Merge pull request #24 from pythonbpf/func_refactor

Refactor handle_return

Author: r41k0u

pythonbpf/codegen.py

@@ -1,7 +1,7 @@
 import ast
 from llvmlite import ir
 from .license_pass import license_processing
-from .functions_pass import func_proc
+from .functions import func_proc
 from .maps import maps_proc
 from .structs import structs_proc
 from .globals_pass import globals_processing

pythonbpf/expr_pass.py

@@ -4,6 +4,8 @@
 import logging
 from typing import Dict
 
+from .type_deducer import ctypes_to_ir, is_ctypes
+
 logger: Logger = logging.getLogger(__name__)
 
 
@@ -88,6 +90,48 @@ def _handle_deref_call(expr: ast.Call, local_sym_tab: Dict, builder: ir.IRBuilde
     return val, local_sym_tab[arg.id].ir_type
 
 
+def _handle_ctypes_call(
+    func,
+    module,
+    builder,
+    expr,
+    local_sym_tab,
+    map_sym_tab,
+    structs_sym_tab=None,
+):
+    """Handle ctypes type constructor calls."""
+    if len(expr.args) != 1:
+        logger.info("ctypes constructor takes exactly one argument")
+        return None
+
+    arg = expr.args[0]
+    val = eval_expr(
+        func,
+        module,
+        builder,
+        arg,
+        local_sym_tab,
+        map_sym_tab,
+        structs_sym_tab,
+    )
+    if val is None:
+        logger.info("Failed to evaluate argument to ctypes constructor")
+        return None
+    call_type = expr.func.id
+    expected_type = ctypes_to_ir(call_type)
+
+    if val[1] != expected_type:
+        # NOTE: We are only considering casting to and from int types for now
+        if isinstance(val[1], ir.IntType) and isinstance(expected_type, ir.IntType):
+            if val[1].width < expected_type.width:
+                val = (builder.sext(val[0], expected_type), expected_type)
+            else:
+                val = (builder.trunc(val[0], expected_type), expected_type)
+        else:
+            raise ValueError(f"Type mismatch: expected {expected_type}, got {val[1]}")
+    return val
+
+
 def eval_expr(
     func,
     module,
@@ -106,6 +150,17 @@ def eval_expr(
         if isinstance(expr.func, ast.Name) and expr.func.id == "deref":
             return _handle_deref_call(expr, local_sym_tab, builder)
 
+        if isinstance(expr.func, ast.Name) and is_ctypes(expr.func.id):
+            return _handle_ctypes_call(
+                func,
+                module,
+                builder,
+                expr,
+                local_sym_tab,
+                map_sym_tab,
+                structs_sym_tab,
+            )
+
         # delayed import to avoid circular dependency
         from pythonbpf.helper import HelperHandlerRegistry, handle_helper_call
 
@@ -153,6 +208,10 @@ def eval_expr(
                         )
     elif isinstance(expr, ast.Attribute):
         return _handle_attribute_expr(expr, local_sym_tab, structs_sym_tab, builder)
+    elif isinstance(expr, ast.BinOp):
+        from pythonbpf.binary_ops import handle_binary_op
+
+        return handle_binary_op(expr, builder, None, local_sym_tab)
     logger.info("Unsupported expression evaluation")
     return None
 

pythonbpf/functions/__init__.py

@@ -0,0 +1,3 @@
+from .functions_pass import func_proc
+
+__all__ = ["func_proc"]

pythonbpf/functions/func_registry_handlers.py

@@ -0,0 +1,22 @@
+from typing import Dict
+
+
+class StatementHandlerRegistry:
+    """Registry for statement handlers."""
+
+    _handlers: Dict = {}
+
+    @classmethod
+    def register(cls, stmt_type):
+        """Register a handler for a specific statement type."""
+
+        def decorator(handler):
+            cls._handlers[stmt_type] = handler
+            return handler
+
+        return decorator
+
+    @classmethod
+    def __getitem__(cls, stmt_type):
+        """Get the handler for a specific statement type."""
+        return cls._handlers.get(stmt_type, None)

pythonbpf/functions_pass.py renamed to pythonbpf/functions/functions_pass.py

@@ -4,10 +4,13 @@
 from typing import Any
 from dataclasses import dataclass
 
-from .helper import HelperHandlerRegistry, handle_helper_call
-from .type_deducer import ctypes_to_ir
-from .binary_ops import handle_binary_op
-from .expr_pass import eval_expr, handle_expr
+from pythonbpf.helper import HelperHandlerRegistry, handle_helper_call
+from pythonbpf.type_deducer import ctypes_to_ir
+from pythonbpf.binary_ops import handle_binary_op
+from pythonbpf.expr_pass import eval_expr, handle_expr
+
+from .return_utils import _handle_none_return, _handle_xdp_return, _is_xdp_name
+
 
 logger = logging.getLogger(__name__)
 
