On Tue, 13 Aug 2024 02:20:41 GMT, David Holmes <dhol...@openjdk.org> wrote:
> This work has been split out from JDK-8328877: [JNI] The JNI Specification > needs to address the limitations of integer UTF-8 String lengths > > The modified UTF-8 format used by the VM can require up to six bytes to > represent one unicode character, but six byte characters are stored as UTF-16 > surrogate pairs. Hence the most bytes per character is 3, and so the maximum > length is 3*`Integer.MAX_VALUE`. Though with compact strings this reduces to > 2*`Integer.MAX_VALUE`. The low-level UTF8/UNICODE API should therefore define > UTF8 lengths as `size_t` to accommodate all possible representations. > Higher-level API's can still use `int` if they know the strings (eg symbols) > are sufficiently constrained in length. See the comments in utf8.hpp that > explain Strings, compact strings and the encoding. > > As the existing JNI `GetStringUTFLength` still requires the current > truncating behaviour of ` UNICODE::utf8_length` we add back > `UNICODE::utf8_length_as_int` for it to use. > > Note that some API's, like ` UNICODE::as_utf8(const T* base, size_t& length)` > use `length` as an IN/OUT parameter: it is the incoming (int) length of the > jbyte/jchar array, and the outgoing (size_t) length of the UTF8 sequence. > This makes some of the call sites a little messy with casts. > > Testing: > - tiers 1-4 > - GHA This pull request has now been integrated. Changeset: a4962ace Author: David Holmes <dhol...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/a4962ace4d3afb36e9d6822a4f02a1515fac40ed Stats: 234 lines in 16 files changed: 112 ins; 5 del; 117 mod 8338257: UTF8 lengths should be size_t not int Reviewed-by: stuefe, coleenp, dlong ------------- PR: https://git.openjdk.org/jdk/pull/20560
