Issue #3268 has been reported by mikdusan.

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Bug #3268: parent process does not receive POLLHUP events
http://bugs.dragonflybsd.org/issues/3268

* Author: mikdusan
* Status: New
* Priority: Normal
* Assignee: 
* Category: Userland
* Target version: Latest stable
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The attached `main.c` code is a reduction which takes as args, a command 
(absolute path) to fork/exec and poll stdout/stderr. POLLHUP events should be 
issued for both pipes when the child is finished.

For the Zig project we have this implemented in the zig language but I've 
provided a similar .c implementation since it was already done during my 
triage. For both .zig and .c code, linux, macos, freebsd, netbsd, openbsd work 
as expected and dragonfly manifests this unexpected behaviour of not receiving 
POLLHUP.

In the provided reduction, the bug manifests as an infinite loop after reading 
the bytes from child stdout/stderr. The parent keeps getting POLLIN events, and 
the read keeps returning 0 nbytes read which indicate the pipe has been closed. 
In the interim I will likely workaround this bug with conditional code for 
dragonfly to key off nbytes=0.

I have reproduced the bug on dragonfly 5.8, 6.0 and 5.0.0 (the oldest .iso I 
could find).

---Files--------------------------------
main.c (3.2 KB)


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