fix(mail): improve Japanese charset decoding reliability on Android#10883
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kaberingo wants to merge 1 commit intothunderbird:mainfrom
Open
fix(mail): improve Japanese charset decoding reliability on Android#10883kaberingo wants to merge 1 commit intothunderbird:mainfrom
kaberingo wants to merge 1 commit intothunderbird:mainfrom
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- Normalize Shift-JIS aliases (shift-jis, sjis, ms932, windows-31j, x-sjis, x-ms-cp932) to shift_jis for consistent handling - Add EUC-JP fallback aliases (x-euc-jp, euc_jp) to the charset fallback map - Always use Iso2022JpToShiftJisInputStream for iso-2022-jp decoding to bypass Android ICU4J's unreliable QP-decoded byte sequence handling, which could cause ESC bytes and "$B"/"(B" escape remnants to appear as literal text - Auto-detect ISO-2022-JP when Content-Type has no charset parameter by scanning for ESC$B / ESC$@ escape sequences, fixing garbled output from Japanese feature phones and carrier webmail that omit the charset header - Implement getAddressFromReceivedHeader() in JisSupport to properly extract addresses from the "for" clause of Received headers (both angle-bracket and bare address forms), enabling correct JIS variant detection Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
This PR improves Japanese email rendering on Android by fixing several
charset handling issues in
CharsetSupportandJisSupport.Changes
CharsetSupport
shift-jis,sjis,ms932,windows-31j,x-sjis,x-ms-cp932) toshift_jisx-euc-jp,euc_jp) to the charsetfallback map
iso-2022-jpthroughIso2022JpToShiftJisInputStreaminstead of relying on Android's ICU4J decoder, which silently
mishandles QP-decoded byte sequences and causes ESC bytes or
$B/(Bescape remnants to appear as literal text
Content-Typehas nocharsetparameterby scanning for
ESC$B/ESC$@escape sequences — Japanese featurephones and carrier webmail systems commonly omit the charset header,
causing garbled output (e.g.
$BJIC...) when decoded as US-ASCIIJisSupport
getAddressFromReceivedHeader()(was a no-op stub) tocorrectly parse the recipient address from the
forclause ofReceivedheaders, enabling proper JIS variant detection for DoCoMo,SoftBank, and KDDI carrier mail
Testing
Unit tests added/updated for all new logic:
CharsetSupportTest: Shift-JIS alias normalization, EUC-JP aliasfallback,
hasIso2022JpEscapeSequence()edge casesMessageExtractorTest: QP-encoded ISO-2022-JP with/without charsetheader, multi-line bodies, raw 7-bit bodies
JisSupportTest(new): carrier address detection viaFromandReceivedheaders, iPhone mailer detection