From: Max Reitz <mreitz@redhat.com>

Date: Sun, 11 Jun 2017 14:37:14 +0200

Subject: [PATCH] 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>

(cherry picked from commit 041e32b8d9d076980b4e35317c0339e57ab888f1)

---

 qemu-nbd.c | 4 ++++

 1 file changed, 4 insertions(+)

diff --git a/qemu-nbd.c b/qemu-nbd.c

index 483dd77a77..5deb37e03e 100644

--- a/qemu-nbd.c

+++ b/qemu-nbd.c

@@ -581,6 +581,10 @@ int main(int argc, char **argv)

     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);