fix: invalid UTF-8 JSON due to escaped bytes in string literals - #3446
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Lua strings are arbitrary bytes, and the Lua parser converts string literals to their values. For example, '\xff' is byte 255, which isn't a valid UTF-8 byte by itself. As a result, we'd end up sending arbitrary bytes over LSP. LSP requires UTF-8 JSON, so the LSP client (e.g. VS Code) wouldn't be able to process the response from lua-language-server. Instead, ensure that we escape byte values that aren't valid UTF-8, so they don't break our JSON output. In our '\xff' example we can send it in an escaped form: \255 I noticed this when trying to use lua-language-server on its own source code. parser/guide.lua which has the literal '[^%w_\x80-\xff]' which triggered this bug. Fix the escaping, and add tests.
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Lua strings are arbitrary bytes, and the Lua parser converts string literals to their values. For example, '\xff' is byte 255, which isn't a valid UTF-8 byte by itself.
As a result, we'd end up sending arbitrary bytes over LSP. LSP requires UTF-8 JSON, so the LSP client (e.g. VS Code) wouldn't be able to process the response from lua-language-server.
Instead, ensure that we escape byte values that aren't valid UTF-8, so they don't break our JSON output. In our '\xff' example we can send it in an escaped form: \255
I noticed this when trying to use lua-language-server on its own source code. parser/guide.lua which has the literal '[^%w_\x80-\xff]' which triggered this bug.
Fix the escaping, and add tests.