Node: Passing empty environment variables to child processes convert to 'undefined' using ConEmu + Node

Created on 2 Aug 2017 · 50Comments · Source: nodejs/node

Version: Since Node 8.0.0. (tested in Node 7.9, Node 8.0.0 and Node 8.2.1)
Platform: Windows 10 version 1703 x64 using a shell (cmd.exe or git-bash) in ConEmu

Problem description

When executing a process which spawns a child process, which in turn creates another child process, the empty environment variables are passed through as 'undefined' (the string literal, NOT an absent value). If you than for example do an npm install command from that child process, bad things happen:

npm WARN invalid config access=undefined
npm WARN invalid config also=undefined
npm WARN invalid config https-proxy=undefined
npm WARN invalid config Must be a full url with \'http://\'
npm WARN onload-script     at Function.Module._resolveFilename (module.js:485:15)
npm WARN onload-script  { Error: Cannot find module \'undefined\'

To my knowledge: this only happens in ConEmu, a popular console emulator on Windows. When i downgrade to node 7.9, this problem does not occur.

Steps to reproduce

I created a small github repo to reproduce the problem.

On windows 10: install ConEmu: https://conemu.github.io/
Clone this repo git clone [email protected]:nicojs/reproduce-conemu-child-process-environment-bug.git
run npm install.
run npm test

This test spawns a child process, which in turn starts a new child process which logs the process.env to console. The tests verifies that npm_config_onload_script (one of the env variables) is set to ''.

Actual results

When ran from within ConEmu: the test failes

1) the env should contain "npm_config_onload_script":
Error: "npm_config_onload_script": "undefined"!"

The test also prints the environment variables to screen. You can see a lot of "undefined" values (the string literal, not an absent value).

For example: "npm_config_onload_script": "undefined",

Expected results

If ran from cmd or git-bash using mintty directly (or on a POSIX environment): the test passes

√ should contain "npm_config_onload_script"

If you now look at the environment variables on screen, you don't see the "undefined" values. Just empty strings.

For example: "npm_config_onload_script": "",

I reported this issue to ConEmu first, but the developer pointed out to me that this seems to be regression in node. See the discussion with Maximus5 here: https://github.com/Maximus5/ConEmu/issues/1209

Screenshots:

ConEmu with cmd.exe shell

using-con-emu-cmd

Command prompt with cmd.exe shell

using-command-promt-cmd

child_process confirmed-bug

Source

nicojs

👍2 ❤1

Most helpful comment

Wow! Disabled it and stuff works again like a charm!

Anyone running into this issue: setting can be found here:

conemu-settings-hkdll

So i guess an issue at ConEmu side after all (or in the injected dll). Tricky stuff. Thanks to all for your time! It took me several days to understand what was going wrong, but solving the issue only took a couple of hours. 💐

nicojs on 2 Aug 2017

❤5

All 50 comments

Thanks for the bug report. Does it reproduce outside of npm? The behavior of process.env hasn't changed between v7.x and v8.x so I expect it's caused by something in npm.

bnoordhuis on 2 Aug 2017

I've thought of that as well, but I'm using npm 5.3.0 in all cases so that doesn't seem to be the issue.

Maybe something changed to 'child_process'? I'm using require('child_process').exec and require('child_process').execSync.

nicojs on 2 Aug 2017

Can you reproduce without npm being involved? If so, can you post that test case? (It's fine to do that inline here in a comment.)

bnoordhuis on 2 Aug 2017

👍1

Hmm good point.

Yes, I can. In one simple script using node -e.

// start.js
const execSync = require('child_process').execSync;
process.env.foobar = '';
const stdout = execSync('node -e "const execSync = require(\'child_process\').execSync;' +
    'execSync(\'node -e "console.log(process.env.foobar);"\', { stdio: [0, 1, 2]});"')
    .toString().trim();
if (stdout === '') {
    console.log('foobar is empty, stuff works.');
} else {
    console.error(`foobar was "${stdout}", using ConEmu?`);
}

If i run that script from a ConEmu tap using cmd shell it says:

> node start.js
foobar was "undefined", using ConEmu?

