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Jul 22, 2024
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rdar://131793235 (Invalid JSON string causes precondition failure) #754

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2 changes: 1 addition & 1 deletion Sources/FoundationEssentials/Decimal/Decimal+Compatibility.swift
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Expand Up @@ -435,7 +435,7 @@ internal func __NSStringToDecimal(
from: string.utf8,
decimalSeparator: ".".utf8,
matchEntireString: false
)
).asOptional
processedLength.pointee = parsed.processedLength
if let parsedResult = parsed.result {
result.pointee = parsedResult
Expand Down
4 changes: 2 additions & 2 deletions Sources/FoundationEssentials/Decimal/Decimal+Conformances.swift
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Expand Up @@ -18,11 +18,11 @@ internal import _ForSwiftFoundation
extension Decimal : CustomStringConvertible {
public init?(string: __shared String, locale: __shared Locale? = nil) {
let decimalSeparator = locale?.decimalSeparator ?? "."
guard let value = Decimal._decimal(
guard case let .success(value, _) = Decimal._decimal(
from: string.utf8,
decimalSeparator: decimalSeparator.utf8,
matchEntireString: false
).result else {
) else {
return nil
}
self = value
Expand Down
107 changes: 61 additions & 46 deletions Sources/FoundationEssentials/Decimal/Decimal.swift
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Expand Up @@ -196,7 +196,7 @@ extension Decimal {
decimalSeparator: String.UTF8View,
matchEntireString: Bool
) -> (result: Decimal?, processedLength: Int) {
_decimal(from: stringView, decimalSeparator: decimalSeparator, matchEntireString: matchEntireString)
_decimal(from: stringView, decimalSeparator: decimalSeparator, matchEntireString: matchEntireString).asOptional
}
#endif
internal func _toString(with locale: Locale? = nil) -> String {
Expand Down Expand Up @@ -250,11 +250,26 @@ extension Decimal {
return String(buffer.reversed())
}

internal static func _decimal(
from stringView: String.UTF8View,
decimalSeparator: String.UTF8View,
internal enum DecimalParseResult {
case success(Decimal, processedLength: Int)
case parseFailure
case overlargeValue

var asOptional: (result: Decimal?, processedLength: Int) {
switch self {
case let .success(decimal, processedLength): (decimal, processedLength: processedLength)
default: (nil, processedLength: 0)
}
}
}

@_specialize(where UTF8Collection == String.UTF8View)
@_specialize(where UTF8Collection == BufferView<UInt8>)
internal static func _decimal<UTF8Collection: Collection>(
from utf8View: UTF8Collection,
decimalSeparator: String.UTF8View = ".".utf8,
matchEntireString: Bool
) -> (result: Decimal?, processedLength: Int) {
) -> DecimalParseResult where UTF8Collection.Element == UTF8.CodeUnit {
func multiplyBy10AndAdd(
_ decimal: Decimal,
number: UInt16
Expand All @@ -268,47 +283,47 @@ extension Decimal {
}
}

func skipWhiteSpaces(from index: String.UTF8View.Index) -> String.UTF8View.Index {
func skipWhiteSpaces(from index: UTF8Collection.Index) -> UTF8Collection.Index {
var i = index
while i != stringView.endIndex &&
Character(utf8Scalar: stringView[i]).isWhitespace {
stringView.formIndex(after: &i)
while i != utf8View.endIndex &&
Character(utf8Scalar: utf8View[i]).isWhitespace {
utf8View.formIndex(after: &i)
}
return i
}

func stringViewContainsDecimalSeparator(at index: String.UTF8View.Index) -> Bool {
func stringViewContainsDecimalSeparator(at index: UTF8Collection.Index) -> Bool {
for indexOffset in 0 ..< decimalSeparator.count {
let stringIndex = stringView.index(index, offsetBy: indexOffset)
let stringIndex = utf8View.index(index, offsetBy: indexOffset)
let decimalIndex = decimalSeparator.index(
decimalSeparator.startIndex,
offsetBy: indexOffset
)
if stringView[stringIndex] != decimalSeparator[decimalIndex] {
if utf8View[stringIndex] != decimalSeparator[decimalIndex] {
return false
}
}
return true
}

