add i32 support and make it extensible

pythonbpf/vmlinux_parser/vmlinux_exports_handler.py

@@ -1,6 +1,6 @@
 import logging
 from typing import Any
-
+import ctypes
 from llvmlite import ir
 
 from pythonbpf.local_symbol import LocalSymbol
@@ -98,18 +98,16 @@ class VmlinuxHandler:
                 python_type.__name__, field_name
             )
             builder.function.args[0].type = ir.PointerType(ir.IntType(8))
-            print(builder.function.args[0])
             field_ptr = self.load_ctx_field(
-                builder, builder.function.args[0], globvar_ir
+                builder, builder.function.args[0], globvar_ir, field_data
             )
-            print(field_ptr)
             # Return pointer to field and field type
             return field_ptr, field_data
         else:
             raise RuntimeError("Variable accessed not found in symbol table")
 
     @staticmethod
-    def load_ctx_field(builder, ctx_arg, offset_global):
+    def load_ctx_field(builder, ctx_arg, offset_global, field_data):
         """
         Generate LLVM IR to load a field from BPF context using offset.
 
@@ -117,7 +115,7 @@ class VmlinuxHandler:
             builder: llvmlite IRBuilder instance
             ctx_arg: The context pointer argument (ptr/i8*)
             offset_global: Global variable containing the field offset (i64)
-
+            field_data: contains data about the field
         Returns:
             The loaded value (i64 register)
         """
@@ -164,9 +162,43 @@ class VmlinuxHandler:
             passthrough_fn, [ir.Constant(ir.IntType(32), 0), field_ptr], tail=True
         )
 
-        # Bitcast to i64* (assuming field is 64-bit, adjust if needed)
-        i64_ptr_type = ir.PointerType(ir.IntType(64))
-        typed_ptr = builder.bitcast(verified_ptr, i64_ptr_type)
+        # Determine the appropriate IR type based on field information
+        int_width = 64  # Default to 64-bit
+
+        if field_data is not None:
+            # Try to determine the size from field metadata
+            if field_data.type.__module__ == ctypes.__name__:
+                try:
+                    field_size_bytes = ctypes.sizeof(field_data.type)
+                    field_size_bits = field_size_bytes * 8
+
+                    if field_size_bits in [8, 16, 32, 64]:
+                        int_width = field_size_bits
+                        logger.info(f"Determined field size: {int_width} bits")
+                    else:
+                        logger.warning(
+                            f"Unusual field size {field_size_bits} bits, using default 64"
+                        )
+                except Exception as e:
+                    logger.warning(
+                        f"Could not determine field size: {e}, using default 64"
+                    )
+
+            elif field_data.type.__module__ == "vmlinux":
+                # For pointers to structs or complex vmlinux types
+                if field_data.ctype_complex_type is not None and issubclass(
+                    field_data.ctype_complex_type, ctypes._Pointer
+                ):
+                    int_width = 64  # Pointers are always 64-bit
+                    logger.info("Field is a pointer type, using 64 bits")
+                # TODO: Add handling for other complex types (arrays, embedded structs, etc.)
+                else:
+                    logger.warning("Complex vmlinux field type, using default 64 bits")
+
+        # Bitcast to appropriate pointer type based on determined width
+        ptr_type = ir.PointerType(ir.IntType(int_width))
+
+        typed_ptr = builder.bitcast(verified_ptr, ptr_type)
 
         # Load and return the value
         value = builder.load(typed_ptr)