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SR-13837: Swift Decimal type crashes on a specific double value #2926

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Merged
merged 1 commit into from
Dec 12, 2020
Merged

SR-13837: Swift Decimal type crashes on a specific double value #2926

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32 changes: 27 additions & 5 deletions Sources/Foundation/Decimal.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ public struct Decimal {
return Int32(__exponent)
}
set {
__exponent = Int8(truncatingIfNeeded: newValue)
__exponent = Int8(newValue)
}
}

Expand Down Expand Up @@ -83,8 +83,9 @@ public struct Decimal {
}

public init(_exponent: Int32, _length: UInt32, _isNegative: UInt32, _isCompact: UInt32, _reserved: UInt32, _mantissa: (UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16)) {
precondition(_length <= 15)
self._mantissa = _mantissa
self.__exponent = Int8(truncatingIfNeeded: _exponent)
self.__exponent = Int8(_exponent)
self.__lengthAndFlags = UInt8(_length & 0b1111)
self.__reserved = 0
self._isNegative = _isNegative
Expand Down Expand Up @@ -625,16 +626,36 @@ extension Decimal {
self = Decimal()
let negative = value < 0
var val = negative ? -1 * value : value
var exponent = 0
var exponent: Int8 = 0

// Try to get val as close to UInt64.max whilst adjusting the exponent
// to reduce the number of digits after the decimal point.
while val < Double(UInt64.max - 1) {
guard exponent > Int8.min else {
setNaN()
return
}
val *= 10.0
exponent -= 1
}
while Double(UInt64.max - 1) < val {
while Double(UInt64.max) <= val {
guard exponent < Int8.max else {
setNaN()
return
}
val /= 10.0
exponent += 1
}
var mantissa = UInt64(val)

var mantissa: UInt64
let maxMantissa = Double(UInt64.max).nextDown
if val > maxMantissa {
// UInt64(Double(UInt64.max)) gives an overflow error, this is the largest
// mantissa that can be set.
mantissa = UInt64(maxMantissa)
} else {
mantissa = UInt64(val)
}

var i: Int32 = 0
// This is a bit ugly but it is the closest approximation of the C
Expand Down Expand Up @@ -1922,6 +1943,7 @@ extension Decimal {
fileprivate static let maxSize: UInt32 = UInt32(NSDecimalMaxSize)

fileprivate init(length: UInt32, mantissa: (UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16)) {
precondition(length <= 15)
self._mantissa = mantissa
self.__exponent = 0
self.__lengthAndFlags = 0
Expand Down
57 changes: 55 additions & 2 deletions Tests/Foundation/Tests/TestDecimal.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,7 @@ class TestDecimal: XCTestCase {
XCTAssertEqual(d1._exponent, 0)
XCTAssertEqual(d1._length, 4)
}

func test_Constants() {
XCTAssertEqual(8, NSDecimalMaxSize)
XCTAssertEqual(32767, NSDecimalNoScale)
Expand Down Expand Up @@ -217,8 +218,8 @@ class TestDecimal: XCTestCase {
let reserved: UInt32 = (1<<18 as UInt32) + (1<<17 as UInt32) + 1
let mantissa: (UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16, UInt16) = (6, 7, 8, 9, 10, 11, 12, 13)
var explicit = Decimal(
_exponent: 0x17f,
_length: 0xff,
_exponent: 0x7f,
_length: 0x0f,
_isNegative: 3,
_isCompact: 4,
_reserved: reserved,
Expand Down Expand Up @@ -501,6 +502,11 @@ class TestDecimal: XCTestCase {
XCTAssertTrue(NSDecimalIsNotANumber(&result), "NaN e5")

XCTAssertFalse(Double(truncating: NSDecimalNumber(decimal: Decimal(0))).isNaN)
XCTAssertTrue(Decimal(Double.leastNonzeroMagnitude).isNaN)
XCTAssertTrue(Decimal(Double.leastNormalMagnitude).isNaN)
XCTAssertTrue(Decimal(Double.greatestFiniteMagnitude).isNaN)
XCTAssertTrue(Decimal(Double("1e-129")!).isNaN)
XCTAssertTrue(Decimal(Double("0.1e-128")!).isNaN)
}

func test_NegativeAndZeroMultiplication() {
Expand Down Expand Up @@ -827,6 +833,52 @@ class TestDecimal: XCTestCase {
XCTAssertEqual(1, negativeSix.raising(toPower: 0))
}

func test_parseDouble() throws {
XCTAssertEqual(Decimal(Double(0.0)), Decimal(Int.zero))
XCTAssertEqual(Decimal(Double(-0.0)), Decimal(Int.zero))

// These values can only be represented as Decimal.nan
XCTAssertEqual(Decimal(Double.nan), Decimal.nan)
XCTAssertEqual(Decimal(Double.signalingNaN), Decimal.nan)