var result = Decimal()
var index = stringView.startIndex
var index = utf8View.startIndex
index = skipWhiteSpaces(from: index)
// Get the sign
if index != stringView.endIndex &&
(stringView[index] == UInt8._plus ||
stringView[index] == UInt8._minus) {
result._isNegative = (stringView[index] == UInt8._minus) ? 1 : 0
if index != utf8View.endIndex &&
(utf8View[index] == UInt8._plus ||
utf8View[index] == UInt8._minus) {
result._isNegative = (utf8View[index] == UInt8._minus) ? 1 : 0
// Advance over the sign
stringView.formIndex(after: &index)
utf8View.formIndex(after: &index)
}
// Build mantissa
var tooBigToFit = false

while index != stringView.endIndex,
let digitValue = stringView[index].digitValue {
while index != utf8View.endIndex,
let digitValue = utf8View[index].digitValue {
defer {
stringView.formIndex(after: &index)
utf8View.formIndex(after: &index)
}
// Multiply the value by 10 and add the current digit
func incrementExponent(_ decimal: inout Decimal) {
Expand All @@ -324,7 +339,7 @@ extension Decimal {
if tooBigToFit {
incrementExponent(&result)
if result.isNaN {
return (result: nil, processedLength: 0)
return .overlargeValue
}
continue
}
Expand All @@ -333,20 +348,20 @@ extension Decimal {
tooBigToFit = true
incrementExponent(&result)
if result.isNaN {
return (result: nil, processedLength: 0)
return .overlargeValue
}
continue
}
result = product
}
// Get the decimal point
if index != stringView.endIndex && stringViewContainsDecimalSeparator(at: index) {
stringView.formIndex(&index, offsetBy: decimalSeparator.count)
if index != utf8View.endIndex && stringViewContainsDecimalSeparator(at: index) {
utf8View.formIndex(&index, offsetBy: decimalSeparator.count)
// Continue to build the mantissa
while index != stringView.endIndex,
let digitValue = stringView[index].digitValue {
while index != utf8View.endIndex,
let digitValue = utf8View[index].digitValue {
defer {
stringView.formIndex(after: &index)
utf8View.formIndex(after: &index)
}
guard !tooBigToFit else {
continue
Expand All @@ -360,38 +375,38 @@ extension Decimal {
// Before decrementing the exponent, we need to check
// if it's still possible to decrement.
if result._exponent == Int8.min {
return (result: nil, processedLength: 0)
return .overlargeValue
}
result._exponent -= 1
}
}
// Get the exponent if any
if index != stringView.endIndex && (stringView[index] == UInt8._E || stringView[index] == UInt8._e) {
stringView.formIndex(after: &index)
if index != utf8View.endIndex && (utf8View[index] == UInt8._E || utf8View[index] == UInt8._e) {
utf8View.formIndex(after: &index)
var exponentIsNegative = false
var exponent = 0
// Get the exponent sign
if stringView[index] == UInt8._minus || stringView[index] == UInt8._plus {
exponentIsNegative = stringView[index] == UInt8._minus
stringView.formIndex(after: &index)
if utf8View[index] == UInt8._minus || utf8View[index] == UInt8._plus {
exponentIsNegative = utf8View[index] == UInt8._minus
utf8View.formIndex(after: &index)
}
// Build the exponent
while index != stringView.endIndex,
let digitValue = stringView[index].digitValue {
while index != utf8View.endIndex,
let digitValue = utf8View[index].digitValue {
exponent = 10 * exponent + digitValue
if exponent > 2 * Int(Int8.max) {
// Too big to fit
return (result: nil, processedLength: 0)
return .overlargeValue
}
stringView.formIndex(after: &index)
utf8View.formIndex(after: &index)
}
if exponentIsNegative {
exponent = -exponent
}
// Check to see if it will fit into the exponent field
exponent += Int(result._exponent)
if exponent > Int8.max || exponent < Int8.min {
return (result: nil, processedLength: 0)
return .overlargeValue
}
result._exponent = Int32(exponent)
}
Expand All @@ -401,27 +416,27 @@ extension Decimal {
if matchEntireString {
// Trim end spaces
index = skipWhiteSpaces(from: index)
guard index == stringView.endIndex else {
guard index == utf8View.endIndex else {
// Any unprocessed content means the string
// contains something not valid
return (result: nil, processedLength: 0)
return .parseFailure
}
}
if index == stringView.startIndex {
if index == utf8View.startIndex {
// If we weren't able to process any character
// the entire string isn't a valid decimal
return (result: nil, processedLength: 0)
return .parseFailure
}
result.compact()
let processedLength = stringView.distance(from: stringView.startIndex, to: index)
let processedLength = utf8View.distance(from: utf8View.startIndex, to: index)
// if we get to this point, and have NaN,
// then the input string was probably "-0"
// or some variation on that, and
// normalize that to zero.
if result.isNaN {
return (result: Decimal(0), processedLength: processedLength)
return .success(Decimal(0), processedLength: processedLength)
}
return (result: result, processedLength: processedLength)
return .success(result, processedLength: processedLength)
}
}

