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

[Jaikiran Pai]

On Fri, 15 Dec 2023 08:23:58 GMT, Markus KARG <duke at openjdk.org> wrote:

> Fixes JDK-8322141
> 
> As suggested by @vlsi and documented by @bplb this PR does not return, but only sets the maximum result value.

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)

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

PR Review Comment: https://git.openjdk.org/jdk/pull/17119#discussion_r1427766162