91 lines
2.7 KiB
Rust
91 lines
2.7 KiB
Rust
use anyhow::{bail, Context, Result};
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use hole_punch::*;
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use std::{
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fs::{File, OpenOptions},
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io::{Read, Seek, SeekFrom, Write},
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path::Path,
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};
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/// Handle the `xcp` command: copy sparse file with optional hole punching.
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pub fn run(args: &[String]) -> Result<()> {
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let mut positional: Vec<&str> = Vec::with_capacity(2);
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let mut punch_hole = false;
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for arg in args {
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match arg.as_str() {
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"--punch-hole" => punch_hole = true,
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"-h" | "--help" => {
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print_usage();
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return Ok(());
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}
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_ => positional.push(arg),
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}
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}
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if positional.len() < 2 {
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print_usage();
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bail!("xcp requires source and destination paths");
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}
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if positional.len() > 2 {
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bail!("unexpected argument: {}", positional[2]);
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}
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copy_sparse_file(positional[0], positional[1], punch_hole)
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}
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fn print_usage() {
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eprintln!("Usage: meta-overlayfs xcp <src> <dst> [--punch-hole]");
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}
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// TODO: use libxcp to improve the speed if cross's MSRV is 1.70
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pub fn copy_sparse_file<P: AsRef<Path>, Q: AsRef<Path>>(
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src: P,
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dst: Q,
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punch_hole: bool,
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) -> Result<()> {
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let mut src_file = File::open(src.as_ref())
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.with_context(|| format!("failed to open {}", src.as_ref().display()))?;
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let mut dst_file = OpenOptions::new()
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.write(true)
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.create(true)
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.truncate(true)
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.open(dst.as_ref())
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.with_context(|| format!("failed to open {}", dst.as_ref().display()))?;
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dst_file.set_len(src_file.metadata()?.len())?;
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let segments = src_file.scan_chunks()?;
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for segment in segments {
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if let SegmentType::Data = segment.segment_type {
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let start = segment.start;
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let end = segment.end + 1;
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src_file.seek(SeekFrom::Start(start))?;
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dst_file.seek(SeekFrom::Start(start))?;
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let mut buffer = [0; 4096];
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let mut total_bytes_copied = 0;
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while total_bytes_copied < end - start {
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let bytes_to_read =
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std::cmp::min(buffer.len() as u64, end - start - total_bytes_copied);
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let bytes_read = src_file.read(&mut buffer[..bytes_to_read as usize])?;
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if bytes_read == 0 {
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break;
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}
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if punch_hole && buffer[..bytes_read].iter().all(|&x| x == 0) {
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dst_file.seek(SeekFrom::Current(bytes_read as i64))?;
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total_bytes_copied += bytes_read as u64;
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continue;
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}
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dst_file.write_all(&buffer[..bytes_read])?;
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total_bytes_copied += bytes_read as u64;
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}
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}
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}
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Ok(())
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}
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