macOS: spawn-helper shipped without execute bit in npm tarball causes posix_spawnp failures (pnpm)

Description

The spawn-helper binary in the darwin prebuilds is published to npm without the execute permission bit (644 instead of 755), causing posix_spawnp failed errors when using package managers that preserve file permissions during extraction.

This primarily affects pnpm users, as pnpm's content-addressable store preserves the original tarball permissions, whereas npm/yarn may not exhibit the issue due to different extraction behavior.

Steps to Reproduce

mkdir test-pty && cd test-pty
npm init -y
pnpm add node-pty

# Check permissions - shows 644 instead of 755
ls -la node_modules/.pnpm/node-pty@1.1.0/node_modules/node-pty/prebuilds/darwin-arm64/spawn-helper

# Try to use node-pty
node -e "require('node-pty').spawn('/bin/echo', ['test'])"

Expected Behavior

spawn-helper should have execute permission (755) and the spawn should succeed.

Actual Behavior

Error: posix_spawnp failed.
    at new UnixTerminal (node_modules/node-pty/lib/unixTerminal.js:92:24)

The tarball contains spawn-helper with 644 permissions:

$ npm pack node-pty@1.1.0 && tar -tvf node-pty-1.1.0.tgz | grep spawn-helper
-rw-r--r--  0 0      0       50480 Oct 26  1985 package/prebuilds/darwin-arm64/spawn-helper
-rw-r--r--  0 0      0        9248 Oct 26  1985 package/prebuilds/darwin-x64/spawn-helper

Workaround

chmod +x node_modules/.pnpm/node-pty@*/node_modules/node-pty/prebuilds/darwin-*/spawn-helper

Environment

node-pty: 1.1.0
Node.js: v25.2.1 (also reproduced on v22.x)
OS: macOS (darwin-arm64)
Package manager: pnpm 10.11.0

Related Issues

[bug] posix_spawnp failed after calling spawn multiple times #670 - posix_spawnp failed (different root cause)
Got Error: posix_spawnp failed in packaged electron js app #789 - posix_spawnp in Electron (different root cause)

Suggested Fix

Ensure spawn-helper has execute permission when creating prebuilds. This might be addressed in the prebuild pipeline or by setting file modes before npm pack.

Spawn helper added in #589

Fresh local build shows it's got executable bit

Missing on prebuilds only:

Ensure 755 permissions on prebuild spawn-helper

fix: pin node-pty to 1.0.0 to avoid spawn-helper permission bug

fix: pin node-pty to 1.0.0 to avoid spawn-helper permission bug (#31)

Verified it fixes it, but only for the active arch prebuild binary.

Unfortunately, chmod +x-ing the file as a (post)install script means that node-pty does not work out of the box in pnpm, since by default it does not run (post)install scripts for security reasons. On macOS, node-pty’s (post)install scripts aren’t really needed – except for the chmod +x. So you have to approve the (post)install scripts for node-pty. Which is easy, but one unnecessary step.

Couldn’t you make sure that the tarball contains an already chmod +x-ed spawn-helper instead? I did that in the just-released @lydell/node-pty@1.2.0-beta.2. It then works out of the box with pnpm.

It looks like the prebuilds are downloaded here:

node-pty/publish.yml

Lines 63 to 78 in 732ebf7

    
           - task: DownloadPipelineArtifact@2 
        
             displayName: 'Download prebuilds' 
        
             inputs: 
        
               buildType: 'specific' 
        
               project: 'Monaco' 
        
               definition: '647' 
        
               buildVersionToDownload: 'latestFromBranch' 
        
               branchName: 'refs/heads/main' 
        
               artifactName: 'prebuilds' 
        
               targetPath: 'prebuilds' 
        
           - script: npm ci 
        
             displayName: 'Install dependencies and build' 
        
           - script: npm test 
        
             displayName: 'Test' 
        
           - script: npm run lint 
        
             displayName: 'Lint'

Then it sounds like it would be possible to add a chmod +x step for spawn-helper there.

