[Libguestfs] [PATCH v2v 2/2] v2v: Send nbdinfo debug information to stderr not stdout

[Laszlo Ersek]

On 01/25/22 11:45, Richard W.M. Jones wrote:
> When running in verbose mode (virt-v2v -vx) debug messages are
> supposed to only be written to stderr.  This allows virt-p2v and other
> wrappers to separate ordinary progress messages and warnings, from
> debugging information.
> 
> However when we added nbdinfo output (only printed in verbose mode),
> the output was wrongly sent to stdout instead of stderr.  You can show
> this as follows:
> 
> $ virt-v2v -vx -i disk /var/tmp/fedora-35.qcow2 -o null 2>/dev/null
> [   0.0] Setting up the source: -i disk /var/tmp/fedora-35.qcow2
> [   1.0] Opening the source
> ... some messages elided ...
> protocol: newstyle-fixed without TLS      <-- debug output to stdout
> export="":
> 	export-size: 6442450944 (6G)
> 	content: DOS/MBR boot sector
> 	uri: nbd+unix:///?socket=/tmp/v2v.Xqvaml/in0
> ... etc ...
> 
> This patch sends the nbdinfo debugging output to stderr instead.
> 
> Reported-by: Tingting Zheng
> Fixes: commit 255722cbf39afc0b012e2ac00d16fa6ba2f8c21f
> ---
>  v2v/v2v.ml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/v2v/v2v.ml b/v2v/v2v.ml
> index d74cc21f0a..a91d8cef8f 100644
> --- a/v2v/v2v.ml
> +++ b/v2v/v2v.ml
> @@ -631,7 +631,7 @@ and nbdcopy output_alloc input_uri output_uri =
>   *)
>  and nbdinfo ?(content = false) uri =
>    let cmd =
> -    sprintf "nbdinfo%s %s"
> +    sprintf "nbdinfo%s %s >&2"
>        (if content then " --content" else " --no-content") (quote uri) in
>    ignore (Sys.command cmd)
>  
> 

Reviewed-by: Laszlo Ersek <lersek at redhat.com>