Copilot commented on code in PR #3859:
URL: https://github.com/apache/avro/pull/3859#discussion_r3568231175
##########
lang/c++/include/avro/Stream.hh:
##########
@@ -345,6 +356,30 @@ 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. next_ and end_ can both be null right after
+ // init()/reset() (before any data is buffered); subtracting two null
+ // pointers is undefined behavior, so treat equal pointers (including
the
+ // both-null case) as zero buffered and only subtract real buffer
+ // pointers. Pointer equality, unlike subtraction, is well-defined
here.
+ int64_t buffered = (next_ == end_) ? 0 : (end_ - next_);
+ return buffered + streamRemaining;
Review Comment:
StreamReader::remainingBytes() only treats the both-null case as zero
buffered via (next_ == end_), but if either pointer is null while the other is
not (e.g., after reset() or a failed/partial fill), the expression (end_ -
next_) would still be evaluated and is undefined behavior. Since this method is
meant to be safe to call right after init/reset, it should defensively treat
any null pointer as zero buffered.
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