Fix doc comments in safe_traversal that still described the old behavior
of replacing symlinks with real directories. Rename and deduplicate tests
that were originally written as race-condition regression tests but now
just verify symlink-following behavior.
Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>
## Summary
Fixes#11469
`install -D` was replacing pre-existing symlinks in the destination path with real directories instead of following them. This broke any workflow where part of the install prefix is a symlink; including BOSH deployments, Homebrew, Nix, stow, and any `make install` targeting a symlinked prefix.
**Reproduction (from the issue):**
```sh
mkdir -p /tmp/target
ln -s /tmp/target /tmp/link
echo hello > /tmp/file.txt
install -D -m 644 /tmp/file.txt /tmp/link/subdir/file.txt
# GNU coreutils 8.32: /tmp/link stays a symlink, file lands in /tmp/target/subdir/file.txt
# uutils 0.7.0: /tmp/link is replaced with a real directory — wrong
```
## Root cause
PR #10140 introduced `create_dir_all_safe()` in `safe_traversal.rs` to prevent TOCTOU symlink race conditions. The fix was correct in intent but too aggressive: `open_or_create_subdir()` unconditionally unlinked and recreated any symlink it encountered, including pre-existing legitimate ones.
## Changes
**`src/uucore/src/lib/features/safe_traversal.rs`**
- `open_or_create_subdir`: when `stat_at` returns `S_IFLNK`, call `open_subdir(Follow)` instead of `unlink_at + mkdir_at`. The `O_DIRECTORY` flag already in `open_subdir` means dangling or non-directory symlinks still return an error cleanly.
- `find_existing_ancestor`: switch from `fs::symlink_metadata` to `fs::metadata` so that a symlink-to-directory is recognised as an existing ancestor rather than a component to recreate (this was already the stated intent in the function's doc comment).
**`src/uu/install/src/install.rs`**
- Align the `dir_exists` check and the `DirFd::open` call to also follow symlinks, consistent with the above.
**`tests/by-util/test_install.rs`**
- Update the two tests added by #10140 — they were asserting the buggy behavior (symlink replaced). Flip the assertions to document the correct GNU behavior.
- Add `test_install_d_follows_symlink_prefix` as a direct regression test for the issue's reproduction case.
## TOCTOU / security note
The true TOCTOU race (a symlink *injected during the operation* into a not-yet-existing path component) is still blocked: `mkdirat` fails with `EEXIST` if an attacker creates a symlink between `stat_at` returning `ENOENT` and our `mkdir_at`. Newly-created directories are still opened with `O_NOFOLLOW`.
What changes is that *pre-existing* symlinks are now followed — which is exactly what GNU coreutils 8.32 does. The previous behavior was stricter than GNU in this regard.
Bulk rename of the antipattern across 19 test files (136 occurrences).
.no_output() is the established shorthand in the uutests framework
for asserting both empty stdout and empty stderr.
* Enhance mode parsing to support comma-separated mode strings in `parse` function. Add tests for comma-separated mode handling in file and directory creation.
* Add comprehensive tests for mode parsing in `parse` function, covering numeric, symbolic, and mixed modes, as well as handling of invalid inputs and umask considerations.
---------
Co-authored-by: Sylvestre Ledru <sylvestre@debian.org>
install should silently override existing target files, but it
inadvertently checked whether the target exists rather than
for the target being a directory, hence the overwrite failed,
saying it cannot overwrite the directory with non-directory.
Bug-Ubuntu: https://bugs.launchpad.net/bugs/2118785
The dir/. special case was handled correctly, but dir/./ was not,
breaking gcc builds, which run:
../../../../src/libstdc++-v3/../install-sh -c -d debug/./
Bug-Ubuntu: https://bugs.launchpad.net/bugs/2117466
Etienne CordonnierandDaniel Hofstetter
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