@@ -350,6 +353,27 @@ def handle_if(
     builder.position_at_end(merge_block)
 
 
+def handle_return(builder, stmt, local_sym_tab, ret_type):
+    logger.info(f"Handling return statement: {ast.dump(stmt)}")
+    if stmt.value is None:
+        return _handle_none_return(builder)
+    elif isinstance(stmt.value, ast.Name) and _is_xdp_name(stmt.value.id):
+        return _handle_xdp_return(stmt, builder, ret_type)
+    else:
+        val = eval_expr(
+            func=None,
+            module=None,
+            builder=builder,
+            expr=stmt.value,
+            local_sym_tab=local_sym_tab,
+            map_sym_tab={},
+            structs_sym_tab={},
+        )
+        logger.info(f"Evaluated return expression to {val}")
+        builder.ret(val[0])
+        return True
+
+
 def process_stmt(
     func,
     module,
@@ -383,61 +407,12 @@ def process_stmt(
             func, module, builder, stmt, map_sym_tab, local_sym_tab, structs_sym_tab
         )
     elif isinstance(stmt, ast.Return):
-        if stmt.value is None:
-            builder.ret(ir.Constant(ir.IntType(64), 0))
-            did_return = True
-        elif (
-            isinstance(stmt.value, ast.Call)
-            and isinstance(stmt.value.func, ast.Name)
-            and len(stmt.value.args) == 1
-        ):
-            if isinstance(stmt.value.args[0], ast.Constant) and isinstance(
-                stmt.value.args[0].value, int
-            ):
-                call_type = stmt.value.func.id
-                if ctypes_to_ir(call_type) != ret_type:
-                    raise ValueError(
-                        "Return type mismatch: expected"
-                        f"{ctypes_to_ir(call_type)}, got {call_type}"
-                    )
-                else:
-                    builder.ret(ir.Constant(ret_type, stmt.value.args[0].value))
-                    did_return = True
-            elif isinstance(stmt.value.args[0], ast.BinOp):
-                # TODO: Should be routed through eval_expr
-                val = handle_binary_op(stmt.value.args[0], builder, None, local_sym_tab)
-                if val is None:
-                    raise ValueError("Failed to evaluate return expression")
-                if val[1] != ret_type:
-                    raise ValueError(
-                        "Return type mismatch: expected " f"{ret_type}, got {val[1]}"
-                    )
-                builder.ret(val[0])
-                did_return = True
-            elif isinstance(stmt.value.args[0], ast.Name):
-                if stmt.value.args[0].id in local_sym_tab:
-                    var = local_sym_tab[stmt.value.args[0].id].var
-                    val = builder.load(var)
-                    if val.type != ret_type:
-                        raise ValueError(
-                            "Return type mismatch: expected"
-                            f"{ret_type}, got {val.type}"
-                        )
-                    builder.ret(val)
-                    did_return = True
-                else:
-                    raise ValueError("Failed to evaluate return expression")
-        elif isinstance(stmt.value, ast.Name):
-            if stmt.value.id == "XDP_PASS":
-                builder.ret(ir.Constant(ret_type, 2))
-                did_return = True
-            elif stmt.value.id == "XDP_DROP":
-                builder.ret(ir.Constant(ret_type, 1))
-                did_return = True
-            else:
-                raise ValueError("Failed to evaluate return expression")
-        else:
-            raise ValueError("Unsupported return value")
+        did_return = handle_return(
+            builder,
+            stmt,
+            local_sym_tab,
+            ret_type,
+        )
     return did_return
 
