blob: dd8c1a2f1d91a2afeaea4289f017da6a14756c5b [file] [log] [blame]
// Copyright 2018 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
mod qcow_raw_file;
mod refcount;
mod vec_cache;
use data_model::{VolatileMemory, VolatileSlice};
use libc::{EINVAL, ENOSPC, ENOTSUP};
use remain::sorted;
use sys_util::{
error, FileGetLen, FileReadWriteAtVolatile, FileReadWriteVolatile, FileSetLen, FileSync,
PunchHole, SeekHole, WriteZeroesAt,
};
use std::cmp::{max, min};
use std::fmt::{self, Display};
use std::fs::File;
use std::io::{self, Read, Seek, SeekFrom, Write};
use std::mem::size_of;
use std::os::unix::io::{AsRawFd, RawFd};
use crate::qcow_raw_file::QcowRawFile;
use crate::refcount::RefCount;
use crate::vec_cache::{CacheMap, Cacheable, VecCache};
#[sorted]
#[derive(Debug)]
pub enum Error {
BackingFilesNotSupported,
CompressedBlocksNotSupported,
EvictingCache(io::Error),
FileTooBig(u64),
GettingFileSize(io::Error),
GettingRefcount(refcount::Error),
InvalidClusterIndex,
InvalidClusterSize,
InvalidIndex,
InvalidL1TableOffset,
InvalidL1TableSize(u32),
InvalidMagic,
InvalidOffset(u64),
InvalidRefcountTableOffset,
InvalidRefcountTableSize(u64),
NoFreeClusters,
NoRefcountClusters,
NotEnoughSpaceForRefcounts,
OpeningFile(io::Error),
ReadingHeader(io::Error),
ReadingPointers(io::Error),
ReadingRefCountBlock(refcount::Error),
ReadingRefCounts(io::Error),
RebuildingRefCounts(io::Error),
RefcountTableOffEnd,
RefcountTableTooLarge,
SeekingFile(io::Error),
SettingRefcountRefcount(io::Error),
SizeTooSmallForNumberOfClusters,
TooManyL1Entries(u64),
TooManyRefcounts(u64),
UnsupportedRefcountOrder,
UnsupportedVersion(u32),
WritingHeader(io::Error),
}
pub type Result<T> = std::result::Result<T, Error>;
impl Display for Error {
#[remain::check]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
#[sorted]
match self {
BackingFilesNotSupported => write!(f, "backing files not supported"),
CompressedBlocksNotSupported => write!(f, "compressed blocks not supported"),
EvictingCache(e) => write!(f, "failed to evict cache: {}", e),
FileTooBig(size) => write!(
f,
"file larger than max of {}: {}",
MAX_QCOW_FILE_SIZE, size
),
GettingFileSize(e) => write!(f, "failed to get file size: {}", e),
GettingRefcount(e) => write!(f, "failed to get refcount: {}", e),
InvalidClusterIndex => write!(f, "invalid cluster index"),
InvalidClusterSize => write!(f, "invalid cluster size"),
InvalidIndex => write!(f, "invalid index"),
InvalidL1TableOffset => write!(f, "invalid L1 table offset"),
InvalidL1TableSize(size) => write!(f, "invalid L1 table size {}", size),
InvalidMagic => write!(f, "invalid magic"),
InvalidOffset(_) => write!(f, "invalid offset"),
InvalidRefcountTableOffset => write!(f, "invalid refcount table offset"),
InvalidRefcountTableSize(size) => write!(f, "invalid refcount table size: {}", size),
NoFreeClusters => write!(f, "no free clusters"),
NoRefcountClusters => write!(f, "no refcount clusters"),
NotEnoughSpaceForRefcounts => write!(f, "not enough space for refcounts"),
OpeningFile(e) => write!(f, "failed to open file: {}", e),
ReadingHeader(e) => write!(f, "failed to read header: {}", e),
ReadingPointers(e) => write!(f, "failed to read pointers: {}", e),
ReadingRefCountBlock(e) => write!(f, "failed to read ref count block: {}", e),
ReadingRefCounts(e) => write!(f, "failed to read ref counts: {}", e),
RebuildingRefCounts(e) => write!(f, "failed to rebuild ref counts: {}", e),
RefcountTableOffEnd => write!(f, "refcount table offset past file end"),
RefcountTableTooLarge => write!(f, "too many clusters specified for refcount table"),
SeekingFile(e) => write!(f, "failed to seek file: {}", e),
SettingRefcountRefcount(e) => write!(f, "failed to set refcount refcount: {}", e),
SizeTooSmallForNumberOfClusters => write!(f, "size too small for number of clusters"),
TooManyL1Entries(count) => write!(f, "l1 entry table too large: {}", count),
TooManyRefcounts(count) => write!(f, "ref count table too large: {}", count),
UnsupportedRefcountOrder => write!(f, "unsupported refcount order"),
UnsupportedVersion(v) => write!(f, "unsupported version: {}", v),
WritingHeader(e) => write!(f, "failed to write header: {}", e),
}
}
}
// Maximum data size supported.
const MAX_QCOW_FILE_SIZE: u64 = 0x01 << 44; // 16 TB.
// QCOW magic constant that starts the header.
pub const QCOW_MAGIC: u32 = 0x5146_49fb;
// Default to a cluster size of 2^DEFAULT_CLUSTER_BITS
const DEFAULT_CLUSTER_BITS: u32 = 16;
// Limit clusters to reasonable sizes. Choose the same limits as qemu. Making the clusters smaller
// increases the amount of overhead for book keeping.
const MIN_CLUSTER_BITS: u32 = 9;
const MAX_CLUSTER_BITS: u32 = 21;
// The L1 and RefCount table are kept in RAM, only handle files that require less than 35M entries.
// This easily covers 1 TB files. When support for bigger files is needed the assumptions made to
// keep these tables in RAM needs to be thrown out.
const MAX_RAM_POINTER_TABLE_SIZE: u64 = 35_000_000;
// Only support 2 byte refcounts, 2^refcount_order bits.
const DEFAULT_REFCOUNT_ORDER: u32 = 4;
const V3_BARE_HEADER_SIZE: u32 = 104;
// bits 0-8 and 56-63 are reserved.
const L1_TABLE_OFFSET_MASK: u64 = 0x00ff_ffff_ffff_fe00;
const L2_TABLE_OFFSET_MASK: u64 = 0x00ff_ffff_ffff_fe00;
// Flags
const COMPRESSED_FLAG: u64 = 1 << 62;
const CLUSTER_USED_FLAG: u64 = 1 << 63;
const COMPATIBLE_FEATURES_LAZY_REFCOUNTS: u64 = 1 << 0;
/// Contains the information from the header of a qcow file.
#[derive(Copy, Clone, Debug)]
pub struct QcowHeader {
pub magic: u32,
pub version: u32,
pub backing_file_offset: u64,
pub backing_file_size: u32,
pub cluster_bits: u32,
pub size: u64,
pub crypt_method: u32,
pub l1_size: u32,
pub l1_table_offset: u64,
pub refcount_table_offset: u64,
pub refcount_table_clusters: u32,
pub nb_snapshots: u32,
pub snapshots_offset: u64,
// v3 entries
pub incompatible_features: u64,
pub compatible_features: u64,
pub autoclear_features: u64,
pub refcount_order: u32,
pub header_size: u32,
}
// Reads the next u16 from the file.
fn read_u16_from_file(mut f: &File) -> Result<u16> {
let mut value = [0u8; 2];
(&mut f)
.read_exact(&mut value)
.map_err(Error::ReadingHeader)?;
Ok(u16::from_be_bytes(value))
}
// Reads the next u32 from the file.
fn read_u32_from_file(mut f: &File) -> Result<u32> {
let mut value = [0u8; 4];
(&mut f)
.read_exact(&mut value)
.map_err(Error::ReadingHeader)?;
Ok(u32::from_be_bytes(value))
}
// Reads the next u64 from the file.
fn read_u64_from_file(mut f: &File) -> Result<u64> {
let mut value = [0u8; 8];
(&mut f)
.read_exact(&mut value)
.map_err(Error::ReadingHeader)?;
Ok(u64::from_be_bytes(value))
}
impl QcowHeader {
/// Creates a QcowHeader from a reference to a file.
pub fn new(f: &mut File) -> Result<QcowHeader> {
f.seek(SeekFrom::Start(0)).map_err(Error::ReadingHeader)?;
let magic = read_u32_from_file(f)?;
if magic != QCOW_MAGIC {
return Err(Error::InvalidMagic);
}
Ok(QcowHeader {
magic,
version: read_u32_from_file(f)?,
backing_file_offset: read_u64_from_file(f)?,
backing_file_size: read_u32_from_file(f)?,
cluster_bits: read_u32_from_file(f)?,
size: read_u64_from_file(f)?,
crypt_method: read_u32_from_file(f)?,
l1_size: read_u32_from_file(f)?,
l1_table_offset: read_u64_from_file(f)?,
refcount_table_offset: read_u64_from_file(f)?,
refcount_table_clusters: read_u32_from_file(f)?,
nb_snapshots: read_u32_from_file(f)?,
snapshots_offset: read_u64_from_file(f)?,
incompatible_features: read_u64_from_file(f)?,
compatible_features: read_u64_from_file(f)?,
autoclear_features: read_u64_from_file(f)?,
refcount_order: read_u32_from_file(f)?,
header_size: read_u32_from_file(f)?,
})
}
/// Create a header for the given `size`.
