Bug fix for `gdb.PARAM_ZUINTEGER*` with GDB < 9

GDB < 9 does not support PARAM_ZUINTEGER*, so we implement it by ourselves for consistency

pwndbg/gdblib/config.py

@@ -21,6 +21,11 @@ import pwndbg.lib.config
 
 config = pwndbg.lib.config.Config()
 
+# GDB < 9 does not support PARAM_ZUINTEGER*, so we implement it by ourselves for consistency
+if not hasattr(gdb, "PARAM_ZUINTEGER"):
+    gdb.PARAM_ZUINTEGER = "PARAM_ZUINTEGER"
+    gdb.PARAM_ZUINTEGER_UNLIMITED = "PARAM_ZUINTEGER_UNLIMITED"
+
 
 # See this for details about the API of `gdb.Parameter`:
 # https://sourceware.org/gdb/onlinedocs/gdb/Parameters-In-Python.html
@@ -32,6 +37,7 @@ class Parameter(gdb.Parameter):
         self.set_doc = "Set " + param.set_show_doc + "."
         self.show_doc = "Show " + param.set_show_doc + "."
         self.__doc__ = param.help_docstring or None
+        self._custom_param_class = None
 
         if param.param_class == gdb.PARAM_ENUM:
             super().__init__(
@@ -40,6 +46,13 @@ class Parameter(gdb.Parameter):
                 param.param_class,
                 param.enum_sequence,
             )
+        elif (
+            param.param_class == "PARAM_ZUINTEGER"
+            or param.param_class == "PARAM_ZUINTEGER_UNLIMITED"
+        ):
+            # GDB < 9 does not support PARAM_ZUINTEGER*, so we implement it by ourselves for consistency
+            self._custom_param_class = param.param_class
+            super().__init__(param.name, gdb.COMMAND_SUPPORT, pwndbg.lib.config.PARAM_CLASSES[int])
         else:
             super().__init__(param.name, gdb.COMMAND_SUPPORT, param.param_class)
         self.param = param
@@ -66,6 +79,15 @@ class Parameter(gdb.Parameter):
             # Anyway, to avoid some unexpected behaviors, we'll still set `self.param.value` to 0 here.
             self.param.value = 0
         else:
+            if self._custom_param_class:
+                if (self._custom_param_class == "PARAM_ZUINTEGER" and self.value < 0) or (  # type: ignore
+                    self._custom_param_class == "PARAM_ZUINTEGER_UNLIMITED" and self.value < -1  # type: ignore
+                ):
+                    err = "integer %d out of range" % self.value  # type: ignore
+                    # Restore the old value
+                    self.value = self.param.value
+                    # GDB < 9 is too buggy, it won't handle `gdb.GdbError`..., so we return a string here
+                    return err
             self.param.value = self.value
 
         for trigger in config.triggers[self.param.name]:
@@ -81,6 +103,8 @@ class Parameter(gdb.Parameter):
     def get_show_string(self, svalue) -> str:
         """Handles the GDB `show <param>` command"""
         more_information_hint = " See `help set %s` for more information." % self.param.name
+        if self._custom_param_class == "PARAM_ZUINTEGER_UNLIMITED" and self.value == -1:
+            svalue = "unlimited"
         return "%s is %r.%s" % (
             self.param.set_show_doc.capitalize(),
             svalue,

tests/gdb-tests/tests/test_gdblib_parameter.py

@@ -14,16 +14,33 @@ import pwndbg.gdblib.config
         ("auto-bool", None, "auto", {"param_class": gdb.PARAM_AUTO_BOOLEAN}),
         ("unlimited-uint", 0, "unlimited", {"param_class": gdb.PARAM_UINTEGER}),
         ("unlimited-int", 0, "unlimited", {"param_class": gdb.PARAM_INTEGER}),
-        # GDB < 9.x does not support PARAM_ZUINTEGER_UNLIMITED
-        ("unlimited-zuint", -1, "unlimited", {"param_class": gdb.PARAM_ZUINTEGER_UNLIMITED})
-        if hasattr(gdb, "PARAM_ZUINTEGER_UNLIMITED")
-        else (),
         (
             "enum",
             "enum1",
             "enum1",
             {"param_class": gdb.PARAM_ENUM, "enum_sequence": ["enum1", "enum2", "enum3"]},
         ),
+        # Note: GDB < 9 does not support PARAM_ZUINTEGER*, so we implement it by ourselves for consistency
+        (
+            "zuint",
+            0,
+            "0",
+            {
+                "param_class": gdb.PARAM_ZUINTEGER
+                if hasattr(gdb, "PARAM_ZUINTEGER")
+                else "PARAM_ZUINTEGER"
+            },
+        ),
+        (
+            "unlimited-zuint",
+            -1,
+            "unlimited",
+            {
+                "param_class": gdb.PARAM_ZUINTEGER_UNLIMITED
+                if hasattr(gdb, "PARAM_ZUINTEGER_UNLIMITED")
+                else "PARAM_ZUINTEGER_UNLIMITED"
+            },
+        ),
     ),
 )
 def test_gdb_parameter_default_value_works(start_binary, params):

tests/gdb-tests/tests/test_nearpc.py

@@ -168,14 +168,16 @@ def test_nearpc_opcode_seperator(start_binary, separator_bytes):
 
 
 def test_nearpc_opcode_invalid_config():
+    expected = "integer -1 out of range"
     try:
-        gdb.execute("set nearpc-opcode-bytes -1")
-        assert False, "nearpc-opcode-bytes should not accept negative values"
+        # We try to catch the output since GDB < 9 won't raise the exception
+        assert gdb.execute("set nearpc-opcode-bytes -1", to_string=True).rstrip() == expected
     except gdb.error as e:
-        pass
+        assert expected == str(e)
 
     try:
-        gdb.execute("set nearpc-opcode-separator-bytes -1")
-        assert False, "nearpc-opcode-separator-bytes should not accept negative values"
+        assert (
+            gdb.execute("set nearpc-opcode-separator-bytes -1", to_string=True).rstrip() == expected
+        )
     except gdb.error as e:
-        pass
+        assert expected == str(e)