RFR: 8320971: Use BufferedInputStream.buf directly when param of implTransferTo() is trusted [v13]

[Alan Bateman]

On Wed, 13 Dec 2023 08:15:21 GMT, Sergey Tsypanov <stsypanov at openjdk.org> wrote:

>> It looks like we can skip copying of `byte[]` in `BufferedInputStream.implTransferTo()` for `OutputStreams` residing in `java.io`.
>> 
>> See comment by @vlsi in https://github.com/openjdk/jdk/pull/10525/files#diff-e19c508d1bb6ee78697ecca66947c395adda0d9c49a85bf696e677ecbd977af1R612
>
> Sergey Tsypanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8320971: Fix JavaDoc

src/java.base/share/classes/com/sun/io/IOStreams.java line 26:

> 24:  */
> 25: 
> 26: package com.sun.io;

The starting point for this PR is getting agreement to relax the checks in BufferedInputStream.transferTo so ideally the changes would be limited to that one method initially. If you really want a supporting utility class then a non-public class like java.io.TransferSupport or something like that would be easier to discuss. We don't need to adding a new package com.sun.io for this.

I think drop  j.u.zip.CheckedOutputStream from the initial discussion as it it "too far away" to be in the mix at this point.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16879#discussion_r1425055930