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NSDateComponents.hash: Fix arithmetic overflows #1645

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NSDateComponents.hash: Fix arithmetic overflows #1645

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123 changes: 84 additions & 39 deletions Foundation/NSCalendar.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1276,49 +1276,94 @@ open class NSDateComponents : NSObject, NSCopying, NSSecureCoding {
public override init() {
super.init()
}

open override var hash: Int {
var calHash = 0
if let cal = calendar {
calHash = cal.hashValue
}
if let tz = timeZone {
calHash ^= tz.hashValue
}
var y = year
if NSDateComponentUndefined == y {
y = 0
}
var m = month
if NSDateComponentUndefined == m {
m = 0
}
var d = day
if NSDateComponentUndefined == d {
d = 0
}
var h = hour
if NSDateComponentUndefined == h {
h = 0
}
var mm = minute
if NSDateComponentUndefined == mm {
mm = 0
}
var s = second
if NSDateComponentUndefined == s {
s = 0
}
var yy = yearForWeekOfYear
if NSDateComponentUndefined == yy {
yy = 0
}
return calHash + (32832013 * (y + yy) + 2678437 * m + 86413 * d + 3607 * h + 61 * mm + s) + (41 * weekOfYear + 11 * weekOfMonth + 7 * weekday + 3 * weekdayOrdinal + quarter) * (1 << 5)
var hasher = Hasher()
var mask = 0
// The list of fields fed to the hasher here must be exactly
// the same as the ones compared in isEqual(_:) (modulo
// ordering).
//
// Given that NSDateComponents instances usually only have a
// few fields present, it makes sense to only hash those, as
// an optimization. We keep track of the fields hashed in the
// mask value, which we also feed to the hasher to make sure
// any two unequal values produce different hash encodings.
//
// FIXME: Why not just feed _values, calendar & timeZone to
// the hasher?
if let calendar = calendar {
hasher.combine(calendar)
mask |= 1 << 0
}
if let timeZone = timeZone {
hasher.combine(timeZone)
mask |= 1 << 1
}
if era != NSDateComponentUndefined {
hasher.combine(era)
mask |= 1 << 2
}
if year != NSDateComponentUndefined {
hasher.combine(year)
mask |= 1 << 3
}
if quarter != NSDateComponentUndefined {
hasher.combine(quarter)
mask |= 1 << 4
}
if month != NSDateComponentUndefined {
hasher.combine(month)
mask |= 1 << 5
}
if day != NSDateComponentUndefined {
hasher.combine(day)
mask |= 1 << 6
}
if hour != NSDateComponentUndefined {
hasher.combine(hour)
mask |= 1 << 7
}
if minute != NSDateComponentUndefined {
hasher.combine(minute)
mask |= 1 << 8
}
if second != NSDateComponentUndefined {
hasher.combine(second)
mask |= 1 << 9
}
if nanosecond != NSDateComponentUndefined {
hasher.combine(nanosecond)
mask |= 1 << 10
}
if weekOfYear != NSDateComponentUndefined {
hasher.combine(weekOfYear)
mask |= 1 << 11
}
if weekOfMonth != NSDateComponentUndefined {
hasher.combine(weekOfMonth)
mask |= 1 << 12
}
if yearForWeekOfYear != NSDateComponentUndefined {
hasher.combine(yearForWeekOfYear)
mask |= 1 << 13
}
if weekday != NSDateComponentUndefined {
hasher.combine(weekday)
mask |= 1 << 14
}
if weekdayOrdinal != NSDateComponentUndefined {
hasher.combine(weekdayOrdinal)
mask |= 1 << 15
}
hasher.combine(isLeapMonth)
hasher.combine(mask)
return hasher.finalize()
}

open override func isEqual(_ object: Any?) -> Bool {
guard let other = object as? NSDateComponents else { return false }

// FIXME: Why not just compare _values, calendar & timeZone?
return self === other
|| (era == other.era
&& year == other.year
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16 changes: 16 additions & 0 deletions TestFoundation/TestCalendar.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -198,10 +198,26 @@ class TestNSDateComponents: XCTestCase {

static var allTests: [(String, (TestNSDateComponents) -> () throws -> Void)] {
return [
("test_hash", test_hash),
("test_copyNSDateComponents", test_copyNSDateComponents),
]
}

func test_hash() {
let c1 = NSDateComponents()
c1.year = 2018
c1.month = 8
c1.day = 1

let c2 = NSDateComponents()
c2.year = 2018
c2.month = 8
c2.day = 1

XCTAssertEqual(c1, c2)
XCTAssertEqual(c1.hash, c2.hash)
}

func test_copyNSDateComponents() {
let components = NSDateComponents()
components.year = 1987
Expand Down