8311906: Improve robustness of String constructors with mutable array inputs

[GoeLin]

I backport this for parity with 21.0.10-oracle.

I had to resolve and adapt the change to the CSR for 21, that differes from the CSR for 22.
In addition, I include four follow-up changes. All steps are seperated into individual commits.
In detail:

Resolved two files (first commit)

src/java.base/share/classes/java/lang/String.java

Resolved complex code in
private String(Charset charset, byte[] bytes, int offset, int length)
at line 563++

This is needed because later change
https://bugs.openjdk.org/browse/JDK-8320570: NegativeArraySizeException decoding >1G UTF8 bytes with non-ascii characters
was already backported.

In 22, this is removed:
- byte[] buf = new byte[length << 1];
In 21, it looks like this:
- byte[] buf = StringUTF16.newBytesFor(length);

I only updated variable buf to utf16 in that line effecitvely keeping 8320570.
After this change, the method looks the same as in 22.0.2.

src/java.base/share/classes/java/lang/StringUTF16.java

Resolved imports.

Adapted to CSR (second commit)

The CSRs for 21 and 22 differ. The CSR for 21 does not mention that the documentation is
changed. Thus, I omit corresponding edits, see extra commit that removes them. Similar
modifications to backports have been done before.

Follow-ups (commits 3-6)

The original change has some minor issues. Notable for example that the test StringRacyConstructor.java is failing. Three follow-up issues exist, and one recursive fix for a test. These are clean backports on top. I decided to include them here as working with four dependent PRs is quite cumbersome, and the main change needs review anyways. I guess reviewing a correct change has some value, too.
In case a backport to 17 is necessary, all can be grabbed from 21 together this way.

Adapt 8325590 to 21 (last commit)

The test modification of 8325590 is not compatible with Java 21. https://bugs.openjdk.org/browse/JDK-8310047: "Add UTF-32 based Charsets into StandardCharsets" is only in 22. Removed the corresponding test cases.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8311906 needs maintainer approval
• JDK-8321180 needs maintainer approval
• Change requires CSR request JDK-8368232 to be approved
• JDK-8321514 needs maintainer approval
• JDK-8325590 needs maintainer approval
• JDK-8322018 needs maintainer approval

Issues

• JDK-8311906: Improve robustness of String constructors with mutable array inputs (Bug - P4)
• JDK-8321180: Condition for non-latin1 string size too large exception is off by one (Bug - P4)
• JDK-8322018: Test java/lang/String/CompactString/MaxSizeUTF16String.java fails with -Xcomp (Bug - P3)
• JDK-8321514: UTF16 string gets constructed incorrectly from codepoints if CompactStrings is not enabled (Bug - P2)
• JDK-8325590: Regression in round-tripping UTF-16 strings after JDK-8311906 (Bug - P1)
• JDK-8368232: Improve robustness of String constructors with mutable array inputs (CSR)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/2437/head:pull/2437
$ git checkout pull/2437

Update a local copy of the PR:
$ git checkout pull/2437
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/2437/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2437

View PR using the GUI difftool:
$ git pr show -t 2437

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/2437.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back goetz! 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.

[GoeLin]

/issue 8321180 8322018 8321514 8325590

[openjdk]

@GoeLin
Adding additional issue to issue list: 8321180: Condition for non-latin1 string size too large exception is off by one.

Adding additional issue to issue list: 8322018: Test java/lang/String/CompactString/MaxSizeUTF16String.java fails with -Xcomp.

Adding additional issue to issue list: 8321514: UTF16 string gets constructed incorrectly from codepoints if CompactStrings is not enabled.

Adding additional issue to issue list: 8325590: Regression in round-tripping UTF-16 strings after JDK-8311906.

[GoeLin]

GHA failure: test/jdk/java/util/concurrent/ExecutorService/CloseTest.java failed with
AssertionError: expected [true] but found [false]
We have seen this fail before, e.g. https://github.com/openjdk-bots/jdk21u-dev/actions/runs/17855005583/attempts/1#summary-50796380616 and I have recorded more failures. So I assume this failure is unrelated.

[mlbridge]

Webrevs

• 00: Full (eeed7fa5)