pub fn create_for_size(size: u64) -> QcowHeader {
let cluster_bits: u32 = DEFAULT_CLUSTER_BITS;
let cluster_size: u32 = 0x01 << cluster_bits;
// L2 blocks are always one cluster long. They contain cluster_size/sizeof(u64) addresses.
let l2_size: u32 = cluster_size / size_of::<u64>() as u32;
let num_clusters: u32 = div_round_up_u64(size, u64::from(cluster_size)) as u32;
let num_l2_clusters: u32 = div_round_up_u32(num_clusters, l2_size);
let l1_clusters: u32 = div_round_up_u32(num_l2_clusters, cluster_size);
let header_clusters = div_round_up_u32(size_of::<QcowHeader>() as u32, cluster_size);
QcowHeader {
magic: QCOW_MAGIC,
version: 3,
backing_file_offset: 0,
backing_file_size: 0,
cluster_bits: DEFAULT_CLUSTER_BITS,
size,
crypt_method: 0,
l1_size: num_l2_clusters,
l1_table_offset: u64::from(cluster_size),
// The refcount table is after l1 + header.
refcount_table_offset: u64::from(cluster_size * (l1_clusters + 1)),
refcount_table_clusters: {
// Pre-allocate enough clusters for the entire refcount table as it must be
// continuous in the file. Allocate enough space to refcount all clusters, including
// the refcount clusters.
let max_refcount_clusters = max_refcount_clusters(
DEFAULT_REFCOUNT_ORDER,
cluster_size,
num_clusters + l1_clusters + num_l2_clusters + header_clusters,
) as u32;
// The refcount table needs to store the offset of each refcount cluster.
div_round_up_u32(
max_refcount_clusters * size_of::<u64>() as u32,
cluster_size,
)
},
nb_snapshots: 0,
snapshots_offset: 0,
incompatible_features: 0,
compatible_features: 0,
autoclear_features: 0,
refcount_order: DEFAULT_REFCOUNT_ORDER,
header_size: V3_BARE_HEADER_SIZE,
}
}
/// Write the header to `file`.
pub fn write_to<F: Write + Seek>(&self, file: &mut F) -> Result<()> {
// Writes the next u32 to the file.
fn write_u32_to_file<F: Write>(f: &mut F, value: u32) -> Result<()> {
f.write_all(&value.to_be_bytes())
.map_err(Error::WritingHeader)
}
// Writes the next u64 to the file.
fn write_u64_to_file<F: Write>(f: &mut F, value: u64) -> Result<()> {
f.write_all(&value.to_be_bytes())
.map_err(Error::WritingHeader)
}
write_u32_to_file(file, self.magic)?;
write_u32_to_file(file, self.version)?;
write_u64_to_file(file, self.backing_file_offset)?;
write_u32_to_file(file, self.backing_file_size)?;
write_u32_to_file(file, self.cluster_bits)?;
write_u64_to_file(file, self.size)?;
write_u32_to_file(file, self.crypt_method)?;
write_u32_to_file(file, self.l1_size)?;
write_u64_to_file(file, self.l1_table_offset)?;
write_u64_to_file(file, self.refcount_table_offset)?;
write_u32_to_file(file, self.refcount_table_clusters)?;
write_u32_to_file(file, self.nb_snapshots)?;
write_u64_to_file(file, self.snapshots_offset)?;
write_u64_to_file(file, self.incompatible_features)?;
write_u64_to_file(file, self.compatible_features)?;
write_u64_to_file(file, self.autoclear_features)?;
write_u32_to_file(file, self.refcount_order)?;
write_u32_to_file(file, self.header_size)?;
// Set the file length by seeking and writing a zero to the last byte. This avoids needing
// a `File` instead of anything that implements seek as the `file` argument.
// Zeros out the l1 and refcount table clusters.
let cluster_size = 0x01u64 << self.cluster_bits;
let refcount_blocks_size = u64::from(self.refcount_table_clusters) * cluster_size;
file.seek(SeekFrom::Start(
self.refcount_table_offset + refcount_blocks_size - 2,
))
.map_err(Error::WritingHeader)?;
file.write(&[0u8]).map_err(Error::WritingHeader)?;
Ok(())
}
}
fn max_refcount_clusters(refcount_order: u32, cluster_size: u32, num_clusters: u32) -> u64 {
// Use u64 as the product of the u32 inputs can overflow.
let refcount_bytes = (0x01 << refcount_order as u64) / 8;
let for_data = div_round_up_u64(num_clusters as u64 * refcount_bytes, cluster_size as u64);
let for_refcounts = div_round_up_u64(for_data * refcount_bytes, cluster_size as u64);
for_data + for_refcounts
}
/// Represents a qcow2 file. This is a sparse file format maintained by the qemu project.
/// Full documentation of the format can be found in the qemu repository.
///
/// # Example
///
/// ```
/// # use std::io::{Read, Seek, SeekFrom};
/// # use qcow::{self, QcowFile};
/// # fn test(file: std::fs::File) -> std::io::Result<()> {
/// let mut q = QcowFile::from(file).expect("Can't open qcow file");
/// let mut buf = [0u8; 12];
/// q.seek(SeekFrom::Start(10 as u64))?;
/// q.read(&mut buf[..])?;
/// # Ok(())
/// # }
/// ```
#[derive(Debug)]
pub struct QcowFile {
raw_file: QcowRawFile,
header: QcowHeader,
l1_table: VecCache<u64>,
l2_entries: u64,
l2_cache: CacheMap<VecCache<u64>>,
refcounts: RefCount,
current_offset: u64,
unref_clusters: Vec<u64>, // List of freshly unreferenced clusters.
// List of unreferenced clusters available to be used. unref clusters become available once the
// removal of references to them have been synced to disk.
avail_clusters: Vec<u64>,
//TODO(dgreid) Add support for backing files. - backing_file: Option<Box<QcowFile<T>>>,
}
impl QcowFile {
/// Creates a QcowFile from `file`. File must be a valid qcow2 image.
pub fn from(mut file: File) -> Result<QcowFile> {
let header = QcowHeader::new(&mut file)?;
// Only v3 files are supported.
if header.version != 3 {
return Err(Error::UnsupportedVersion(header.version));
}
// Make sure that the L1 table fits in RAM.
if u64::from(header.l1_size) > MAX_RAM_POINTER_TABLE_SIZE {
return Err(Error::InvalidL1TableSize(header.l1_size));
}
let cluster_bits: u32 = header.cluster_bits;
if cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS {
return Err(Error::InvalidClusterSize);
}
let cluster_size = 0x01u64 << cluster_bits;
// Limit the total size of the disk.
if header.size > MAX_QCOW_FILE_SIZE {
return Err(Error::FileTooBig(header.size));
}
// No current support for backing files.
if header.backing_file_offset != 0 {
return Err(Error::BackingFilesNotSupported);
}
// Only support two byte refcounts.
let refcount_bits: u64 = 0x01u64
.checked_shl(header.refcount_order)
.ok_or(Error::UnsupportedRefcountOrder)?;
if refcount_bits != 16 {
return Err(Error::UnsupportedRefcountOrder);
}
let refcount_bytes = (refcount_bits + 7) / 8;
// Need at least one refcount cluster
if header.refcount_table_clusters == 0 {
return Err(Error::NoRefcountClusters);
}
offset_is_cluster_boundary(header.backing_file_offset, header.cluster_bits)?;
offset_is_cluster_boundary(header.l1_table_offset, header.cluster_bits)?;
offset_is_cluster_boundary(header.snapshots_offset, header.cluster_bits)?;
// refcount table must be a cluster boundary, and within the file's virtual or actual size.
offset_is_cluster_boundary(header.refcount_table_offset, header.cluster_bits)?;
let file_size = file.metadata().map_err(Error::GettingFileSize)?.len();
if header.refcount_table_offset > max(file_size, header.size) {
return Err(Error::RefcountTableOffEnd);
}
// The first cluster should always have a non-zero refcount, so if it is 0,
// this is an old file with broken refcounts, which requires a rebuild.
let mut refcount_rebuild_required = true;
file.seek(SeekFrom::Start(header.refcount_table_offset))
.map_err(Error::SeekingFile)?;
let first_refblock_addr = read_u64_from_file(&file)?;
if first_refblock_addr != 0 {
file.seek(SeekFrom::Start(first_refblock_addr))
.map_err(Error::SeekingFile)?;
let first_cluster_refcount = read_u16_from_file(&file)?;
if first_cluster_refcount != 0 {
refcount_rebuild_required = false;
}
}
if (header.compatible_features & COMPATIBLE_FEATURES_LAZY_REFCOUNTS) != 0 {
refcount_rebuild_required = true;
}
let mut raw_file =
QcowRawFile::from(file, cluster_size).ok_or(Error::InvalidClusterSize)?;
if refcount_rebuild_required {
QcowFile::rebuild_refcounts(&mut raw_file, header)?;
}
let l2_size = cluster_size / size_of::<u64>() as u64;
let num_clusters = div_round_up_u64(header.size, cluster_size);
let num_l2_clusters = div_round_up_u64(num_clusters, l2_size);
let l1_clusters = div_round_up_u64(num_l2_clusters, cluster_size);
let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size);
if num_l2_clusters > MAX_RAM_POINTER_TABLE_SIZE {
return Err(Error::TooManyL1Entries(num_l2_clusters));
}
let l1_table = VecCache::from_vec(
raw_file
.read_pointer_table(
header.l1_table_offset,
num_l2_clusters,
Some(L1_TABLE_OFFSET_MASK),
)
.map_err(Error::ReadingHeader)?,
);
let num_clusters = div_round_up_u64(header.size, cluster_size);
let refcount_clusters = max_refcount_clusters(
header.refcount_order,
cluster_size as u32,
(num_clusters + l1_clusters + num_l2_clusters + header_clusters) as u32,
);
// Check that the given header doesn't have a suspiciously sized refcount table.
