Libguestfs - Jan 2016 - [PATCHv2 3/3] resize: preserve GPT disk GUID.

Some OSes (e.g. Windows Server 2012 R2) fail to boot after virt-resize
due to changed disk guid. To fix it, we add new APIs:
part_get_disk_guid
part_set_disk_guid
part_set_disk_guid_random

We also preserve disk GUID in virt-resize.

Maxim Perevedentsev (3):
  New API: part_get_disk_guid and part_set_disk_guid.
  New API: part_set_disk_guid_random.
  resize: preserve GPT disk GUID.

 daemon/parted.c      | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 generator/actions.ml | 52 ++++++++++++++++++++++++++++++++++++
 resize/resize.ml     | 12 ++++++++-
 src/MAX_PROC_NR      |  2 +-
 4 files changed, 139 insertions(+), 2 deletions(-)

--
1.8.3.1

Some OSes (e.g. Windows Server 2012 R2) fail to boot if the disk
GPT GUID has changed. To preserve disk guid e.g. during virt-resize,
we need a way to get/set disk GUIDs.
---
 daemon/parted.c      | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 generator/actions.ml | 37 ++++++++++++++++++++++++++++++++
 src/MAX_PROC_NR      |  2 +-
 3 files changed, 98 insertions(+), 1 deletion(-)

diff --git a/daemon/parted.c b/daemon/parted.c
index b073bd8..40f9676 100644
--- a/daemon/parted.c
+++ b/daemon/parted.c
@@ -928,3 +928,63 @@ do_part_get_mbr_part_type (const char *device, int partnum)
   reply_with_error ("strdup failed");
   return NULL;
 }
+
+char *
+do_part_get_disk_guid (const char *device)
+{
+  const char *pattern = "Disk identifier (GUID):";
+  size_t i;
+
+  CLEANUP_FREE char *err = NULL;
+  int r = commandf (NULL, &err, COMMAND_FLAG_FOLD_STDOUT_ON_STDERR,
+                    str_sgdisk, device, "-p", NULL);
+  if (r == -1) {
+    reply_with_error ("%s %s -p: %s", str_sgdisk, device, err);
+    return NULL;
+  }
+
+  CLEANUP_FREE_STRING_LIST char **lines = split_lines (err);
+  if (lines == NULL) {
+    reply_with_error ("'%s %s -p' returned no output",
+                      str_sgdisk, device);
+    return NULL;
+  }
+
+  for (i = 0; lines[i] != NULL; ++i) {
+    if (STRPREFIX (lines[i], pattern)) {
+      char *value = lines[i] + strlen (pattern);
+
+      /* Skip any leading whitespace */
+      value += strspn (value, " \t");
+
+      /* Extract the actual information from the field. */
+      char *ret = extract_uuid (value);
+      if (ret == NULL) {
+        /* The extraction function already sends the error. */
+        return NULL;
+      }
+
+      return ret;
+    }
+  }
+
+  /* If we got here it means we didn't find the field */
+  reply_with_error ("sgdisk output did not contain disk GUID. "
+                    "See LIBGUESTFS_DEBUG output for more details");
+  return NULL;
+}
+
+int
+do_part_set_disk_guid (const char *device, const char *guid)
+{
+  CLEANUP_FREE char *err = NULL;
+  int r = commandf (NULL, &err, COMMAND_FLAG_FOLD_STDOUT_ON_STDERR,
+                    str_sgdisk, device, "-U", guid, NULL);
+
+  if (r == -1) {
+    reply_with_error ("%s %s -U %s: %s", str_sgdisk, device, guid,
err);
+    return -1;
+  }
+
+  return 0;
+}
diff --git a/generator/actions.ml b/generator/actions.ml
index 7f8e80b..62c4839 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12793,6 +12793,43 @@ See also L<ntfsresize(8)>, L<resize2fs(8)>,
L<btrfs(8)>, L<xfs_info(8)>." };
     longdesc = "\
 This is the internal call which implements
C<guestfs_feature_available>." };

+  { defaults with
+    name = "part_set_disk_guid"; added = (1, 33, 2);
+    style = RErr, [Device "device"; GUID "guid"], [];
+    proc_nr = Some 459;
+    optional = Some "gdisk";
+    tests = [
+      InitGPT, Always, TestLastFail (
+        [["part_set_disk_guid"; "/dev/sda";
"f"]]), [];
+      InitGPT, Always, TestResultString (
+        [["part_set_disk_guid"; "/dev/sda";
+          "01234567-89AB-CDEF-0123-456789ABCDEF"];
+         ["part_get_disk_guid"; "/dev/sda"]],
+        "01234567-89AB-CDEF-0123-456789ABCDEF"), [];
+    ];
+    shortdesc = "set the GUID of a GPT-partitioned disk";
+    longdesc = "\
+Set the disk identifier (GUID) of a GPT-partitioned C<device> to
C<guid>.
+Return an error if the partition table of C<device> isn't GPT,
+or if C<guid> is not a valid GUID." };
+
+  { defaults with
+    name = "part_get_disk_guid"; added = (1, 33, 2);
+    style = RString "guid", [Device "device"], [];
+    proc_nr = Some 460;
+    optional = Some "gdisk";
+    tests = [
+      InitGPT, Always, TestResultString (
+        [["part_set_disk_guid"; "/dev/sda";
+          "01234567-89AB-CDEF-0123-456789ABCDEF"];
+         ["part_get_disk_guid"; "/dev/sda"]],
+        "01234567-89AB-CDEF-0123-456789ABCDEF"), [];
+    ];
+    shortdesc = "get the GUID of a GPT-partitioned disk";
+    longdesc = "\
+Return the disk identifier (GUID) of a GPT-partitioned C<device>.
+Behaviour is undefined for other partition types." };
+
 ]

