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qcow: Add a zero_cluster method to raw file

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Zeroing a cluster will be done from more than one place in qcow.rs soon,
add a helper to reduce duplication.

Change-Id: Idb40539f8e4ed2338fc84c0d53b37c913f2d90fe
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1697122
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Dylan Reid 2019-07-10 19:44:50 -07:00 committed by Commit Bot
parent cb3ec5ed2b
commit 13c2191395
2 changed files with 10 additions and 5 deletions
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6
qcow/src/qcow.rs
View file

@ -1035,11 +1035,7 @@ impl QcowFile {
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() {
let cluster_size = self.raw_file.cluster_size() as usize;
self.raw_file
.file_mut()
.seek(SeekFrom::Start(free_cluster))?;
self.raw_file.file_mut().write_zeroes(cluster_size)?;
self.raw_file.zero_cluster(free_cluster)?;
return Ok(free_cluster);
}

9
qcow/src/qcow_raw_file.rs
View file

@ -7,6 +7,7 @@ use std::io::{self, BufWriter, Seek, SeekFrom};
use std::mem::size_of;
use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use sys_util::WriteZeroes;
/// A qcow file. Allows reading/writing clusters and appending clusters.
#[derive(Debug)]
@ -133,4 +134,12 @@ impl QcowRawFile {
pub fn cluster_offset(&self, address: u64) -> u64 {
address & self.cluster_mask
}
/// Zeros out a cluster in the file.
pub fn zero_cluster(&mut self, address: u64) -> io::Result<()> {
let cluster_size = self.cluster_size as usize;
self.file.seek(SeekFrom::Start(address))?;
self.file.write_zeroes(cluster_size)?;
Ok(())
}
}