Swift: Additional test cases.

Author: geoffw0

swift/ql/test/query-tests/Security/CWE-135/StringLengthConflation.expected

@@ -73,6 +73,12 @@ nodes
 | StringLengthConflation.swift:138:36:138:46 | ... .-(_:_:) ... | semmle.label | ... .-(_:_:) ... |
 | StringLengthConflation.swift:144:28:144:30 | .count :  | semmle.label | .count :  |
 | StringLengthConflation.swift:144:28:144:38 | ... .-(_:_:) ... | semmle.label | ... .-(_:_:) ... |
+| StringLengthConflation.swift:151:45:151:53 | .count | semmle.label | .count |
+| StringLengthConflation.swift:152:57:152:65 | .count | semmle.label | .count |
+| StringLengthConflation.swift:156:45:156:52 | .count | semmle.label | .count |
+| StringLengthConflation.swift:157:55:157:62 | .count | semmle.label | .count |
+| StringLengthConflation.swift:161:45:161:53 | .count | semmle.label | .count |
+| StringLengthConflation.swift:162:57:162:65 | .count | semmle.label | .count |
 | file://:0:0:0:0 | .length :  | semmle.label | .length :  |
 subpaths
 #select
@@ -111,3 +117,9 @@ subpaths
 | StringLengthConflation.swift:137:34:137:44 | ... .-(_:_:) ... | StringLengthConflation.swift:137:34:137:36 | .count :  | StringLengthConflation.swift:137:34:137:44 | ... .-(_:_:) ... | This String length is used in an NSString, but it may not be equivalent. |
 | StringLengthConflation.swift:138:36:138:46 | ... .-(_:_:) ... | StringLengthConflation.swift:138:36:138:38 | .count :  | StringLengthConflation.swift:138:36:138:46 | ... .-(_:_:) ... | This String length is used in an NSString, but it may not be equivalent. |
 | StringLengthConflation.swift:144:28:144:38 | ... .-(_:_:) ... | StringLengthConflation.swift:144:28:144:30 | .count :  | StringLengthConflation.swift:144:28:144:38 | ... .-(_:_:) ... | This String length is used in an NSString, but it may not be equivalent. |
+| StringLengthConflation.swift:151:45:151:53 | .count | StringLengthConflation.swift:151:45:151:53 | .count | StringLengthConflation.swift:151:45:151:53 | .count | This String.unicodeScalars length is used in a String, but it may not be equivalent. |
+| StringLengthConflation.swift:152:57:152:65 | .count | StringLengthConflation.swift:152:57:152:65 | .count | StringLengthConflation.swift:152:57:152:65 | .count | This String.unicodeScalars length is used in a String, but it may not be equivalent. |
+| StringLengthConflation.swift:156:45:156:52 | .count | StringLengthConflation.swift:156:45:156:52 | .count | StringLengthConflation.swift:156:45:156:52 | .count | This String.utf8 length is used in a String, but it may not be equivalent. |
+| StringLengthConflation.swift:157:55:157:62 | .count | StringLengthConflation.swift:157:55:157:62 | .count | StringLengthConflation.swift:157:55:157:62 | .count | This String.utf8 length is used in a String, but it may not be equivalent. |
+| StringLengthConflation.swift:161:45:161:53 | .count | StringLengthConflation.swift:161:45:161:53 | .count | StringLengthConflation.swift:161:45:161:53 | .count | This String.utf16 length is used in a String, but it may not be equivalent. |
+| StringLengthConflation.swift:162:57:162:65 | .count | StringLengthConflation.swift:162:57:162:65 | .count | StringLengthConflation.swift:162:57:162:65 | .count | This String.unicodeScalars length is used in a String, but it may not be equivalent. |

swift/ql/test/query-tests/Security/CWE-135/StringLengthConflation.swift

@@ -143,6 +143,24 @@ func test(s: String) {
     let nmstr8 = NSMutableString(string: s)
     nmstr8.insert("*", at: s.count - 1) // BAD: String length used in NSString
     print("insert '\(nmstr7)' / '\(nmstr8)'")
+
+    // --- inspired by real world cases ---
+
+    let scalars = s.unicodeScalars
+    let _ = s.index(s.startIndex, offsetBy: s.count) // GOOD
+    let _ = s.index(s.startIndex, offsetBy: scalars.count) // BAD
+    let _ = scalars.index(scalars.startIndex, offsetBy: scalars.count) // GOOD [FALSE POSITIVE]
+    let _ = scalars.index(scalars.startIndex, offsetBy: s.count) // BAD [NOT DETECTED]
+
+    let s_utf8 = s.utf8
+    let _ = s.index(s.startIndex, offsetBy: s_utf8.count) // BAD
+    let _ = s_utf8.index(s_utf8.startIndex, offsetBy: s_utf8.count) // GOOD [FALSE POSITIVE]
+    let _ = s_utf8.index(s_utf8.startIndex, offsetBy: s.count) // BAD [NOT DETECTED]
+
+    let s_utf16 = s.utf16
+    let _ = s.index(s.startIndex, offsetBy: s_utf16.count) // BAD
+    let _ = s_utf16.index(s_utf16.startIndex, offsetBy: scalars.count) // GOOD [FALSE POSITIVE]
+    let _ = s_utf16.index(s_utf16.startIndex, offsetBy: s.count) // BAD [NOT DETECTED]
 }
 
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