vhdx: Fixed and dynamic VHDx block device implementation

Microsoft’s VHDx block device format specification is implemented
here as a crate. This commit includes the implementation for the
fixed and dynamic formats, where the other format is known as
differencing. The vhdx_header.rs, vhdx_bat.rs, vhdx_metadata.rs
implements parser and manipulators for the VHDx header, Block
Allocation Table, and metadata, respectively, for the VHDx file.
The vhdx_io.rs implements read and write routines for the VHDx file.
The vhdx.rs implements the Vhdx structure, which provides the wrapper
functions for standard I/O operations like read, write, and seek.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Fazla Mehrab <akm.fazla.mehrab@intel.com>

vhdx/src/lib.rs

@@ -0,0 +1,31 @@
+// Copyright © 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+use byteorder::{BigEndian, ByteOrder};
+use std::result::Result;
+use uuid::Uuid;
+
+macro_rules! div_round_up {
+    ($n:expr,$d:expr) => {
+        ($n + $d - 1) / $d
+    };
+}
+
+pub mod vhdx;
+mod vhdx_bat;
+mod vhdx_header;
+mod vhdx_io;
+mod vhdx_metadata;
+
+pub(crate) fn uuid_from_guid(buf: &[u8]) -> Result<Uuid, uuid::Error> {
+    // The first 3 fields of UUID are stored in Big Endian format, and
+    // the last 8 bytes are stored as byte array. Therefore, we read the
+    // first 3 fields in Big Endian format instead of Little Endian.
+    Uuid::from_fields_le(
+        BigEndian::read_u32(&buf[0..4]),
+        BigEndian::read_u16(&buf[4..6]),
+        BigEndian::read_u16(&buf[6..8]),
+        &buf[8..16],
+    )
+}