if u64::from(header.refcount_table_clusters) > 2 * refcount_clusters {
return Err(Error::RefcountTableTooLarge);
}
if l1_clusters + refcount_clusters > MAX_RAM_POINTER_TABLE_SIZE {
return Err(Error::TooManyRefcounts(refcount_clusters));
}
let refcount_block_entries = cluster_size / refcount_bytes;
let refcounts = RefCount::new(
&mut raw_file,
header.refcount_table_offset,
refcount_clusters,
refcount_block_entries,
cluster_size,
)
.map_err(Error::ReadingRefCounts)?;
let l2_entries = cluster_size / size_of::<u64>() as u64;
let mut qcow = QcowFile {
raw_file,
header,
l1_table,
l2_entries,
l2_cache: CacheMap::new(100),
refcounts,
current_offset: 0,
unref_clusters: Vec::new(),
avail_clusters: Vec::new(),
};
// Check that the L1 and refcount tables fit in a 64bit address space.
qcow.header
.l1_table_offset
.checked_add(qcow.l1_address_offset(qcow.virtual_size()))
.ok_or(Error::InvalidL1TableOffset)?;
qcow.header
.refcount_table_offset
.checked_add(u64::from(qcow.header.refcount_table_clusters) * cluster_size)
.ok_or(Error::InvalidRefcountTableOffset)?;
qcow.find_avail_clusters()?;
Ok(qcow)
}
/// Creates a new QcowFile at the given path.
pub fn new(mut file: File, virtual_size: u64) -> Result<QcowFile> {
let header = QcowHeader::create_for_size(virtual_size);
file.seek(SeekFrom::Start(0)).map_err(Error::SeekingFile)?;
header.write_to(&mut file)?;
let mut qcow = Self::from(file)?;
// Set the refcount for each refcount table cluster.
let cluster_size = 0x01u64 << qcow.header.cluster_bits;
let refcount_table_base = qcow.header.refcount_table_offset as u64;
let end_cluster_addr =
refcount_table_base + u64::from(qcow.header.refcount_table_clusters) * cluster_size;
let mut cluster_addr = 0;
while cluster_addr < end_cluster_addr {
let mut unref_clusters = qcow
.set_cluster_refcount(cluster_addr, 1)
.map_err(Error::SettingRefcountRefcount)?;
qcow.unref_clusters.append(&mut unref_clusters);
cluster_addr += cluster_size;
}
Ok(qcow)
}
/// Returns the `QcowHeader` for this file.
pub fn header(&self) -> &QcowHeader {
&self.header
}
/// Returns the L1 lookup table for this file. This is only useful for debugging.
pub fn l1_table(&self) -> &[u64] {
&self.l1_table.get_values()
}
/// Returns an L2_table of cluster addresses, only used for debugging.
pub fn l2_table(&mut self, l1_index: usize) -> Result<Option<&[u64]>> {
let l2_addr_disk = *self.l1_table.get(l1_index).ok_or(Error::InvalidIndex)?;
if l2_addr_disk == 0 {
// Reading from an unallocated cluster will return zeros.
return Ok(None);
}
if !self.l2_cache.contains_key(&l1_index) {
// Not in the cache.
let table = VecCache::from_vec(
Self::read_l2_cluster(&mut self.raw_file, l2_addr_disk)
.map_err(Error::ReadingPointers)?,
);
let l1_table = &self.l1_table;
let raw_file = &mut self.raw_file;
self.l2_cache
.insert(l1_index, table, |index, evicted| {
raw_file.write_pointer_table(
l1_table[index],
evicted.get_values(),
CLUSTER_USED_FLAG,
)
})
.map_err(Error::EvictingCache)?;
}
// The index must exist as it was just inserted if it didn't already.
Ok(Some(self.l2_cache.get(&l1_index).unwrap().get_values()))
}
/// Returns the refcount table for this file. This is only useful for debugging.
pub fn ref_table(&self) -> &[u64] {
&self.refcounts.ref_table()
}
/// Returns the `index`th refcount block from the file.
pub fn refcount_block(&mut self, index: usize) -> Result<Option<&[u16]>> {
self.refcounts
.refcount_block(&mut self.raw_file, index)
.map_err(Error::ReadingRefCountBlock)
}
/// Returns the first cluster in the file with a 0 refcount. Used for testing.
pub fn first_zero_refcount(&mut self) -> Result<Option<u64>> {
let file_size = self
.raw_file
.file_mut()
.metadata()
.map_err(Error::GettingFileSize)?
.len();
let cluster_size = 0x01u64 << self.header.cluster_bits;
let mut cluster_addr = 0;
while cluster_addr < file_size {
let cluster_refcount = self
.refcounts
.get_cluster_refcount(&mut self.raw_file, cluster_addr)
.map_err(Error::GettingRefcount)?;
if cluster_refcount == 0 {
return Ok(Some(cluster_addr));
}
cluster_addr += cluster_size;
}
Ok(None)
}
fn find_avail_clusters(&mut self) -> Result<()> {
let cluster_size = self.raw_file.cluster_size();
let file_size = self
.raw_file
.file_mut()
.metadata()
.map_err(Error::GettingFileSize)?
.len();
for i in (0..file_size).step_by(cluster_size as usize) {
let refcount = self
.refcounts
.get_cluster_refcount(&mut self.raw_file, i)
.map_err(Error::GettingRefcount)?;
if refcount == 0 {
self.avail_clusters.push(i);
}
}
Ok(())
}
/// Rebuild the reference count tables.
fn rebuild_refcounts(raw_file: &mut QcowRawFile, header: QcowHeader) -> Result<()> {
fn add_ref(refcounts: &mut [u16], cluster_size: u64, cluster_address: u64) -> Result<()> {
let idx = (cluster_address / cluster_size) as usize;
if idx >= refcounts.len() {
return Err(Error::InvalidClusterIndex);
}
refcounts[idx] += 1;
Ok(())
}
// Add a reference to the first cluster (header plus extensions).
fn set_header_refcount(refcounts: &mut [u16], cluster_size: u64) -> Result<()> {
add_ref(refcounts, cluster_size, 0)
}
// Add references to the L1 table clusters.
fn set_l1_refcounts(
refcounts: &mut [u16],
header: QcowHeader,
cluster_size: u64,
) -> Result<()> {
let l1_clusters = div_round_up_u64(header.l1_size as u64, cluster_size);
let l1_table_offset = header.l1_table_offset;
for i in 0..l1_clusters {
add_ref(refcounts, cluster_size, l1_table_offset + i * cluster_size)?;
}
Ok(())
}
// Traverse the L1 and L2 tables to find all reachable data clusters.
fn set_data_refcounts(
refcounts: &mut [u16],
header: QcowHeader,
cluster_size: u64,
raw_file: &mut QcowRawFile,
) -> Result<()> {
let l1_table = raw_file
.read_pointer_table(
header.l1_table_offset,
header.l1_size as u64,
Some(L1_TABLE_OFFSET_MASK),
)
.map_err(Error::ReadingPointers)?;
for l1_index in 0..header.l1_size as usize {
let l2_addr_disk = *l1_table.get(l1_index).ok_or(Error::InvalidIndex)?;
if l2_addr_disk != 0 {
// Add a reference to the L2 table cluster itself.
add_ref(refcounts, cluster_size, l2_addr_disk)?;
// Read the L2 table and find all referenced data clusters.
let l2_table = raw_file
.read_pointer_table(
l2_addr_disk,
cluster_size / size_of::<u64>() as u64,
Some(L2_TABLE_OFFSET_MASK),
)
.map_err(Error::ReadingPointers)?;
for data_cluster_addr in l2_table {
if data_cluster_addr != 0 {
add_ref(refcounts, cluster_size, data_cluster_addr)?;
}
}
}
}
Ok(())
}
// Add references to the top-level refcount table clusters.
fn set_refcount_table_refcounts(
refcounts: &mut [u16],
header: QcowHeader,
cluster_size: u64,
) -> Result<()> {
let refcount_table_offset = header.refcount_table_offset;
for i in 0..header.refcount_table_clusters as u64 {
add_ref(
refcounts,
cluster_size,
refcount_table_offset + i * cluster_size,
)?;
}
Ok(())
}
// Allocate clusters for refblocks.
