Libguestfs - May 2018 - [PATCH 0/1] libldm: Make libldm to parse and return volume GUID.

The result of this patch will be used by libguestfs to return drive mappings
for LDM volumes.  Note, that "show volume" ldmtool command already
returns
hint which is a drive letter assigned by Windows to corresponding volume.
But it is not reliable source of information.  More over, in multiboot
environment it is unclear which drive letter belongs to which operating
system.  Volume GUID allows to overcome this shortcomming.

Mykola Ivanets (1):
  libldm: Make libldm to parse and return volume GUID.

 src/ldm.c     |  6 ++++--
 src/ldm.h     | 10 ++++++++++
 src/ldmtool.c |  3 +++
 3 files changed, 17 insertions(+), 2 deletions(-)

-- 
2.17.0

LDM volume GUID is a significant piece of information about LDM volume
analogously to GPT disk/partition GUID. Windows use volume GUID to keep track of
assigned drive letters, for example.

We extract volume GUID while parsing volume VBLK in _parse_vblk_vol function. 
"show volume" ldmtool command returns extracted volume GUID alongside
with other volume information.
---
 src/ldm.c     |  6 ++++--
 src/ldm.h     | 10 ++++++++++
 src/ldmtool.c |  3 +++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/ldm.c b/src/ldm.c
index 19a0663..fe5a19b 100644
--- a/src/ldm.c
+++ b/src/ldm.c
@@ -467,6 +467,7 @@ typedef enum {
 
 struct _LDMVolumePrivate
 {
+    uuid_t guid;
     guint32 id;
     gchar *name;
     gchar *dgname;
@@ -535,6 +536,7 @@ ldm_volume_get_property(GObject * const o, const guint
property_id,
 }
 
 EXPORT_PROP_STRING(volume, LDMVolume, name)
+EXPORT_PROP_GUID(volume, LDMVolume)
 EXPORT_PROP_SCALAR(volume, LDMVolume, size, guint64)
 EXPORT_PROP_SCALAR(volume, LDMVolume, part_type, guint8)
 EXPORT_PROP_STRING(volume, LDMVolume, hint)
@@ -1514,8 +1516,8 @@ _parse_vblk_vol(const guint8 revision, const guint16
flags,
 
     vol->part_type = *((uint8_t *)vblk); vblk++;
 
-    /* Volume id */
-    vblk += 16;
+    /* Volume GUID */
+    memcpy(&vol->guid, vblk, 16); vblk += 16;
 
     if (flags & 0x08) vol->id1 = _parse_var_string(&vblk);
     if (flags & 0x20) vol->id2 = _parse_var_string(&vblk);
diff --git a/src/ldm.h b/src/ldm.h
index af0726e..280fbfb 100644
--- a/src/ldm.h
+++ b/src/ldm.h
@@ -369,6 +369,16 @@ GArray *ldm_volume_get_partitions(LDMVolume *o);
  */
 gchar *ldm_volume_get_name(const LDMVolume *o);
 
+/**
+ * ldm_volume_get_guid:
+ * @o: An #LDMVolume
+ *
+ * Get the Windows-assigned GUID of a volume.
+ *
+ * Returns: (transfer full): The string representation of the GUID
+ */
+gchar *ldm_volume_get_guid(const LDMVolume *o);
+
 /**
  * ldm_volume_get_voltype:
  * @o: An #LDMVolume
diff --git a/src/ldmtool.c b/src/ldmtool.c
index 4899539..4a76126 100644
--- a/src/ldmtool.c
+++ b/src/ldmtool.c
@@ -279,6 +279,7 @@ show_volume(LDM *const ldm, const gint argc, gchar ** const
argv,
         LDMVolume * const vol = g_array_index(volumes, LDMVolume *, i);
 
         gchar *name = ldm_volume_get_name(vol);
+        gchar* guid = ldm_volume_get_guid(vol);
         LDMVolumeType type = ldm_volume_get_voltype(vol);
         guint64 size = ldm_volume_get_size(vol);
         guint64 chunk_size = ldm_volume_get_chunk_size(vol);
@@ -294,6 +295,8 @@ show_volume(LDM *const ldm, const gint argc, gchar ** const
argv,
 
             json_builder_set_member_name(jb, "name");
             json_builder_add_string_value(jb, name);
+            json_builder_set_member_name(jb, "guid");
+            json_builder_add_string_value(jb, guid);
             json_builder_set_member_name(jb, "type");
             json_builder_add_string_value(jb, type_v->value_nick);
             json_builder_set_member_name(jb, "size");
-- 
2.17.0