Copilot commented on code in PR #3859:
URL: https://github.com/apache/avro/pull/3859#discussion_r3567569593
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lang/c++/include/avro/Stream.hh:
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@@ -345,6 +356,28 @@ struct StreamReader {
return next_ != end_ || fill();
}
+ /**
+ * Returns the number of bytes still available to be read: those already
+ * buffered in this reader plus whatever the underlying stream reports as
+ * remaining. Returns a negative value when the underlying stream cannot
+ * report its remaining size.
+ */
+ int64_t remainingBytes() const {
+ if (in_ == nullptr) {
+ return -1;
+ }
+ int64_t streamRemaining = in_->remainingBytes();
+ if (streamRemaining < 0) {
+ return -1;
+ }
+ // Bytes already buffered in this reader, added to what the underlying
+ // stream still has. When next_ and end_ are both null (right after
+ // init()/reset(), before any data is buffered), the subtraction is
+ // well-defined and yields 0.
+ int64_t buffered = end_ - next_;
+ return buffered + streamRemaining;
Review Comment:
StreamReader::remainingBytes() performs pointer subtraction (end_ - next_)
even when both pointers are nullptr right after reset()/init(). Pointer
subtraction is only defined for pointers into the same array object;
subtracting null pointers is undefined behavior and can make bytesRemaining()
unreliable on some platforms/optimizations. Compute the buffered byte count
conditionally (treat it as 0 when no buffer has been filled yet) and update the
comment accordingly.
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