Remove redundant functions from struct_pass

Author: r41k0u

pythonbpf/structs_pass.py

@@ -5,6 +5,13 @@
 
 logger = logging.getLogger(__name__)
 
+# TODO: Shall we allow the following syntax:
+# struct MyStruct:
+#     field1: int
+#     field2: str(32)
+# Where int is mapped to c_uint64?
+# Shall we just int64, int32 and uint32 similarly?
+
 
 def structs_proc(tree, module, chunks):
     """ Process all class definitions to find BPF structs """
@@ -27,62 +34,16 @@ def is_bpf_struct(cls_node):
 def process_bpf_struct(cls_node, module):
     """ Process a single BPF struct definition """
 
-    field_names = []
-    field_types = []
-
-    for item in cls_node.body:
-        #
-        # field syntax:
-        # class struct_example:
-        #     num: c_uint64
-        #
-        if isinstance(item, ast.AnnAssign):
-            if isinstance(item.target, ast.Name):
-                print(f"Field: {item.target.id}, Type: "
-                      f"{ast.dump(item.annotation)}")
-                field_names.append(item.target.id)
-                if isinstance(item.annotation, ast.Call):
-                    if isinstance(item.annotation.func, ast.Name):
-                        if item.annotation.func.id == "str":
-                            # This is a char array with fixed length
-                            # TODO: For now assume str is always with constant
-                            field_types.append(ir.ArrayType(
-                                ir.IntType(8), item.annotation.args[0].value))
-                        else:
-                            field_types.append(
-                                ctypes_to_ir(item.annotation.id))
-        else:
-            print(f"Unsupported struct field: {ast.dump(item)}")
-            return
-
-    curr_offset = 0
-    for ftype in field_types:
-        if isinstance(ftype, ir.IntType):
-            fsize = ftype.width // 8
-            alignment = fsize
-        elif isinstance(ftype, ir.ArrayType):
-            fsize = ftype.count * (ftype.element.width // 8)
-            alignment = ftype.element.width // 8
-        elif isinstance(ftype, ir.PointerType):
-            fsize = 8
-            alignment = 8
-        else:
-            print(f"Unsupported field type in struct {cls_node.name}")
-            return
-        padding = (alignment - (curr_offset % alignment)) % alignment
-        curr_offset += padding
-        curr_offset += fsize
-    final_padding = (8 - (curr_offset % 8)) % 8
-    total_size = curr_offset + final_padding
-
+    field_names, field_types = parse_struct_fields(cls_node)
+    total_size = calc_struct_size(field_types)
     struct_type = ir.LiteralStructType(field_types)
-    structs_sym_tab[cls_node.name] = {
+    logger.info(f"Created struct {cls_node.name} with fields {field_names}")
+    return {
         "type": struct_type,
         "fields": {name: idx for idx, name in enumerate(field_names)},
         "size": total_size,
         "field_types": field_types,
     }
-    print(f"Created struct {cls_node.name} with fields {field_names}")
 
 
 def parse_struct_fields(cls_node):
@@ -91,7 +52,8 @@ def parse_struct_fields(cls_node):
     field_types = []
 
     for item in cls_node.body:
-        if isinstance(item, ast.AnnAssign) and isinstance(item.target, ast.Name):
+        if isinstance(item, ast.AnnAssign) and \
+           isinstance(item.target, ast.Name):
             field_names.append(item.target.id)
             field_types.append(get_type_from_ann(item.annotation))
         else:
@@ -112,3 +74,26 @@ def get_type_from_ann(annotation):
         return ctypes_to_ir(annotation.id)
 
     raise TypeError(f"Unsupported annotation type: {ast.dump(annotation)}")
+
+
+def calc_struct_size(field_types):
+    """ Calculate total size of the struct with alignment and padding """
+    curr_offset = 0
+    for ftype in field_types:
+        if isinstance(ftype, ir.IntType):
+            fsize = ftype.width // 8
+            alignment = fsize
+        elif isinstance(ftype, ir.ArrayType):
+            fsize = ftype.count * (ftype.element.width // 8)
+            alignment = ftype.element.width // 8
+        elif isinstance(ftype, ir.PointerType):
+            fsize = 8
+            alignment = 8
+        else:
+            raise TypeError(f"Unsupported field type: {ftype}")
+
+        padding = (alignment - (curr_offset % alignment)) % alignment
+        curr_offset += padding + fsize
+
+    final_padding = (8 - (curr_offset % 8)) % 8
+    return curr_offset + final_padding