[PULL v3 6/8] qemu-nbd: Honor SIGINT and SIGHUP

[Eric Blake <eblake@redhat.com>]

Honoring just SIGTERM on Linux is too weak; we also want to handle
other common signals, and do so even on BSD.  Why?  Because at least
'qemu-nbd -B bitmap' needs a chance to clean up the in-use bit on
bitmaps when the server is shut down via a signal.

See also: http://bugzilla.redhat.com/1883608

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200930121105.667049-2-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: apply comment tweak suggested by Vladimir; fix ifdef around
termsig_handler]
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 qemu-nbd.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index bacb69b0898b..bc644a0670b6 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -154,13 +154,13 @@ QEMU_COPYRIGHT "\n"
     , name);
 }

-#if HAVE_NBD_DEVICE
+#ifdef CONFIG_POSIX
 static void termsig_handler(int signum)
 {
     qatomic_cmpxchg(&state, RUNNING, TERMINATE);
     qemu_notify_event();
 }
-#endif /* HAVE_NBD_DEVICE */
+#endif /* CONFIG_POSIX */

 static int qemu_nbd_client_list(SocketAddress *saddr, QCryptoTLSCreds *tls,
                                 const char *hostname)
@@ -581,17 +581,18 @@ int main(int argc, char **argv)
     const char *pid_file_name = NULL;
     BlockExportOptions *export_opts;

-#if HAVE_NBD_DEVICE
-    /* The client thread uses SIGTERM to interrupt the server.  A signal
-     * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
+#ifdef CONFIG_POSIX
+    /*
+     * Exit gracefully on various signals, which includes SIGTERM used
+     * by 'qemu-nbd -v -c'.
      */
     struct sigaction sa_sigterm;
     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
     sa_sigterm.sa_handler = termsig_handler;
     sigaction(SIGTERM, &sa_sigterm, NULL);
-#endif /* HAVE_NBD_DEVICE */
+    sigaction(SIGINT, &sa_sigterm, NULL);
+    sigaction(SIGHUP, &sa_sigterm, NULL);

-#ifdef CONFIG_POSIX
     signal(SIGPIPE, SIG_IGN);
 #endif

-- 
2.28.0