JDK-8361748 : Enforce limits on the size of an XBM image

[honkar-jdk]

XBM (X Bitmap) images are small one-bit deep images that were developed as a simple uncompressed format that could easily be included in C source files as include files.

Format of XBM image:

 #define width w
 #define height h
 static char foo_bits[] = {
 0xnn,0xnn,0xnn,0xnn,0xnn, .......
 0xnn,0xnn,0xnn,0xnn, .........
 0xnn,0xnn,0xnn,0xnn};

The first two #defines statements specify the width and height of the bitmap in pixels followed by hex byte array which represent pixel data itself.

The current implementation allows an arbitrarily large XBM which is not a valid use case for any XBM.
Also it doesn't validate that the provided byte array is sufficient to populate the specified WxH. Since these are small one-bit mono images a reasonable size limit is set to MAX_XBM_SIZE = 16384 bytes. It can be set to a larger limit if someone thinks it is necessary.

The XBMDecoder's produceImage() has outdated logic, it has been restructured by adding more efficient parser logic and better error handling checks.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue

Issue

• JDK-8361748: Enforce limits on the size of an XBM image (Bug - P3)

Reviewers

• Phil Race (@prrace - Reviewer)
• Jayathirth D V (@jayathirthrao - Reviewer)

Reviewing

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[bridgekeeper]

👋 Welcome back honkar! 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]

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

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8361748: Enforce limits on the size of an XBM image

Reviewed-by: prr, jdv

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At the time when this comment was updated there had been 133 new commits pushed to the master branch:

• f95af74: 8364312: debug agent should set FD_CLOEXEC flag rather than explicitly closing every open file
• 72d1066: 8364722: Parallel: Move CLDG mark clearing to the end of full GC
• 0ceb366: 8356645: Javac should utilize new ZIP file system read-only access mode
• ... and 130 more: https://git.openjdk.org/jdk/compare/e756c0dbbb7d99df0751d71726b173e4eabcc903...master

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[mlbridge]

Webrevs

• 01: Full - Incremental (f3df2849)
• 00: Full (6bbe3e73)

[prrace]

LGTM

[jayathirthrao]

Apart from minor indentation issue, change looks good to me.

[honkar-jdk]

/integrate

[openjdk]

Going to push as commit c71be80.
Since your change was applied there have been 149 commits pushed to the master branch:

• b8acbc3: 8364315: Remove unused xml files from test/jaxp/javax/xml/jaxp/functional/javax/xml/transform/xmlfiles
• 244e629: 8364984: Many jpackage tests are failing on Linux after JDK-8334238
• c0e6ffa: 8364954: (bf) CleaningThread should be InnocuousThread
• ... and 146 more: https://git.openjdk.org/jdk/compare/e756c0dbbb7d99df0751d71726b173e4eabcc903...master

Your commit was automatically rebased without conflicts.

[openjdk]

@honkar-jdk Pushed as commit c71be80.

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