Re: [rfc] expose gdb values to python

Thiago Jung Bauermann
2008-09-26T02:00:34Z

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Daniel Jacobowitz wrote:
> On Thu, Sep 25, 2008 at 01:32:57AM -0300, Thiago Jung Bauermann wrote:
>> Is it useful to provide a casting mechanism, to enable for instance
>> access to elements from a specific type in the inheritance hierarchy?
>
> I think so. This reminds me of another reason why length is a
> peculiar concept here: GDB should (though I think does not, at
> present) support "v->D::x" and "v->C::x". So v['C::x'] would make
> sense, but you can't iterate over things like that. So maybe length
> should be the number of direct fields? Or the number of fields + base
> classes? Either way, I suggest it match what iterators do if you
> support iteration.

There's no iterator support. Not yet at least.

This version has no FIXMEs. It uses current_language for value printing, and
its length operation always fails with NotImplemented. Ok to commit?
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

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2008-09-25 Thiago Jung Bauermann <bauerman@br.ibm.com>

gdb/
* Makefile.in (SUBDIR_PYTHON_OBS): Add python-value.o.
(SUBDIR_PYTHON_SRCS): Add python-value.c.
(python-value.o): New target.
* configure.ac (CONFIG_OBS): Add python-value.o.
(CONFIG_SRCS): Add python/python-value.c
* python-internal.h (value_object_type): Add external declaration.
(gdbpy_get_value_from_history, value_to_value_object,
convert_value_from_python, gdbpy_initialize_values): Add function
prototype.
* python/python-value.c: New file.
* python/python.c (GdbMethods): Add gdbpy_get_value_from_history.
(_initialize_python): Call gdbpy_initialize_values.
* python/python.h (values_in_python): Add external declaration.
* value.c (value_prepend_to_list, value_remove_from_list): New
functions.
(preserve_values): Iterate over values_in_python list as well.
* value.h (value_prepend_to_list, value_remove_from_list): Add
function prototypes.

gdb/doc/
* gdb.texinfo. (Values From Inferior): New subsubsection.

gdb/testsuite/
* gdb.python/python-values.c: New file.
* gdb.python/python-values.exp: New file.

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 003467d..2cfd0d8 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -271,10 +271,12 @@ SUBDIR_TUI_CFLAGS= \
#
SUBDIR_PYTHON_OBS = \
python.o \
- python-utils.o
+ python-utils.o \
+ python-value.o
SUBDIR_PYTHON_SRCS = \
python/python.c \
- python/python-utils.c
+ python/python-utils.c \
+ python/python-value.c
SUBDIR_PYTHON_DEPS =
SUBDIR_PYTHON_LDFLAGS=
SUBDIR_PYTHON_CFLAGS=
@@ -1839,6 +1841,10 @@ python-utils.o: $(srcdir)/python/python-utils.c
$(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/python-utils.c
$(POSTCOMPILE)

+python-value.o: $(srcdir)/python/python-value.c
+ $(COMPILE) $(PYTHON_CFLAGS) $(srcdir)/python/python-value.c
+ $(POSTCOMPILE)
+
\f

#
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 680fba0..677a6ae 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -624,10 +624,10 @@ if test "${have_libpython}" = yes; then
AC_MSG_RESULT(${PYTHON_CFLAGS})
fi
else
- # Even if Python support is not compiled in, we need to have this file
+ # Even if Python support is not compiled in, we need to have these files
# included in order to recognize the GDB command "python".
- CONFIG_OBS="$CONFIG_OBS python.o"
- CONFIG_SRCS="$CONFIG_SRCS python/python.c"
+ CONFIG_OBS="$CONFIG_OBS python.o python-value.o"
+ CONFIG_SRCS="$CONFIG_SRCS python/python.c python/python-value.c"
fi
AC_SUBST(PYTHON_CFLAGS)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 891dfb2..8758d1e 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -17393,6 +17393,7 @@ situation, a Python @code{KeyboardInterrupt} exception is thrown.
@menu
* Basic Python:: Basic Python Functions.
* Exception Handling::
+* Values From Inferior::
@end menu

@node Basic Python
@@ -17471,6 +17472,36 @@ message as its value, and the Python call stack backtrace at the
Python statement closest to where the @value{GDBN} error occured as the
traceback.

