Libguestfs - Dec 2018 - Re: [PATCH] v2v: -o rhv-upload: Fix emulated zero

Replace python 2 only "buffer" with "memoryview".

Falling back to emulated zero would fail with:

    NameError: name 'buffer' is not defined

I did not test the changed code but it was not tested before so it is
unlikely to be worse.

Detected by pylint.
---
 v2v/rhv-upload-plugin.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py
index 3272c3ce3..12d4e68f7 100644
--- a/v2v/rhv-upload-plugin.py
+++ b/v2v/rhv-upload-plugin.py
@@ -416,41 +416,41 @@ def emulate_zero(h, count, offset):
     transfer = h['transfer']
 
     # qemu-img convert starts by trying to zero/trim the whole device.
     # Since we've just created a new disk it's safe to ignore these
     # requests as long as they are smaller than the highest write seen.
     # After that we must emulate them with writes.
     if offset+count < h['highestwrite']:
         http.putrequest("PUT", h['path'])
         if h['needs_auth']:
             http.putheader("Authorization", transfer.signed_ticket)
         http.putheader("Content-Range",
                        "bytes %d-%d/*" % (offset, offset+count-1))
         http.putheader("Content-Length", str(count))
         http.endheaders()
 
         try:
             buf = bytearray(128*1024)
             while count > len(buf):
                 http.send(buf)
                 count -= len(buf)
-            http.send(buffer(buf, 0, count))
+            http.send(memoryview(buf)[:count])
         except BrokenPipeError:
             pass
 
         r = http.getresponse()
         if r.status != 200:
             request_failed(h, r,
                            "could not write zeroes offset %d size %d"
%
                            (offset, count))
 
         r.read()
 
 def trim(h, count, offset):
     http = h['http']
 
     # Construct the JSON request for trimming.
     buf = json.dumps({'op': "trim",
                       'offset': offset,
                       'size': count,
                       'flush': False}).encode()
 
-- 
2.17.2

On Fri, Dec 07, 2018 at 07:55:28PM +0200, Nir Soffer
wrote:
> Replace python 2 only "buffer" with "memoryview".
> 
> Falling back to emulated zero would fail with:
> 
>     NameError: name 'buffer' is not defined
> 
> I did not test the changed code but it was not tested before so it is
> unlikely to be worse.
> 
> Detected by pylint.
Thanks - I pushed both.

I wonder how the pread method worked before?  That's on the main path
I think.

Rich.
>  v2v/rhv-upload-plugin.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py
> index 3272c3ce3..12d4e68f7 100644
> --- a/v2v/rhv-upload-plugin.py
> +++ b/v2v/rhv-upload-plugin.py
> @@ -416,41 +416,41 @@ def emulate_zero(h, count, offset):
>      transfer = h['transfer']
>  
>      # qemu-img convert starts by trying to zero/trim the whole device.
>      # Since we've just created a new disk it's safe to ignore
these
>      # requests as long as they are smaller than the highest write seen.
>      # After that we must emulate them with writes.
>      if offset+count < h['highestwrite']:
>          http.putrequest("PUT", h['path'])
>          if h['needs_auth']:
>              http.putheader("Authorization",
transfer.signed_ticket)
>          http.putheader("Content-Range",
>                         "bytes %d-%d/*" % (offset,
offset+count-1))
>          http.putheader("Content-Length", str(count))
>          http.endheaders()
>  
>          try:
>              buf = bytearray(128*1024)
>              while count > len(buf):
>                  http.send(buf)
>                  count -= len(buf)
> -            http.send(buffer(buf, 0, count))
> +            http.send(memoryview(buf)[:count])
>          except BrokenPipeError:
>              pass
>  
>          r = http.getresponse()
>          if r.status != 200:
>              request_failed(h, r,
>                             "could not write zeroes offset %d size
%d" %
>                             (offset, count))
>  
>          r.read()
>  
>  def trim(h, count, offset):
>      http = h['http']
>  
>      # Construct the JSON request for trimming.
>      buf = json.dumps({'op': "trim",
>                        'offset': offset,
>                        'size': count,
>                        'flush': False}).encode()
>  
> -- 
> 2.17.2
-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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http://people.redhat.com/~rjones/virt-top

On Fri, Dec 7, 2018 at 8:50 PM Richard W.M. Jones <rjones@redhat.com>
wrote:
> On Fri, Dec 07, 2018 at 07:55:28PM +0200, Nir Soffer wrote:
> > Replace python 2 only "buffer" with "memoryview".
> >
> > Falling back to emulated zero would fail with:
> >
> >     NameError: name 'buffer' is not defined
> >
> > I did not test the changed code but it was not tested before so it is
> > unlikely to be worse.
> >
> > Detected by pylint.
>
> Thanks - I pushed both.
>
> I wonder how the pread method worked before?  That's on the main path
> I think.
>
I never seen a READ request on imageio log, so it seems that qemu-img
convert
never read from the destination.

Nir