 (* Non-API meta-commands available only in guestfish.
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index c92ddb6..ccbd68f 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-458
+460
--
1.8.3.1

Provides a way to set a new randomly-generated GUID to disk.
---
 daemon/parted.c      | 15 +++++++++++++++
 generator/actions.ml | 15 +++++++++++++++
 src/MAX_PROC_NR      |  2 +-
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/daemon/parted.c b/daemon/parted.c
index 40f9676..22cd92b 100644
--- a/daemon/parted.c
+++ b/daemon/parted.c
@@ -988,3 +988,18 @@ do_part_set_disk_guid (const char *device, const char
*guid)

   return 0;
 }
+
+int
+do_part_set_disk_guid_random (const char *device)
+{
+  CLEANUP_FREE char *err = NULL;
+  int r = commandf (NULL, &err, COMMAND_FLAG_FOLD_STDOUT_ON_STDERR,
+                    str_sgdisk, device, "-U", "R", NULL);
+
+  if (r == -1) {
+    reply_with_error ("%s %s -U R: %s", str_sgdisk, device, err);
+    return -1;
+  }
+
+  return 0;
+}
diff --git a/generator/actions.ml b/generator/actions.ml
index 62c4839..d345175 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12830,6 +12830,21 @@ or if C<guid> is not a valid GUID." };
 Return the disk identifier (GUID) of a GPT-partitioned C<device>.
 Behaviour is undefined for other partition types." };

+  { defaults with
+    name = "part_set_disk_guid_random"; added = (1, 33, 2);
+    style = RErr, [Device "device"], [];
+    proc_nr = Some 461;
+    optional = Some "gdisk";
+    tests = [
+      InitGPT, Always, TestRun (
+        [["part_set_disk_guid_random"; "/dev/sda"]]), [];
+    ];
+    shortdesc = "set the GUID of a GPT-partitioned disk to random
value";
+    longdesc = "\
+Set the disk identifier (GUID) of a GPT-partitioned C<device> to
+a randomly generated value.
+Return an error if the partition table of C<device> isn't GPT."
};
+
 ]

 (* Non-API meta-commands available only in guestfish.
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index ccbd68f..408b885 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-460
+461
--
1.8.3.1

Changed disk GUID makes some OSes fail to boot.
To enable virt-resize to support such OSes we
have to preserve disk GUID.
---
 resize/resize.ml | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/resize/resize.ml b/resize/resize.ml
index d6dd9a5..8ff4793 100644
--- a/resize/resize.ml
+++ b/resize/resize.ml
@@ -407,6 +407,13 @@ read the man page virt-resize(1).
       error (f_"%s: unknown partition table type\nvirt-resize only
supports MBR (DOS) and GPT partition tables.")
         (fst infile) in

+  let disk_guid +    match parttype with
+    | MBR -> None
+    | GPT ->
+      try Some (g#part_get_disk_guid "/dev/sda")
+      with G.Error _ -> None in
+
   (* Build a data structure describing the source disk's partition layout.
*)
   let get_partition_content      let pvs_full = Array.to_list (g#pvs_full ())
in
@@ -977,7 +984,10 @@ read the man page virt-resize(1).
     let last_error = ref "" in
     let rec initialize_partition_table g attempts        let ok -        try
g#part_init "/dev/sdb" parttype_string; true
+        try
+          g#part_init "/dev/sdb" parttype_string;
+          may (g#part_set_disk_guid "/dev/sdb") disk_guid;
+          true
         with G.Error error -> last_error := error; false in
       if ok then g, true
       else if attempts > 0 then (
--
1.8.3.1

On Tue, Jan 19, 2016 at 03:02:58PM +0300, Maxim Perevedentsev
wrote:
> Some OSes (e.g. Windows Server 2012 R2) fail to boot after virt-resize
> due to changed disk guid. To fix it, we add new APIs:
> part_get_disk_guid
> part_set_disk_guid
> part_set_disk_guid_random
> 
> We also preserve disk GUID in virt-resize.
> 
> Maxim Perevedentsev (3):
>   New API: part_get_disk_guid and part_set_disk_guid.
>   New API: part_set_disk_guid_random.
>   resize: preserve GPT disk GUID.
This all looks fine to me.  I'll push this later on once I've run
some tests.

Thanks,

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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