// This needs to be done last so that we have the correct refcounts for all other
// clusters.
fn alloc_refblocks(
refcounts: &mut [u16],
cluster_size: u64,
refblock_clusters: u64,
pointers_per_cluster: u64,
) -> Result<Vec<u64>> {
let refcount_table_entries = div_round_up_u64(refblock_clusters, pointers_per_cluster);
let mut ref_table = vec![0; refcount_table_entries as usize];
let mut first_free_cluster: u64 = 0;
for refblock_addr in &mut ref_table {
while refcounts[first_free_cluster as usize] != 0 {
first_free_cluster += 1;
if first_free_cluster >= refcounts.len() as u64 {
return Err(Error::NotEnoughSpaceForRefcounts);
}
}
*refblock_addr = first_free_cluster * cluster_size;
add_ref(refcounts, cluster_size, *refblock_addr)?;
first_free_cluster += 1;
}
Ok(ref_table)
}
// Write the updated reference count blocks and reftable.
fn write_refblocks(
refcounts: &[u16],
mut header: QcowHeader,
ref_table: &[u64],
raw_file: &mut QcowRawFile,
refcount_block_entries: u64,
) -> Result<()> {
// Rewrite the header with lazy refcounts enabled while we are rebuilding the tables.
header.compatible_features |= COMPATIBLE_FEATURES_LAZY_REFCOUNTS;
raw_file
.file_mut()
.seek(SeekFrom::Start(0))
.map_err(Error::SeekingFile)?;
header.write_to(raw_file.file_mut())?;
for (i, refblock_addr) in ref_table.iter().enumerate() {
// Write a block of refcounts to the location indicated by refblock_addr.
let refblock_start = i * (refcount_block_entries as usize);
let refblock_end = min(
refcounts.len(),
refblock_start + refcount_block_entries as usize,
);
let refblock = &refcounts[refblock_start..refblock_end];
raw_file
.write_refcount_block(*refblock_addr, refblock)
.map_err(Error::WritingHeader)?;
// If this is the last (partial) cluster, pad it out to a full refblock cluster.
if refblock.len() < refcount_block_entries as usize {
let refblock_padding =
vec![0u16; refcount_block_entries as usize - refblock.len()];
raw_file
.write_refcount_block(
*refblock_addr + refblock.len() as u64 * 2,
&refblock_padding,
)
.map_err(Error::WritingHeader)?;
}
}
// Rewrite the top-level refcount table.
raw_file
.write_pointer_table(header.refcount_table_offset, &ref_table, 0)
.map_err(Error::WritingHeader)?;
// Rewrite the header again, now with lazy refcounts disabled.
header.compatible_features &= !COMPATIBLE_FEATURES_LAZY_REFCOUNTS;
raw_file
.file_mut()
.seek(SeekFrom::Start(0))
.map_err(Error::SeekingFile)?;
header.write_to(raw_file.file_mut())?;
Ok(())
}
let cluster_size = raw_file.cluster_size();
let file_size = raw_file
.file_mut()
.metadata()
.map_err(Error::GettingFileSize)?
.len();
let refcount_bits = 1u64 << header.refcount_order;
let refcount_bytes = div_round_up_u64(refcount_bits, 8);
let refcount_block_entries = cluster_size / refcount_bytes;
let pointers_per_cluster = cluster_size / size_of::<u64>() as u64;
let data_clusters = div_round_up_u64(header.size, cluster_size);
let l2_clusters = div_round_up_u64(data_clusters, pointers_per_cluster);
let l1_clusters = div_round_up_u64(l2_clusters, cluster_size);
let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size);
let max_clusters = data_clusters + l2_clusters + l1_clusters + header_clusters;
let mut max_valid_cluster_index = max_clusters;
let refblock_clusters = div_round_up_u64(max_valid_cluster_index, refcount_block_entries);
let reftable_clusters = div_round_up_u64(refblock_clusters, pointers_per_cluster);
// Account for refblocks and the ref table size needed to address them.
let refblocks_for_refs = div_round_up_u64(
refblock_clusters + reftable_clusters,
refcount_block_entries,
);
let reftable_clusters_for_refs =
div_round_up_u64(refblocks_for_refs, refcount_block_entries);
max_valid_cluster_index += refblock_clusters + reftable_clusters;
max_valid_cluster_index += refblocks_for_refs + reftable_clusters_for_refs;
if max_valid_cluster_index > MAX_RAM_POINTER_TABLE_SIZE {
return Err(Error::InvalidRefcountTableSize(max_valid_cluster_index));
}
let max_valid_cluster_offset = max_valid_cluster_index * cluster_size;
if max_valid_cluster_offset < file_size - cluster_size {
return Err(Error::InvalidRefcountTableSize(max_valid_cluster_offset));
}
let mut refcounts = vec![0; max_valid_cluster_index as usize];
// Find all references clusters and rebuild refcounts.
set_header_refcount(&mut refcounts, cluster_size)?;
set_l1_refcounts(&mut refcounts, header, cluster_size)?;
set_data_refcounts(&mut refcounts, header, cluster_size, raw_file)?;
set_refcount_table_refcounts(&mut refcounts, header, cluster_size)?;
// Allocate clusters to store the new reference count blocks.
let ref_table = alloc_refblocks(
&mut refcounts,
cluster_size,
refblock_clusters,
pointers_per_cluster,
)?;
// Write updated reference counts and point the reftable at them.
write_refblocks(
&refcounts,
header,
&ref_table,
raw_file,
refcount_block_entries,
)
}
// Limits the range so that it doesn't exceed the virtual size of the file.
fn limit_range_file(&self, address: u64, count: usize) -> usize {
if address.checked_add(count as u64).is_none() || address > self.virtual_size() {
return 0;
}
min(count as u64, self.virtual_size() - address) as usize
}
// Limits the range so that it doesn't overflow the end of a cluster.
fn limit_range_cluster(&self, address: u64, count: usize) -> usize {
let offset: u64 = self.raw_file.cluster_offset(address);
let limit = self.raw_file.cluster_size() - offset;
min(count as u64, limit) as usize
}
// Gets the maximum virtual size of this image.
fn virtual_size(&self) -> u64 {
self.header.size
}
// Gets the offset of `address` in the L1 table.
fn l1_address_offset(&self, address: u64) -> u64 {
let l1_index = self.l1_table_index(address);
l1_index * size_of::<u64>() as u64
}
// Gets the offset of `address` in the L1 table.
fn l1_table_index(&self, address: u64) -> u64 {
(address / self.raw_file.cluster_size()) / self.l2_entries
}
// Gets the offset of `address` in the L2 table.
fn l2_table_index(&self, address: u64) -> u64 {
(address / self.raw_file.cluster_size()) % self.l2_entries
}
// Gets the offset of the given guest address in the host file. If L1, L2, or data clusters have
// yet to be allocated, return None.
fn file_offset_read(&mut self, address: u64) -> std::io::Result<Option<u64>> {
if address >= self.virtual_size() as u64 {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
let l1_index = self.l1_table_index(address) as usize;
let l2_addr_disk = *self
.l1_table
.get(l1_index)
.ok_or(std::io::Error::from_raw_os_error(EINVAL))?;
if l2_addr_disk == 0 {
// Reading from an unallocated cluster will return zeros.
return Ok(None);
}
let l2_index = self.l2_table_index(address) as usize;
if !self.l2_cache.contains_key(&l1_index) {
// Not in the cache.
let table =
VecCache::from_vec(Self::read_l2_cluster(&mut self.raw_file, l2_addr_disk)?);
let l1_table = &self.l1_table;
let raw_file = &mut self.raw_file;
self.l2_cache.insert(l1_index, table, |index, evicted| {
raw_file.write_pointer_table(
l1_table[index],
evicted.get_values(),
CLUSTER_USED_FLAG,
)
})?;
};
let cluster_addr = self.l2_cache.get(&l1_index).unwrap()[l2_index];
if cluster_addr == 0 {
return Ok(None);
}
Ok(Some(cluster_addr + self.raw_file.cluster_offset(address)))
}
// Gets the offset of the given guest address in the host file. If L1, L2, or data clusters need
// to be allocated, they will be.
fn file_offset_write(&mut self, address: u64) -> std::io::Result<u64> {
if address >= self.virtual_size() as u64 {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
let l1_index = self.l1_table_index(address) as usize;
let l2_addr_disk = *self
.l1_table
.get(l1_index)
.ok_or(std::io::Error::from_raw_os_error(EINVAL))?;
let l2_index = self.l2_table_index(address) as usize;
let mut set_refcounts = Vec::new();
if !self.l2_cache.contains_key(&l1_index) {
// Not in the cache.
let l2_table = if l2_addr_disk == 0 {
// Allocate a new cluster to store the L2 table and update the L1 table to point
// to the new table.
let new_addr: u64 = self.get_new_cluster()?;
// The cluster refcount starts at one meaning it is used but doesn't need COW.
set_refcounts.push((new_addr, 1));
self.l1_table[l1_index] = new_addr;
VecCache::new(self.l2_entries as usize)
} else {
VecCache::from_vec(Self::read_l2_cluster(&mut self.raw_file, l2_addr_disk)?)
};
let l1_table = &self.l1_table;
let raw_file = &mut self.raw_file;
self.l2_cache.insert(l1_index, l2_table, |index, evicted| {
raw_file.write_pointer_table(
l1_table[index],
evicted.get_values(),
CLUSTER_USED_FLAG,
)
})?;
}
let cluster_addr = match self.l2_cache.get(&l1_index).unwrap()[l2_index] {
0 => {
// Need to allocate a data cluster
let cluster_addr = self.append_data_cluster()?;
self.update_cluster_addr(l1_index, l2_index, cluster_addr, &mut set_refcounts)?;
cluster_addr
}
a => a,
};
for (addr, count) in set_refcounts {
let mut newly_unref = self.set_cluster_refcount(addr, count)?;
self.unref_clusters.append(&mut newly_unref);
}
Ok(cluster_addr + self.raw_file.cluster_offset(address))
}
// Updates the l1 and l2 tables to point to the new `cluster_addr`.
fn update_cluster_addr(
&mut self,
l1_index: usize,
l2_index: usize,
cluster_addr: u64,
set_refcounts: &mut Vec<(u64, u16)>,
) -> io::Result<()> {
if !self.l2_cache.get(&l1_index).unwrap().dirty() {
// Free the previously used cluster if one exists. Modified tables are always
// witten to new clusters so the L1 table can be committed to disk after they
// are and L1 never points at an invalid table.