Simon Lydell (@lydell)

Simon Lydell (@lydell) thanks for the extra nudge, sounds like a good plan

empacotamento electron-builder, release por tag e aviso de update

chore(server): node-pty spawn-helper の実行権限欠落を postinstall で恒久対処 (#91)

fix(desktop): upgrade node-pty to 1.2.0-beta.14, drop redundant termi…

Reproduced on npm rather than pnpm. macOS 26.5.2, arm64, node-pty 1.1.0, from a clean npm ci. The published tarball itself carries mode 0644:

tar -tvf node-pty-1.1.0.tgz
-rw-r--r--  package/prebuilds/darwin-arm64/spawn-helper
-rw-r--r--  package/prebuilds/darwin-x64/spawn-helper

A plain tar -xzf outside any package manager gives the same, so the extractor is not the variable. 1.2.0-beta.15 ships both as 0755, so the fix exists but not on the stable line.

Source builds are unaffected because loadNativeModule checks build/Release before prebuilds, and darwin prebuilds are new in 1.1.0, which is likely why this is not reported more widely.

Worth adding for anyone packaging: asar preserves the mode through pack and unpack, so a 0644 helper in the tree at package time becomes a 0644 helper in the shipped .app, where posix_spawnp fails for every user and reproduces on no development machine that ran a fix locally.

BENZOOgataga (@BENZOOgataga)

BENZOOgataga (@BENZOOgataga) v1.1.0 is broken, this PR was shipped in v1.2.0-beta.2. There is unfortunately no release marked as “stable” with a fix in it. (But the beta isn't really a beta, it's stable, IMO.)

BENZOOgataga (@BENZOOgataga) v1.1.0 is broken, this PR was shipped in v1.2.0-beta.2. There is unfortunately no release marked as “stable” with a fix in it. (But the beta isn't really a beta, it's stable, IMO.)

Oh alright thank you for your answer!

v0.9.2: repair node-pty's spawn-helper permissions automatically

Fix macOS CI: restore execute bit on node-pty's spawn-helper

fix(terminal): chmod spawn-helper postinstall for macOS node-pty 1.1.0

Rebuilt build process (#104)

feat(workspaces): folder creation + darwin pty fix

feat(agent): PTY 턴 실행기 — 프로세스 종료가 곧 턴 종료다

fix: restore execute bit on node-pty's macOS spawn-helper via postins…

fix: install node-pty from prebuilds so `npm i -g crewly` needs no co…

Ship the /pi-web extension and an executable spawn-helper in the Nix …

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macOS: spawn-helper shipped without execute bit in npm tarball causes posix_spawnp failures (pnpm) #850

Description

Steps to Reproduce

Expected Behavior

Actual Behavior

Workaround

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Related Issues

Suggested Fix

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	- task: DownloadPipelineArtifact@2
	displayName: 'Download prebuilds'
	inputs:
	buildType: 'specific'
	project: 'Monaco'
	definition: '647'
	buildVersionToDownload: 'latestFromBranch'
	branchName: 'refs/heads/main'
	artifactName: 'prebuilds'
	targetPath: 'prebuilds'
	- script: npm ci
	displayName: 'Install dependencies and build'
	- script: npm test
	displayName: 'Test'
	- script: npm run lint
	displayName: 'Lint'

macOS: spawn-helper shipped without execute bit in npm tarball causes posix_spawnp failures (pnpm) #850

Description

Description

Steps to Reproduce

Expected Behavior

Actual Behavior

Workaround

Environment

Related Issues

Suggested Fix

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Tyriar commented on Jan 3, 2026

Tyriar commented on Jan 3, 2026

Tyriar commented on Jan 3, 2026

Tyriar commented on Jan 4, 2026

lydell commented on Jan 4, 2026

Tyriar commented on Jan 4, 2026

20 remaining items

BENZOOgataga commented on Aug 8, 2026

lydell commented on Aug 8, 2026

BENZOOgataga commented on Aug 8, 2026

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