Motivation:
The fix provided in #2407 was subtly wrong. ignoreSIGPIPE, which throws
the error in question, closes the FD on error _except_ on EINVAL from
fcntl, where it instead does not. This inconsistent behaviour is the
source of the bug. Because this behaviour is inconsistent, the fix from
PR #2407 is also inconsistent and can in some cases double-close the
socket.
The actual issue is not as old as I expected: the code can be observed
by reviewing the change in #1598, which incorrectly inserted the error
transformation before the call to close.
Modifications:
- Revert the change from #2407.
- Move the close in ignoreSIGPIPE to before the error check, rather than
after, so we unconditionally execute it.
Result:
More resilient fix.
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