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use serde::{Deserialize, Serialize};
use zstd::stream::{decode_all as zstd_decode, Encoder};
use garage_util::data::*;
use garage_util::error::*;
/// A possibly compressed block of data
#[derive(Debug, Serialize, Deserialize)]
pub enum DataBlock {
/// Uncompressed data
Plain(#[serde(with = "serde_bytes")] Vec<u8>),
/// Data compressed with zstd
Compressed(#[serde(with = "serde_bytes")] Vec<u8>),
}
impl DataBlock {
/// Query whether this block is compressed
pub fn is_compressed(&self) -> bool {
matches!(self, DataBlock::Compressed(_))
}
/// Get the inner, possibly compressed buffer. You should probably use [`DataBlock::verify_get`]
/// instead
pub fn inner_buffer(&self) -> &[u8] {
use DataBlock::*;
let (Plain(ref res) | Compressed(ref res)) = self;
res
}
/// Get the buffer, possibly decompressing it, and verify it's integrity.
/// For Plain block, data is compared to hash, for Compressed block, zstd checksumming system
/// is used instead.
pub fn verify_get(self, hash: Hash) -> Result<Vec<u8>, Error> {
match self {
DataBlock::Plain(data) => {
if blake2sum(&data) == hash {
Ok(data)
} else {
Err(Error::CorruptData(hash))
}
}
DataBlock::Compressed(data) => {
zstd_decode(&data[..]).map_err(|_| Error::CorruptData(hash))
}
}
}
/// Verify data integrity. Allocate less than [`DataBlock::verify_get`] and don't consume self, but
/// does not return the buffer content.
pub fn verify(&self, hash: Hash) -> Result<(), Error> {
match self {
DataBlock::Plain(data) => {
if blake2sum(data) == hash {
Ok(())
} else {
Err(Error::CorruptData(hash))
}
}
DataBlock::Compressed(data) => zstd::stream::copy_decode(&data[..], std::io::sink())
.map_err(|_| Error::CorruptData(hash)),
}
}
pub fn from_buffer(data: Vec<u8>, level: Option<i32>) -> DataBlock {
if let Some(level) = level {
if let Ok(data) = zstd_encode(&data[..], level) {
return DataBlock::Compressed(data);
}
}
DataBlock::Plain(data)
}
}
fn zstd_encode<R: std::io::Read>(mut source: R, level: i32) -> std::io::Result<Vec<u8>> {
let mut result = Vec::<u8>::new();
let mut encoder = Encoder::new(&mut result, level)?;
encoder.include_checksum(true)?;
std::io::copy(&mut source, &mut encoder)?;
encoder.finish()?;
Ok(result)
}
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