emscripten-core/emscripten

fread returns garbage when pipe is closed

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#13,645 opened on Mar 12, 2021

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Description

On Windows, when content provided on the stdin pipe is read and pipe is closed, the following code throws with errno equal to undefined and fread keeps returning data instead of indicating EOF.

https://github.com/emscripten-core/emscripten/blob/0589ed2211831fe74c5b340de544b3d5d9fe5388/src/library_syscall.js#L150

ErrnoError
    at Object.ensureErrnoError (C:\***\a.out.js:11068:35)
    at Object.staticInit (C:\***\a.out.js:11076:12)
    at Object.<anonymous> (C:\***\a.out.js:12037:6)
    at Module._compile (internal/modules/cjs/loader.js:999:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1027:10)
    at Module.load (internal/modules/cjs/loader.js:863:32)
    at Function.Module._load (internal/modules/cjs/loader.js:708:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:60:12)
    at internal/main/run_main_module.js:17:47 {
  node: undefined,
  setErrno: [Function],
  errno: undefined,
  message: 'FS error'

Contributor guide

Research direction
Inspect the handling of stdin pipe closure in library syscall.js, specifically the fread implementation for Windows.
Tech stack
ccppjavascript
Domain
compilerstooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++JavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65