// The index must be valid from when it was insterted.
let addr = self.l1_table[l1_index];
if addr != 0 {
self.unref_clusters.push(addr);
set_refcounts.push((addr, 0));
}
// Allocate a new cluster to store the L2 table and update the L1 table to point
// to the new table. The cluster will be written when the cache is flushed, no
// need to copy the data now.
let new_addr: u64 = self.get_new_cluster()?;
// The cluster refcount starts at one indicating it is used but doesn't need
// COW.
set_refcounts.push((new_addr, 1));
self.l1_table[l1_index] = new_addr;
}
// 'unwrap' is OK because it was just added.
self.l2_cache.get_mut(&l1_index).unwrap()[l2_index] = cluster_addr;
Ok(())
}
// Allocate a new cluster and return its offset within the raw file.
fn get_new_cluster(&mut self) -> std::io::Result<u64> {
// First use a pre allocated cluster if one is available.
if let Some(free_cluster) = self.avail_clusters.pop() {
self.raw_file.zero_cluster(free_cluster)?;
return Ok(free_cluster);
}
let max_valid_cluster_offset = self.refcounts.max_valid_cluster_offset();
if let Some(new_cluster) = self.raw_file.add_cluster_end(max_valid_cluster_offset)? {
Ok(new_cluster)
} else {
error!("No free clusters in get_new_cluster()");
Err(std::io::Error::from_raw_os_error(ENOSPC))
}
}
// Allocate and initialize a new data cluster. Returns the offset of the
// cluster in to the file on success.
fn append_data_cluster(&mut self) -> std::io::Result<u64> {
let new_addr: u64 = self.get_new_cluster()?;
// The cluster refcount starts at one indicating it is used but doesn't need COW.
let mut newly_unref = self.set_cluster_refcount(new_addr, 1)?;
self.unref_clusters.append(&mut newly_unref);
Ok(new_addr)
}
// Returns true if the cluster containing `address` is already allocated.
fn cluster_allocated(&mut self, address: u64) -> std::io::Result<bool> {
if address >= self.virtual_size() as u64 {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
let l1_index = self.l1_table_index(address) as usize;
let l2_addr_disk = *self
.l1_table
.get(l1_index)
.ok_or(std::io::Error::from_raw_os_error(EINVAL))?;
let l2_index = self.l2_table_index(address) as usize;
if l2_addr_disk == 0 {
// The whole L2 table for this address is not allocated yet,
// so the cluster must also be unallocated.
return Ok(false);
}
if !self.l2_cache.contains_key(&l1_index) {
// Not in the cache.
let table =
VecCache::from_vec(Self::read_l2_cluster(&mut self.raw_file, l2_addr_disk)?);
let l1_table = &self.l1_table;
let raw_file = &mut self.raw_file;
self.l2_cache.insert(l1_index, table, |index, evicted| {
raw_file.write_pointer_table(
l1_table[index],
evicted.get_values(),
CLUSTER_USED_FLAG,
)
})?;
}
let cluster_addr = self.l2_cache.get(&l1_index).unwrap()[l2_index];
// If cluster_addr != 0, the cluster is allocated.
Ok(cluster_addr != 0)
}
// Find the first guest address greater than or equal to `address` whose allocation state
// matches `allocated`.
fn find_allocated_cluster(
&mut self,
address: u64,
allocated: bool,
) -> std::io::Result<Option<u64>> {
let size = self.virtual_size();
if address >= size {
return Ok(None);
}
// If offset is already within a hole, return it.
if self.cluster_allocated(address)? == allocated {
return Ok(Some(address));
}
// Skip to the next cluster boundary.
let cluster_size = self.raw_file.cluster_size();
let mut cluster_addr = (address / cluster_size + 1) * cluster_size;
// Search for clusters with the desired allocation state.
while cluster_addr < size {
if self.cluster_allocated(cluster_addr)? == allocated {
return Ok(Some(cluster_addr));
}
cluster_addr += cluster_size;
}
Ok(None)
}
// Deallocate the storage for the cluster starting at `address`.
// Any future reads of this cluster will return all zeroes.
fn deallocate_cluster(&mut self, address: u64) -> std::io::Result<()> {
if address >= self.virtual_size() as u64 {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
let l1_index = self.l1_table_index(address) as usize;
let l2_addr_disk = *self
.l1_table
.get(l1_index)
.ok_or(std::io::Error::from_raw_os_error(EINVAL))?;
let l2_index = self.l2_table_index(address) as usize;
if l2_addr_disk == 0 {
// The whole L2 table for this address is not allocated yet,
// so the cluster must also be unallocated.
return Ok(());
}
if !self.l2_cache.contains_key(&l1_index) {
// Not in the cache.
let table =
VecCache::from_vec(Self::read_l2_cluster(&mut self.raw_file, l2_addr_disk)?);
let l1_table = &self.l1_table;
let raw_file = &mut self.raw_file;
self.l2_cache.insert(l1_index, table, |index, evicted| {
raw_file.write_pointer_table(
l1_table[index],
evicted.get_values(),
CLUSTER_USED_FLAG,
)
})?;
}
let cluster_addr = self.l2_cache.get(&l1_index).unwrap()[l2_index];
if cluster_addr == 0 {
// This cluster is already unallocated; nothing to do.
return Ok(());
}
// Decrement the refcount.
let refcount = self
.refcounts
.get_cluster_refcount(&mut self.raw_file, cluster_addr)
.map_err(|_| std::io::Error::from_raw_os_error(EINVAL))?;
if refcount == 0 {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
let new_refcount = refcount - 1;
let mut newly_unref = self.set_cluster_refcount(cluster_addr, new_refcount)?;
self.unref_clusters.append(&mut newly_unref);
// Rewrite the L2 entry to remove the cluster mapping.
// unwrap is safe as we just checked/inserted this entry.
self.l2_cache.get_mut(&l1_index).unwrap()[l2_index] = 0;
if new_refcount == 0 {
let cluster_size = self.raw_file.cluster_size();
// This cluster is no longer in use; deallocate the storage.
// The underlying FS may not support FALLOC_FL_PUNCH_HOLE,
// so don't treat an error as fatal. Future reads will return zeros anyways.
let _ = self
.raw_file
.file_mut()
.punch_hole(cluster_addr, cluster_size);
self.unref_clusters.push(cluster_addr);
}
Ok(())
}
// Deallocate the storage for `length` bytes starting at `address`.
// Any future reads of this range will return all zeroes.
fn deallocate_bytes(&mut self, address: u64, length: usize) -> std::io::Result<()> {
let write_count: usize = self.limit_range_file(address, length);
let mut nwritten: usize = 0;
while nwritten < write_count {
let curr_addr = address + nwritten as u64;
let count = self.limit_range_cluster(curr_addr, write_count - nwritten);
if count == self.raw_file.cluster_size() as usize {
// Full cluster - deallocate the storage.
self.deallocate_cluster(curr_addr)?;
} else {
// Partial cluster - zero out the relevant bytes if it was allocated.
// Any space in unallocated clusters can be left alone, since
// unallocated clusters already read back as zeroes.
if let Some(offset) = self.file_offset_read(curr_addr)? {
// Partial cluster - zero it out.
self.raw_file
.file_mut()
.write_zeroes_all_at(offset, count)?;
}
}
nwritten += count;
}
Ok(())
}
// Reads an L2 cluster from the disk, returning an error if the file can't be read or if any
// cluster is compressed.
fn read_l2_cluster(raw_file: &mut QcowRawFile, cluster_addr: u64) -> std::io::Result<Vec<u64>> {
let file_values = raw_file.read_pointer_cluster(cluster_addr, None)?;
if file_values.iter().any(|entry| entry & COMPRESSED_FLAG != 0) {
return Err(std::io::Error::from_raw_os_error(ENOTSUP));
}
Ok(file_values
.iter()
.map(|entry| *entry & L2_TABLE_OFFSET_MASK)
.collect())
}
// Set the refcount for a cluster with the given address.
// Returns a list of any refblocks that can be reused, this happens when a refblock is moved,
// the old location can be reused.
fn set_cluster_refcount(&mut self, address: u64, refcount: u16) -> std::io::Result<Vec<u64>> {
let mut added_clusters = Vec::new();
let mut unref_clusters = Vec::new();
let mut refcount_set = false;
let mut new_cluster = None;
while !refcount_set {
match self.refcounts.set_cluster_refcount(
&mut self.raw_file,
address,
refcount,
new_cluster.take(),
) {
Ok(None) => {
refcount_set = true;
}
Ok(Some(freed_cluster)) => {
unref_clusters.push(freed_cluster);
refcount_set = true;
}
Err(refcount::Error::EvictingRefCounts(e)) => {
return Err(e);
}
Err(refcount::Error::InvalidIndex) => {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
Err(refcount::Error::NeedCluster(addr)) => {
// Read the address and call set_cluster_refcount again.
new_cluster = Some((
addr,
VecCache::from_vec(self.raw_file.read_refcount_block(addr)?),
));
}
Err(refcount::Error::NeedNewCluster) => {
// Allocate the cluster and call set_cluster_refcount again.
let addr = self.get_new_cluster()?;
added_clusters.push(addr);
new_cluster = Some((
addr,
VecCache::new(self.refcounts.refcounts_per_block() as usize),
));
}
Err(refcount::Error::ReadingRefCounts(e)) => {
return Err(e);
}
}
}
for addr in added_clusters {
self.set_cluster_refcount(addr, 1)?;
}
Ok(unref_clusters)
}
fn sync_caches(&mut self) -> std::io::Result<()> {
// Write out all dirty L2 tables.
for (l1_index, l2_table) in self.l2_cache.iter_mut().filter(|(_k, v)| v.dirty()) {
// The index must be valid from when we insterted it.
