8380959: Update Libpng to 1.6.56

[vieiro]

Mostly clean backport of JDK-8380959 from 17u, that makes 11u libpng on par with the upper JDK versions. It would be great if this could make it for the April CPU.

Backport is not clean because of the differences in make/lib/Awt2dLibraries.gmk from JDK17.

Tested on both Fedora 42/gcc 15.2.1 and Windows 10/Visual Studio 2022 and RHEL-8 with the following tests:

==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk:jdk_imageio                          197   197     0     0   
==============================
TEST SUCCESS

==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk/java/awt/SplashScreen                  1     1     0     0   
==============================
TEST SUCCESS

==============================
Test summary
==============================
   TEST                                              TOTAL  PASS  FAIL ERROR   
   jtreg:test/jdk:jfc_demo                               1     1     0     0   
==============================
TEST SUCCESS

Let's see how this builds on GHA's Visual Studio version, though.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• JDK-8380959 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8380959: Update Libpng to 1.6.56 (Bug - P3 - Approved)

Reviewers

• Andrew John Hughes (@gnu-andrew - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u.git pull/116/head:pull/116
$ git checkout pull/116

Update a local copy of the PR:
$ git checkout pull/116
$ git pull https://git.openjdk.org/jdk11u.git pull/116/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 116

View PR using the GUI difftool:
$ git pr show -t 116

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u/pull/116.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back avieiro! 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]

@vieiro This change now passes all automated pre-integration checks.

After integration, the commit message for the final commit will be:

8380959: Update Libpng to 1.6.56

Reviewed-by: andrew

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

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[openjdk]

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

[mlbridge]

Webrevs

• 00: Full (7d3112b9)

[vieiro]

Full GHA tests here: https://github.com/vieiro/jdk11u-dev/actions/runs/23813024303

[vieiro]

The full GHA tests passed but on macos, but that's unrelated: GHA bumped clang to 17, something we should fix in jdk11u-dev.

[gnu-andrew]

As with 17u, looks mostly clean bar copyright header and context differences in the Makefile. Testing looks good.

[openjdk]

⚠️ @vieiro 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.

[gnu-andrew]

The full GHA tests passed but on macos, but that's unrelated: GHA bumped clang to 17, something we should fix in jdk11u-dev.

Ok, I guess running on jdk11u won't make a difference. It looks like we just need to force down the default C standard, a fix we also need on GNU/Linux + 8u with newer gccs. I'll have a look when I'm back at work next week. Do you have actions enabled on your jdk11u fork for future PRs?

[vieiro]

Do you have actions enabled on your jdk11u fork for future PRs?

Yep, but looks like his stopped working on 2026-03-20.

[vieiro]

/approval request Please consider approving this backport from JDK17u that bumps libpng to the latest version, on par with highter JDK versions. Tested on Fedora/Windows 10 and RHEL-8. Relevant tests pass.

[openjdk]

@vieiro
8380959: The approval request has been created successfully.

[gnu-andrew]

/approve yes

[openjdk]

@gnu-andrew
8380959: The approval request has been approved.

[vieiro]

/integrate

[openjdk]

Going to push as commit 57b1881.

[openjdk]

@vieiro Pushed as commit 57b1881.

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