fix(package): exclude target/package from backups #16272

SepehrGanji · 2025-11-17T22:12:24Z

What does this PR try to resolve?

The target directory is not excluded from backups when created with
cargo package or cargo publish. This causes the target/package
directory to be included in Time Machine backups on macOS and other
backup systems that respect CACHEDIR.TAG files.

The issue occurs because when Filesystem::open() creates parent
directories in src/cargo/util/flock.rs:336, it uses
paths::create_dir_all() instead of the backup-excluding version,
bypassing the normal target directory creation logic.

This commit adds a new create_dir_with_backup_exclusion() method to
Filesystem and uses it to ensure the target/package directory is
properly excluded from backups before creating files in it.

Fixes #16238

How to test and review this PR?

Run the following:
cargo new foo
cd foo
cargo package --allow-dirty
ls -al target/package/

Verify that CACHEDIR.TAG now exists in target/package/.

All existing package tests pass.

rustbot · 2025-11-17T22:12:29Z

r? @epage

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src/cargo/ops/cargo_package/mod.rs

src/cargo/util/flock.rs

src/cargo/ops/cargo_package/mod.rs

epage · 2025-11-17T22:21:02Z

Should we have automated tests for this?

Note that our contrib guide normally recommends creating a passing test in a commit before the fix, showing the old behavior. Then the commit with the fix updates the test so it still passes, showing the new behavior. Then the diff will show how the behavior changed.

epage · 2025-11-18T03:12:53Z

Looks like this needs cargo fmt run. As a warning, force pushes don't always generate notifications, so be sure to post here when you do it so we know it is ready to merge.

SepehrGanji · 2025-11-18T03:21:52Z

Looks like this needs cargo fmt run. As a warning, force pushes don't always generate notifications, so be sure to post here when you do it so we know it is ready to merge.

Thanks for all your help! I have did the cargo fmt, could you please take a look?

weihanglo

You'll need to update test snapshots accordingly (with env SNAPSHOTS=overwrite): https://github.com/rust-lang/cargo/actions/runs/19452875528/job/55661053577?pr=16272#step:15:4779

View changes since this review

weihanglo · 2025-11-18T04:37:12Z

tests/testsuite/package.rs

+    // This test documents the current behavior where target directory is NOT excluded from backups.
+    // After the fix, this test will be updated to verify that CACHEDIR.TAG exists.
+    let p = project()
+        .file("src/main.rs", r#"fn main() { println!("hello"); }"#)


nit: for faster test execution (avoid to binary linking)

Suggested change

.file("src/main.rs", r#"fn main() { println!("hello"); }"#)

.file("src/lib.rs", "")

Thanks for the tip! Done.

weihanglo · 2025-11-22T15:47:58Z

@rustbot author

rustbot · 2025-11-22T15:48:01Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2025-11-23T00:37:39Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

weihanglo · 2025-11-23T01:25:24Z

tests/testsuite/package.rs

+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("package --allow-dirty -v")


We probably don't need -v here, since we just want to check cachedir tag file existing

You might need to change that , regenerate snapshots, and cargo fmt

Add a failing test that demonstrates the current buggy behavior where `cargo package` does not create a CACHEDIR.TAG file in the target directory. This causes backup tools to unnecessarily include temporary packaging artifacts. The test currently passes by asserting that CACHEDIR.TAG does NOT exist (the buggy behavior). The next commit will implement the fix and update this test to verify correct behavior. Relates to rust-lang#16238

Create CACHEDIR.TAG files in build directories during `cargo package` to exclude them from system backups. This ensures that temporary packaging artifacts in target/package are not unnecessarily included by backup tools like Time Machine on macOS. The fix calls `create_dir_all_excluded_from_backups_atomic` when creating the build directory and target directory for packaging, which automatically creates the CACHEDIR.TAG file. Update existing tests to verify that CACHEDIR.TAG files are now created in the expected locations. Fixes rust-lang#16238

SepehrGanji · 2025-11-23T02:02:10Z

@rustbot ready

weihanglo

Thanks!

View changes since this review

rustbot assigned epage Nov 17, 2025

rustbot added A-filesystem Area: issues with filesystems Command-package S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 17, 2025

epage reviewed Nov 17, 2025

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SepehrGanji force-pushed the fix-cachedir branch from 4d928f4 to 5bb82db Compare November 18, 2025 03:05

SepehrGanji force-pushed the fix-cachedir branch from 5bb82db to d77851d Compare November 18, 2025 03:19

weihanglo reviewed Nov 18, 2025

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rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 22, 2025

rustbot added the S-waiting-on-author Status: The marked PR is awaiting some action (such as code changes) from the PR author. label Nov 22, 2025

SepehrGanji force-pushed the fix-cachedir branch from d77851d to 454b4f5 Compare November 23, 2025 00:37

SepehrGanji force-pushed the fix-cachedir branch from 454b4f5 to 4c118e5 Compare November 23, 2025 01:03

weihanglo reviewed Nov 23, 2025

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SepehrGanji force-pushed the fix-cachedir branch from 4c118e5 to 8e2fcdf Compare November 23, 2025 01:40

SepehrGanji marked this pull request as draft November 23, 2025 01:41

SepehrGanji added 2 commits November 22, 2025 18:54

SepehrGanji force-pushed the fix-cachedir branch from 8e2fcdf to b8dc393 Compare November 23, 2025 02:00

SepehrGanji marked this pull request as ready for review November 23, 2025 02:02

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 23, 2025

weihanglo approved these changes Nov 23, 2025

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weihanglo added this pull request to the merge queue Nov 23, 2025

Merged via the queue into rust-lang:master with commit 8e43074 Nov 23, 2025
26 checks passed

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 23, 2025

	.file("src/main.rs", r#"fn main() { println!("hello"); }"#)
	.file("src/lib.rs", "")

fix(package): exclude target/package from backups #16272

fix(package): exclude target/package from backups #16272

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SepehrGanji commented Nov 17, 2025

What does this PR try to resolve?

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