+@node Values From Inferior
+@subsubsection Values From Inferior
+
+@value{GDBN} provides values it obtains from the inferior program in an
+object of type @code{gdb.Value}. This object keeps track of information
+related to the value such as its type, the address where it is kept in
+the inferior, and so on.
+
+You can directly use @code{gdb.Value} objects in places which make sense
+for the type of the value they contain. For instance, you can use the
+value of an integer variable in the inferior as if it were a Python
+integer variable.
+
+If the @code{gdb.Value} object is of a structure type or an instance of a
+class, its elements and methods are provided using dictionary syntax.
+For example, if @code{some_val} is a @code{gdb.Value} instance holding
+a structure, you can access its @code{foo} element with:
+
+@smallexample
+bar = some_val['foo']
+@end smallexample
+
+The following method is provided:
+
+@defmethod Value dereference
+If the @code{gdb.Value} object is of a pointer type, you can dereference
+it using the @code{dereference} method. This gives you a new
+@code{gdb.Value} object for the pointed-to contents.
+@end defmethod
+
@node Interpreters
@chapter Command Interpreters
@cindex command interpreters
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index f850448..72f7a5f 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -43,11 +43,18 @@ typedef Py_intptr_t Py_ssize_t;
#error "Unable to find usable Python.h"
#endif

-struct block;
-struct symbol;
-struct symtab_and_line;
+struct value;

extern PyObject *gdb_module;
+extern PyTypeObject value_object_type;
+
+PyObject *gdbpy_get_value_from_history (PyObject *self, PyObject *args);
+
+PyObject *value_to_value_object (struct value *v);
+
+struct value *convert_value_from_python (PyObject *obj);
+
+void gdbpy_initialize_values (void);

struct cleanup *make_cleanup_py_decref (PyObject *py);

