Fix: Bridge JNI strings as standard UTF-8 - #128
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## fix/jni-boundary-correctness #128 +/- ##
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Coverage 72.25% 72.25%
Complexity 38 38
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Files 62 62
Lines 2350 2350
Branches 286 286
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Hits 1698 1698
Misses 493 493
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GetStringUTFChars and NewStringUTF operate in JNI modified UTF-8: supplementary-plane characters such as emoji become CESU-8 surrogate pairs the Rust FFI rejects on the way in, and NewStringUTF on a genuine 4-byte UTF-8 sequence from the core is undefined behavior that aborts under CheckJNI on the way out. The string helpers now transcode through UTF-16 (GetStringChars/NewString) with an explicit standard UTF-8 encoder and decoder in native code, mapping malformed input to U+FFFD in both directions. All call sites, the String array path, and every Kotlin signature are unchanged. Adds a shared test round-tripping a manifest title with supplementary-plane characters through sign and read.
The UTF-8 encoder wrote U+0000 as a literal zero byte, so a Kotlin string containing it reached the core as a NUL-terminated string cut short at that point. Before the standard-UTF-8 bridge, modified UTF-8 encoded it as C0 80, which the core rejected as invalid, so the input failed loudly instead of being truncated. Treat U+0000 as invalid input in jstring_to_cstring: free the buffer and throw IllegalArgumentException. Callers already handle the NULL return with an exception pending. Add a shared test that a remote URL containing U+0000 is rejected. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The strdup existed when jstring_to_cstring returned a JVM-pinned buffer that had to be released before the local ref. It now returns a malloc'd buffer and release_cstring_array frees each element, so store the conversion directly. This also removes a double throw: when the conversion failed, the OutOfMemoryError was raised on top of the exception the conversion had already left pending. Document why release_cstring keeps its unused env and jstr parameters. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Changes in this pull request
Replaces the modified-UTF-8 string bridging (GetStringUTFChars/NewStringUTF) with a UTF-16 transcode and explicit standard UTF-8 conversion in native code, so supplementary-plane characters like emoji survive the JNI boundary instead of being CESU-8-mangled inbound or hitting undefined behavior outbound. Confined entirely to the two string helpers — no call-site or Kotlin changes — with a round-trip test for a manifest title containing supplementary-plane characters.
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