[Libguestfs] [PATCH common v2 4/4] options: Ignore errors from guestfs_luks_uuid.

[Martin Kletzander]

On Mon, Sep 07, 2020 at 10:41:20AM +0100, Richard W.M. Jones wrote:
>For BitLocker disks cryptsetup does not (yet? ever?) support reading
>UUIDs and this function will fail.  This does not matter here so just
>ignore the error.
>
>Note there is no error message, cryptsetup simply returns with a bad
>exit code:
>
>><rescue> cryptsetup luksUUID /dev/sda2
>><rescue> echo $?
>1
>
>Updates commit bb4a2dc17a78b53437896d4215ae82df8e11b788.
>---
> options/decrypt.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
>diff --git a/options/decrypt.c b/options/decrypt.c
>index 8eb24bc..6b1c0a8 100644
>--- a/options/decrypt.c
>+++ b/options/decrypt.c
>@@ -25,6 +25,7 @@
>
> #include <stdio.h>
> #include <stdlib.h>
>+#include <stdbool.h>
> #include <string.h>
> #include <libintl.h>
> #include <error.h>
>@@ -82,11 +83,23 @@ inspect_do_decrypt (guestfs_h *g, struct key_store *ks)
>     CLEANUP_FREE char *type = guestfs_vfs_type (g, partitions[i]);
>     if (type &&
>         (STREQ (type, "crypto_LUKS") || STREQ (type, "BitLocker"))) {
>+      bool is_bitlocker = STREQ (type, "BitLocker");
>       char mapname[32];
>       make_mapname (partitions[i], mapname, sizeof mapname);
>
> #ifdef GUESTFS_HAVE_LUKS_UUID
>-      CLEANUP_FREE char *uuid = guestfs_luks_uuid (g, partitions[i]);
>+      CLEANUP_FREE char *uuid;
>+      if (!is_bitlocker)
>+        uuid = guestfs_luks_uuid (g, partitions[i]);
>+      else {
>+        /* This may fail for Windows BitLocker disks because
>+         * cryptsetup luksUUID cannot read a UUID (unclear if
>+         * this is a limitation of the format or cryptsetup).
>+         */
>+        guestfs_push_error_handler (g, NULL, NULL);
>+        uuid = guestfs_luks_uuid (g, partitions[i]);

I have yet to look at the libguestfs patches, but I do not completely understand
what is the reason for calling "guestfs_luks_uuid" when you know it will fail.
Or is there a case when it might be useful to get the result?

Other than that the series looks fine to me.

>+        guestfs_pop_error_handler (g);
>+      }
> #else
>       const char *uuid = NULL;
> #endif
>-- 
>2.27.0
>
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