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tamasvajktamasvajk
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C#: Flow summary for Nullable<T>
1 parent 77abff7 commit faf663a

3 files changed

Lines changed: 84 additions & 1 deletion

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‎csharp/ql/src/semmle/code/csharp/dataflow/LibraryTypeDataFlow.qll‎

Lines changed: 44 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -339,7 +339,7 @@ abstract class LibraryTypeDataFlow extends Type {
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* Holds if data may flow from `source` to `sink` when calling callable `c`.
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*
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* `sourceAp` describes the contents of `source` that flows to `sink`
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* (if any), and `sinkContent` describes the contents of `sink` that it
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* (if any), and `sinkAp` describes the contents of `sink` that it
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* flows to (if any).
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*/
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pragma[nomagic]
@@ -728,6 +728,49 @@ class SystemLazyFlow extends LibraryTypeDataFlow, SystemLazyClass {
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}
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}
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/** Data flow for `System.Nullable<>`. */
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class SystemNullableFlow extends LibraryTypeDataFlow, SystemNullableStruct {
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override predicate callableFlow(
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CallableFlowSource source, AccessPath sourceAp, CallableFlowSink sink, AccessPath sinkAp,
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SourceDeclarationCallable c, boolean preservesValue
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) {
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preservesValue = true and
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c.(Constructor).getDeclaringType() = this and
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source = getFlowSourceArg(c, 0, sourceAp) and
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sourceAp = AccessPath::empty() and
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sink = TCallableFlowSinkReturn() and
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sinkAp = AccessPath::property(this.getValueProperty())
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or
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preservesValue = true and
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c = this.getAGetValueOrDefaultMethod() and
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source = TCallableFlowSourceQualifier() and
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sourceAp = AccessPath::property(this.getValueProperty()) and
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sink = TCallableFlowSinkReturn() and
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sinkAp = AccessPath::empty()
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or
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preservesValue = false and
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c = this.getHasValueProperty().getGetter() and
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source = TCallableFlowSourceQualifier() and
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sourceAp = AccessPath::property(this.getValueProperty()) and
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sink = TCallableFlowSinkReturn() and
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sinkAp = AccessPath::empty()
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or
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preservesValue = true and
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c = this.getAGetValueOrDefaultMethod() and
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source = getFlowSourceArg(c, 0, _) and
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sourceAp = AccessPath::empty() and
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sink = TCallableFlowSinkReturn() and
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sinkAp = AccessPath::empty()
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or
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preservesValue = false and
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c = this.getValueProperty().getGetter() and
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source = TCallableFlowSourceQualifier() and
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sourceAp = AccessPath::empty() and
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sink = TCallableFlowSinkReturn() and
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sinkAp = AccessPath::empty()
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}
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}
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/** Data flow for `System.Collections.IEnumerable` (and sub types). */
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class IEnumerableFlow extends LibraryTypeDataFlow, RefType {
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IEnumerableFlow() { this.getABaseType*() instanceof SystemCollectionsIEnumerableInterface }

‎csharp/ql/src/semmle/code/csharp/frameworks/System.qll‎

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,11 @@ class SystemUnboundGenericClass extends UnboundGenericClass {
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SystemUnboundGenericClass() { this.getNamespace() instanceof SystemNamespace }
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}
2323

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/** An unbound generic struct in the `System` namespace. */
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class SystemUnboundGenericStruct extends UnboundGenericStruct {
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SystemUnboundGenericStruct() { this.getNamespace() instanceof SystemNamespace }
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}
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/** An interface in the `System` namespace. */
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class SystemInterface extends Interface {
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SystemInterface() { this.getNamespace() instanceof SystemNamespace }
@@ -215,6 +220,35 @@ class SystemLazyClass extends SystemUnboundGenericClass {
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}
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}
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/** The `System.Nullable<T>` struct. */
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class SystemNullableStruct extends SystemUnboundGenericStruct {
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SystemNullableStruct() {
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this.hasName("Nullable<>") and
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this.getNumberOfTypeParameters() = 1
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}
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/** Gets the `Value` property. */
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Property getValueProperty() {
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result.getDeclaringType() = this and
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result.hasName("Value") and
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result.getType() = getTypeParameter(0)
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}
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/** Gets the `HasValue` property. */
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Property getHasValueProperty() {
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result.getDeclaringType() = this and
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result.hasName("HasValue") and
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result.getType() instanceof BoolType
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}
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/** Gets a `GetValueOrDefault()` method. */
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Method getAGetValueOrDefaultMethod() {
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result.getDeclaringType() = this and
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result.hasName("GetValueOrDefault") and
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result.getReturnType() = getTypeParameter(0)
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}
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}
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/** The `System.NullReferenceException` class. */
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class SystemNullReferenceExceptionClass extends SystemClass {
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SystemNullReferenceExceptionClass() { this.hasName("NullReferenceException") }

‎csharp/ql/test/library-tests/dataflow/library/LibraryTypeDataFlow.expected‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -494,6 +494,8 @@ callableFlow
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| System.Net.WebUtility.HtmlEncode(string) | argument 0 -> return | false |
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| System.Net.WebUtility.HtmlEncode(string, TextWriter) | argument 0 -> return | false |
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| System.Net.WebUtility.UrlEncode(string) | argument 0 -> return | false |
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| System.Nullable<>.GetValueOrDefault(T) | argument 0 -> return | true |
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| System.Nullable<>.get_Value() | qualifier -> return | false |
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| System.Security.Cryptography.CryptoStream.BeginRead(Byte[], int, int, AsyncCallback, object) | qualifier -> argument 0 | false |
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| System.Security.Cryptography.CryptoStream.BeginWrite(Byte[], int, int, AsyncCallback, object) | argument 0 -> qualifier | false |
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| System.Security.Cryptography.CryptoStream.Read(Byte[], int, int) | qualifier -> argument 0 | false |
@@ -1848,6 +1850,10 @@ callableFlowAccessPath
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| System.Net.NetworkInformation.IPAddressCollection.Add(IPAddress) | argument 0 [<empty>] -> qualifier [[]] | true |
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| System.Net.NetworkInformation.IPAddressCollection.CopyTo(IPAddress[], int) | qualifier [[]] -> argument 0 [[]] | true |
18501852
| System.Net.NetworkInformation.IPAddressCollection.GetEnumerator() | qualifier [[]] -> return [Current] | true |
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| System.Nullable<>.GetValueOrDefault() | qualifier [Value] -> return [<empty>] | true |
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| System.Nullable<>.GetValueOrDefault(T) | qualifier [Value] -> return [<empty>] | true |
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| System.Nullable<>.Nullable(T) | argument 0 [<empty>] -> return [Value] | true |
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| System.Nullable<>.get_HasValue() | qualifier [Value] -> return [<empty>] | false |
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| System.Resources.ResourceReader.GetEnumerator() | qualifier [[]] -> return [Current] | true |
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| System.Resources.ResourceSet.GetEnumerator() | qualifier [[]] -> return [Current] | true |
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| System.Runtime.CompilerServices.ConditionalWeakTable<,>.GetEnumerator() | qualifier [[]] -> return [Current] | true |

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