[libvirt] [PATCH] Access qemu backing_file with relative pool path

[Jesse J Cook]

On Wed, 2011-03-09 at 16:07 +0000, Daniel P. Berrange wrote:
> On Thu, Mar 03, 2011 at 09:06:25PM -0600, Jesse Cook wrote:
> > This patch enables the relative backing file path support provided by
> > qemu-img create.
> > 
> > If the storage pool is not found with the specified path, check if the
> > file exists relative to the pool where the new image will be created by
> > prepending the storage pool path.
> > ---
> >  src/storage/storage_backend.c |   32 ++++++++++++++++++++++++++++----
> >  1 files changed, 28 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> > index 2eede74..bb49f22 100644
> > --- a/src/storage/storage_backend.c
> > +++ b/src/storage/storage_backend.c
> > @@ -687,10 +687,34 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
> >              return -1;
> >          }
> >          if (access(vol->backingStore.path, R_OK) != 0) {
> > -            virReportSystemError(errno,
> > -                                 _("inaccessible backing store volume %s"),
> > -                                 vol->backingStore.path);
> > -            return -1;
> > +            /* If the backing store image is not found with the specified path,
> > +             * check for the file relative to the pool path. */
> > +            int accessRetCode = -1;
> > +
> > +            char *absolutePath = NULL;
> > +
> > +            virBuffer absPathBuf = VIR_BUFFER_INITIALIZER;
> > +
> > +            virBufferVSprintf(&absPathBuf,
> > +                              "%s/%s",
> > +                              pool->def->target.path,
> > +                              vol->backingStore.path);
> > +
> > +            if (virBufferError(&absPathBuf)) {
> > +                virBufferFreeAndReset(&absPathBuf);
> > +                virReportOOMError();
> > +                return -1;
> > +            }
> > +
> > +            absolutePath = virBufferContentAndReset(&absPathBuf);
> 
> Since you're only doing one single virBufferVSprintf() call, using
> virBuffer is overkill. You can get away with the simpler
> 
>    virAsprintf(&absolutePath, "%s/%s",
>                pool->def->target.path,
>                vol->backingStore.path);

Thank you. I will incorporate that into the new patch.

> 
> > +            accessRetCode = access(absolutePath, R_OK);
> > +            VIR_FREE(absolutePath);
> > +            if (accessRetCode != 0) {
> > +                virReportSystemError(errno,
> > +                                     _("inaccessible backing store volume %s"),
> > +                                     vol->backingStore.path);
> > +                return -1;
> > +            }
> >          }
> >      }
> 
> Regards,
> Daniel

-- 
Jesse Cook
Research Scientist
EADS NA Defense Security & Systems Solutions, Inc. (DS3)
1476 N. Green Mount Rd
O'Fallon, Illinois 62269
Office: 618.206.4032 x436
Email: jesse.cook at eads-na-security.com
http://www.eads-na-security.com