gdb/python: have UnwindInfo.add_saved_register accept named args

Update gdb.UnwindInfo.add_saved_register to accept named keyword
arguments.

As part of this update we now use gdb_PyArg_ParseTupleAndKeywords
instead of PyArg_UnpackTuple to parse the function arguments.

By switching to gdb_PyArg_ParseTupleAndKeywords, we can now use 'O!'
as the argument format for the function's value argument.  This means
that we can check the argument type (is gdb.Value) as part of the
argument processing rather than manually performing the check later in
the function.  One result of this is that we now get a better error
message (at least, I think so).  Previously we would get something
like:

  ValueError: Bad register value

Now we get:

  TypeError: argument 2 must be gdb.Value, not XXXX

It's unfortunate that the exception type changed, but I think the new
exception type actually makes more sense.

My preference for argument names is to use full words where that's not
too excessive.  As such, I've updated the name of the argument from
'reg' to 'register' in the documentation, which is the argument name
I've made GDB look for here.

For existing unwinder code that doesn't throw any exceptions nothing
should change with this commit.  It is possible that a user has some
code that throws and catches the ValueError, and this code will break
after this commit, but I think this is going to be sufficiently rare
that we can take the risk here.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Reviewed-By: Tom Tromey <tom@tromey.com>

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index c74d586ef39c95f095f45c82c2e613f697e99162..a4fd0095c43dd6b39b959fa933ac799e0ddd4a89 100644 (file)
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -2882,8 +2882,8 @@ Use @code{PendingFrame.create_unwind_info} method described above to
 create a @code{gdb.UnwindInfo} instance.  Use the following method to
 specify caller registers that have been saved in this frame:
 
-@defun gdb.UnwindInfo.add_saved_register (reg, value)
-@var{reg} identifies the register, for a description of the acceptable
+@defun gdb.UnwindInfo.add_saved_register (register, value)
+@var{register} identifies the register, for a description of the acceptable
 values see @ref{gdbpy_frame_read_register,,Frame.read_register}.
 @var{value} is a register value (a @code{gdb.Value} object).
 @end defun

diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index 409dbd3a470fd77eac961c8c79cd58c95b31c6b1..2e13b84eb126c66ae019431a70af4dc0f1075e6a 100644 (file)
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -292,7 +292,7 @@ pyuw_create_unwind_info (PyObject *pyo_pending_frame,
    gdb.UnwindInfo.add_saved_register (REG, VALUE) -> None.  */
 
 static PyObject *
-unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
+unwind_infopy_add_saved_register (PyObject *self, PyObject *args, PyObject *kw)
 {
   unwind_info_object *unwind_info = (unwind_info_object *) self;
   pending_frame_object *pending_frame
@@ -305,11 +305,15 @@ unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
     {
       PyErr_SetString (PyExc_ValueError,
                       "UnwindInfo instance refers to a stale PendingFrame");
-      return NULL;
+      return nullptr;
     }
-  if (!PyArg_UnpackTuple (args, "previous_frame_register", 2, 2,
-                         &pyo_reg_id, &pyo_reg_value))
-    return NULL;
+
+  static const char *keywords[] = { "register", "value", nullptr };
+  if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "OO!", keywords,
+                                       &pyo_reg_id, &value_object_type,
+                                       &pyo_reg_value))
+    return nullptr;
+
   if (!gdbpy_parse_register_id (pending_frame->gdbarch, pyo_reg_id, &regnum))
     return nullptr;
 
@@ -332,43 +336,38 @@ unwind_infopy_add_saved_register (PyObject *self, PyObject *args)
        }
     }
 
-  {
-    struct value *value;
-    size_t data_size;
+  /* The argument parsing above guarantees that PYO_REG_VALUE will be a
+     gdb.Value object, as a result the value_object_to_value call should
+     succeed.  */
+  gdb_assert (pyo_reg_value != nullptr);
+  struct value *value = value_object_to_value (pyo_reg_value);
+  gdb_assert (value != nullptr);
+
+  ULONGEST reg_size = register_size (pending_frame->gdbarch, regnum);
+  if (reg_size != value->type ()->length ())
+    {
+      PyErr_Format (PyExc_ValueError,
+                   "The value of the register returned by the Python "
+                   "sniffer has unexpected size: %s instead of %s.",
+                   pulongest (value->type ()->length ()),
+                   pulongest (reg_size));
+      return nullptr;
+    }
+
+  gdbpy_ref<> new_value = gdbpy_ref<>::new_reference (pyo_reg_value);
+  bool found = false;
+  for (saved_reg &reg : *unwind_info->saved_regs)
+    {
+      if (regnum == reg.number)
+       {
+         found = true;
+         reg.value = std::move (new_value);
+         break;
+       }
+    }
+  if (!found)
+    unwind_info->saved_regs->emplace_back (regnum, std::move (new_value));
 
