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Make mtime of reproducible tarball dependent on git commit

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This commit is contained in:
Jakub Beránek 2024-06-27 19:03:47 +02:00
parent be99243afc
commit c54a2a53f8
2 changed files with 41 additions and 3 deletions
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26
src/bootstrap/src/utils/tarball.rs
View file

@ -9,9 +9,9 @@ use std::path::{Path, PathBuf};
use crate::core::builder::Builder;
use crate::core::{build_steps::dist::distdir, builder::Kind};
use crate::utils::channel;
use crate::utils::exec::BootstrapCommand;
use crate::utils::helpers::{move_file, t};
use crate::utils::{channel, helpers};
#[derive(Copy, Clone)]
pub(crate) enum OverlayKind {
@ -351,6 +351,30 @@ impl<'a> Tarball<'a> {
};
cmd.args(["--compression-profile", compression_profile]);
// We want to use a pinned modification time for files in the archive
// to achieve better reproducibility. However, using the same mtime for all
// releases is not ideal, because it can break e.g. Cargo mtime checking
// (https://github.com/rust-lang/rust/issues/125578).
// Therefore, we set mtime to the date of the latest commit (if we're managed
// by git). In this way, the archive will still be always the same for a given commit
// (achieving reproducibility), but it will also change between different commits and
// Rust versions, so that it won't break mtime-based caches.
//
// Note that this only overrides the mtime of files, not directories, due to the
// limitations of the tarballer tool. Directories will have their mtime set to 2006.
// Get the UTC timestamp of the last git commit, if we're under git.
// We need to use UTC, so that anyone who tries to rebuild from the same commit
// gets the same timestamp.
if self.builder.rust_info().is_managed_git_subrepository() {
// %ct means committer date
let timestamp = helpers::output(
helpers::git(Some(&self.builder.src)).arg("log").arg("-1").arg("--format=%ct"),
);
cmd.args(["--override-file-mtime", timestamp.trim()]);
}
self.builder.run(cmd);
// Ensure there are no symbolic links in the tarball. In particular,

18
src/tools/rust-installer/src/tarballer.rs
View file

@ -32,6 +32,12 @@ actor! {
/// The formats used to compress the tarball.
#[arg(value_name = "FORMAT", default_value_t)]
compression_formats: CompressionFormats,
/// Modification time that will be set for all files added to the archive.
/// The default is the date of the first Rust commit from 2006.
/// This serves for better reproducibility of the archives.
#[arg(value_name = "FILE_MTIME", default_value_t = 1153704088)]
override_file_mtime: u64,
}
}
@ -65,6 +71,8 @@ impl Tarballer {
let buf = BufWriter::with_capacity(1024 * 1024, encoder);
let mut builder = Builder::new(buf);
// Make uid, gid and mtime deterministic to improve reproducibility
// The modification time of directories will be set to the date of the first Rust commit.
// The modification time of files will be set to `override_file_mtime` (see `append_path`).
builder.mode(HeaderMode::Deterministic);
let pool = rayon::ThreadPoolBuilder::new().num_threads(2).build().unwrap();
@ -77,7 +85,7 @@ impl Tarballer {
}
for path in files {
let src = Path::new(&self.work_dir).join(&path);
append_path(&mut builder, &src, &path)
append_path(&mut builder, &src, &path, self.override_file_mtime)
.with_context(|| format!("failed to tar file '{}'", src.display()))?;
}
builder
@ -93,10 +101,16 @@ impl Tarballer {
}
}
fn append_path<W: Write>(builder: &mut Builder<W>, src: &Path, path: &String) -> Result<()> {
fn append_path<W: Write>(
builder: &mut Builder<W>,
src: &Path,
path: &String,
override_file_mtime: u64,
) -> Result<()> {
let stat = symlink_metadata(src)?;
let mut header = Header::new_gnu();
header.set_metadata_in_mode(&stat, HeaderMode::Deterministic);
header.set_mtime(override_file_mtime);
if stat.file_type().is_symlink() {
let link = read_link(src)?;