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Ensure that hashing data with zero bytes avoids empty allocations and fix bridged empty data hashes from de-referencing null values #12511

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Merged
merged 1 commit into from
Oct 19, 2017
Merged

Ensure that hashing data with zero bytes avoids empty allocations and fix bridged empty data hashes from de-referencing null values #12511

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8 changes: 5 additions & 3 deletions stdlib/public/SDK/Foundation/Data.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1627,9 +1627,11 @@ public struct Data : ReferenceConvertible, Equatable, Hashable, RandomAccessColl
public var hashValue: Int {
var hashValue = 0
let hashRange: Range<Int> = _sliceRange.lowerBound..<Swift.min(_sliceRange.lowerBound + 80, _sliceRange.upperBound)
_withStackOrHeapBuffer(hashRange.count) { buffer in
_backing.withUnsafeBytes(in: hashRange) {
memcpy(buffer.pointee.memory, $0.baseAddress!, hashRange.count)
_withStackOrHeapBuffer(hashRange.count + 1) { buffer in
if hashRange.count > 0 {
_backing.withUnsafeBytes(in: hashRange) {
memcpy(buffer.pointee.memory, $0.baseAddress!, hashRange.count)
}
}
hashValue = Int(bitPattern: CFHashBytes(buffer.pointee.memory.assumingMemoryBound(to: UInt8.self), hashRange.count))
}
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15 changes: 15 additions & 0 deletions test/stdlib/TestData.swift
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Expand Up @@ -3656,6 +3656,20 @@ class TestData : TestDataSuper {
expectEqual(Data(bytes: [0, 1, 2, 3, 4]), regionData[1]) //passes
expectEqual(Data(bytes: [0]), regionData[2]) //fails
}

func test_hashEmptyData() {
let d1 = Data()
let h1 = d1.hashValue

let d2 = NSData() as Data
let h2 = d2.hashValue
expectEqual(h1, h2)

let data = Data(bytes: [0, 1, 2, 3, 4, 5, 6])
let d3 = data[4..<4]
let h3 = d3.hashValue
expectEqual(h1, h3)
}
}

#if !FOUNDATION_XCTEST
Expand Down Expand Up @@ -3966,6 +3980,7 @@ DataTests.test("test_validateMutation_slice_cow_customMutableBacking_replaceSubr
DataTests.test("test_sliceHash") { TestData().test_sliceHash() }
DataTests.test("test_slice_resize_growth") { TestData().test_slice_resize_growth() }
DataTests.test("test_sliceEnumeration") { TestData().test_sliceEnumeration() }
DataTests.test("test_hashEmptyData") { TestData().test_hashEmptyData() }


// XCTest does not have a crash detection, whereas lit does
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