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

[Martin Kletzander]

On Tue, Oct 06, 2020 at 03:06:54PM +0100, Richard W.M. Jones wrote:
>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.
>

Glad I understood it then, ACK to that.

>--
>Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
>Read my programming and virtualization blog: http://rwmj.wordpress.com
>virt-builder quickly builds VMs from scratch
>http://libguestfs.org/virt-builder.1.html
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