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Guard float token boundaries #324

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Merged
dduan merged 1 commit into from
Jul 9, 2026
Merged

Guard float token boundaries #324

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30 changes: 18 additions & 12 deletions Sources/TOMLDecoder/Parsing/Parser.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1164,28 +1164,34 @@ extension Token {
resultCodeUnits.append(bytes[index])
index += 1
}
guard index < text.upperBound else {
throw TOMLError(.invalidFloat(context: context, lineNumber: lineNumber, reason: "expected digit, nan or inf after sign"))
}

if !bytes[index].isDecimalDigit {
guard (
bytes[index] == CodeUnits.lowerN &&
bytes[index + 1] == CodeUnits.lowerA &&
bytes[index + 2] == CodeUnits.lowerN
) ||
(
bytes[index] == CodeUnits.lowerI &&
bytes[index + 1] == CodeUnits.lowerN &&
bytes[index + 2] == CodeUnits.lowerF
)
let nameEnd = index + 3
guard nameEnd == text.upperBound,
(
bytes[index] == CodeUnits.lowerN &&
bytes[index + 1] == CodeUnits.lowerA &&
bytes[index + 2] == CodeUnits.lowerN
) ||
(
bytes[index] == CodeUnits.lowerI &&
bytes[index + 1] == CodeUnits.lowerN &&
bytes[index + 2] == CodeUnits.lowerF
)
else {
throw TOMLError(.invalidFloat(context: context, lineNumber: lineNumber, reason: "Expected nan or inf, found \(bytes[index])"))
}
resultCodeUnits.append(bytes[index])
resultCodeUnits.append(bytes[index + 1])
resultCodeUnits.append(bytes[index + 2])
} else {
let nextIndex = index + 1
if bytes[index] == CodeUnits.number0,
index < text.upperBound,
case let next = bytes[index + 1],
nextIndex < text.upperBound,
case let next = bytes[nextIndex],
next != CodeUnits.dot, next != CodeUnits.lowerE, next != CodeUnits.upperE
{
throw TOMLError(.invalidFloat(context: context, lineNumber: lineNumber, reason: "Float begins with 0 must be followed by a '.', 'e' or 'E'"))
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14 changes: 14 additions & 0 deletions Tests/TOMLDecoderTests/TOMLTableKeyMembershipTests.swift
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Expand Up @@ -59,4 +59,18 @@ struct TOMLTableKeyMembershipTests {
_ = try Dictionary(TOMLTable(source: "x = 0x\n"))
}
}

@Test
func singleZeroFloatAccessorDecodesWithoutTrapping() throws {
let table = try TOMLTable(source: "s = 0\n")

#expect(try table.float(forKey: "s") == 0)
}

@Test(arguments: ["x = +\n", "x = n\n", "x = na\n", "x = i\n", "x = in\n"])
func truncatedFloatThrowsWithoutTrapping(toml: String) throws {
#expect(throws: TOMLError.self) {
_ = try Dictionary(TOMLTable(source: toml))
}
}
}
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