On Wed, Aug 03, 2016 at 12:51:24PM +0200, Tomáš Golembiovský wrote:
On Wed, 3 Aug 2016 11:14:26 +0100
"Richard W.M. Jones" <rjones(a)redhat.com> wrote:
> On Mon, Aug 01, 2016 at 02:46:14PM +0200, Tomáš Golembiovský wrote:
> > What was happening in file_owner function did not match the description
> > in the comment. When a path is owned by multiple packages the returned
> > string was in fact a concatenation of the names of all packages that own
> > it. E.g. for `Linux.is_file_owned g inspect "/etc"` the returned
value
> > was "filesystemyum" (i.e. "filesystem" + "yum").
> >
> > Signed-off-by: Tomáš Golembiovský <tgolembi(a)redhat.com>
> > ---
> > v2v/linux.ml | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/v2v/linux.ml b/v2v/linux.ml
> > index d20194b..aeff5c5 100644
> > --- a/v2v/linux.ml
> > +++ b/v2v/linux.ml
> > @@ -99,14 +99,18 @@ let rec file_owner g inspect path =
> > (* Although it is possible in RPM for multiple packages to own
> > * a file, this deliberately only returns one package.
> > *)
> > - let cmd = [| "rpm"; "-qf"; "--qf";
"%{NAME}"; path |] in
> > + let cmd = [| "rpm"; "-qf"; "--qf";
"%{NAME}\\n"; path |] in
> > debug "%s" (String.concat " " (Array.to_list cmd));
> > - (try g#command cmd
> > + (try
> > + let pkgs = g#command_lines cmd in
> > + pkgs.(0)
> > with Guestfs.Error msg as exn ->
> > if String.find msg "is not owned" >= 0 then
> > raise Not_found
> > else
> > raise exn
> > + | Invalid_argument msg ->
> > + raise Not_found
>
> My concern/confusion about this patch is what raises Invalid_argument?
>
> I'm assuming it's the array index, which could raise `Invalid_argument
> "index out of bounds"' if the g#command_lines returns a zero-length
> list, but then my question would be why is the rpm command not
> returning any lines?
>
> Even if this can happen, the exception shouldn't be converted to
> Not_found. It should be an internal error or the exception should be
> left unchanged.
Yes, it is to catch the case when rpm reports nothing. Don't know
if/when this can happen. Do you prefer an error in the exception handler
(instead of raise Not_found), or should I check the array length (and
report error) before accessing it?
Since this should never happen, something like this:
| Invalid_argument "index out of bounds" ->
error (f_"internal error: file_owner: rpm command returned no output")
which will immediately exit with a clear error if this case happens.
Rich.
--
Richard Jones, Virtualization Group, Red Hat
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