// These values are out out range for Decimal
XCTAssertEqual(Decimal(-Double.leastNonzeroMagnitude), Decimal.nan)
XCTAssertEqual(Decimal(Double.leastNonzeroMagnitude), Decimal.nan)
XCTAssertEqual(Decimal(-Double.leastNormalMagnitude), Decimal.nan)
XCTAssertEqual(Decimal(Double.leastNormalMagnitude), Decimal.nan)
XCTAssertEqual(Decimal(-Double.greatestFiniteMagnitude), Decimal.nan)
XCTAssertEqual(Decimal(Double.greatestFiniteMagnitude), Decimal.nan)

// SR-13837
let testDoubles: [(Double, String)] = [
(1.8446744073709550E18, "1844674407370954752"),
(1.8446744073709551E18, "1844674407370954752"),
(1.8446744073709552E18, "1844674407370955264"),
(1.8446744073709553E18, "1844674407370955264"),
(1.8446744073709554E18, "1844674407370955520"),
(1.8446744073709555E18, "1844674407370955520"),

(1.8446744073709550E19, "18446744073709547520"),
(1.8446744073709551E19, "18446744073709552640"),
(1.8446744073709552E19, "18446744073709552640"),
(1.8446744073709553E19, "18446744073709552640"),
(1.8446744073709554E19, "18446744073709555200"),
(1.8446744073709555E19, "18446744073709555200"),

(1.8446744073709550E20, "184467440737095526400"),
(1.8446744073709551E20, "184467440737095526400"),
(1.8446744073709552E20, "184467440737095526400"),
(1.8446744073709553E20, "184467440737095526400"),
(1.8446744073709554E20, "184467440737095552000"),
(1.8446744073709555E20, "184467440737095552000"),
]

for (d, s) in testDoubles {
XCTAssertEqual(Decimal(d), Decimal(string: s))
XCTAssertEqual(Decimal(d).description, try XCTUnwrap(Decimal(string: s)).description)
}
}

func test_doubleValue() {
XCTAssertEqual(NSDecimalNumber(decimal:Decimal(0)).doubleValue, 0)
XCTAssertEqual(NSDecimalNumber(decimal:Decimal(1)).doubleValue, 1)
Expand Down Expand Up @@ -1302,6 +1354,7 @@ class TestDecimal: XCTestCase {
("test_SimpleMultiplication", test_SimpleMultiplication),
("test_SmallerNumbers", test_SmallerNumbers),
("test_ZeroPower", test_ZeroPower),
("test_parseDouble", test_parseDouble),
("test_doubleValue", test_doubleValue),
("test_NSDecimalNumberValues", test_NSDecimalNumberValues),
("test_bridging", test_bridging),
Expand Down
2 changes: 1 addition & 1 deletion Tests/Foundation/Tests/TestJSONEncoder.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@ class TestJSONEncoder : XCTestCase {
_testFragment(value: true, fragment: "true")
_testFragment(value: Float(1), fragment: "1")
_testFragment(value: Double(2), fragment: "2")
_testFragment(value: Decimal(Double.leastNormalMagnitude), fragment: "0.0000000000000000000000000000000000000000000000000002225073858507201792")
_testFragment(value: Decimal(Double(Float.leastNormalMagnitude)), fragment: "0.000000000000000000000000000000000000011754943508222875648")
_testFragment(value: "test", fragment: "\"test\"")
let v: Int? = nil
_testFragment(value: v, fragment: "null")
Expand Down
33 changes: 17 additions & 16 deletions Tests/Foundation/Tests/TestJSONSerialization.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -968,8 +968,9 @@ extension TestJSONSerialization {
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSNumber(value: true), NSNumber(value: Float.greatestFiniteMagnitude), NSNumber(value: Double.greatestFiniteMagnitude)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSNumber(value: Int.max), NSNumber(value: Int8.max), NSNumber(value: Int16.max), NSNumber(value: Int32.max), NSNumber(value: Int64.max)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSNumber(value: UInt.max), NSNumber(value: UInt8.max), NSNumber(value: UInt16.max), NSNumber(value: UInt32.max), NSNumber(value: UInt64.max)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSDecimalNumber(booleanLiteral: true), NSDecimalNumber(decimal: Decimal.greatestFiniteMagnitude), NSDecimalNumber(floatLiteral: Double.greatestFiniteMagnitude), NSDecimalNumber(integerLiteral: Int.min)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([Decimal(123), Decimal(Double.leastNonzeroMagnitude)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSDecimalNumber(booleanLiteral: true), NSDecimalNumber(decimal: Decimal.greatestFiniteMagnitude)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([NSDecimalNumber(floatLiteral: Double(Float.greatestFiniteMagnitude)), NSDecimalNumber(integerLiteral: Int.min)]))
XCTAssertTrue(JSONSerialization.isValidJSONObject([Decimal(123), Decimal(Double(Float.leastNonzeroMagnitude))]))

