block: merge qcow, vhdx and block_util into block crate

This commit merges crates `qcow`, `vhdx` and `block_util` into the
crate `block`, which can allow `qcow` to use functions from `block_util`
without introducing a circular crate dependency.

This commit is based on crosvm implementation:
https://chromium.googlesource.com/crosvm/crosvm/+/f2eecc4152eca8d395566cffa2c102ec090a152d

Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>

block/src/vhdx/mod.rs

@@ -0,0 +1,237 @@
+// Copyright © 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::vhdx::{
+    vhdx_bat::{BatEntry, VhdxBatError},
+    vhdx_header::{RegionInfo, RegionTableEntry, VhdxHeader, VhdxHeaderError},
+    vhdx_io::VhdxIoError,
+    vhdx_metadata::{DiskSpec, VhdxMetadataError},
+};
+use byteorder::{BigEndian, ByteOrder};
+use remain::sorted;
+use std::collections::btree_map::BTreeMap;
+use std::fs::File;
+use std::io::{Read, Seek, SeekFrom, Write};
+use thiserror::Error;
+use uuid::Uuid;
+
+macro_rules! div_round_up {
+    ($n:expr,$d:expr) => {
+        ($n + $d - 1) / $d
+    };
+}
+
+mod vhdx_bat;
+mod vhdx_header;
+mod vhdx_io;
+mod vhdx_metadata;
+
+#[sorted]
+#[derive(Error, Debug)]
+pub enum VhdxError {
+    #[error("Not a VHDx file {0}")]
+    NotVhdx(#[source] VhdxHeaderError),
+    #[error("Failed to parse VHDx header {0}")]
+    ParseVhdxHeader(#[source] VhdxHeaderError),
+    #[error("Failed to parse VHDx metadata {0}")]
+    ParseVhdxMetadata(#[source] VhdxMetadataError),
+    #[error("Failed to parse VHDx region entries {0}")]
+    ParseVhdxRegionEntry(#[source] VhdxHeaderError),
+    #[error("Failed reading metadata {0}")]
+    ReadBatEntry(#[source] VhdxBatError),
+    #[error("Failed reading sector from disk {0}")]
+    ReadFailed(#[source] VhdxIoError),
+    #[error("Failed writing to sector on disk {0}")]
+    WriteFailed(#[source] VhdxIoError),
+}
+
+pub type Result<T> = std::result::Result<T, VhdxError>;
+
+#[derive(Debug)]
+pub struct Vhdx {
+    file: File,
+    vhdx_header: VhdxHeader,
+    region_entries: BTreeMap<u64, u64>,
+    bat_entry: RegionTableEntry,
+    mdr_entry: RegionTableEntry,
+    disk_spec: DiskSpec,
+    bat_entries: Vec<BatEntry>,
+    current_offset: u64,
+    first_write: bool,
+}
+
+impl Vhdx {
+    /// Parse the Vhdx header, BAT, and metadata from a file and store info
+    // in Vhdx structure.
+    pub fn new(mut file: File) -> Result<Vhdx> {
+        let vhdx_header = VhdxHeader::new(&mut file).map_err(VhdxError::ParseVhdxHeader)?;
+
+        let collected_entries = RegionInfo::new(
+            &mut file,
+            vhdx_header::REGION_TABLE_1_START,
+            vhdx_header.region_entry_count(),
+        )
+        .map_err(VhdxError::ParseVhdxRegionEntry)?;
+
+        let bat_entry = collected_entries.bat_entry;
+        let mdr_entry = collected_entries.mdr_entry;
+
+        let disk_spec =
+            DiskSpec::new(&mut file, &mdr_entry).map_err(VhdxError::ParseVhdxMetadata)?;
+        let bat_entries = BatEntry::collect_bat_entries(&mut file, &disk_spec, &bat_entry)
+            .map_err(VhdxError::ReadBatEntry)?;
+
+        Ok(Vhdx {
+            file,
+            vhdx_header,
+            region_entries: collected_entries.region_entries,
+            bat_entry,
+            mdr_entry,
+            disk_spec,
+            bat_entries,
+            current_offset: 0,
+            first_write: true,
+        })
+    }
+
+    pub fn virtual_disk_size(&self) -> u64 {
+        self.disk_spec.virtual_disk_size
+    }
+}
+
+impl Read for Vhdx {
+    /// Wrapper function to satisfy Read trait implementation for VHDx disk.
+    /// Convert the offset to sector index and buffer length to sector count.
+    fn read(&mut self, buf: &mut [u8]) -> std::result::Result<usize, std::io::Error> {
+        let sector_count =
+            div_round_up!(buf.len() as u64, self.disk_spec.logical_sector_size as u64);
+        let sector_index = self.current_offset / self.disk_spec.logical_sector_size as u64;