From command prompt and cmd.exe:

>node start.js
foobar is empty, stuff works.

nicojs on 2 Aug 2017

Well, that does point to ConEmu. FWIW, it works in the expected way on Linux and OS X too.

bnoordhuis on 2 Aug 2017

Well, that does point to ConEmu. FWIW, it works in the expected way on Linux and OS X too.

ConEmu maintainer Maximus5 says it does not change any environment variables. Also, it is translated to the actual string value 'undefined'. This seems to be something that happens in the JavaScript world.

If you change my script to print the entire environment like this:

const execSync = require('child_process').execSync;
process.env.foobar = '';
const stdout = execSync('node -e "require(\'child_process\').execSync(\'node -e "console.log(process.env);"\', { stdio: [0, 1, 2]});"')
    .toString().trim();
console.log(stdout);

If i run that script from a ConEmu tap it says:

> node start.js
...
foobar: 'undefined',
...

From cmd.exe:

>node start.js
...
foobar: undefined,
...

nicojs on 2 Aug 2017

Can't reproduce, I'm afraid; it prints foobar: '', for me.

cc @nodejs/platform-windows in case any of you can reproduce.

bnoordhuis on 2 Aug 2017

Just double checking: you have Node version 8.0.0 or 8.2.1 and running from inside ConEmu with cmd shell?

Did you let it print the entire process.env (my second inline sample)? In that case it should not print foobar: '', instead it should print foobar: undefined (but from ConEmu it prints foobar: 'undefined'). I've just tested it on an other windows 10 machine with ConEmu and was able to reproduce it using node version 8.1.2.

nicojs on 2 Aug 2017

Unable to reproduce with ConEmu 161206 (stable build) and node 8.2.1 on Windows 10. Both npm install in your repository and your snippet work just fine. Which ConEmu version are you using? How is your shell inside ConEmu configured? Please post the full shell command line along with any additional options.

tniessen on 2 Aug 2017

170402 (preview), but just now also installed 161206 and same issue.

These are my ConEmu settings, but also tried on an other laptop with default settings: https://gist.github.com/nicojs/3abd0b4b2a996c1633bd97c9fd33ec27

See this screenshot for a side by side comparison of what i'm doing. On the left you can see the content of the file "start.js" (which is the first code snippet i shared) and executed from within ConEmu. On the right site you can see the same file executed from command prompt. Also on screen is the about window of ConEmu (with the version).

side-by-side

EDIT:

These are my shell settings for cmd (which are default). But i can reproduce with all shells. Tested with gitbash, powershell and cmd (64bits and 32bits)

cmd-shell-settings

nicojs on 2 Aug 2017

@nicojs, could you provide output of env from both ConEmu and cmd.exe?

bzoz on 2 Aug 2017

And node -e console.log(process.env)?

bzoz on 2 Aug 2017

👍1

I feel slightly naked for doing this. Everything for the cause. Please don't make fun of the size of my P...ATH

https://gist.github.com/nicojs/4de5af23fa937deb8372ced562ef0878

I did the same thing on both console applications and output can be found in the gist:

> type start.js
> node start.js
> SET
> node -e "console.log(process.env)"

nicojs on 2 Aug 2017

❤1

I can repro:
node - v8.1.3
windows 10x64 build 15063
ConEmu 170517x64
ConEmu shell - cmd.exe /k "%ConEmuBaseDir%\CmdInitRef.cmd" -new_console:a

CmdInitRef.cmd

@rem !!! Do not change this file in-place, change its copy instead !!!
@rem !!!  Otherwise you will lose your settings after next update  !!!

