parent process does not receive POLLHUP events
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).
Updated by dillon over 1 year ago
- File pollhup01.patch pollhup01.patch added
- Status changed from New to In Progress
- Assignee set to dillon
- Priority changed from Normal to High
Please try the included patch. I did a quick test and it appears to work.
Currently only the socket code allows POLLHUP to be set. This patch will also enable it for the pipe code. And if it looks good I should probably also implement the same thing for the fifo code.