[Libguestfs] [PATCH libguestfs-common] options: Don't attempt to scan LVs if "lvm2" feature is not available

[Laszlo Ersek]

On 09/27/22 14:10, Richard W.M. Jones wrote:
> Since we added support for transparent decryption of LUKS in
> commit a232e62dcf ("fish: '-i' option automatically handles whole-disk
> encryption") we have always assumed that the "lvm2" feature is
> available and so we could call guestfs_vg_activate_all.  That API
> would have failed in the unlikely event that the feature is not
> available, preventing opening any (even unencrypted) disk.
> 
> The code has changed greatly since then but the basic problem remains.
> Test for the "lvm2" feature, otherwise avoid trying to scan LVs.
> 
> Reported-by: Feng Li
> Fixes: a232e62dcf
> ---
>  options/decrypt.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/options/decrypt.c b/options/decrypt.c
> index 6fc7760e3..19fe93ce2 100644
> --- a/options/decrypt.c
> +++ b/options/decrypt.c
> @@ -202,8 +202,8 @@ decrypt_mountables (guestfs_h *g, const char * const *mountables,
>  void
>  inspect_do_decrypt (guestfs_h *g, struct key_store *ks)
>  {
> +  const char *lvm2_feature[] = { "lvm2", NULL };
>    CLEANUP_FREE_STRING_LIST char **partitions = guestfs_list_partitions (g);
> -  CLEANUP_FREE_STRING_LIST char **lvs = NULL;
>    bool need_rescan;
>  
>    if (partitions == NULL)
> @@ -211,13 +211,17 @@ inspect_do_decrypt (guestfs_h *g, struct key_store *ks)
>  
>    need_rescan = decrypt_mountables (g, (const char * const *)partitions, ks);
>  
> -  if (need_rescan) {
> -    if (guestfs_lvm_scan (g, 1) == -1)
> +  if (guestfs_feature_available (g, (char **) lvm2_feature) > 0) {
> +    CLEANUP_FREE_STRING_LIST char **lvs = NULL;
> +
> +    if (need_rescan) {
> +      if (guestfs_lvm_scan (g, 1) == -1)
> +        exit (EXIT_FAILURE);
> +    }
> +
> +    lvs = guestfs_lvs (g);
> +    if (lvs == NULL)
>        exit (EXIT_FAILURE);
> +    decrypt_mountables (g, (const char * const *)lvs, ks);
>    }
> -
> -  lvs = guestfs_lvs (g);
> -  if (lvs == NULL)
> -    exit (EXIT_FAILURE);
> -  decrypt_mountables (g, (const char * const *)lvs, ks);
>  }
> 

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

Thanks for fixing this!
Laszlo