8290499: new File(parent, "/") breaks normalization – creates File with slash at the end

[rm-gh-8]

Backporting JDK-8290499: New File(parent, "/") breaks normalization – creates File with slash at the end. Fixes the file separator logic and updates a test. Ran GHA Sanity Checks (passed), and related file tests (passed). Patch is clean.

---

Progress

• Change must not contain extraneous whitespace
• JDK-8290499 needs maintainer approval
• Commit message must refer to an issue

Warning

 ⚠️ Found leading lowercase letter in issue title for 8290499: new File(parent, "/") breaks normalization – creates File with slash at the end

Issue

• JDK-8290499: new File(parent, "/") breaks normalization – creates File with slash at the end (Bug - P4 - Requested)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/4175/head:pull/4175
$ git checkout pull/4175

Update a local copy of the PR:
$ git checkout pull/4175
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/4175/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 4175

View PR using the GUI difftool:
$ git pr show -t 4175

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk17u-dev/pull/4175.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back rm-gh-8! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @rm-gh-8 This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (466dbdda)

[rm-gh-8]

/approval request for backport of JDK-8290499: New File(parent, "/") breaks normalization – creates File with slash at the end.

Ran the updated and related tests on linux-x64, linux-aarch64, macos-aarch64 and windows-x64:

(All Passed) - make test TEST=test/jdk/java/io/File

Results are attached.
linux-aarch64-specific-test.log
linux-x64-specific-test.log
macos-aarch64-specific-test.log
windows-x64-specific-test.log

[openjdk]

@rm-gh-8
8290499: The approval request has been created successfully.

[GoeLin]

Hi @rm-gh-8
please give a risk assessment for this backport.

[rm-gh-8]

Risk Mitigation:
• Cross-platform testing completed successfully
• Issue is deterministic and well-understood
• Fix addresses core path normalization logic
• No breaking changes to existing API

Potential Risk:
• File system operations - Applications relying on exact path strings may be affected
• Path comparison logic - Code comparing file paths as strings could break
• Legacy compatibility - Existing workarounds for double slashes might become redundant

Impact Areas:
• File I/O operations using constructed paths
• Path-based caching or indexing systems
• Configuration files with hardcoded path expectations
• Third-party libraries expecting specific path formats