RFR: JDK-8361748 : Enforce limits on the size of an XBM image [v2]

[Phil Race]

On Fri, 25 Jul 2025 23:58:39 GMT, Harshitha Onkar <honkar at openjdk.org> wrote:

>> 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 The XBMDecoder's produceImage() has outdated logic, it has been restructured by adding more efficient parser logic and better error handling checks.
>
> Harshitha Onkar has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - rename
>  - test summary

LGTM

-------------

Marked as reviewed by prr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26488#pullrequestreview-3068654119