@echo off

rem Simple "ver" prints empty line before Windows version
rem Use this construction to print just a version info
cmd /d /c ver | "%windir%\system32\find.exe" "Windows"

rem Now we form the command prompt

rem This will start prompt with `User@PC `
rem set ConEmuPrompt0=$E[m$E[32m$E]9;8;"USERNAME"$E\@$E]9;8;"COMPUTERNAME"$E\$S
set ConEmuPrompt0=

rem Followed by colored `Path`
set ConEmuPrompt1=%ConEmuPrompt0%$P
if NOT "%PROCESSOR_ARCHITECTURE%" == "AMD64" (
  if "%PROCESSOR_ARCHITEW6432%" == "AMD64" if "%PROCESSOR_ARCHITECTURE%" == "x86" (
    rem Use another text color if cmd was run from SysWow64
    set ConEmuPrompt1=%ConEmuPrompt0%$P
  )
)

rem Carriage return and `$` or `>`
rem Spare `$E[90m` was specially added because of GitShowBranch.cmd
if "%ConEmuIsAdmin%" == "ADMIN" (
  set ConEmuPrompt2=$$
) else (
  set ConEmuPrompt2=$G
)

rem Finally reset color and add space
set ConEmuPrompt3=$S

if /I "%~1" == "/git" goto git
if /I "%~1" == "-git" goto git
goto no_git

:git
call "%~dp0GitShowBranch.cmd" /i
goto :EOF

:no_git
rem Set new prompt
PROMPT %ConEmuPrompt1%%ConEmuPrompt2%%ConEmuPrompt3%

refack on 2 Aug 2017

👍1

feel slightly naked for doing this. Everything for the cause. Please don't make fun of the size of my P...ATH

We're all friends here...

Procmon output:

