RFR: JDK-8322141: SequenceInputStream.transferTo should not return as soon as Long.MAX_VALUE bytes have been transferred [v2]

[Markus KARG]

On Fri, 15 Dec 2023 09:41:38 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Markus KARG has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Keep transferring beyond MAX_VALUE bytes
>
> src/java.base/share/classes/java/io/SequenceInputStream.java line 249:
> 
>> 247:                         transferred = Math.addExact(transferred, in.transferTo(out));
>> 248:                     } catch (ArithmeticException ignore) {
>> 249:                         transferred = Long.MAX_VALUE;
> 
> Hello Markus, looking at this code, even with this change, I think we still have a bug here. Once the `transferred` becomes `Long.MAX_VALUE`, if there is a `nextStream()` available, then when we continue in this `while` loop, then this check:
> 
> if (transferred < Long.MAX_VALUE) {
> 
> will prevent it from transfering to the output stream, the next input stream's content and thus ignoring the next stream's content.
> 
> I think what we might want here is something like:
> 
> 
> 
> diff --git a/src/java.base/share/classes/java/io/SequenceInputStream.java b/src/java.base/share/classes/java/io/SequenceInputStream.java
> index de3fafc884d..b89d9ca80b0 100644
> --- a/src/java.base/share/classes/java/io/SequenceInputStream.java
> +++ b/src/java.base/share/classes/java/io/SequenceInputStream.java
> @@ -242,11 +242,14 @@ public long transferTo(OutputStream out) throws IOException {
>          if (getClass() == SequenceInputStream.class) {
>              long transferred = 0;
>              while (in != null) {
> +                long numTransferred = in.transferTo(out);
> +                // increment the total transferred byte count
> +                // only if we haven't already reached the Long.MAX_VALUE
>                  if (transferred < Long.MAX_VALUE) {
>                      try {
> -                        transferred = Math.addExact(transferred, in.transferTo(out));
> +                        transferred = Math.addExact(transferred, numTransferred);
>                      } catch (ArithmeticException ignore) {
> -                        return Long.MAX_VALUE;
> +                        transferred = Long.MAX_VALUE;
>                      }
>                  }
>                  nextStream();
> 
> (I haven't tested it)

@jaikiran Good catch! I have added your proposed solution in https://github.com/openjdk/jdk/pull/17119/commits/8181dccd9217aa5d57b2df0888373904510183df.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/17119#discussion_r1427890488