Re: [Libguestfs] Few libnbd questions/concerns
On Wed, Jun 26, 2019 at 09:33:04PM -0500, Eric Blake wrote:
Another thing I just noticed: nbd_poll returns 0 both for timeout
and
for when it notified the state machine about POLLIN or POLLOUT making
progress. We probably want to switch it to return 0 on timeout and 1
when it made progress, so that a user can detect timeout (all our
internal callers pass -1 for the timeout parameter, and thus can't time
out, but external callers may care).
Agreed.
And another thing you said on IRC:
04:26 < eblake> urgh - libnbd is prone to die from SIGPIPE, but
as a library, I don't know if we can ignore it
04:26 < eblake> should we be using pthread_sigmask and blocking SIGPIPE around our
reads, and restoring it to the calling application's default the rest of the
time?
04:28 < eblake> ooh - maybe we can rely on MSG_NOSIGNAL :)
04:28 < eblake> that's a lot cleaner, even if it is Linux-specific
MSG_NOSIGNAL is also available on FreeBSD and seems to make a lot of
sense here, given that as you say changing the signal handler isn't a
good idea from a library.
Rich.
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