let addr = self.l1_table[*l1_index];
if addr != 0 {
self.raw_file.write_pointer_table(
addr,
l2_table.get_values(),
CLUSTER_USED_FLAG,
)?;
} else {
return Err(std::io::Error::from_raw_os_error(EINVAL));
}
l2_table.mark_clean();
}
// Write the modified refcount blocks.
self.refcounts.flush_blocks(&mut self.raw_file)?;
// Make sure metadata(file len) and all data clusters are written.
self.raw_file.file_mut().sync_all()?;
// Push L1 table and refcount table last as all the clusters they point to are now
// guaranteed to be valid.
let mut sync_required = false;
if self.l1_table.dirty() {
self.raw_file.write_pointer_table(
self.header.l1_table_offset,
&self.l1_table.get_values(),
0,
)?;
self.l1_table.mark_clean();
sync_required = true;
}
sync_required |= self.refcounts.flush_table(&mut self.raw_file)?;
if sync_required {
self.raw_file.file_mut().sync_data()?;
}
Ok(())
}
// Reads `count` bytes starting at `address`, calling `cb` repeatedly with the backing file,
// number of bytes read so far, and number of bytes to read from the file in that invocation. If
// None is given to `cb` in place of the backing file, the `cb` should infer zeros would have
// been read.
fn read_cb<F>(&mut self, address: u64, count: usize, mut cb: F) -> std::io::Result<usize>
where
F: FnMut(Option<&mut File>, usize, usize) -> std::io::Result<()>,
{
let read_count: usize = self.limit_range_file(address, count);
let mut nread: usize = 0;
while nread < read_count {
let curr_addr = address + nread as u64;
let file_offset = self.file_offset_read(curr_addr)?;
let count = self.limit_range_cluster(curr_addr, read_count - nread);
if let Some(offset) = file_offset {
self.raw_file.file_mut().seek(SeekFrom::Start(offset))?;
cb(Some(self.raw_file.file_mut()), nread, count)?;
} else {
cb(None, nread, count)?;
}
nread += count;
}
Ok(read_count)
}
// Writes `count` bytes starting at `address`, calling `cb` repeatedly with the backing file,
// number of bytes written so far, and number of bytes to write to the file in that invocation.
fn write_cb<F>(&mut self, address: u64, count: usize, mut cb: F) -> std::io::Result<usize>
where
F: FnMut(&mut File, usize, usize) -> std::io::Result<()>,
{
let write_count: usize = self.limit_range_file(address, count);
let mut nwritten: usize = 0;
while nwritten < write_count {
let curr_addr = address + nwritten as u64;
let offset = self.file_offset_write(curr_addr)?;
let count = self.limit_range_cluster(curr_addr, write_count - nwritten);
if let Err(e) = self.raw_file.file_mut().seek(SeekFrom::Start(offset)) {
return Err(e);
}
if let Err(e) = cb(self.raw_file.file_mut(), nwritten, count) {
return Err(e);
}
nwritten += count;
}
Ok(write_count)
}
}
impl Drop for QcowFile {
fn drop(&mut self) {
let _ = self.sync_caches();
}
}
impl AsRawFd for QcowFile {
fn as_raw_fd(&self) -> RawFd {
self.raw_file.file().as_raw_fd()
}
}
impl Read for QcowFile {
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
let read_count =
self.read_cb(
self.current_offset,
buf.len(),
|file, offset, count| match file {
Some(f) => f.read_exact(&mut buf[offset..(offset + count)]),
None => {
for b in &mut buf[offset..(offset + count)] {
*b = 0;
}
Ok(())
}
},
)?;
self.current_offset += read_count as u64;
Ok(read_count)
}
}
impl Seek for QcowFile {
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_size().checked_sub(increment as u64))
} else {
self.virtual_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_size() {
self.current_offset = o;
return Ok(o);
}
}
Err(std::io::Error::from_raw_os_error(EINVAL))
}
}
impl Write for QcowFile {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
let write_count =
self.write_cb(self.current_offset, buf.len(), |file, offset, count| {
file.write_all(&buf[offset..(offset + count)])
})?;
self.current_offset += write_count as u64;
Ok(write_count)
}
fn flush(&mut self) -> std::io::Result<()> {
self.sync_caches()?;
self.avail_clusters.append(&mut self.unref_clusters);
Ok(())
}
}
impl FileReadWriteVolatile for QcowFile {
fn read_volatile(&mut self, slice: VolatileSlice) -> io::Result<usize> {
let read_count = self.read_cb(
self.current_offset,
slice.size() as usize,
|file, offset, count| {
let sub_slice = slice.get_slice(offset as u64, count as u64).unwrap();
match file {
Some(f) => f.read_exact_volatile(sub_slice),
None => {
sub_slice.write_bytes(0);
Ok(())
}
}
},
)?;
self.current_offset += read_count as u64;
Ok(read_count)
}
fn write_volatile(&mut self, slice: VolatileSlice) -> io::Result<usize> {
let write_count = self.write_cb(
self.current_offset,
slice.size() as usize,
|file, offset, count| {
let sub_slice = slice.get_slice(offset as u64, count as u64).unwrap();
file.write_all_volatile(sub_slice)
},
)?;
self.current_offset += write_count as u64;
Ok(write_count)
}
}
impl FileReadWriteAtVolatile for QcowFile {
fn read_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> io::Result<usize> {
self.read_cb(offset, slice.size() as usize, |file, offset, count| {
let sub_slice = slice.get_slice(offset as u64, count as u64).unwrap();
match file {
Some(f) => f.read_exact_volatile(sub_slice),
None => {
sub_slice.write_bytes(0);
Ok(())
}
}
})
}
fn write_at_volatile(&mut self, slice: VolatileSlice, offset: u64) -> io::Result<usize> {
self.write_cb(offset, slice.size() as usize, |file, offset, count| {
let sub_slice = slice.get_slice(offset as u64, count as u64).unwrap();
file.write_all_volatile(sub_slice)
})
}
}
impl FileSync for QcowFile {
fn fsync(&mut self) -> std::io::Result<()> {
self.flush()
}
}
impl FileSetLen for QcowFile {
fn set_len(&self, _len: u64) -> std::io::Result<()> {
Err(std::io::Error::new(
std::io::ErrorKind::Other,
"set_len() not supported for QcowFile",
))
}
}
impl FileGetLen for QcowFile {
fn get_len(&self) -> io::Result<u64> {
Ok(self.virtual_size())
}
}
impl PunchHole for QcowFile {
fn punch_hole(&mut self, offset: u64, length: u64) -> std::io::Result<()> {
let mut remaining = length;
let mut offset = offset;
while remaining > 0 {
let chunk_length = min(remaining, std::usize::MAX as u64) as usize;
self.deallocate_bytes(offset, chunk_length)?;
remaining -= chunk_length as u64;
offset += chunk_length as u64;
}
Ok(())
}
}
impl WriteZeroesAt for QcowFile {
fn write_zeroes_at(&mut self, offset: u64, length: usize) -> io::Result<usize> {
self.punch_hole(offset, length as u64)?;
Ok(length)
}
}
impl SeekHole for QcowFile {
fn seek_hole(&mut self, offset: u64) -> io::Result<Option<u64>> {
match self.find_allocated_cluster(offset, false) {
Err(e) => Err(e),
Ok(None) => {
if offset < self.virtual_size() {
Ok(Some(self.seek(SeekFrom::End(0))?))
} else {
Ok(None)
}
}
Ok(Some(o)) => {
self.seek(SeekFrom::Start(o))?;
Ok(Some(o))
}
}
}
fn seek_data(&mut self, offset: u64) -> io::Result<Option<u64>> {
match self.find_allocated_cluster(offset, true) {
Err(e) => Err(e),
Ok(None) => Ok(None),
Ok(Some(o)) => {
self.seek(SeekFrom::Start(o))?;
Ok(Some(o))
}
}
}
}
// Returns an Error if the given offset doesn't align to a cluster boundary.
fn offset_is_cluster_boundary(offset: u64, cluster_bits: u32) -> Result<()> {
if offset & ((0x01 << cluster_bits) - 1) != 0 {
return Err(Error::InvalidOffset(offset));
}
Ok(())
}
// Ceiling of the division of `dividend`/`divisor`.
fn div_round_up_u64(dividend: u64, divisor: u64) -> u64 {
dividend / divisor + if dividend % divisor != 0 { 1 } else { 0 }
}
// Ceiling of the division of `dividend`/`divisor`.
fn div_round_up_u32(dividend: u32, divisor: u32) -> u32 {
dividend / divisor + if dividend % divisor != 0 { 1 } else { 0 }
}
#[cfg(test)]
mod tests {
use super::*;
use std::fs::File;
use std::io::{Read, Seek, SeekFrom, Write};
use sys_util::{SharedMemory, WriteZeroes};
fn valid_header() -> Vec<u8> {
vec![
0x51u8, 0x46, 0x49, 0xfb, // magic
0x00, 0x00, 0x00, 0x03, // version
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // backing file offset
0x00, 0x00, 0x00, 0x00, // backing file size
0x00, 0x00, 0x00, 0x10, // cluster_bits
0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x00, // size
0x00, 0x00, 0x00, 0x00, // crypt method
0x00, 0x00, 0x01, 0x00, // L1 size
0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, // L1 table offset
0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, // refcount table offset
0x00, 0x00, 0x00, 0x03, // refcount table clusters
0x00, 0x00, 0x00, 0x00, // nb snapshots
0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, // snapshots offset
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // incompatible_features
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // compatible_features
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // autoclear_features
0x00, 0x00, 0x00, 0x04, // refcount_order
0x00, 0x00, 0x00, 0x68, // header_length
]
}
// Test case found by clusterfuzz to allocate excessive memory.
fn test_huge_header() -> Vec<u8> {
vec![
0x51, 0x46, 0x49, 0xfb, // magic
0x00, 0x00, 0x00, 0x03, // version
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // backing file offset
0x00, 0x00, 0x00, 0x00, // backing file size
0x00, 0x00, 0x00, 0x09, // cluster_bits
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, // size
0x00, 0x00, 0x00, 0x00, // crypt method
0x00, 0x00, 0x01, 0x00, // L1 size
0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, // L1 table offset
0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, // refcount table offset
0x00, 0x00, 0x00, 0x03, // refcount table clusters
0x00, 0x00, 0x00, 0x00, // nb snapshots
0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, // snapshots offset
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // incompatible_features
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // compatible_features
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // autoclear_features
0x00, 0x00, 0x00, 0x04, // refcount_order
0x00, 0x00, 0x00, 0x68, // header_length
]
}
fn with_basic_file<F>(header: &[u8], mut testfn: F)
where
F: FnMut(File),
{
let shm = SharedMemory::anon().unwrap();
let mut disk_file: File = shm.into();
disk_file.write_all(&header).unwrap();
disk_file.set_len(0x1_0000_0000).unwrap();
disk_file.seek(SeekFrom::Start(0)).unwrap();
testfn(disk_file); // File closed when the function exits.