child (node) 4640

High Resolution Date & Time:    02/08/2017 09:17:07.5786824
Event Class:    Process
Operation:  Process Start
Result: SUCCESS
Path:   
TID:    10428
Duration:   0.0000000
Parent PID: 4640
Command line:   node  -e "const execSync = require('child_process').execSync;execSync('node -e "console.log(process.env.foobar);"', { stdio: [0, 1, 2]});"
Current directory:  d:\code\4node\
Environment:    
    =D:=d:\code\4node
    ALLUSERSPROFILE=C:\ProgramData
    ANSICON=182x10000 (182x51)
    ANSICON_DEF=7
    APPDATA=d:\refael\AppData\Roaming
    CommonProgramFiles=C:\Program Files\Common Files
    CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
    CommonProgramW6432=C:\Program Files\Common Files
    COMPUTERNAME=REFAELUX
    ComSpec=C:\WINDOWS\System32\cmd.exe
    ConEmuANSI=ON
    ConEmuAnsiLog=
    ConEmuArgs=/dir "d:\code\node"
    ConEmuArgs2=
    ConEmuBackHWND=0x00060A5A
    ConEmuBaseDir=C:\Tools\maint\conemu\ConEmu
    ConEmuBuild=170517
    ConEmuConfig=
    ConEmuDir=C:\Tools\maint\conemu
    ConEmuDrawHWND=0x00060A22
    ConEmuDrive=C:
    ConEmuHooks=Enabled
    ConEmuHWND=0x000606E4
    ConEmuIsAdmin=ADMIN
    ConEmuPalette=<Solarized>
    ConEmuPID=3252
    ConEmuPrompt1=$P
    ConEmuPrompt2=$$
    ConEmuPrompt3=$S
    ConEmuServerPID=540
    ConEmuTask={Shells::cmd}
    ConEmuWorkDir=d:\code\node
    ConEmuWorkDrive=d:
    foobar=
    FSHARPINSTALLDIR=C:\Program Files (x86)\Microsoft SDKs\F#\4.1\Framework\v4.0\
    GOPATH=C:\bin\dev\go\work
    GOROOT=C:\bin\dev\go
    HOME=d:\refael
    HOMEDRIVE=d:
    HOMEPATH=\refael
    JAVA_HOME=C:\WINDOWS\System32\Java
    JDK_HOME=C:\WINDOWS\System32\Java
    LC_ALL=en_GB.UTF-8
    LOCALAPPDATA=d:\refael\AppData\Local
    LOGONSERVER=\\REFAELUX
    MSMPI_BIN=c:\Program Files\Microsoft MPI\Bin\
    NODE_PRESERVE_SYMLINKS=1
    NODE_REPL_MODE=strict
    NUMBER_OF_PROCESSORS=4
    OS=Windows_NT
    Path=C:\Tools\maint\conemu\ConEmu\Scripts;C:\Tools\maint\conemu;C:\Tools\maint\conemu\ConEmu;C:\Program Files\Docker\Docker\Resources\bin;c:\Program Files\Microsoft MPI\Bin\;C:\WINDOWS\system32\Tools;C:\WINDOWS\system32\downlevel;C:\WINDOWS\system32\Java\jre\bin;C:\WINDOWS\system32;C:\WINDOWS\system32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\Wbem;C:\WINDOWS;C:\bin\dev\node;C:\bin\dev\python27;C:\bin\dev\python27\Scripts;C:\bin\git\usr\bin;C:\bin\git\cmd;C:\Tools\maint;C:\Tools\dev;C:\code\tools;C:\code\tools\scripts;.\node_modules\.bin\;C:\Program Files\dotnet\;C:\Program Files (x86)\Windows Kits\8.1\Windows Performance Toolkit\
    PATHEXT=.JS;.;.CMD;.BAT;.EXE;.MSC;.COM
    PROCESSOR_ARCHITECTURE=AMD64
    PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
    PROCESSOR_LEVEL=6
    PROCESSOR_REVISION=3a09
    ProgramData=C:\ProgramData
    ProgramFiles=C:\Program Files
    ProgramFiles(x86)=C:\Program Files (x86)
    ProgramW6432=C:\Program Files
    PROMPT=@CLINK_PROMPT$P$$$S
    PSModulePath=C:\Program Files (x86)\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules;C:\bin\dev\gcloud\google-cloud-sdk\platform\PowerShell;C:\Program Files (x86)\AWS Tools\PowerShell\
    PUBLIC=C:\Users\Public
    SEE_MASK_NOZONECHECKS=1
    SystemDrive=C:
    SystemRoot=C:\WINDOWS
    TEMP=c:\temp\usr
    TMP=c:\temp\usr
    USERDOMAIN=REFAELUX
    USERDOMAIN_ROAMINGPROFILE=REFAELUX
    USERNAME=refael
    USERPROFILE=d:\refael
    windir=C:\WINDOWS
    _NT_SYMBOL_PATH=srv*c:\bin\symbols*http://msdl.microsoft.com/download/symbols;srv*c:\bin\symbols*http://chromium-browser-symsrv.commondatastorage.googleapis.com

