Instead of parsing help options as normal object properties and
returning an error, provide the same help functionality as the system
emulator in qemu-nbd, too.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qemu-nbd.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 9032b6de2a..caacf0ed73 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -507,6 +507,13 @@ static QemuOptsList qemu_object_opts = {
     },
 };
 
+static bool qemu_nbd_object_print_help(const char *type, QemuOpts *opts)
+{
+    if (user_creatable_print_help(type, opts)) {
+        exit(0);
+    }
+    return true;
+}
 
 
 static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, bool list,
@@ -902,7 +909,7 @@ int main(int argc, char **argv)
 
     qemu_opts_foreach(&qemu_object_opts,
                       user_creatable_add_opts_foreach,
-                      NULL, &error_fatal);
+                      qemu_nbd_object_print_help, &error_fatal);
 
     if (!trace_init_backends()) {
         exit(1);
-- 
2.20.1

On 10/11/19 3:55 PM, Kevin Wolf wrote:
> Instead of parsing help options as normal object properties and
> returning an error, provide the same help functionality as the system
> emulator in qemu-nbd, too.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   qemu-nbd.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)

Missing a change in qemu-nbd.texi for man page coverage.  But the patch 
is a strict improvement, so even if we have to add a followup patch for 
documentation, I'm okay with:

Reviewed-by: Eric Blake <eblake@redhat.com>

This patch touches NBD, but I'm assuming it's easier to take the series 
through your tree.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Am 11.10.2019 um 23:39 hat Eric Blake geschrieben:
> On 10/11/19 3:55 PM, Kevin Wolf wrote:
> > Instead of parsing help options as normal object properties and
> > returning an error, provide the same help functionality as the system
> > emulator in qemu-nbd, too.
> > 
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> 
> Missing a change in qemu-nbd.texi for man page coverage.

Hm... Both qemu-img and qemu-nbd manpages refer to qemu(1) for the
details. I wouldn't mind copying the text for '-object help' from there
anyway, but unfortunately it doesn't even exist. :-)

So this looks like a separate patch that fixes it for qemu, too.

> But the patch is a strict improvement, so even if we have to add a
> followup patch for documentation, I'm okay with:
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> This patch touches NBD, but I'm assuming it's easier to take the series
> through your tree.

Yes, thanks.

Kevin