diff --git a/gdb/python/python-value.c b/gdb/python/python-value.c
new file mode 100644
index 0000000..26b8ae1
--- /dev/null
+++ b/gdb/python/python-value.c
@@ -0,0 +1,665 @@
+/* Python interface to values.
+
+ Copyright (C) 2008 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include "defs.h"
+#include "charset.h"
+#include "value.h"
+#include "exceptions.h"
+#include "language.h"
+#include "dfp.h"
+
+/* List of all values which are currently exposed to Python. It is
+ maintained so that when an objfile is discarded, preserve_values
+ can copy the values' types if needed. This is declared
+ unconditionally to reduce the number of uses of HAVE_PYTHON in the
+ generic code. */
+struct value *values_in_python;
+
+#ifdef HAVE_PYTHON
+
+#include "python-internal.h"
+
+typedef struct {
+ PyObject_HEAD
+ struct value *value;
+ int owned_by_gdb;
+} value_object;
+
+static void valpy_dealloc (PyObject *obj);
+static PyObject *valpy_new (PyTypeObject *subtype, PyObject *args,
+ PyObject *keywords);
+static Py_ssize_t valpy_length (PyObject *self);
+static PyObject *valpy_getitem (PyObject *self, PyObject *key);
+static int valpy_setitem (PyObject *self, PyObject *key, PyObject *value);
+static PyObject *valpy_str (PyObject *self);
+static PyObject *valpy_add (PyObject *self, PyObject *other);
+static PyObject *valpy_subtract (PyObject *self, PyObject *other);
+static PyObject *valpy_multiply (PyObject *self, PyObject *other);
+static PyObject *valpy_divide (PyObject *self, PyObject *other);
+static PyObject *valpy_remainder (PyObject *self, PyObject *other);
+static PyObject *valpy_power (PyObject *self, PyObject *other, PyObject *unused);
+static PyObject *valpy_negative (PyObject *self);
+static PyObject *valpy_positive (PyObject *self);
+static PyObject *valpy_absolute (PyObject *self);
+static int valpy_nonzero (PyObject *self);
+static PyObject *valpy_richcompare (PyObject *self, PyObject *other, int op);
+static PyObject *valpy_dereference (PyObject *self, PyObject *args);
+
+static PyMethodDef value_object_methods[] = {
+ { "dereference", valpy_dereference, METH_NOARGS, "Dereferences the value." },
+ {NULL} /* Sentinel */
+};
+
+static PyNumberMethods value_object_as_number = {
+ valpy_add,
+ valpy_subtract,
+ valpy_multiply,
+ valpy_divide,
+ valpy_remainder,
+ NULL, /* nb_divmod */
+ valpy_power, /* nb_power */
+ valpy_negative, /* nb_negative */
+ valpy_positive, /* nb_positive */
+ valpy_absolute, /* nb_absolute */
+ valpy_nonzero /* nb_nonzero */
+};
+
+static PyMappingMethods value_object_as_mapping = {
+ valpy_length,
+ valpy_getitem,
+ valpy_setitem
+};
+
+PyTypeObject value_object_type = {
+ PyObject_HEAD_INIT (NULL)
+ 0, /*ob_size*/
+ "gdb.Value", /*tp_name*/
+ sizeof (value_object), /*tp_basicsize*/
+ 0, /*tp_itemsize*/
+ valpy_dealloc, /*tp_dealloc*/
+ 0, /*tp_print*/
+ 0, /*tp_getattr*/
+ 0, /*tp_setattr*/
+ 0, /*tp_compare*/
+ 0, /*tp_repr*/
+ &value_object_as_number, /*tp_as_number*/
+ 0, /*tp_as_sequence*/
+ &value_object_as_mapping, /*tp_as_mapping*/
+ 0, /*tp_hash */
+ 0, /*tp_call*/
+ valpy_str, /*tp_str*/
+ 0, /*tp_getattro*/
+ 0, /*tp_setattro*/
+ 0, /*tp_as_buffer*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES, /*tp_flags*/
+ "GDB value object", /* tp_doc */
+ 0, /* tp_traverse */
+ 0, /* tp_clear */
+ valpy_richcompare, /* tp_richcompare */
+ 0, /* tp_weaklistoffset */
+ 0, /* tp_iter */
+ 0, /* tp_iternext */
+ value_object_methods /* tp_methods */
+};
+
+
+/* Called by the Python interpreter when deallocating a value object. */
+static void
+valpy_dealloc (PyObject *obj)
+{
+ value_object *self = (value_object *) obj;
+
+ value_remove_from_list (&values_in_python, self->value);
+
+ if (!self->owned_by_gdb)
+ value_free (self->value);
+ self->ob_type->tp_free (self);
+}
+
+/* Called when a new gdb.Value object needs to be allocated. */
+static PyObject *
+valpy_new (PyTypeObject *subtype, PyObject *args, PyObject *keywords)
+{
+ struct value *value = NULL; /* Initialize to appease gcc warning. */
+ value_object *value_obj;
+ volatile struct gdb_exception except;
+
+ if (PyTuple_Size (args) != 1)
+ {
+ PyErr_SetString (PyExc_TypeError, _("Value object creation takes only " \
+ "1 argument"));
+ return NULL;
+ }
+
+ value_obj = (value_object *) subtype->tp_alloc (subtype, 1);
+ if (value_obj == NULL)
+ {
