] 0x55bfb030d843 → os_stat(name=0x55bfb1594910 "/tmp/nvimE8wDVQ/10", statbuf=0x7fff84d2f920)
[#1] 0x55bfb030d9b3 → os_getperm(name=0x55bfb1594910 "/tmp/nvimE8wDVQ/10")
[#2] 0x55bfb0246061 → readfile(fname=0x55bfb1594910 "/tmp/nvimE8wDVQ/10", sfname=0x55bfb1594910 "/tmp/nvimE8wDVQ/10", from=0x3, lines_to_skip=0x0, lines_to_read=0x7fffffff, eap=0x7fff84d2fff0, flags=0x2)
[#3] 0x55bfb01fdb51 → do_filter(line1=0x1, line2=0x3, eap=0x7fff84d2fff0, cmd=0x55bfb1491850 "sort", do_in=0x1, do_out=0x1)
[#4] 0x55bfb01fd72b → do_bang(addr_count=0x2, eap=0x7fff84d2fff0, forceit=0x0, do_in=0x1, do_out=0x1)
[#5] 0x55bfb0223d2f → ex_bang(eap=0x7fff84d2fff0)
[#6] 0x55bfb0216325 → do_one_cmd(cmdlinep=0x7fff84d30200, flags=0x0, cstack=0x7fff84d30320, fgetline=0x55bfb02329ed <getexline>, cookie=0x0)
[#7] 0x55bfb02135d1 → do_cmdline(cmdline=0x0, fgetline=0x55bfb02329ed <getexline>, cookie=0x0, flags=0x0)
[#8] 0x55bfb02db6d4 → nv_colon(cap=0x7fff84d30990)
[#9] 0x55bfb02d3803 → normal_execute(state=0x7fff84d30900, key=0x3a)

[3N4N]

Changing the title because nvim can create both in and out temp files, but just can't read the out temp file. I was wrong. Nvim with powershell actually cannot even create the out temp file. So the problem is not with the file permission, but with the powershell redirection.

Need some insight from devs, though, to make sense of what's happening.

[3N4N]

Okay, the problem was with powershell redirection. The one suggested in :h shell-powershell gives cmd_buf to be --

gdb> p cmd_buf
$1 = (char_u *) 0x2513025da80 "sort.exe < C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/0 2>&1 | Out-File -Encoding UTF8 C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/1; exit $LastExitCode"

But PowerShell doesn't use < as file input redirection. It has a special argument. When I change cmd_buf like in the following, the filter works (the lines are sorted, I mean).

gdb> set cmd_buf = "Start-Process sort.exe -RedirectStandardInput C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/0 -RedirectStandardOutput C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/1  -NoNewWindow -Wait"
gdb> p cmd_buf
$2 = (char_u *) 0x2513026b0b0 "Start-Process sort.exe -RedirectStandardInput C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/0 -RedirectStandardOutput C:/Users/ACER/AppData/Local/Temp/nvimnr4hM4/1  -NoNewWindow -Wait"

I guess the easy workaround would be to force-use cmd.exe whatever the shell is set to. I don't think we users would care who is doing our work, as long as the work is done. Then again, someone may want to use powershell-specific command. Then you'd have to create a powershell-specific command for make_filter_cmd function. But judging by how no one except me found this bug, I'm gonna bet no one actually cares.