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game-activity: tolerate the NULL pre-IME GameTextInput buffer #252

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game-activity: tolerate the NULL pre-IME GameTextInput buffer #252

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14 changes: 12 additions & 2 deletions android-activity/src/game_activity/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -713,8 +713,18 @@ impl AndroidAppInner {
// Java uses a modified UTF-8 format, which is a modified cesu8 format
let out_ptr: *mut TextInputState = context.cast();
let text_modified_utf8: *const u8 = (*state).text_UTF8.cast();
let text_modified_utf8 =
std::slice::from_raw_parts(text_modified_utf8, (*state).text_length as usize);
// Before the IME has attached, GameTextInput hands us its initial
// state with a NULL text buffer (and length 0). `from_raw_parts`
// requires a non-null pointer even for empty slices, so feeding it
// NULL is UB — and under `debug_assertions` the standard library's
// precondition check turns it into an immediate abort (a
// non-unwinding panic inside an `extern "C"` callback) on the first
// frame of every debug build.
let text_modified_utf8 = if text_modified_utf8.is_null() {
&[]
} else {
std::slice::from_raw_parts(text_modified_utf8, (*state).text_length as usize)
};
match simd_cesu8::mutf8::decode(text_modified_utf8) {
Ok(str) => {
let len = str.len();
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