+ PyErr_SetString (PyExc_MemoryError, _("Could not allocate memory to " \
+ "create Value object."));
+ return NULL;
+ }
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ value = convert_value_from_python (PyTuple_GetItem (args, 0));
+ }
+ if (except.reason < 0)
+ {
+ subtype->tp_free (value_obj);
+ return PyErr_Format (except.reason == RETURN_QUIT
+ ? PyExc_KeyboardInterrupt : PyExc_TypeError,
+ "%s", except.message);
+ }
+
+ value_obj->value = value;
+ release_value (value);
+ value_prepend_to_list (&values_in_python, value);
+
+ return (PyObject *) value_obj;
+}
+
+/* Given a value of a pointer type, apply the C unary * operator to it. */
+static PyObject *
+valpy_dereference (PyObject *self, PyObject *args)
+{
+ struct value *res_val = NULL; /* Initialize to appease gcc warning. */
+ volatile struct gdb_exception except;
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ res_val = value_ind (((value_object *) self)->value);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ return value_to_value_object (res_val);
+}
+
+static Py_ssize_t
+valpy_length (PyObject *self)
+{
+ /* We don't support getting the number of elements in a struct / class. */
+ PyErr_SetString (PyExc_NotImplementedError,
+ "Invalid operation on gdb.Value.");
+ return -1;
+}
+
+/* Given string name of an element inside structure, return its value
+ object. */
+static PyObject *
+valpy_getitem (PyObject *self, PyObject *key)
+{
+ value_object *self_value = (value_object *) self;
+ char *field;
+ struct value *res_val = NULL; /* Initialize to appease gcc warning. */
+ struct cleanup *old;
+ volatile struct gdb_exception except;
+
+ field = python_string_to_target_string (key);
+ if (field == NULL)
+ return NULL;
+
+ old = make_cleanup (xfree, field);
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ res_val = value_struct_elt (&self_value->value, NULL, field, 0, NULL);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ do_cleanups (old);
+
+ return value_to_value_object (res_val);
+}
+
+static int
+valpy_setitem (PyObject *self, PyObject *key, PyObject *value)
+{
+ PyErr_Format (PyExc_NotImplementedError,
+ _("Setting of struct elements is not currently supported."));
+ return -1;
+}
+
+/* Called by the Python interpreter to obtain string representation
+ of the object. */
+static PyObject *
+valpy_str (PyObject *self)
+{
+ char *s = NULL;
+ long dummy;
+ struct ui_file *stb;
+ struct cleanup *old_chain;
+ PyObject *result;
+ volatile struct gdb_exception except;
+
+ stb = mem_fileopen ();
+ old_chain = make_cleanup_ui_file_delete (stb);
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ common_val_print (((value_object *) self)->value, stb, 0, 0, 0,
+ Val_pretty_default, current_language);
+ s = ui_file_xstrdup (stb, &dummy);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ do_cleanups (old_chain);
+
+ result = PyUnicode_Decode (s, strlen (s), host_charset (), NULL);
+ xfree (s);
+
+ return result;
+}
+
+enum valpy_opcode
+{
+ VALPY_ADD,
+ VALPY_SUB,
+ VALPY_MUL,
+ VALPY_DIV,
+ VALPY_REM,
+ VALPY_POW
+};
+
+/* Returns a value object which is the sum of this value with the given
+ integer argument. */
+static PyObject *
+valpy_binop (enum valpy_opcode opcode, PyObject *self, PyObject *other)
+{
+ long l;
+ double d;
+ struct value *res_val = NULL; /* Initialize to appease gcc warning. */
+ struct value *other_val;
+ value_object *self_value;
+ volatile struct gdb_exception except;
+
+ /* If the gdb.Value object is the second operand, then it will be passed
+ to us as the OTHER argument, and SELF will be an entirely different
+ kind of object, altogether. Swap them to avoid surprises. */
+ if (!PyObject_TypeCheck (self, &value_object_type))
+ {
+ PyObject *tmp;
+
+ tmp = self;
+ self = other;
+ other = tmp;
+ }
+
+ self_value = (value_object *) self;
+
+ if (PyObject_TypeCheck (other, &value_object_type))
+ other_val = ((value_object *) other)->value;
+ else if (PyInt_Check (other))
+ {
+ l = PyInt_AsLong (other);
+ if (PyErr_Occurred ())
+ return Py_NotImplemented;
+
+ other_val = value_from_longest (builtin_type_int, l);
+ }
+ else if (PyFloat_Check (other))
+ {
+ d = PyFloat_AsDouble (other);
+ if (PyErr_Occurred ())
+ return Py_NotImplemented;
+
+ other_val = value_from_double (builtin_type_double, d);
+ }
+ else
