RFR: 8329728: Read long lines in ClassListParser [v2]

[Calvin Cheung]

On Tue, 9 Apr 2024 17:22:47 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Today the `ClassListParser` has a hard-coded limit of 4096 chars for each line in the CDS class list file. However, it's possible for a line to be much longer than than (64KB for the class name, plus extra information that can include path names, IDs, etc).
>> 
>> I wrote a utility class `LineReader` that automatically allocates a buffer before calling `fgets()`. Hopefully this can be useful for other cases where we call `fgets()` with a fixed buffer size.
>> 
>> Max line width is limited to 4M to simplify testing (and avoid running into corner cases when we approach INT_MAX).
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   @matias9927 and @calvinccheung comments - limit line to 4M. Added gtest cases. Test for class names > 64K

src/hotspot/share/utilities/lineReader.hpp line 43:

> 41:   bool  _is_oom;
> 42: public:
> 43:   static const int MAX_LEN = 4 * 1024 * 1024;

How about `4 * M` instead of `4 * 1024 * 1024`?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18669#discussion_r1558847183