fs: accept uppercase UTF8 encoding in fast paths#63576
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The readFileSync and writeFileSync UTF8 fast paths only accepted lowercase 'utf8' and 'utf-8' encodings. Accept 'UTF8' and 'UTF-8' as well, since they are valid encoding aliases per Buffer.isEncoding(). Refs: nodejs#49888
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It might be fine to leave this as-is, since utf-8 and utf8 are the most commonly used labels and fast paths inherently focus on common cases, and the extra comparisons aren't completely free either
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Summary
Fixes #49888
The and UTF8 fast paths (introduced in #48658 and #49884) only accepted lowercase encoding strings
'utf8'and'utf-8'. The uppercase variants'UTF8'and'UTF-8'are valid encodings (accepted byBuffer.isEncoding()) but were not routed to the fast path, causing them to fall through to the slower generic code path.Changes
lib/fs.js: Extended the fast path checks inreadFileSyncandwriteFileSyncto also accept'UTF8'and'UTF-8'test/parallel/test-fs-utf8-fast-path-encoding.jsverifying all four encoding variants work correctly with both string and object form optionsTesting
New test covers:
writeFileSync(path, data, encoding)— string formreadFileSync(path, encoding)— string formreadFileSync(path, { encoding })— object formwriteFileSync(path, data, { encoding })— object formAll four encoding variants (
'utf8','utf-8','UTF8','UTF-8') are tested with Unicode characters (CJK, emoji) to verify correctness.