DynamicTablesPkg: Clear pointer in node creation fcts

The following functions:
- AmlCreateRootNode()
- AmlCreateObjectNode()
- AmlCreateDataNode()
create a node and return it by populating a pointer. This pointer
should only be considered/used if the function returns successfully.
Otherwise, the value stored in this pointer should be ignored.

For their error handling, some other functions assume that this
pointer is reset to NULL if an error occurs during a node creation.
To make this assumption correct, explicitly clear this input pointer.

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>

DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c

@@ -22,7 +22,9 @@
   @param [in]  Node           Newly created node.
   @param [in]  ParentNode     If provided, set ParentNode as the parent
                               of the node created.
-  @param [out] NewObjectNode  If success, contains the created object node.
+  @param [out] NewObjectNode  If not NULL:
+                               - and Success, contains the created Node.
+                               - and Error, reset to NULL.
 
   @retval  EFI_SUCCESS            The function completed successfully.
   @retval  EFI_INVALID_PARAMETER  Invalid parameter.
@@ -39,7 +41,7 @@ LinkNode (
   EFI_STATUS    Status;
 
   if (NewObjectNode != NULL) {
-    *NewObjectNode = Node;
+    *NewObjectNode = NULL;
   }
 
   // Add RdNode as the last element.
@@ -51,6 +53,10 @@ LinkNode (
     }
   }
 
+  if (NewObjectNode != NULL) {
+    *NewObjectNode = Node;
+  }
+
   return EFI_SUCCESS;
 }
 

DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.c

@@ -33,7 +33,9 @@
                             RdNode is then added at the end of the variable
                             list of resource data elements, but before the
                             "End Tag" Resource Data.
-  @param [out] NewRdNode    If not NULL, update the its value to RdNode.
+  @param [out] NewRdNode    If not NULL:
+                             - and Success, contains RdNode.
+                             - and Error, reset to NULL.
 
   @retval  EFI_SUCCESS            The function completed successfully.
   @retval  EFI_INVALID_PARAMETER  Invalid parameter.
@@ -52,7 +54,7 @@ LinkRdNode (
   AML_OBJECT_NODE   *BufferOpNode;
 
   if (NewRdNode != NULL) {
-    *NewRdNode = RdNode;
+    *NewRdNode = NULL;
   }
 
   if (ParentNode != NULL) {
@@ -85,6 +87,10 @@ LinkRdNode (
     }
   }
 
+  if (NewRdNode != NULL) {
+    *NewRdNode = RdNode;
+  }
+
   return Status;
 
 error_handler:

DynamicTablesPkg/Library/Common/AmlLib/Tree/AmlNode.c

@@ -79,7 +79,9 @@ AmlDeleteRootNode (
 
   @param  [in]  SdtHeader       Pointer to an ACPI DSDT/SSDT header to copy
                                 the data from.
-  @param  [out] NewRootNodePtr  The created AML_ROOT_NODE.
+  @param  [out] NewRootNodePtr  If success, contains the created
+                                AML_ROOT_NODE.
+                                Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.
@@ -101,6 +103,8 @@ AmlCreateRootNode (
     return EFI_INVALID_PARAMETER;
   }
 
+  *NewRootNodePtr = NULL;
+
   RootNode = AllocateZeroPool (sizeof (AML_ROOT_NODE));
   if (RootNode == NULL) {
     ASSERT (0);
@@ -163,7 +167,9 @@ AmlDeleteObjectNode (
   @param  [in]  PkgLength         PkgLength of the node if the AmlByteEncoding
                                   has the PkgLen attribute.
                                   0 otherwise.
-  @param  [out] NewObjectNodePtr  The created AML_OBJECT_NODE.
+  @param  [out] NewObjectNodePtr  If success, contains the created
+                                  AML_OBJECT_NODE.
+                                  Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.
@@ -186,6 +192,8 @@ AmlCreateObjectNode (
     return EFI_INVALID_PARAMETER;
   }
 
+  *NewObjectNodePtr = NULL;
+
   ObjectNode = AllocateZeroPool (sizeof (AML_OBJECT_NODE));
   if (ObjectNode == NULL) {
     ASSERT (0);
@@ -252,7 +260,9 @@ AmlDeleteDataNode (
                                 this node. Data is copied from there.
   @param  [in]  DataSize        Number of bytes to consider at the address
                                 pointed by Data.
-  @param  [out] NewDataNodePtr  The created AML_DATA_NODE.
+  @param  [out] NewDataNodePtr  If success, contains the created
+                                AML_DATA_NODE.
+                                Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.
@@ -284,6 +294,8 @@ AmlCreateDataNode (
     return EFI_INVALID_PARAMETER;
   }
 
+  *NewDataNodePtr = NULL;
+
   DataNode = AllocateZeroPool (sizeof (AML_DATA_NODE));
   if (DataNode == NULL) {
     ASSERT (0);

DynamicTablesPkg/Library/Common/AmlLib/Tree/AmlNode.h

@@ -17,7 +17,9 @@
 
   @param  [in]  SdtHeader       Pointer to an ACPI DSDT/SSDT header to copy
                                 the data from.
-  @param  [out] NewRootNodePtr  The created AML_ROOT_NODE.
+  @param  [out] NewRootNodePtr  If success, contains the created
+                                AML_ROOT_NODE.
+                                Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.
@@ -36,7 +38,9 @@ AmlCreateRootNode (
   @param  [in]  PkgLength         PkgLength of the node if the AmlByteEncoding
                                   has the PkgLen attribute.
                                   0 otherwise.
-  @param  [out] NewObjectNodePtr  The created AML_OBJECT_NODE.
+  @param  [out] NewObjectNodePtr  If success, contains the created
+                                  AML_OBJECT_NODE.
+                                  Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.
@@ -57,7 +61,9 @@ AmlCreateObjectNode (
                                 this node. Data is copied from there.
   @param  [in]  DataSize        Number of bytes to consider at the address
                                 pointed by Data.
-  @param  [out] NewDataNodePtr  The created AML_DATA_NODE.
+  @param  [out] NewDataNodePtr  If success, contains the created
+                                AML_DATA_NODE.
+                                Otherwise reset to NULL.
 
   @retval EFI_SUCCESS             The function completed successfully.
   @retval EFI_INVALID_PARAMETER   Invalid parameter.