+
+        vhdx_io::read(
+            &mut self.file,
+            buf,
+            &self.disk_spec,
+            &self.bat_entries,
+            sector_index,
+            sector_count,
+        )
+        .map_err(|e| {
+            std::io::Error::new(
+                std::io::ErrorKind::Other,
+                format!(
+                    "Failed reading {sector_count} sectors from VHDx at index {sector_index}: {e}"
+                ),
+            )
+        })
+    }
+}
+
+impl Write for Vhdx {
+    fn flush(&mut self) -> std::result::Result<(), std::io::Error> {
+        self.file.flush()
+    }
+
+    /// Wrapper function to satisfy Write trait implementation for VHDx disk.
+    /// Convert the offset to sector index and buffer length to sector count.
+    fn write(&mut self, buf: &[u8]) -> std::result::Result<usize, std::io::Error> {
+        let sector_count =
+            div_round_up!(buf.len() as u64, self.disk_spec.logical_sector_size as u64);
+        let sector_index = self.current_offset / self.disk_spec.logical_sector_size as u64;
+
+        if self.first_write {
+            self.first_write = false;
+            self.vhdx_header.update(&mut self.file).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::Other,
+                    format!("Failed to update VHDx header: {e}"),
+                )
+            })?;
+        }
+
+        vhdx_io::write(
+            &mut self.file,
+            buf,
+            &mut self.disk_spec,
+            self.bat_entry.file_offset,
+            &mut self.bat_entries,
+            sector_index,
+            sector_count,
+        )
+        .map_err(|e| {
+            std::io::Error::new(
+                std::io::ErrorKind::Other,
+                format!(
+                    "Failed writing {sector_count} sectors on VHDx at index {sector_index}: {e}"
+                ),
+            )
+        })
+    }
+}
+
+impl Seek for Vhdx {
+    /// Wrapper function to satisfy Seek trait implementation for VHDx disk.
+    /// Updates the offset field in the Vhdx struct.
+    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
+        let new_offset: Option<u64> = match pos {
+            SeekFrom::Start(off) => Some(off),
+            SeekFrom::End(off) => {
+                if off < 0 {
+                    0i64.checked_sub(off).and_then(|increment| {
+                        self.virtual_disk_size().checked_sub(increment as u64)
+                    })
+                } else {
+                    self.virtual_disk_size().checked_add(off as u64)
+                }
+            }
+            SeekFrom::Current(off) => {
+                if off < 0 {
+                    0i64.checked_sub(off)
+                        .and_then(|increment| self.current_offset.checked_sub(increment as u64))
+                } else {
+                    self.current_offset.checked_add(off as u64)
+                }
+            }
+        };
+
+        if let Some(o) = new_offset {
+            if o <= self.virtual_disk_size() {
+                self.current_offset = o;
+                return Ok(o);
+            }
+        }
+
+        Err(std::io::Error::new(
+            std::io::ErrorKind::InvalidData,
+            "Failed seek operation",
+        ))
+    }
+}
+
+impl Clone for Vhdx {
+    fn clone(&self) -> Self {
+        Vhdx {
+            file: self.file.try_clone().unwrap(),
+            vhdx_header: self.vhdx_header.clone(),
+            region_entries: self.region_entries.clone(),
+            bat_entry: self.bat_entry,
+            mdr_entry: self.mdr_entry,
+            disk_spec: self.disk_spec.clone(),
+            bat_entries: self.bat_entries.clone(),
+            current_offset: self.current_offset,
+            first_write: self.first_write,
+        }
+    }
+}
+
+pub(crate) fn uuid_from_guid(buf: &[u8]) -> Uuid {
+    // 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].try_into().unwrap(),
+    )
+}