Merge pull request #12511 from phausler/swift-4.0-branch-empty_data_hashing_fix
Ensure that hashing data with zero bytes avoids empty allocations and fix bridged empty data hashes from de-referencing null values
diff --git a/stdlib/public/SDK/Foundation/Data.swift b/stdlib/public/SDK/Foundation/Data.swift
index b8dfff3..acac34f 100644
--- a/stdlib/public/SDK/Foundation/Data.swift
+++ b/stdlib/public/SDK/Foundation/Data.swift
@@ -1627,9 +1627,11 @@
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))
}
diff --git a/test/stdlib/TestData.swift b/test/stdlib/TestData.swift
index f58df85..1f69cf6 100644
--- a/test/stdlib/TestData.swift
+++ b/test/stdlib/TestData.swift
@@ -3656,6 +3656,20 @@
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
@@ -3966,6 +3980,7 @@
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
