From fc3297d5d4be30141ef8923db6b128f788646a5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niklas=20Hamb=C3=BCchen?= <mail@nh2.me>
Date: Mon, 26 Feb 2018 09:19:17 +0100
Subject: [PATCH] Add comment why `closeFd` doesn't have to retry on EINTR.
Fixes #88
---
System/Posix/IO/Common.hsc | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/System/Posix/IO/Common.hsc b/System/Posix/IO/Common.hsc
index 4191d5e..b658dbd 100644
--- a/System/Posix/IO/Common.hsc
+++ b/System/Posix/IO/Common.hsc
@@ -221,6 +221,12 @@ foreign import capi unsafe "HsUnix.h open"
closeFd :: Fd -> IO ()
closeFd (Fd fd) = throwErrnoIfMinus1_ "closeFd" (c_close fd)
+-- Here we don't to retry on EINTR because according to
+-- http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html
+-- "with errno set to [EINTR] [...] the state of fildes is unspecified"
+-- and on Linux, already the first close() removes the FD from the process's
+-- FD table so closing a second time is invalid
+-- (see http://man7.org/linux/man-pages/man2/close.2.html#NOTES).
foreign import ccall unsafe "HsUnix.h close"
c_close :: CInt -> IO CInt
--
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