grandchild (cmd) 12272

High Resolution Date & Time:    02/08/2017 09:17:07.9592797
Event Class:    Process
Operation:  Process Start
Result: SUCCESS
Path:   
TID:    13168
Duration:   0.0000000
Parent PID: 12272
Command line:   C:\WINDOWS\System32\cmd.exe /d /s /c "node -e console.log(process.env.foobar);"
Current directory:  d:\code\4node\
Environment:    
    ALLUSERSPROFILE=C:\ProgramData
    ANSICON=182x10000 (182x51)
    ANSICON_DEF=7
    APPDATA=d:\refael\AppData\Roaming
    CommonProgramFiles=C:\Program Files\Common Files
    CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
    CommonProgramW6432=C:\Program Files\Common Files
    COMPUTERNAME=REFAELUX
    ComSpec=C:\WINDOWS\System32\cmd.exe
    ConEmuANSI=ON
    ConEmuAnsiLog=undefined
    ConEmuArgs=/dir "d:\code\node"
    ConEmuArgs2=undefined
    ConEmuBackHWND=0x00060A5A
    ConEmuBaseDir=C:\Tools\maint\conemu\ConEmu
    ConEmuBuild=170517
    ConEmuConfig=undefined
    ConEmuDir=C:\Tools\maint\conemu
    ConEmuDrawHWND=0x00060A22
    ConEmuDrive=C:
    ConEmuHooks=Enabled
    ConEmuHWND=0x000606E4
    ConEmuIsAdmin=ADMIN
    ConEmuPalette=<Solarized>
    ConEmuPID=3252
    ConEmuPrompt1=$P
    ConEmuPrompt2=$$
    ConEmuPrompt3=$S
    ConEmuServerPID=540
    ConEmuTask={Shells::cmd}
    ConEmuWorkDir=d:\code\node
    ConEmuWorkDrive=d:
    foobar=undefined
    FSHARPINSTALLDIR=C:\Program Files (x86)\Microsoft SDKs\F#\4.1\Framework\v4.0\
    GOPATH=C:\bin\dev\go\work
    GOROOT=C:\bin\dev\go
    HOME=d:\refael
    HOMEDRIVE=d:
    HOMEPATH=\refael
    JAVA_HOME=C:\WINDOWS\System32\Java
    JDK_HOME=C:\WINDOWS\System32\Java
    LC_ALL=en_GB.UTF-8
    LOCALAPPDATA=d:\refael\AppData\Local
    LOGONSERVER=\\REFAELUX
    MSMPI_BIN=c:\Program Files\Microsoft MPI\Bin\
    NODE_PRESERVE_SYMLINKS=1
    NODE_REPL_MODE=strict
    NUMBER_OF_PROCESSORS=4
    OS=Windows_NT
    Path=C:\Tools\maint\conemu\ConEmu\Scripts;C:\Tools\maint\conemu;C:\Tools\maint\conemu\ConEmu;C:\Program Files\Docker\Docker\Resources\bin;c:\Program Files\Microsoft MPI\Bin\;C:\WINDOWS\system32\Tools;C:\WINDOWS\system32\downlevel;C:\WINDOWS\system32\Java\jre\bin;C:\WINDOWS\system32;C:\WINDOWS\system32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\Wbem;C:\WINDOWS;C:\bin\dev\node;C:\bin\dev\python27;C:\bin\dev\python27\Scripts;C:\bin\git\usr\bin;C:\bin\git\cmd;C:\Tools\maint;C:\Tools\dev;C:\code\tools;C:\code\tools\scripts;.\node_modules\.bin\;C:\Program Files\dotnet\;C:\Program Files (x86)\Windows Kits\8.1\Windows Performance Toolkit\
    PATHEXT=.JS;.;.CMD;.BAT;.EXE;.MSC;.COM
    PROCESSOR_ARCHITECTURE=AMD64
    PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
    PROCESSOR_LEVEL=6
    PROCESSOR_REVISION=3a09
    ProgramData=C:\ProgramData
    ProgramFiles=C:\Program Files
    ProgramFiles(x86)=C:\Program Files (x86)
    ProgramW6432=C:\Program Files
    PROMPT=@CLINK_PROMPT$P$$$S
    PSModulePath=C:\Program Files (x86)\WindowsPowerShell\Modules;C:\WINDOWS\system32\WindowsPowerShell\v1.0\Modules;C:\bin\dev\gcloud\google-cloud-sdk\platform\PowerShell;C:\Program Files (x86)\AWS Tools\PowerShell\
    PUBLIC=C:\Users\Public
    SEE_MASK_NOZONECHECKS=1
    SystemDrive=C:
    SystemRoot=C:\WINDOWS
    TEMP=c:\temp\usr
    TMP=c:\temp\usr
    USERDOMAIN=REFAELUX
    USERDOMAIN_ROAMINGPROFILE=REFAELUX
    USERNAME=refael
    USERPROFILE=d:\refael
    windir=C:\WINDOWS
    _NT_SYMBOL_PATH=srv*c:\bin\symbols*http://msdl.microsoft.com/download/symbols;srv*c:\bin\symbols*http://chromium-browser-symsrv.commondatastorage.googleapis.com

refack on 2 Aug 2017

👍1

@refack if it's not too much to ask, can you also confirm that you cannot reproduce it in Node v7.9? Just to make sure that it is indeed related to node 8 and up.