+ /* If the types cannot be added, Python documentation says to return
+ NotImplemented (http://docs.python.org/ref/numeric-types.html). */
+ return Py_NotImplemented;
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ switch (opcode)
+ {
+ case VALPY_ADD:
+ res_val = value_add (self_value->value, other_val);
+ break;
+ case VALPY_SUB:
+ res_val = value_sub (self_value->value, other_val);
+ break;
+ case VALPY_MUL:
+ res_val = value_binop (self_value->value, other_val, BINOP_MUL);
+ break;
+ case VALPY_DIV:
+ res_val = value_binop (self_value->value, other_val, BINOP_DIV);
+ break;
+ case VALPY_REM:
+ res_val = value_binop (self_value->value, other_val, BINOP_REM);
+ break;
+ case VALPY_POW:
+ res_val = value_binop (self_value->value, other_val, BINOP_EXP);
+ break;
+ }
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ return value_to_value_object (res_val);
+}
+
+static PyObject *
+valpy_add (PyObject *self, PyObject *other)
+{
+ return valpy_binop (VALPY_ADD, self, other);
+}
+
+static PyObject *
+valpy_subtract (PyObject *self, PyObject *other)
+{
+ return valpy_binop (VALPY_SUB, self, other);
+}
+
+static PyObject *
+valpy_multiply (PyObject *self, PyObject *other)
+{
+ return valpy_binop (VALPY_MUL, self, other);
+}
+
+static PyObject *
+valpy_divide (PyObject *self, PyObject *other)
+{
+ return valpy_binop (VALPY_DIV, self, other);
+}
+
+static PyObject *
+valpy_remainder (PyObject *self, PyObject *other)
+{
+ return valpy_binop (VALPY_REM, self, other);
+}
+
+static PyObject *
+valpy_power (PyObject *self, PyObject *other, PyObject *unused)
+{
+ /* We don't support the ternary form of pow. I don't know how to express
+ that, so let's just throw NotImplementedError to at least do something
+ about it. */
+ if (unused != Py_None)
+ {
+ PyErr_SetString (PyExc_NotImplementedError,
+ "Invalid operation on gdb.Value.");
+ return NULL;
+ }
+
+ return valpy_binop (VALPY_POW, self, other);
+}
+
+static PyObject *
+valpy_negative (PyObject *self)
+{
+ struct value *val = NULL;
+ volatile struct gdb_exception except;
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ val = value_neg (((value_object *) self)->value);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ return value_to_value_object (val);
+}
+
+static PyObject *
+valpy_positive (PyObject *self)
+{
+ struct value *copy = value_copy (((value_object *) self)->value);
+
+ return value_to_value_object (copy);
+}
+
+static PyObject *
+valpy_absolute (PyObject *self)
+{
+ if (value_less (((value_object *) self)->value,
+ value_from_longest (builtin_type_int, 0)))
+ return valpy_negative (self);
+ else
+ return valpy_positive (self);
+}
+
+/* Implements boolean evaluation of gdb.Value. */
+static int
+valpy_nonzero (PyObject *self)
+{
+ value_object *self_value = (value_object *) self;
+ struct type *type;
+
+ type = check_typedef (value_type (self_value->value));
+
+ if (is_integral_type (type))
+ return !!value_as_long (self_value->value);
+ else if (TYPE_CODE (type) == TYPE_CODE_FLT)
+ return value_as_double (self_value->value) != 0;
+ else if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
+ return !decimal_is_zero (value_contents (self_value->value),
+ TYPE_LENGTH (type));
+ else
+ {
+ PyErr_SetString (PyExc_TypeError, _("Attempted truth testing on invalid "
+ "gdb.Value type."));
+ return 0;
+ }
+}
+
+/* Implements comparison operations for value objects. */
+static PyObject *
+valpy_richcompare (PyObject *self, PyObject *other, int op)
+{
+ int result = 0;
+ struct value *value_self, *value_other;
+ volatile struct gdb_exception except;
+
+ if (PyObject_TypeCheck (other, &value_object_type))
+ value_other = ((value_object *) other)->value;
+ else if (PyInt_Check (other))
+ {
+ LONGEST l;
+
+ l = PyInt_AsLong (other);
+ if (PyErr_Occurred ())
+ return NULL;
+
+ value_other = value_from_longest (builtin_type_int, l);
+ }
+ else if (PyFloat_Check (other))
+ {
+ DOUBLEST d;
+
+ d = PyFloat_AsDouble (other);
+ if (PyErr_Occurred ())
+ return NULL;
+
+ value_other = value_from_double (builtin_type_double, d);
+ }
+ else if (PyString_Check (other) || PyUnicode_Check (other))
+ {
+ char *str;
+
+ str = python_string_to_target_string (other);
+ value_other = value_from_string (str);
+ xfree (str);
+ }
+ else if (other == Py_None)
+ /* Comparing with None is special. From what I can tell, in Python
