Swift: Add taint test of Data.

Author: geoffw0

swift/ql/test/library-tests/dataflow/taint/LocalTaint.expected

@@ -1,3 +1,11 @@
+| data.swift:12:6:12:6 | WriteDef | data.swift:16:12:16:12 | dataClean |
+| data.swift:12:18:12:36 | call to ... | data.swift:12:6:12:6 | WriteDef |
+| data.swift:13:6:13:6 | WriteDef | data.swift:14:26:14:26 | dataTainted |
+| data.swift:13:20:13:38 | call to ... | data.swift:13:6:13:6 | WriteDef |
+| data.swift:14:6:14:6 | WriteDef | data.swift:18:12:18:12 | dataTainted2 |
+| data.swift:14:21:14:37 | call to ... | data.swift:14:6:14:6 | WriteDef |
+| data.swift:14:26:14:26 | dataTainted | data.swift:17:12:17:12 | dataTainted |
+| data.swift:16:12:16:12 | dataClean | data.swift:20:33:20:33 | dataClean |
 | file://:0:0:0:0 | Phi | string.swift:7:14:7:14 | $interpolation |
 | file://:0:0:0:0 | Phi | string.swift:9:14:9:14 | $interpolation |
 | file://:0:0:0:0 | Phi | string.swift:11:14:11:14 | $interpolation |

swift/ql/test/library-tests/dataflow/taint/data.swift

@@ -0,0 +1,25 @@
+
+class Data
+{
+    init<S>(_ elements: S) {}
+}
+
+func source() -> String { return "" }
+func sink(arg: Data) {}
+func sink2(arg: String) {}
+
+func taintThroughData() {
+	let dataClean = Data("123456".utf8)
+	let dataTainted = Data(source().utf8)
+	let dataTainted2 = Data(dataTainted)
+
+	sink(arg: dataClean)
+	sink(arg: dataTainted) // tainted [NOT DETECTED]
+	sink(arg: dataTainted2) // tainted [NOT DETECTED]
+
+	let stringClean = String(data: dataClean, encoding: String.Encoding.utf8)
+	let stringTainted = String(data: dataTainted, encoding: String.Encoding.utf8)
+
+	sink2(arg: stringClean!) // tainted [NOT DETECTED]
+	sink2(arg: stringTainted!) // tainted [NOT DETECTED]
+}