XML: harden parser against malformed input crashes#7555
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ANTLR error recovery synthesizes closing-tag tokens when input ends with an unclosed element, which caused `XmlParserVisitor` to throw `IndexOutOfBoundsException` from `advanceCursor` and `NullPointerException` when accessing `Name(1)`. Clamp `advanceCursor` to the source length and tolerate null `OPEN(1)`/`Name(1)`/`CLOSE(1)` so these inputs fall back to a `ParseError` (preserving original text) instead of crashing. See #7554 (comment)
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Summary
Fixes two crashes in
XmlParserVisitorwhen ANTLR's default error strategy synthesizes closing-tag tokens for malformed XML at EOF:advanceCursorno longer throwsIndexOutOfBoundsExceptionwhen a synthesized token would advance past the end of the source — it clamps tosource.length()instead.visitElementtolerates any combination of nullOPEN(1)/Name(1)/CLOSE(1)tokens so it no longer NPEs when error recovery couldn't produce them.After these changes, all three remaining
rewrite-xmlparse failures reported in "There were problems parsing" should show line number and/or excerpt of source code #7554 (comment) (MarcXmlParserTestSummaryAndKeywords.xml,MarcXmlParserTestArticle.xml,MedlineImporterTestMalformedEntry.xml) parse to aParseErrorthat preserves the original source text instead of throwing.The bare-ampersand and unterminated end-tag cases are intentionally malformed test fixtures — preserving them as a
ParseError(which round-trips the original text) is the documented fallback.Test plan
./gradlew :rewrite-xml:test— 3 new tests added inXmlParserTest, all rewrite-xml suites green