[PATCH] libxl: don't require vncpasswd when empty

[PATCH] libxl: don't require vncpasswd when empty

[Christoph Egger]

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Hi!

Attached patch fixes a regression introduced in c/s 22866:ed9ef3b07d2a:

Don't require a NULL-byte password when the guest config file
has the entry
     vncpasswd=''

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>


-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

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diff -r 12de39a2c580 tools/libxl/libxl_dm.c
--- a/tools/libxl/libxl_dm.c	Thu Feb 10 15:18:51 2011 +0100
+++ b/tools/libxl/libxl_dm.c	Fri Feb 11 11:03:59 2011 +0100
@@ -74,7 +74,7 @@ static char ** libxl_build_device_model_
         } else {
             vncarg = "127.0.0.1:0";
         }
-        if (info->vncpasswd)
+        if (info->vncpasswd && (info->vncpasswd[0] != '\0'))
             vncarg = libxl__sprintf(gc, "%s,password", vncarg);
         flexarray_append(dm_args, "-vnc");
         flexarray_append(dm_args, vncarg);

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Re: [PATCH] libxl: don't require vncpasswd when empty

[Ian Jackson]

Christoph Egger writes ("[Xen-devel] [PATCH] libxl: don't require vncpasswd when empty"):
> Attached patch fixes a regression introduced in c/s 22866:ed9ef3b07d2a:
> 
> Don't require a NULL-byte password when the guest config file
> has the entry
>      vncpasswd=''

I'm afraid I don't understand this patch.

If you say "vncpasswd=''" in the config file then info->vncpasswd
would be "" and therefore info->vncpasswd[0] would be '\0' so the
branch would not be taken and you would end up without ",password" on
the qemu command line.  The result should be that qemu should not
require a password.

Is that not what you would intend with such a config statement ?

Your patch seems to do the opposite of what you say it does.  It would
seem to make qemu require an empty string as a password, which is
daft.

Ian.

Re: [PATCH] libxl: don't require vncpasswd when empty

[Christoph Egger]

On Friday 11 February 2011 17:45:03 Ian Jackson wrote:
> Christoph Egger writes ("[Xen-devel] [PATCH] libxl: don't require vncpasswd 
when empty"):
> > Attached patch fixes a regression introduced in c/s 22866:ed9ef3b07d2a:
> >
> > Don't require a NULL-byte password when the guest config file
> > has the entry
> >      vncpasswd=''
>
> I'm afraid I don't understand this patch.
>
> If you say "vncpasswd=''" in the config file then info->vncpasswd
> would be "" and therefore info->vncpasswd[0] would be '\0' so the
> branch would not be taken and you would end up without ",password" on 
> the qemu command line.  The result should be that qemu should not
> require a password.

I actually end up with ",password" on qemu command line because

    info->vncpasswd != info->vncpasswd[0] :-)

The command 'ps axuww | grep qemu' makes that visible.

> Is that not what you would intend with such a config statement ?
>
> Your patch seems to do the opposite of what you say it does.  It would
> seem to make qemu require an empty string as a password, which is
> daft.

Yes, qemu wants me to enter a NULL-byte as password.
With my patch, qemu doesn't ask me for a password at all.

Christoph


-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632