8374343: Fix SIGSEGV when lib/modules is unreadable

[bulasevich]

This pull request contains a backport of commit 48846744 from the openjdk/jdk repository.

The simple change fixes SIGSEGV crash during startup if the runtime image (lib/modules) exists but is unreadable.

• I confirm that I make this contribution in accordance with the OpenJDK Interim AI Policy

---

Progress

• JDK-8374343 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Error

 ⚠️ Pull request body is missing required line: - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).

Issue

• JDK-8374343: Fix SIGSEGV when lib/modules is unreadable (Bug - P4 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/2720/head:pull/2720
$ git checkout pull/2720

Update a local copy of the PR:
$ git checkout pull/2720
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/2720/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2720

View PR using the GUI difftool:
$ git pr show -t 2720

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/2720.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back bulasevich! 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]

@bulasevich This change is no longer ready for integration - check the PR body for details.

[openjdk]

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

[openjdk]

⚠️ @bulasevich 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 (4ef6daf0)

[GoeLin]

Hi @bulasevich
please first backport to 26 and 25.
I remove the labels in the meantime.

[bulasevich]

/approval request This simple change fixes a specific startup crash. The backport is clean and small, with low risk.

[openjdk]

@bulasevich
8374343: The approval request has been created successfully.

[bridgekeeper]

@bulasevich This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply issue a /touch or /keepalive command to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[bulasevich]

/touch

[openjdk]

@bulasevich The pull request is being re-evaluated and the inactivity timeout has been reset.