* [PATCH] preserve errno when inside sig handler for self-pipe
@ 2015-03-09 21:39 Eric Wong
0 siblings, 0 replies; only message in thread
From: Eric Wong @ 2015-03-09 21:39 UTC (permalink / raw)
To: cmogstored-public; +Cc: Mykola Golub, Steven Stewart-Gallus
We must not clobber errno of the main thread inside signal
handler in case write fails.
This bug only affects systems without epoll_pwait where the
self-pipe is required, so it does not affect modern GNU/Linux
systems; but does affect FreeBSD systems and anybody else
relying on kqueue.
Thanks to Steven Stewart-Gallus for a Ruby bug report which
inspired this fix: https://bugs.ruby-lang.org/issues/10866
Cc: Mykola Golub <trociny@FreeBSD.org>
Cc: Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>
---
Steven: just wanted you to know your original bug report
went a long way :)
selfwake.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/selfwake.c b/selfwake.c
index 1a6908b..06e9d62 100644
--- a/selfwake.c
+++ b/selfwake.c
@@ -42,8 +42,7 @@ void mog_selfwake_wait(struct mog_fd *mfd)
mog_selfwake_drain(mfd);
}
-/* this is async-signal safe (except in the case of bugs) */
-void mog_selfwake_trigger(struct mog_fd *mfd)
+static void selfwake_trigger(struct mog_fd *mfd)
{
ssize_t w;
@@ -64,6 +63,12 @@ retry:
abort();
}
+/* this is async-signal safe (except in the case of our usage bugs) */
+void mog_selfwake_trigger(struct mog_fd *mfd)
+{
+ PRESERVE_ERRNO(selfwake_trigger(mfd));
+}
+
void mog_selfwake_drain(struct mog_fd *mfd)
{
ssize_t r;
--
EW
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