}
fn with_default_file<F>(file_size: u64, mut testfn: F)
where
F: FnMut(QcowFile),
{
let shm = SharedMemory::anon().unwrap();
let qcow_file = QcowFile::new(shm.into(), file_size).unwrap();
testfn(qcow_file); // File closed when the function exits.
}
#[test]
fn default_header() {
let header = QcowHeader::create_for_size(0x10_0000);
let shm = SharedMemory::anon().unwrap();
let mut disk_file: File = shm.into();
header
.write_to(&mut disk_file)
.expect("Failed to write header to shm.");
disk_file.seek(SeekFrom::Start(0)).unwrap();
QcowFile::from(disk_file).expect("Failed to create Qcow from default Header");
}
#[test]
fn header_read() {
with_basic_file(&valid_header(), |mut disk_file: File| {
QcowHeader::new(&mut disk_file).expect("Failed to create Header.");
});
}
#[test]
fn invalid_magic() {
let invalid_header = vec![0x51u8, 0x46, 0x4a, 0xfb];
with_basic_file(&invalid_header, |mut disk_file: File| {
QcowHeader::new(&mut disk_file).expect_err("Invalid header worked.");
});
}
#[test]
fn invalid_refcount_order() {
let mut header = valid_header();
header[99] = 2;
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Invalid refcount order worked.");
});
}
#[test]
fn invalid_cluster_bits() {
let mut header = valid_header();
header[23] = 3;
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Failed to create file.");
});
}
#[test]
fn test_header_huge_file() {
let header = test_huge_header();
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Failed to create file.");
});
}
#[test]
fn test_header_crazy_file_size_rejected() {
let mut header = valid_header();
&mut header[24..32].copy_from_slice(&[0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1e]);
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Failed to create file.");
});
}
#[test]
fn test_huge_l1_table() {
let mut header = valid_header();
header[36] = 0x12;
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Failed to create file.");
});
}
#[test]
fn test_header_1_tb_file_min_cluster() {
let mut header = test_huge_header();
header[24] = 0;
header[26] = 1;
header[31] = 0;
// 1 TB with the min cluster size makes the arrays too big, it should fail.
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Failed to create file.");
});
}
#[test]
fn test_header_1_tb_file() {
let mut header = test_huge_header();
// reset to 1 TB size.
header[24] = 0;
header[26] = 1;
header[31] = 0;
// set cluster_bits
header[23] = 16;
with_basic_file(&header, |disk_file: File| {
let mut qcow = QcowFile::from(disk_file).expect("Failed to create file.");
qcow.seek(SeekFrom::Start(0x100_0000_0000 - 8))
.expect("Failed to seek.");
let value = 0x0000_0040_3f00_ffffu64;
qcow.write_all(&value.to_le_bytes())
.expect("failed to write data");
});
}
#[test]
fn test_header_huge_num_refcounts() {
let mut header = valid_header();
&mut header[56..60].copy_from_slice(&[0x02, 0x00, 0xe8, 0xff]);
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Created disk with crazy refcount clusters");
});
}
#[test]
fn test_header_huge_refcount_offset() {
let mut header = valid_header();
&mut header[48..56].copy_from_slice(&[0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x02, 0x00]);
with_basic_file(&header, |disk_file: File| {
QcowFile::from(disk_file).expect_err("Created disk with crazy refcount offset");
});
}
#[test]
fn write_read_start() {
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
q.write(b"test first bytes")
.expect("Failed to write test string.");
let mut buf = [0u8; 4];
q.seek(SeekFrom::Start(0)).expect("Failed to seek.");
q.read(&mut buf).expect("Failed to read.");
assert_eq!(&buf, b"test");
});
}
#[test]
fn offset_write_read() {
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
let b = [0x55u8; 0x1000];
q.seek(SeekFrom::Start(0xfff2000)).expect("Failed to seek.");
q.write(&b).expect("Failed to write test string.");
let mut buf = [0u8; 4];
q.seek(SeekFrom::Start(0xfff2000)).expect("Failed to seek.");
q.read(&mut buf).expect("Failed to read.");
assert_eq!(buf[0], 0x55);
});
}
#[test]
fn write_zeroes_read() {
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
// Write some test data.
let b = [0x55u8; 0x1000];
q.seek(SeekFrom::Start(0xfff2000)).expect("Failed to seek.");
q.write(&b).expect("Failed to write test string.");
// Overwrite the test data with zeroes.
q.seek(SeekFrom::Start(0xfff2000)).expect("Failed to seek.");
q.write_zeroes_all(0x200).expect("Failed to write zeroes.");
// Verify that the correct part of the data was zeroed out.
let mut buf = [0u8; 0x1000];
q.seek(SeekFrom::Start(0xfff2000)).expect("Failed to seek.");
q.read(&mut buf).expect("Failed to read.");
assert_eq!(buf[0], 0);
assert_eq!(buf[0x1FF], 0);
assert_eq!(buf[0x200], 0x55);
assert_eq!(buf[0xFFF], 0x55);
});
}
#[test]
fn write_zeroes_full_cluster() {
// Choose a size that is larger than a cluster.
// valid_header uses cluster_bits = 12, which corresponds to a cluster size of 4096.
const CHUNK_SIZE: usize = 4096 * 2 + 512;
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
// Write some test data.
let b = [0x55u8; CHUNK_SIZE];
q.seek(SeekFrom::Start(0)).expect("Failed to seek.");
q.write(&b).expect("Failed to write test string.");
// Overwrite the full cluster with zeroes.
q.seek(SeekFrom::Start(0)).expect("Failed to seek.");
q.write_zeroes_all(CHUNK_SIZE)
.expect("Failed to write zeroes.");
// Verify that the data was zeroed out.
let mut buf = [0u8; CHUNK_SIZE];
q.seek(SeekFrom::Start(0)).expect("Failed to seek.");
q.read(&mut buf).expect("Failed to read.");
assert_eq!(buf[0], 0);
assert_eq!(buf[CHUNK_SIZE - 1], 0);
});
}
#[test]
fn test_header() {
with_basic_file(&valid_header(), |disk_file: File| {
let q = QcowFile::from(disk_file).unwrap();
assert_eq!(q.virtual_size(), 0x20_0000_0000);
});
}
#[test]
fn read_small_buffer() {
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
let mut b = [5u8; 16];
q.seek(SeekFrom::Start(1000)).expect("Failed to seek.");
q.read(&mut b).expect("Failed to read.");
assert_eq!(0, b[0]);
assert_eq!(0, b[15]);
});
}
#[test]
fn replay_ext4() {
with_basic_file(&valid_header(), |disk_file: File| {
let mut q = QcowFile::from(disk_file).unwrap();
const BUF_SIZE: usize = 0x1000;
let mut b = [0u8; BUF_SIZE];
struct Transfer {
pub write: bool,
pub addr: u64,
};
// Write transactions from mkfs.ext4.
