On Mon, 8 Apr 2024 08:54:21 GMT, Raffaello Giulietti <rgiulie...@openjdk.org>
wrote:
>> When encoding a vary large string in String.getBytes(StandardCharset.UTF_8)
>> computation of the buffer size may exceed the range of a positive 32-bit
>> Integer.
>> If the estimated size for the result byte array is too large, pre-compute
>> the exact buffer size.
>> If that exceeds the range, then throw OutOfMemoryError.
>
> test/jdk/java/lang/String/CompactString/MaxSizeUTF16String.java line 143:
>
>> 141: // Strings of size min+1...min+2, throw OOME
>> 142: // The resulting byte array would exceed implementation limits
>> 143: for (int count = min + 1; count < max; count++) {
>
> The case `min + 1` cannot lead to a `NegativeArraySizeException` in the
> current code, since `3 * (min + 1) <= MAX_VALUE`. In theory, it should
> succeed by returning the encoded `byte[]`, although It throws `OOME` for
> exceeding VM limits. That is, this case does not trigger the invocation of
> `computeSizeUTF8_UTF16()` in the proposed fix.
>
> Only `min + 2` throws `NegativeArraySizeException` in the current code, and
> thus the invocation of `computeSizeUTF8_UTF16()` in the proposed fix.
Indeed, different OOMEs are thrown in the two cases triggered by different
limits, min +2 is due to integer overflow, while min +1 is due a VM limit on
the size of byte[Integer.MAX_VALUE]. Different VM implementations may have
different limits. on the max size of a byte array.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/18663#discussion_r1555866610
