RFR: 8271003: hs_err improvement: handle CLASSPATH env setting longer than O_BUFLEN

[Calvin Cheung]

On Mon, 2 Aug 2021 07:02:35 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Please review this small enhancement for addressing the problem of the CLASSPATH env variable setting being truncated in a hs err log.
>> 
>> For printing a char string, it doesn't need to go through `do_vsnprintf()` which does the truncation based on the input buffer length. The change is local to the code path pertaining to hs err log.
>> 
>> Testing:
>> 
>> - [x] tiers 1, 2 (including the new test)
>
> `outputStream::do_vsnprintf` already states that it uses the buffer "if necessary". In the two highlighted cases there is no need to use the buffer, so I would argue that we should just modify the existing `outputStream::do_vsnprintf` logic to not truncate in these two cases as it is not necessary.
> 
> David

@dholmes-ora, @tstuefe, @iklam, @yminqi Thanks for the review.

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PR: https://git.openjdk.java.net/jdk/pull/4947