let xfers: Vec<Transfer> = vec![
Transfer {
write: false,
addr: 0xfff0000,
},
Transfer {
write: false,
addr: 0xfffe000,
},
Transfer {
write: false,
addr: 0x0,
},
Transfer {
write: false,
addr: 0x1000,
},
Transfer {
write: false,
addr: 0xffff000,
},
Transfer {
write: false,
addr: 0xffdf000,
},
Transfer {
write: false,
addr: 0xfff8000,
},
Transfer {
write: false,
addr: 0xffe0000,
},
Transfer {
write: false,
addr: 0xffce000,
},
Transfer {
write: false,
addr: 0xffb6000,
},
Transfer {
write: false,
addr: 0xffab000,
},
Transfer {
write: false,
addr: 0xffa4000,
},
Transfer {
write: false,
addr: 0xff8e000,
},
Transfer {
write: false,
addr: 0xff86000,
},
Transfer {
write: false,
addr: 0xff84000,
},
Transfer {
write: false,
addr: 0xff89000,
},
Transfer {
write: false,
addr: 0xfe7e000,
},
Transfer {
write: false,
addr: 0x100000,
},
Transfer {
write: false,
addr: 0x3000,
},
Transfer {
write: false,
addr: 0x7000,
},
Transfer {
write: false,
addr: 0xf000,
},
Transfer {
write: false,
addr: 0x2000,
},
Transfer {
write: false,
addr: 0x4000,
},
Transfer {
write: false,
addr: 0x5000,
},
Transfer {
write: false,
addr: 0x6000,
},
Transfer {
write: false,
addr: 0x8000,
},
Transfer {
write: false,
addr: 0x9000,
},
Transfer {
write: false,
addr: 0xa000,
},
Transfer {
write: false,
addr: 0xb000,
},
Transfer {
write: false,
addr: 0xc000,
},
Transfer {
write: false,
addr: 0xd000,
},
Transfer {
write: false,
addr: 0xe000,
},
Transfer {
write: false,
addr: 0x10000,
},
Transfer {
write: false,
addr: 0x11000,
},
Transfer {
write: false,
addr: 0x12000,
},
Transfer {
write: false,
addr: 0x13000,
},
Transfer {
write: false,
addr: 0x14000,
},
Transfer {
write: false,
addr: 0x15000,
},
Transfer {
write: false,
addr: 0x16000,
},
Transfer {
write: false,
addr: 0x17000,
},
Transfer {
write: false,
addr: 0x18000,
},
Transfer {
write: false,
addr: 0x19000,
},
Transfer {
write: false,
addr: 0x1a000,
},
Transfer {
write: false,
addr: 0x1b000,
},
Transfer {
write: false,
addr: 0x1c000,
},
Transfer {
write: false,
addr: 0x1d000,
},
Transfer {
write: false,
addr: 0x1e000,
},
Transfer {
write: false,
addr: 0x1f000,
},
Transfer {
write: false,
addr: 0x21000,
},
Transfer {
write: false,
addr: 0x22000,
},
Transfer {
write: false,
addr: 0x24000,
},
Transfer {
write: false,
addr: 0x40000,
},
Transfer {
write: false,
addr: 0x0,
},
Transfer {
write: false,
addr: 0x3000,
},
Transfer {
write: false,
addr: 0x7000,
},
Transfer {
write: false,
addr: 0x0,
},
Transfer {
write: false,
addr: 0x1000,
},
Transfer {
write: false,
addr: 0x2000,
},
Transfer {
write: false,
addr: 0x3000,
},
Transfer {
write: false,
addr: 0x0,
},
Transfer {
write: false,
addr: 0x449000,
},
Transfer {
write: false,
addr: 0x48000,
},
Transfer {
write: false,
addr: 0x48000,
},
Transfer {
write: false,
addr: 0x448000,
},
Transfer {
write: false,
addr: 0x44a000,
},
Transfer {
write: false,
addr: 0x48000,
},
Transfer {
write: false,
addr: 0x48000,
},
Transfer {
write: true,
addr: 0x0,
},
Transfer {
write: true,
addr: 0x448000,
},
Transfer {
write: true,
addr: 0x449000,
},
Transfer {
write: true,
addr: 0x44a000,
},
Transfer {
write: true,
addr: 0xfff0000,
},
Transfer {
write: true,
addr: 0xfff1000,
},
Transfer {
write: true,
addr: 0xfff2000,
},
Transfer {
write: true,
addr: 0xfff3000,
},
Transfer {
write: true,
addr: 0xfff4000,
},
Transfer {
write: true,
addr: 0xfff5000,
},
Transfer {
write: true,
addr: 0xfff6000,
},
Transfer {
write: true,
addr: 0xfff7000,
},
Transfer {
write: true,
addr: 0xfff8000,
},
Transfer {
write: true,
addr: 0xfff9000,
},
Transfer {
write: true,
addr: 0xfffa000,
},
Transfer {
write: true,
addr: 0xfffb000,
},
Transfer {
write: true,
addr: 0xfffc000,
},
Transfer {
write: true,
addr: 0xfffd000,
},
Transfer {
write: true,
addr: 0xfffe000,
},
Transfer {
write: true,
addr: 0xffff000,
},
];
for xfer in &xfers {
q.seek(SeekFrom::Start(xfer.addr)).expect("Failed to seek.");
if xfer.write {
q.write(&b).expect("Failed to write.");
} else {
let read_count: usize = q.read(&mut b).expect("Failed to read.");
assert_eq!(read_count, BUF_SIZE);
}
}
});
}
#[test]
fn combo_write_read() {
with_default_file(1024 * 1024 * 1024 * 256, |mut qcow_file| {
const NUM_BLOCKS: usize = 555;
const BLOCK_SIZE: usize = 0x1_0000;
const OFFSET: usize = 0x1_0000_0020;
let data = [0x55u8; BLOCK_SIZE];
let mut readback = [0u8; BLOCK_SIZE];
for i in 0..NUM_BLOCKS {
let seek_offset = OFFSET + i * BLOCK_SIZE;
qcow_file
.seek(SeekFrom::Start(seek_offset as u64))
.expect("Failed to seek.");
let nwritten = qcow_file.write(&data).expect("Failed to write test data.");
assert_eq!(nwritten, BLOCK_SIZE);
// Read back the data to check it was written correctly.
qcow_file
.seek(SeekFrom::Start(seek_offset as u64))
.expect("Failed to seek.");
let nread = qcow_file.read(&mut readback).expect("Failed to read.");
assert_eq!(nread, BLOCK_SIZE);
for (orig, read) in data.iter().zip(readback.iter()) {
assert_eq!(orig, read);
}
}
// Check that address 0 is still zeros.
qcow_file.seek(SeekFrom::Start(0)).expect("Failed to seek.");
let nread = qcow_file.read(&mut readback).expect("Failed to read.");
assert_eq!(nread, BLOCK_SIZE);
for read in readback.iter() {
assert_eq!(*read, 0);
}
// Check the data again after the writes have happened.
for i in 0..NUM_BLOCKS {
let seek_offset = OFFSET + i * BLOCK_SIZE;
qcow_file
.seek(SeekFrom::Start(seek_offset as u64))
.expect("Failed to seek.");
let nread = qcow_file.read(&mut readback).expect("Failed to read.");
assert_eq!(nread, BLOCK_SIZE);
for (orig, read) in data.iter().zip(readback.iter()) {
assert_eq!(orig, read);
}
}
assert_eq!(qcow_file.first_zero_refcount().unwrap(), None);
});
}
fn seek_cur(file: &mut QcowFile) -> u64 {
file.seek(SeekFrom::Current(0)).unwrap()
}
#[test]
fn seek_data() {
with_default_file(0x30000, |mut file| {
// seek_data at or after the end of the file should return None
assert_eq!(file.seek_data(0x10000).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0);
assert_eq!(file.seek_data(0x10001).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0);
// Write some data to [0x10000, 0x20000)
let b = [0x55u8; 0x10000];
file.seek(SeekFrom::Start(0x10000)).unwrap();
file.write_all(&b).unwrap();
assert_eq!(file.seek_data(0).unwrap(), Some(0x10000));
assert_eq!(seek_cur(&mut file), 0x10000);
// seek_data within data should return the same offset
assert_eq!(file.seek_data(0x10000).unwrap(), Some(0x10000));
assert_eq!(seek_cur(&mut file), 0x10000);
assert_eq!(file.seek_data(0x10001).unwrap(), Some(0x10001));
assert_eq!(seek_cur(&mut file), 0x10001);
assert_eq!(file.seek_data(0x1FFFF).unwrap(), Some(0x1FFFF));
assert_eq!(seek_cur(&mut file), 0x1FFFF);
assert_eq!(file.seek_data(0).unwrap(), Some(0x10000));
assert_eq!(seek_cur(&mut file), 0x10000);
assert_eq!(file.seek_data(0x1FFFF).unwrap(), Some(0x1FFFF));
assert_eq!(seek_cur(&mut file), 0x1FFFF);
assert_eq!(file.seek_data(0x20000).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0x1FFFF);
});
}
#[test]
fn seek_hole() {
with_default_file(0x30000, |mut file| {
// File consisting entirely of a hole
assert_eq!(file.seek_hole(0).unwrap(), Some(0));
assert_eq!(seek_cur(&mut file), 0);
assert_eq!(file.seek_hole(0xFFFF).unwrap(), Some(0xFFFF));
assert_eq!(seek_cur(&mut file), 0xFFFF);
// seek_hole at or after the end of the file should return None
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x30000).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0);
assert_eq!(file.seek_hole(0x30001).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0);
// Write some data to [0x10000, 0x20000)
let b = [0x55u8; 0x10000];
file.seek(SeekFrom::Start(0x10000)).unwrap();
file.write_all(&b).unwrap();
// seek_hole within a hole should return the same offset
assert_eq!(file.seek_hole(0).unwrap(), Some(0));
assert_eq!(seek_cur(&mut file), 0);
assert_eq!(file.seek_hole(0xFFFF).unwrap(), Some(0xFFFF));
assert_eq!(seek_cur(&mut file), 0xFFFF);
// seek_hole within data should return the next hole
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x10000).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x10001).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x1FFFF).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0xFFFF).unwrap(), Some(0xFFFF));
assert_eq!(seek_cur(&mut file), 0xFFFF);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x10000).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x1FFFF).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x20000).unwrap(), Some(0x20000));
assert_eq!(seek_cur(&mut file), 0x20000);
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x20001).unwrap(), Some(0x20001));
assert_eq!(seek_cur(&mut file), 0x20001);
// seek_hole at EOF should return None
file.seek(SeekFrom::Start(0)).unwrap();
assert_eq!(file.seek_hole(0x30000).unwrap(), None);
assert_eq!(seek_cur(&mut file), 0);
// Write some data to [0x20000, 0x30000)
file.seek(SeekFrom::Start(0x20000)).unwrap();