Expand Down
40 changes: 17 additions & 23 deletions Sources/FoundationEssentials/JSON/JSONDecoder.swift
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Expand Up @@ -727,20 +727,27 @@ extension JSONDecoderImpl: Decoder {
// TODO: Proper handling of Infinity and NaN Decimal values.
return Decimal.quietNaN
} else {
let numberString = String(decoding: numberBuffer, as: UTF8.self)
if let decimal = Decimal(entire: numberString) {
return decimal
switch Decimal._decimal(from: numberBuffer, matchEntireString: true) {
case .success(let result, _):
return result
case .overlargeValue:
throw JSONError.numberIsNotRepresentableInSwift(parsed: String(decoding: numberBuffer, as: UTF8.self))
case .parseFailure:
throw JSON5Scanner.validateNumber(from: numberBuffer.suffix(from: digitsStartPtr), fullSource: fullSource)
}
throw JSON5Scanner.validateNumber(from: numberBuffer.suffix(from: digitsStartPtr), fullSource: fullSource)

}

} else {
let digitsStartPtr = try JSONScanner.prevalidateJSONNumber(from: numberBuffer, hasExponent: hasExponent, fullSource: fullSource)
let numberString = String(decoding: numberBuffer, as: UTF8.self)
if let decimal = Decimal(entire: numberString) {
return decimal
switch Decimal._decimal(from: numberBuffer, matchEntireString: true) {
case .success(let result, _):
return result
case .overlargeValue:
throw JSONError.numberIsNotRepresentableInSwift(parsed: String(decoding: numberBuffer, as: UTF8.self))
case .parseFailure:
throw JSONScanner.validateNumber(from: numberBuffer.suffix(from: digitsStartPtr), fullSource: fullSource)
}
throw JSONScanner.validateNumber(from: numberBuffer.suffix(from: digitsStartPtr), fullSource: fullSource)
}
}
}
Expand Down Expand Up @@ -996,8 +1003,8 @@ extension JSONDecoderImpl: Decoder {
}
}

let number = String(decoding: numberBuffer, as: Unicode.ASCII.self)
if let decimal = Decimal(entire: number) {
let decimalParseResult = Decimal._decimal(from: numberBuffer, matchEntireString: true).asOptional
if let decimal = decimalParseResult.result {
guard let value = T(decimal) else {
throw JSONError.numberIsNotRepresentableInSwift(parsed: String(decoding: numberBuffer, as: UTF8.self))
}
Expand Down Expand Up @@ -1072,19 +1079,6 @@ extension FixedWidthInteger {
}
}

extension Decimal {
init?(entire string: String) {
guard let value = Decimal._decimal(
from: string.utf8,
decimalSeparator: ".".utf8,
matchEntireString: true
).result else {
return nil
}
self = value
}
}

extension JSONDecoderImpl : SingleValueDecodingContainer {
func decodeNil() -> Bool {
switch topValue {
Expand Down
5 changes: 5 additions & 0 deletions Tests/FoundationEssentialsTests/JSONEncoderTests.swift
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Expand Up @@ -2613,6 +2613,11 @@ extension JSONEncoderTests {
let testBigDecimal = TestBigDecimal()
_testRoundTrip(of: testBigDecimal)
}

func testOverlargeDecimal() {
// Check value too large fails to decode.
XCTAssertThrowsError(try JSONDecoder().decode(Decimal.self, from: "100e200".data(using: .utf8)!))
}
}

// MARK: - Framework-only tests
Expand Down