nicojs on 2 Aug 2017

@nicojs was just about to... but bad news:

d:\code\4node$ node790 -v             
v7.9.0                                

d:\code\4node$ node790 conemu-bug.js  
foobar was "undefined", using ConEmu? 

d:\code\4node$ node6 conemu-bug.js    
foobar was "undefined", using ConEmu? 

d:\code\4node$ node6 -v               
v6.11.1                               

d:\code\4node$ node4 conemu-bug.js    
foobar was "undefined", using ConEmu? 

d:\code\4node$ node4 -v               
v4.8.2

Seems like it's a ConEmu thing, but I'm dubugging

refack on 2 Aug 2017

Okay, I found the problem, this is caused by ConEmuHk.dll which is injected into all processes by default. (I had this feature disabled in my ConEmu setup so I was unable to reproduce the issue.)

By default, ConEmu injects its own DLL into all processes, including node:

conemu

tniessen on 2 Aug 2017

👍2

Wow! Disabled it and stuff works again like a charm!

Anyone running into this issue: setting can be found here:

conemu-settings-hkdll

nicojs on 2 Aug 2017

❤5

I'm reopening since there is a node bug here:
__An env variable with an undefined value gets converted into the string 'undefined'__

refack on 2 Aug 2017

👍2

@refack see https://github.com/nodejs/node/issues/4920

evanlucas on 2 Aug 2017

This is documented behavior though.

cjihrig on 2 Aug 2017

@refack see #4920

Ack, but that's just part of the story, here node is spawned in an environment with an undefined value...

refack on 2 Aug 2017

So how do we proceed? Apparently, node converts null to undefined, which it should not do? And only when the ConEmuHK.dll is injected into child processes an empty value is transformed to null? Is that the correct conclusion?

nicojs on 3 Aug 2017

Node treats an empty string as an empty string. If it doesn't, that's a bug but I doubt that's the case here, or we would have received a small avalanche of bug reports by now.

I think a more likely explanation is that the parasitic code that ConEmu injects does something to GetEnvironmentVariableW() that breaks node. In fact, it seems like an inescapable conclusion because you mentioned that disabling injection of that DLL fixes the issue.

bnoordhuis on 3 Aug 2017

Thanks @bnoordhuis

@refack @Maximus5 do you agree with this assessment?

nicojs on 3 Aug 2017

I'm focusing to reproducing the bug I see on the node side (handling of an environment variable with a Null value).
If I can reproduce without ConEmuHK.dll then I'll open a PR.

P.S. I agree with @bnoordhuis that the "empty string part" of this issue is ConEmu's responsibility.

refack on 3 Aug 2017

Try to open non-existent file before environment access. Actually any function (which do SetLastError) called before environment access may confuse node I think.

Maximus5 on 4 Aug 2017

Environment variable contains empty string, but Node checks for non-zero GetLastError() instead of described ERROR_ENVVAR_NOT_FOUND.

Maximus5 on 4 Aug 2017

👍2

Node.js checks this: result > 0 || GetLastError() == ERROR_SUCCESS. I'm not a Windows programmer, I've no idea if that is correct, but that logic hasn't changed in five or six years.

bnoordhuis on 4 Aug 2017

👍2

Looks like it was changed in node 8.x because version 7.x doesn't suffer from the problem.