+ None is smaller than anything else. */
+ switch (op) {
+ case Py_LT:
+ case Py_LE:
+ case Py_EQ:
+ Py_RETURN_FALSE;
+ case Py_NE:
+ case Py_GT:
+ case Py_GE:
+ Py_RETURN_TRUE;
+ default:
+ /* Can't happen. */
+ PyErr_SetString (PyExc_NotImplementedError,
+ "Invalid operation on gdb.Value.");
+ return NULL;
+ }
+ else
+ {
+ PyErr_SetString (PyExc_NotImplementedError,
+ "Operation not supported on gdb.Value of this type.");
+ return NULL;
+ }
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ switch (op) {
+ case Py_LT:
+ result = value_less (((value_object *) self)->value, value_other);
+ break;
+ case Py_LE:
+ result = value_less (((value_object *) self)->value, value_other)
+ || value_equal (((value_object *) self)->value, value_other);
+ break;
+ case Py_EQ:
+ result = value_equal (((value_object *) self)->value, value_other);
+ break;
+ case Py_NE:
+ result = !value_equal (((value_object *) self)->value, value_other);
+ break;
+ case Py_GT:
+ result = value_less (value_other, ((value_object *) self)->value);
+ break;
+ case Py_GE:
+ result = value_less (value_other, ((value_object *) self)->value)
+ || value_equal (((value_object *) self)->value, value_other);
+ break;
+ default:
+ /* Can't happen. */
+ PyErr_SetString (PyExc_NotImplementedError,
+ "Invalid operation on gdb.Value.");
+ return NULL;
+ }
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ if (result == 1)
+ Py_RETURN_TRUE;
+
+ Py_RETURN_FALSE;
+}
+
+/* Returns an object for a value which is released from the all_values chain,
+ so its lifetime is not bound to the execution of a command. */
+PyObject *
+value_to_value_object (struct value *val)
+{
+ value_object *val_obj;
+
+ val_obj = PyObject_New (value_object, &value_object_type);
+ if (val_obj != NULL)
+ {
+ val_obj->value = val;
+ release_value (val);
+ value_prepend_to_list (&values_in_python, val);
+ }
+
+ return (PyObject *) val_obj;
+}
+
+/* Try to convert a Python value to a gdb value. If the value cannot
+ be converted, throw a gdb exception. */
+
+struct value *
+convert_value_from_python (PyObject *obj)
+{
+ struct value *value = NULL; /* -Wall */
+ PyObject *target_str, *unicode_str;
+ struct cleanup *old;
+
+ if (! obj)
+ error (_("Internal error while converting Python value."));
+
+ if (PyBool_Check (obj))
+ value = value_from_longest (builtin_type_bool, obj == Py_True);
+ else if (PyInt_Check (obj))
+ value = value_from_longest (builtin_type_int, PyInt_AsLong (obj));
+ else if (PyLong_Check (obj))
+ {
+ LONGEST l = PyLong_AsLongLong (obj);
+ if (! PyErr_Occurred ())
+ value = value_from_longest (builtin_type_long, l);
+ }
+ else if (PyFloat_Check (obj))
+ {
+ double d = PyFloat_AsDouble (obj);
+ if (! PyErr_Occurred ())
+ value = value_from_double (builtin_type_double, d);
+ }
+ else if (PyString_Check (obj) || PyUnicode_Check (obj))
+ {
+ char *s;
+
+ s = python_string_to_target_string (obj);
+ if (s == NULL)
+ return NULL;
+
+ old = make_cleanup (xfree, s);
+ value = value_from_string (s);
+ do_cleanups (old);
+ }
+ else if (PyObject_TypeCheck (obj, &value_object_type))
+ value = ((value_object *) obj)->value;
+ else
+ error (_("Could not convert Python object: %s"),
+ PyString_AsString (PyObject_Str (obj)));
+
+ if (PyErr_Occurred ())
+ error (_("Error converting Python value."));
+
+ return value;
+}
+
+/* Returns value object in the ARGth position in GDB's history. */
+PyObject *
+gdbpy_get_value_from_history (PyObject *self, PyObject *args)
+{
+ int i;
+ struct value *res_val = NULL; /* Initialize to appease gcc warning. */
+ volatile struct gdb_exception except;
+
+ if (!PyArg_ParseTuple (args, "i", &i))
+ return NULL;
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ res_val = access_value_history (i);
+ }
+ GDB_PY_HANDLE_EXCEPTION (except);
+
+ return value_to_value_object (res_val);
+}
+
+void
+gdbpy_initialize_values (void)
+{
+ value_object_type.tp_new = valpy_new;
+ if (PyType_Ready (&value_object_type) < 0)
+ return;
+
+ Py_INCREF (&value_object_type);
+ PyModule_AddObject (gdb_module, "Value", (PyObject *) &value_object_type);
+
+ values_in_python = NULL;
+}
+
+#endif /* HAVE_PYTHON */
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 7186914..2159271 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -52,6 +52,8 @@ static PyObject *gdbpy_flush (PyObject *, PyObject *);

