Re: [Libguestfs] [PATCH virt-v2v] convert: If listing RPM applications fails, rebuild DB and retry

On 05/25/22 18:02, Richard W.M. Jones wrote: > In libguestfs we didn't bother to check the return values from any > librpm calls. In some cases where possibly the RPM database is > faulty, this caused us to return a zero-length list of installed > applications (but no error indication). Libguestfs has subsequently > been fixed so now it returns an error if the RPM database is corrupt. > > This commit changes virt-v2v behaviour so that if either > guestfs_inspect_list_applications2 returns a zero-length list (ie. old > libguestfs) or it throws an error (new libguestfs) then we attempt to > rebuild the RPM database and retry the operation. Rebuilding the > database can recover from some but not all RPM DB corruption. > > See-also: https://bugzilla.redhat.com/show_bug.cgi?id=2089623#c12 What an absolutely horrific error mode. Great job debugging it! > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2089623 > Reported-by: Xiaodai Wang > Reported-by: Ming Xie > --- > convert/inspect_source.ml | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/convert/inspect_source.ml b/convert/inspect_source.ml > index 1736009629..16058de644 100644 > --- a/convert/inspect_source.ml > +++ b/convert/inspect_source.ml > @@ -34,6 +34,7 @@ let rec inspect_source root_choice g = > reject_if_not_installed_image g root; > > let typ = g#inspect_get_type root in > + let package_format = g#inspect_get_package_format root in > > (* Mount up the filesystems. *) > let mps = g#inspect_get_mountpoints root in > @@ -71,7 +72,7 @@ let rec inspect_source root_choice g = > ) mps; > > (* Get list of applications/packages installed. *) > - let apps = g#inspect_list_applications2 root in > + let apps = list_applications g root package_format in > let apps = Array.to_list apps in > > (* A map of app2_name -> application2, for easier lookups. Note > @@ -106,7 +107,7 @@ let rec inspect_source root_choice g = > i_arch = g#inspect_get_arch root; > i_major_version = g#inspect_get_major_version root; > i_minor_version = g#inspect_get_minor_version root; > - i_package_format = g#inspect_get_package_format root; > + i_package_format = package_format; > i_package_management = g#inspect_get_package_management root; > i_product_name = g#inspect_get_product_name root; > i_product_variant = g#inspect_get_product_variant root; > @@ -186,6 +187,27 @@ and reject_if_not_installed_image g root = > if fmt <> "installed" then > error (f_"libguestfs thinks this is not an installed operating system (it might be, for example, an installer disk or live CD). If this is wrong, it is probably a bug in libguestfs. root=%s fmt=%s") root fmt > > +(* Wrapper around g#inspect_list_applications2 which, for RPM > + * guests, on failure tries to rebuild the RPM database before > + * repeating the operation. > + *) > +and list_applications g root = function > + | "rpm" -> > + (* RPM guest. *) > + (try [*] > + let apps = g#inspect_list_applications2 root in > + if apps = [||] then raise (G.Error "no applications returned"); > + apps > + with G.Error msg -> > + debug "%s" msg; > + debug "rebuilding RPM database and retrying ..."; > + ignore (g#sh "rpmdb --rebuilddb"); > + g#inspect_list_applications2 root > + ) > + | _ -> > + (* Non-RPM guest, just do it. *) > + g#inspect_list_applications2 root > + > (* See if this guest could use UEFI to boot. It should use GPT and > * it should have an EFI System Partition (ESP). > * > The commit message explains well why the "g#inspect_list_applications2" method call that is at the top of each "match" pattern cannot be factored out (to a common call just before the "match"). However, looking at the code, it's not easy to understand. Can you please: (1) Commit the libguestfs patch, (2) insert a comment at [*], saying that either of the two lines just below may raise an exception, and which one does depends on libguestfs having the commit <HASH> from point (1)? With that: Reviewed-by: Laszlo Ersek <lersek(a)redhat.com&gt;