XCTAssertFalse(JSONSerialization.isValidJSONObject(Float.nan))
XCTAssertFalse(JSONSerialization.isValidJSONObject(Float.infinity))
Expand Down Expand Up @@ -1320,19 +1321,19 @@ extension TestJSONSerialization {
}

func test_serialize_NSDecimalNumber() {
let dn0: [Any] = [NSDecimalNumber(floatLiteral: -Double.leastNonzeroMagnitude)]
let dn1: [Any] = [NSDecimalNumber(floatLiteral: Double.leastNonzeroMagnitude)]
let dn2: [Any] = [NSDecimalNumber(floatLiteral: -Double.leastNormalMagnitude)]
let dn3: [Any] = [NSDecimalNumber(floatLiteral: Double.leastNormalMagnitude)]
let dn4: [Any] = [NSDecimalNumber(floatLiteral: -Double.greatestFiniteMagnitude)]
let dn5: [Any] = [NSDecimalNumber(floatLiteral: Double.greatestFiniteMagnitude)]

XCTAssertEqual(try trySerialize(dn0), "[-0.00000000000000000000000000000000000000000000000000000000000000000004940656458412464128]")
XCTAssertEqual(try trySerialize(dn1), "[0.00000000000000000000000000000000000000000000000000000000000000000004940656458412464128]")
XCTAssertEqual(try trySerialize(dn2), "[-0.0000000000000000000000000000000000000000000000000002225073858507201792]")
XCTAssertEqual(try trySerialize(dn3), "[0.0000000000000000000000000000000000000000000000000002225073858507201792]")
XCTAssertEqual(try trySerialize(dn4), "[-17976931348623167488000000000000000000000000000000000]")
XCTAssertEqual(try trySerialize(dn5), "[17976931348623167488000000000000000000000000000000000]")
let dn0: [Any] = [NSDecimalNumber(floatLiteral: Double(-Float.leastNonzeroMagnitude))]
let dn1: [Any] = [NSDecimalNumber(floatLiteral: Double(Float.leastNonzeroMagnitude))]
let dn2: [Any] = [NSDecimalNumber(floatLiteral: Double(-Float.leastNormalMagnitude))]
let dn3: [Any] = [NSDecimalNumber(floatLiteral: Double(Float.leastNormalMagnitude))]
let dn4: [Any] = [NSDecimalNumber(floatLiteral: Double(-Float.greatestFiniteMagnitude))]
let dn5: [Any] = [NSDecimalNumber(floatLiteral: Double(Float.greatestFiniteMagnitude))]

XCTAssertEqual(try trySerialize(dn0), "[-0.0000000000000000000000000000000000000000000014012984643248173056]")
XCTAssertEqual(try trySerialize(dn1), "[0.0000000000000000000000000000000000000000000014012984643248173056]")
XCTAssertEqual(try trySerialize(dn2), "[-0.000000000000000000000000000000000000011754943508222875648]")
XCTAssertEqual(try trySerialize(dn3), "[0.000000000000000000000000000000000000011754943508222875648]")
XCTAssertEqual(try trySerialize(dn4), "[-340282346638528921600000000000000000000]")
XCTAssertEqual(try trySerialize(dn5), "[340282346638528921600000000000000000000]")
XCTAssertEqual(try trySerialize([NSDecimalNumber(string: "0.0001"), NSDecimalNumber(string: "0.00"), NSDecimalNumber(string: "-0.0")]), "[0.0001,0,0]")
XCTAssertEqual(try trySerialize([NSDecimalNumber(integerLiteral: Int(Int16.min)), NSDecimalNumber(integerLiteral: 0), NSDecimalNumber(integerLiteral: Int(Int16.max))]), "[-32768,0,32767]")
XCTAssertEqual(try trySerialize([NSDecimalNumber(booleanLiteral: true), NSDecimalNumber(booleanLiteral: false)]), "[1,0]")
Expand Down Expand Up @@ -1379,7 +1380,7 @@ extension TestJSONSerialization {
XCTAssertEqual(try trySerialize(true, options: .fragmentsAllowed), "true")
XCTAssertEqual(try trySerialize(Float(1), options: .fragmentsAllowed), "1")
XCTAssertEqual(try trySerialize(Double(2), options: .fragmentsAllowed), "2")
XCTAssertEqual(try trySerialize(Decimal(Double.leastNormalMagnitude), options: .fragmentsAllowed), "0.0000000000000000000000000000000000000000000000000002225073858507201792")
XCTAssertEqual(try trySerialize(Decimal(Double(Float.leastNormalMagnitude)), options: .fragmentsAllowed), "0.000000000000000000000000000000000000011754943508222875648")
XCTAssertEqual(try trySerialize("test", options: .fragmentsAllowed), "\"test\"")
}

Expand Down