static PyMethodDef GdbMethods[] =
{
+ { "get_value_from_history", gdbpy_get_value_from_history, METH_VARARGS,
+ "Get a value from history" },
{ "execute", execute_gdb_command, METH_VARARGS,
"Execute a gdb command" },
{ "get_parameter", get_parameter, METH_VARARGS,
@@ -407,6 +409,8 @@ Enables or disables printing of Python stack traces."),
PyModule_AddStringConstant (gdb_module, "HOST_CONFIG", (char*) host_name);
PyModule_AddStringConstant (gdb_module, "TARGET_CONFIG", (char*) target_name);

+ gdbpy_initialize_values ();
+
PyRun_SimpleString ("import gdb");

/* Create a couple objects which are used for Python's stdout and
diff --git a/gdb/python/python.h b/gdb/python/python.h
index 00ff159..102fef6 100644
--- a/gdb/python/python.h
+++ b/gdb/python/python.h
@@ -22,6 +22,8 @@

#include "value.h"

+extern struct value *values_in_python;
+
void eval_python_from_control_command (struct command_line *);

#endif /* GDB_PYTHON_H */
diff --git a/gdb/testsuite/gdb.python/python-values.c b/gdb/testsuite/gdb.python/python-values.c
new file mode 100644
index 0000000..82cfd9a
--- /dev/null
+++ b/gdb/testsuite/gdb.python/python-values.c
@@ -0,0 +1,41 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2008 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+struct s
+{
+ int a;
+ int b;
+};
+
+union u
+{
+ int a;
+ float b;
+};
+
+int
+main (int argc, char *argv[])
+{
+ struct s s;
+ union u u;
+
+ s.a = 3;
+ s.b = 5;
+ u.a = 7;
+
+ return 0; /* break to inspect struct and union */
+}
diff --git a/gdb/testsuite/gdb.python/python-values.exp b/gdb/testsuite/gdb.python/python-values.exp
new file mode 100644
index 0000000..7b9ea03
--- /dev/null
+++ b/gdb/testsuite/gdb.python/python-values.exp
@@ -0,0 +1,278 @@
+# Copyright (C) 2008 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite. It tests the mechanism
+# exposing values to Python.
+
+if $tracelevel then {
+ strace $tracelevel
+}
+
+set testfile "python-values"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+ untested "Couldn't compile ${srcfile}"
+ return -1
+}
+
+# Usage: gdb_py_test_multiple NAME INPUT RESULT {INPUT RESULT}...
+# Run a test named NAME, consisting of multiple lines of input.
+# After each input line INPUT, search for result line RESULT.
+# Succeed if all results are seen; fail otherwise.
+proc gdb_py_test_multiple {name args} {
+ global gdb_prompt
+ foreach {input result} $args {
+ if {[gdb_test_multiple $input "$name - $input" {
+ -re "\[\r\n\]*($result)\[\r\n\]+($gdb_prompt | *>)$" {
+ pass "$name - $input"
+ }
+ }]} {
+ return 1
+ }
+ }
+ return 0
+}
+
+proc test_value_creation {} {
+ global gdb_prompt
+
+ gdb_test_multiple "python i = gdb.Value (True)" "create boolean value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create boolean value"}
+ -re "$gdb_prompt $" {pass "create boolean value"}
+ }
+
+ gdb_test_multiple "python i = gdb.Value (5)" "create integer value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create integer value"}
+ -re "$gdb_prompt $" {pass "create integer value"}
+ }
+
+ gdb_test_multiple "python i = gdb.Value (5L)" "create long value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create long value"}
+ -re "$gdb_prompt $" {pass "create long value"}
+ }
+
+ gdb_test_multiple "python f = gdb.Value (1.25)" "create double value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create double value"}
+ -re "$gdb_prompt $" {pass "create double value"}
+ }
+
+ gdb_test_multiple "python a = gdb.Value ('string test')" "create 8-bit string value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create 8-bit string value"}
+ -re "$gdb_prompt $" {pass "create 8-bit string value"}
+ }
+
+ gdb_test "python print a" "\"string test\"" "print 8-bit string"
+ gdb_test "python print a.__class__" "<type 'gdb.Value'>" "verify type of 8-bit string"
+
+ gdb_test_multiple "python a = gdb.Value (u'unicode test')" "create unicode value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create unicode value"}
+ -re "$gdb_prompt $" {pass "create unicode value"}
+ }
+
+ gdb_test "python print a" "\"unicode test\"" "print Unicode string"
+ gdb_test "python print a.__class__" "<type 'gdb.Value'>" "verify type of unicode string"
+}
+
+proc test_value_numeric_ops {} {