Maximus5 on 4 Aug 2017

👍2

I'll dig a bit.

refack on 4 Aug 2017

👍3

@refack Any news?

bnoordhuis on 9 Aug 2017

First @Maximus5 patched ConEmuHK.dll so it does not leak or swallow WIN32 errors anymore - https://github.com/Maximus5/ConEmu/commit/5324aa03500fdb9d198f152c93f23eed57113858
I had a bit of trouble with https://github.com/nodejs/node/pull/14641, but I think it's something I can manage once I get a free hour. That PR should close this issue.

refack on 9 Aug 2017

❤2

I am still affected by this bug in some CI setup without ConEmu. For the time being I downgraded nodejs to 6.11.1. Could we put the label confirmed-bug on this issue?

payload on 18 Sep 2017

👍1

@payload which version were you working with before?

refack on 18 Sep 2017

8.4.0

payload on 18 Sep 2017

Experiencing this too, was driving me insane preventing me from building sqlite3 with node-gyp.

Win 10 / ConEmu / Node 8.8.0

After reading this thread I just tried it in cmd.exe and it worked first time.

v9Chris on 31 Oct 2017

@v9Chris glad this issue could help you. I know the feeling :metal:

nicojs on 31 Oct 2017

That's why software updates are recommended.

Maximus5 on 31 Oct 2017

Any news whether node can be hardened against this without fixing the emulator? Sometimes these things are not under your control.

hoodie on 23 Jan 2018

Possibly related, without ConEmu:

var exec = require('child_process').exec

process.env.test = ''

if (process.argv[2] === 'trigger') {
  try { require('fs').readFileSync('foobar') } catch (e) {}
}

exec('node -p "process.env.test === \'undefined\' ? \'BUG\' : \'OK\'"', function (err, stdout) {
  if (err) throw err
  console.log(stdout)
})

Output:

> node test.js
OK
> node test.js trigger
BUG

But I can only trigger this on 4.8.7 x86 (also tried 9.2.0, 8.4.0, 8.0.0, 7.9.0, no problems there).

vweevers on 29 Jan 2018

😕2 👍2

Hello,

Maybe I have found something very similar related to the access of an undefined process.env variable in Windows. The env variable that does not exist in this test is "DUMMY_VAR".
The test code is extremely simple and I cannot give an explanation of the difference results I get with node v8.9.4:

process.env.applicationpath = "";
console.log("typeof process.env.applicationpath = " + typeof(process.env.applicationpath));

if (!process.env.DUMMY_VAR) {
// if (true) {
  console.log("  typeof process.env.applicationpath = " + typeof(process.env.applicationpath));
}

console.log("typeof process.env.applicationpath = " + typeof(process.env.applicationpath));

Output:

typeof process.env.applicationpath = string
  **typeof process.env.applicationpath = undefined**
typeof process.env.applicationpath = string

Which I think is wrong.
If I uncomment the "if true" line and I comment the if that access the undefined environment var the it works fine. The output now is:

typeof process.env.applicationpath = string
  **typeof process.env.applicationpath = string**
typeof process.env.applicationpath = string

I have tested the same code with node v5.5 and it gives the right expected result. In some way it seems that accessing the undefined environment variable is affecting the results in the other?

ajflash on 11 Feb 2018

👍2

In some way it seems that accessing the undefined environment variable is affecting the results in the other?

I suspect this is also why fs.readFileSync triggers the bug in my example. It's not the reading of an (unexisting) file that triggers it per se but that readFileSync does something with/to the environment.

BTW @payload I was unable to trigger it on v6.

vweevers on 12 Feb 2018

In some way it seems that accessing the undefined environment variable is affecting the results in the other?

@addaleax recently fixed https://github.com/nodejs/node/pull/18463 which sounds like the example given by @ajflash.

richardlau on 12 Feb 2018

Yes, it’s exactly that bug.

/cc @nodejs/lts @gibfahn Just so you are aware, this seems to be a bug that quite a few people are running into and a (pretty much zero-risk) fix has been landed on master two weeks ago. It might be good to have this in 8.10.0, even if it doesn’t technically fulfill the lived-in-Current-for-2-weeks rule.