proxmox-backup/src/bin/dynamic-files.rs

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use failure::*;
use std::thread;
use std::path::PathBuf;
use std::io::Write;
// tar handle files that shrink during backup, by simply padding with zeros.
//
// this binary run multiple thread which writes some large files, then truncates
// them in a loop.
// # tar cf test.tar ./dyntest1/
// tar: dyntest1/testfile0.dat: File shrank by 2768972800 bytes; padding with zeros
// tar: dyntest1/testfile17.dat: File shrank by 2899853312 bytes; padding with zeros
// tar: dyntest1/testfile2.dat: File shrank by 3093422080 bytes; padding with zeros
// tar: dyntest1/testfile7.dat: File shrank by 2833252864 bytes; padding with zeros
// # pxar create test.pxar ./dyntest1/
// Error: detected shrinked file "./dyntest1/testfile0.dat" (22020096 < 12679380992)
fn create_large_file(path: PathBuf) {
println!("TEST {:?}", path);
let mut file = std::fs::OpenOptions::new()
.write(true)
.create_new(true)
.open(&path).unwrap();
let buffer = vec![0u8; 64*1024];
loop {
for _ in 0..64 {
file.write_all(&buffer).unwrap();
}
file.sync_all().unwrap();
//println!("TRUNCATE {:?}", path);
file.set_len(0).unwrap();
}
}
fn main() -> Result<(), Error> {
let base = PathBuf::from("dyntest1");
let _ = std::fs::create_dir(&base);
let mut handles = vec![];
for i in 0..20 {
let base = base.clone();
handles.push(thread::spawn(move || {
create_large_file(base.join(format!("testfile{}.dat", i)));
}));
}
for h in handles {
if let Err(_) = h.join() {
bail!("join failed");
}
}
Ok(())
}