-    if (pyo_reg_value == NULL
-      || (value = value_object_to_value (pyo_reg_value)) == NULL)
-      {
-       PyErr_SetString (PyExc_ValueError, "Bad register value");
-       return NULL;
-      }
-    data_size = register_size (pending_frame->gdbarch, regnum);
-    if (data_size != value->type ()->length ())
-      {
-       PyErr_Format (
-           PyExc_ValueError,
-           "The value of the register returned by the Python "
-           "sniffer has unexpected size: %u instead of %u.",
-           (unsigned) value->type ()->length (),
-           (unsigned) data_size);
-       return NULL;
-      }
-  }
-  {
-    gdbpy_ref<> new_value = gdbpy_ref<>::new_reference (pyo_reg_value);
-    bool found = false;
-    for (saved_reg &reg : *unwind_info->saved_regs)
-      {
-       if (regnum == reg.number)
-         {
-           found = true;
-           reg.value = std::move (new_value);
-           break;
-         }
-      }
-    if (!found)
-      unwind_info->saved_regs->emplace_back (regnum, std::move (new_value));
-  }
   Py_RETURN_NONE;
 }
 
@@ -1087,7 +1086,8 @@ PyTypeObject pending_frame_object_type =
 static PyMethodDef unwind_info_object_methods[] =
 {
   { "add_saved_register",
-    unwind_infopy_add_saved_register, METH_VARARGS,
+    (PyCFunction) unwind_infopy_add_saved_register,
+    METH_VARARGS | METH_KEYWORDS,
     "add_saved_register (REG, VALUE) -> None\n"
     "Set the value of the REG in the previous frame to VALUE." },
   { NULL }  /* Sentinel */

diff --git a/gdb/testsuite/gdb.python/py-unwind.exp b/gdb/testsuite/gdb.python/py-unwind.exp
index d0a1960058bff27b73e1dc73eea203e5fe69afd6..e7c4c23dae24e307603d52d88430875ec3c017ec 100644 (file)
--- a/gdb/testsuite/gdb.python/py-unwind.exp
+++ b/gdb/testsuite/gdb.python/py-unwind.exp
@@ -131,10 +131,17 @@ gdb_test "disable unwinder global \"test unwinder\"" \
 check_for_broken_backtrace "stack is broken after command disabling"
 check_info_unwinder "info unwinder after command disabling" off
 
-# Check that invalid register names cause errors.
-gdb_test "python print(add_saved_register_error)" "True" \
-    "add_saved_register error"
-gdb_test "python print(read_register_error)" "True" \
+# Check that invalid register names and values cause errors.
+gdb_test "python print(add_saved_register_errors\[\"unknown_name\"\])" \
+    "Bad register" \
+    "add_saved_register error when an unknown register name is used"
+gdb_test "python print(add_saved_register_errors\[\"unknown_number\"\])" \
+    "Bad register" \
+    "add_saved_register error when an unknown register number is used"
+gdb_test "python print(add_saved_register_errors\[\"bad_value\"\])" \
+    "argument 2 must be gdb.Value, not int" \
+    "add_saved_register error when invalid register value is used"
+gdb_test "python print(read_register_error)" "Bad register" \
     "read_register error"
 
 # Try to create an unwinder object with a non-string name.

diff --git a/gdb/testsuite/gdb.python/py-unwind.py b/gdb/testsuite/gdb.python/py-unwind.py
index 4e110c51e3b3f756ea73b165233c4accfe234306..5853abc7486c95bbc8abc76b48d30992607915e6 100644 (file)
--- a/gdb/testsuite/gdb.python/py-unwind.py
+++ b/gdb/testsuite/gdb.python/py-unwind.py
@@ -18,7 +18,7 @@ from gdb.unwinder import Unwinder, FrameId
 
 
 # These are set to test whether invalid register names cause an error.
-add_saved_register_error = False
+add_saved_register_errors = {}
 read_register_error = False
 
 
@@ -94,9 +94,9 @@ class TestUnwinder(Unwinder):
 
             try:
                 pending_frame.read_register("nosuchregister")
-            except ValueError:
+            except ValueError as ve:
                 global read_register_error
-                read_register_error = True
+                read_register_error = str(ve)
 
             frame_id = FrameId(
                 pending_frame.read_register(TestUnwinder.AMD64_RSP),
@@ -104,13 +104,25 @@ class TestUnwinder(Unwinder):
             )
             unwind_info = pending_frame.create_unwind_info(frame_id)
             unwind_info.add_saved_register(TestUnwinder.AMD64_RBP, previous_bp)
-            unwind_info.add_saved_register("rip", previous_ip)
-            unwind_info.add_saved_register("rsp", previous_sp)
+            unwind_info.add_saved_register(value=previous_ip, register="rip")
+            unwind_info.add_saved_register(register="rsp", value=previous_sp)
+
+            global add_saved_register_errors
             try:
                 unwind_info.add_saved_register("nosuchregister", previous_sp)
-            except ValueError:
-                global add_saved_register_error
-                add_saved_register_error = True
+            except ValueError as ve:
+                add_saved_register_errors["unknown_name"] = str(ve)
+
+            try:
+                unwind_info.add_saved_register(999, previous_sp)
+            except ValueError as ve:
+                add_saved_register_errors["unknown_number"] = str(ve)
+
+            try:
+                unwind_info.add_saved_register("rsp", 1234)
+            except TypeError as ve:
+                add_saved_register_errors["bad_value"] = str(ve)
+
             return unwind_info
         except (gdb.error, RuntimeError):
             return None