 

pythonbpf/functions/return_utils.py

@@ -0,0 +1,45 @@
+import logging
+import ast
+
+from llvmlite import ir
+
+logger: logging.Logger = logging.getLogger(__name__)
+
+XDP_ACTIONS = {
+    "XDP_ABORTED": 0,
+    "XDP_DROP": 1,
+    "XDP_PASS": 2,
+    "XDP_TX": 3,
+    "XDP_REDIRECT": 4,
+}
+
+
+def _handle_none_return(builder) -> bool:
+    """Handle return or return None -> returns 0."""
+    builder.ret(ir.Constant(ir.IntType(64), 0))
+    logger.debug("Generated default return: 0")
+    return True
+
+
+def _is_xdp_name(name: str) -> bool:
+    """Check if a name is an XDP action"""
+    return name in XDP_ACTIONS
+
+
+def _handle_xdp_return(stmt: ast.Return, builder, ret_type) -> bool:
+    """Handle XDP returns"""
+    if not isinstance(stmt.value, ast.Name):
+        return False
+
+    action_name = stmt.value.id
+
+    if action_name not in XDP_ACTIONS:
+        raise ValueError(
+            f"Unknown XDP action: {action_name}. Available: {XDP_ACTIONS.keys()}"
+        )
+        return False
+
+    value = XDP_ACTIONS[action_name]
+    builder.ret(ir.Constant(ret_type, value))
+    logger.debug(f"Generated XDP action return: {action_name} = {value}")
+    return True

pythonbpf/type_deducer.py

@@ -1,24 +1,28 @@
 from llvmlite import ir
 
 # TODO: THIS IS NOT SUPPOSED TO MATCH STRINGS :skull:
+mapping = {
+    "c_int8": ir.IntType(8),
+    "c_uint8": ir.IntType(8),
+    "c_int16": ir.IntType(16),
+    "c_uint16": ir.IntType(16),
+    "c_int32": ir.IntType(32),
+    "c_uint32": ir.IntType(32),
+    "c_int64": ir.IntType(64),
+    "c_uint64": ir.IntType(64),
+    "c_float": ir.FloatType(),
+    "c_double": ir.DoubleType(),
+    "c_void_p": ir.IntType(64),
+    # Not so sure about this one
+    "str": ir.PointerType(ir.IntType(8)),
+}
 
 
 def ctypes_to_ir(ctype: str):
-    mapping = {
-        "c_int8": ir.IntType(8),
-        "c_uint8": ir.IntType(8),
-        "c_int16": ir.IntType(16),
-        "c_uint16": ir.IntType(16),
-        "c_int32": ir.IntType(32),
-        "c_uint32": ir.IntType(32),
-        "c_int64": ir.IntType(64),
-        "c_uint64": ir.IntType(64),
-        "c_float": ir.FloatType(),
-        "c_double": ir.DoubleType(),
-        "c_void_p": ir.IntType(64),
-        # Not so sure about this one
-        "str": ir.PointerType(ir.IntType(8)),
-    }
     if ctype in mapping:
         return mapping[ctype]
     raise NotImplementedError(f"No mapping for {ctype}")
+
+
+def is_ctypes(ctype: str) -> bool:
+    return ctype in mapping

tests/passing_tests/return/binop_const.py

@@ -0,0 +1,18 @@
+from pythonbpf import bpf, section, bpfglobal, compile
+from ctypes import c_void_p, c_int64
+
+
+@bpf
+@section("tracepoint/syscalls/sys_enter_execve")
+def hello_world(ctx: c_void_p) -> c_int64:
+    print("Hello, World!")
+    return 1 + 1 - 2
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile()

tests/passing_tests/return/binop_var.py

@@ -0,0 +1,19 @@
+from pythonbpf import bpf, section, bpfglobal, compile
+from ctypes import c_void_p, c_int64
+
+
+@bpf
+@section("tracepoint/syscalls/sys_enter_execve")
+def hello_world(ctx: c_void_p) -> c_int64:
+    print("Hello, World!")
+    a = 2
+    return a - 2
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile()

tests/passing_tests/return/int.py

@@ -0,0 +1,18 @@
+from pythonbpf import bpf, section, bpfglobal, compile
+from ctypes import c_void_p, c_int64
+
+
+@bpf
+@section("tracepoint/syscalls/sys_enter_execve")
+def hello_world(ctx: c_void_p) -> c_int64:
+    print("Hello, World!")
+    return 1
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile()