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



On Tue, Oct 06, 2020 at 03:25:20PM +0200, Martin Kletzander wrote:
> 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?

Yes I don't know what I was thinking there.  It's difficult to revisit
and revise patches months later.  It would be better as simply:

diff --git a/options/decrypt.c b/options/decrypt.c
index 8eb24bc..ca2a0bb 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 +83,19 @@ 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 = NULL;
+
+      /* This fails for Windows BitLocker disks because cryptsetup
+       * luksUUID cannot read a UUID (unclear if this is a limitation
+       * of the format or cryptsetup).
+       */
+      if (!is_bitlocker)
+        uuid = guestfs_luks_uuid (g, partitions[i]);
 #else
       const char *uuid = NULL;
 #endif

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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