qemu-nbd: Ignore SIGPIPE
qemu proper has done so for 13 years
(8a7ddc38a60648257dc0645ab4a05b33d6040063), qemu-img and qemu-io have
done so for four years (526eda14a68d5b3596be715505289b541288ef2a).
Ignoring this signal is especially important in qemu-nbd because
otherwise a client can easily take down the qemu-nbd server by dropping
the connection when the server wants to send something, for example:
$ qemu-nbd -x foo -f raw -t null-co:// &
[1] 12726
$ qemu-io -c quit nbd://localhost/bar
can't open device nbd://localhost/bar: No export with name 'bar' available
[1] + 12726 broken pipe qemu-nbd -x foo -f raw -t null-co://
In this case, the client sends an NBD_OPT_ABORT and closes the
connection (because it is not required to wait for a reply), but the
server replies with an NBD_REP_ACK (because it is required to reply).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20170611123714.31292-1-mreitz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 9464a04..4dd3fd4 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -581,6 +581,10 @@
sa_sigterm.sa_handler = termsig_handler;
sigaction(SIGTERM, &sa_sigterm, NULL);
+#ifdef CONFIG_POSIX
+ signal(SIGPIPE, SIG_IGN);
+#endif
+
module_call_init(MODULE_INIT_TRACE);
qcrypto_init(&error_fatal);
