8358623: Avoid unnecessary data copying in ICC_Profile

[mrserb]

This PR simplifies several aspects of the ICC_Profile class:

• Change 1:
  The ICC_Profile.getInstance(byte[] data) method used to copy the profile header for validation. This copy appears redundant, as the original data array is used later anyway. This logic was originally introduced by JDK-8347377.

• Change 2:
  In some places, the code retrieves the profile header using getData(icSigHead), which always creates a new array. It is now replaced with private getData(cmmProfile(), icSigHead) to avoid unnecessary copying. To clarify the purpose of the private method, I have added documentation.

• Change 3:
  After Change 2, static analysis tools began reporting a potential NPE when using getData(cmmProfile(), icSigHead), since it may return null. To address this, the internal implementation of getData was updated to always return a non-null value or throw an exception. The public method now catches this exception and returns null, as required by the specification. Note: this potential NPE is not a regression introduced by any changes, it simply became easier for tools to detect due to the simplified code.

@prrace @honkar-jdk please take a look

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Issue

• JDK-8358623: Avoid unnecessary data copying in ICC_Profile (Bug - P4)

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[bridgekeeper]

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[openjdk]

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[openjdk]

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[mrserb]

The above checks are moved to the corresponding constructors.

[mrserb]

Also added a test for the changed methods, since they were not covered by any jtreg tests.

[mrserb]

Interestingly, ICC_Profile.getMinorVersion() does not return just the minor version as specified, but instead returns the raw byte, which includes both the minor and patch versions. Perhaps the specification should be updated to reflect this behavior?

[mlbridge]

Webrevs

• 00: Full (450f35e9)

[honkar-jdk]

verifyHeader(byte[] data), expects header byte array and not the entire profile array, is it technically correct to send the entire profile byte array?

Please note verifyHeader() is called from two places from getInstance(byte[] data) and setData(int tagSignature, byte[] tagData),

With the current fix, logically all the checks within verifyHeader() work (getProfileClass(data), getColorSpaceType(data) ...) because the data is extracted at specified index from the superset - entire profile byte array instead of the header byte array.

If it is decided to send only header byte array to verifyHeader() then changing the method param name to header instead of data may be clearer.

    private static void verifyHeader(byte[] header) {
        if (header == null || header.length < HEADER_SIZE) {
            throw new IllegalArgumentException("Invalid header data");
        }
        getProfileClass(header);
        getColorSpaceType(header);
        getPCSType(header);
        checkRenderingIntent(header);
    }

[mrserb]

verifyHeader(byte[] data), expects header byte array and not the entire profile array, is it technically correct to send the entire profile byte array?

Validating the header directly without cloning is fine and actually better. The old code effectively skipped the "header.length < HEADER_SIZE" check because it always created a "new byte[HEADER_SIZE]".

[honkar-jdk]

In reference to the above comment , these lines may need to be reverted as verifyHeader(byte[] header) expects the header array and not the entire profile byte array.

[honkar-jdk]

@prrace @jayathirthrao You may want to take a look at this PR changes when you get a chance.