raise WasmParseError instead of ValueError on func/code length mismatch

zip(function_section, code_section, strict=True) surfaced a bare
Python ValueError on mismatch, unlike every other malformed-input
path in the parser, which raises WasmParseError.

Author: bbyalcinkaya

pykwasm/src/pykwasm/binary/module.py

@@ -335,6 +335,11 @@ def parse_module(s: InputStream) -> KInner:
     else:
         raise WasmParseError('Unexpected data after end of module')
 
+    if len(function_section) != len(code_section):
+        raise WasmParseError(
+            f'Function and code section length mismatch: {len(function_section)} != {len(code_section)}'
+        )
+
     functions = [
         wast.func(
             wast.KInt(typ_idx),

pykwasm/src/tests/unit/test_binary_parser.py

@@ -208,6 +208,20 @@ def test_trailing_garbage_after_sections_rejected(self) -> None:
             parse_module(stream(MAGIC + VERSION + type_section + b'\xff'))
 
 
+class TestFuncCodeLengthMismatch:
+    def test_more_funcs_than_code_entries_rejected(self) -> None:
+        func_section = section(3, uleb128(1) + uleb128(0))
+        code_section = section(10, uleb128(0))
+        with pytest.raises(WasmParseError):
+            parse_module(stream(MAGIC + VERSION + func_section + code_section))
+
+    def test_more_code_entries_than_funcs_rejected(self) -> None:
+        func_section = section(3, uleb128(0))
+        code_section = section(10, uleb128(1) + (uleb128(2) + bytes([0x00, 0x0B])))
+        with pytest.raises(WasmParseError):
+            parse_module(stream(MAGIC + VERSION + func_section + code_section))
+
+
 def unwrap_instr(k: KApply) -> KApply:
     """Helper: strip the `aInstrWithPos` position wrapper added by `instr()`."""
     assert k.label.name == 'aInstrWithPos'