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Fix race condition in local registry crate unpacking #6591

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Merged
bors merged 3 commits into from
Jan 29, 2019
Merged

Fix race condition in local registry crate unpacking #6591

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5cd68f8
Fix race condition in local registry crate downloading.
hugwijst Jan 23, 2019
1f87b6d
Lock unpacking instead of local registry tarball.
hugwijst Jan 24, 2019
a23612d
First try opening the package source lock read-only.
hugwijst Jan 28, 2019
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49 changes: 25 additions & 24 deletions src/cargo/sources/registry/local.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,15 +11,15 @@ use hex;

pub struct LocalRegistry<'cfg> {
index_path: Filesystem,
cache_path: Filesystem,
root: Filesystem,
src_path: Filesystem,
config: &'cfg Config,
}

impl<'cfg> LocalRegistry<'cfg> {
pub fn new(root: &Path, config: &'cfg Config, name: &str) -> LocalRegistry<'cfg> {
LocalRegistry {
src_path: config.registry_source_path().join(name),
cache_path: config.registry_cache_path().join(name),
index_path: Filesystem::new(root.join("index")),
root: Filesystem::new(root.to_path_buf()),
config,
Expand Down Expand Up @@ -70,38 +70,39 @@ impl<'cfg> RegistryData for LocalRegistry<'cfg> {
}

fn download(&mut self, pkg: PackageId, checksum: &str) -> CargoResult<MaybeLock> {
let crate_file = format!("{}-{}.crate", pkg.name(), pkg.version());
let mut crate_file = self.root.open_ro(&crate_file, self.config, "crate file")?;

// If we've already got an unpacked version of this crate, then skip the
// checksum below as it is in theory already verified.
let dst = format!("{}-{}", pkg.name(), pkg.version());
if self.src_path.join(dst).into_path_unlocked().exists() {
return Ok(MaybeLock::Ready(crate_file));
let filename = format!("{}-{}.crate", pkg.name(), pkg.version());

// Attempt to open an read-only lock first to avoid an exclusive write lock.
//
// If this fails then we fall through to the exclusive path where we copy
// the file.
if let Ok(dst) = self.cache_path.open_ro(&filename, self.config, &filename) {
let meta = dst.file().metadata()?;
if meta.len() > 0 {
return Ok(MaybeLock::Ready(dst));
}
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@hugwijst hugwijst Jan 23, 2019

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This is directly copied from RemoteRegistry. Probably not necessary, though I'm wondering how necessary it is in the current version of RemoteRegistry anyway.

}

self.config.shell().status("Unpacking", pkg)?;

// We don't actually need to download anything per-se, we just need to
// verify the checksum matches the .crate file itself.
// Verify the checksum and copy over the .crate.
let mut buf = Vec::new();
let mut crate_file_source = self.root.open_ro(&filename, self.config, "crate file")?;
let _ = crate_file_source
.read_to_end(&mut buf)
.chain_err(|| format!("failed to read `{}`", crate_file_source.path().display()))?;

let mut state = Sha256::new();
let mut buf = [0; 64 * 1024];
loop {
let n = crate_file
.read(&mut buf)
.chain_err(|| format!("failed to read `{}`", crate_file.path().display()))?;
if n == 0 {
break;
}
state.update(&buf[..n]);
}
state.update(&buf);
if hex::encode(state.finish()) != checksum {
failure::bail!("failed to verify the checksum of `{}`", pkg)
}

crate_file.seek(SeekFrom::Start(0))?;
let mut dst = self.cache_path.open_rw(&filename, self.config, &filename)?;
dst.write_all(&buf)?;
dst.seek(SeekFrom::Start(0))?;

Ok(MaybeLock::Ready(crate_file))
Ok(MaybeLock::Ready(dst))
}

fn finish_download(
Expand Down