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

[David Holmes]

On Fri, 30 Jul 2021 18:17:54 GMT, Calvin Cheung <ccheung 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

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