On Mon, 30 Oct 2023 18:34:44 GMT, Roger Riggs <rri...@openjdk.org> wrote:
> Strings, after construction, are immutable but may be constructed from > mutable arrays of bytes, characters, or integers. > The string constructors should guard against the effects of mutating the > arrays during construction that might invalidate internal invariants for the > correct behavior of operations on the resulting strings. In particular, a > number of operations have optimizations for operations on pairs of latin1 > strings and pairs of non-latin1 strings, while operations between latin1 and > non-latin1 strings use a more general implementation. > > The changes include: > > - Adding a warning to each constructor with an array as an argument to > indicate that the results are indeterminate > if the input array is modified before the constructor returns. > The resulting string may contain any combination of characters sampled from > the input array. > > - Ensure that strings that are represented as non-latin1 contain at least one > non-latin1 character. > For latin1 inputs, whether the arrays contain ASCII, ISO-8859-1, UTF8, or > another encoding decoded to latin1 the scanning and compression is unchanged. > If a non-latin1 character is found, the string is represented as non-latin1 > with the added verification that a non-latin1 character is present at the > same index. > If that character is found to be latin1, then the input array has been > modified and the result of the scan may be incorrect. > Though a ConcurrentModificationException could be thrown, the risk to an > existing application of an unexpected exception should be avoided. > Instead, the non-latin1 copy of the input is re-scanned and compressed; > that scan determines whether the latin1 or the non-latin1 representation is > returned. > > - The methods that scan for non-latin1 characters and their intrinsic > implementations are updated to return the index of the non-latin1 character. > > - String construction from StringBuilder and CharSequence must also be > guarded as their contents may be modified during construction. This pull request has now been integrated. Changeset: 155abc57 Author: Roger Riggs <rri...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/155abc576a0212932825485380d4e2a9c7dd2fdc Stats: 1415 lines in 15 files changed: 1162 ins; 110 del; 143 mod 8311906: Improve robustness of String constructors with mutable array inputs Co-authored-by: Damon Fenacci <dfena...@openjdk.org> Co-authored-by: Claes Redestad <redes...@openjdk.org> Co-authored-by: Amit Kumar <amitku...@openjdk.org> Co-authored-by: Martin Doerr <mdo...@openjdk.org> Reviewed-by: rgiulietti, thartmann, redestad, dfenacci ------------- PR: https://git.openjdk.org/jdk/pull/16425