+ global gdb_prompt
+
+ gdb_test_multiple "python i = gdb.Value (5)" "create first integer value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create first integer value"}
+ -re "$gdb_prompt $" {}
+ }
+
+ gdb_test_multiple "python j = gdb.Value (2)" "create second integer value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create second integer value"}
+ -re "$gdb_prompt $" {}
+ }
+
+ gdb_test_multiple "python f = gdb.Value (1.25)" "create first double value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create first double value"}
+ -re "$gdb_prompt $" {}
+ }
+
+ gdb_test_multiple "python g = gdb.Value (2.5)" "create second double value" {
+ -re "Traceback.*$gdb_prompt $" {fail "create second double value"}
+ -re "$gdb_prompt $" {}
+ }
+
+ gdb_test "python print 'result = ' + str(i+j)" " = 7" "add two integer values"
+ gdb_test "python print (i+j).__class__" "<type 'gdb.Value'>" "verify type of integer add result"
+
+ gdb_test "python print 'result = ' + str(f+g)" " = 3.75" "add two double values"
+ gdb_test "python print 'result = ' + str(i-j)" " = 3" "subtract two integer values"
+ gdb_test "python print 'result = ' + str(f-g)" " = -1.25" "subtract two double values"
+ gdb_test "python print 'result = ' + str(i*j)" " = 10" "multiply two integer values"
+ gdb_test "python print 'result = ' + str(f*g)" " = 3.125" "multiply two double values"
+ gdb_test "python print 'result = ' + str(i/j)" " = 2" "divide two integer values"
+ gdb_test "python print 'result = ' + str(f/g)" " = 0.5" "divide two double values"
+ gdb_test "python print 'result = ' + str(i%j)" " = 1" "take remainder of two integer values"
+ # Remainder of float is implemented in Python but not in GDB's value system.
+
+ gdb_test "python print 'result = ' + str(i**j)" " = 25" "integer value raised to the power of another integer value"
+ gdb_test "python print 'result = ' + str(g**j)" " = 6.25" "double value raised to the power of integer value"
+
+ gdb_test "python print 'result = ' + str(-i)" " = -5" "negated integer value"
+ gdb_test "python print 'result = ' + str(+i)" " = 5" "positive integer value"
+ gdb_test "python print 'result = ' + str(-f)" " = -1.25" "negated double value"
+ gdb_test "python print 'result = ' + str(+f)" " = 1.25" "positive double value"
+ gdb_test "python print 'result = ' + str(abs(j-i))" " = 3" "absolute of integer value"
+ gdb_test "python print 'result = ' + str(abs(f-g))" " = 1.25" "absolute of double value"
+
+ # Test gdb.Value mixed with Python types.
+
+ gdb_test "python print 'result = ' + str(i+1)" " = 6" "add integer value with python integer"
+ gdb_test "python print (i+1).__class__" "<type 'gdb.Value'>" "verify type of mixed integer add result"
+ gdb_test "python print 'result = ' + str(f+1.5)" " = 2.75" "add double value with python float"
+
+ gdb_test "python print 'result = ' + str(1+i)" " = 6" "add python integer with integer value"
+ gdb_test "python print 'result = ' + str(1.5+f)" " = 2.75" "add python float with double value"
+
+ # Test some invalid operations.
+
+ gdb_test_multiple "python print 'result = ' + str(i+'foo')" "catch error in python type conversion" {
+ -re "unsupported operand type.*$gdb_prompt $" {pass "catch error in python type conversion"}
+ -re "result = .*$gdb_prompt $" {fail "catch error in python type conversion"}
+ -re "$gdb_prompt $" {fail "catch error in python type conversion"}
+ }
+
+ gdb_test_multiple "python print 'result = ' + str(i+gdb.Value('foo'))" "catch throw of GDB error" {
+ -re "Traceback.*$gdb_prompt $" {pass "catch throw of GDB error"}
+ -re "result = .*$gdb_prompt $" {fail "catch throw of GDB error"}
+ -re "$gdb_prompt $" {fail "catch throw of GDB error"}
+ }
+}
+
+proc test_value_boolean {} {
+ # First, define a useful function to test booleans.
+ gdb_py_test_multiple "define function to test booleans" \
+ "python" "" \
+ "def test_bool (val):" "" \
+ " if val:" "" \
+ " print 'yay'" "" \
+ " else:" "" \
+ " print 'nay'" "" \
+ "end" ""
+
+ gdb_test "py test_bool (gdb.Value (True))" "yay" "check evaluation of true boolean value in expression"
+
+ gdb_test "py test_bool (gdb.Value (False))" "nay" "check evaluation of false boolean value in expression"
+
+ gdb_test "py test_bool (gdb.Value (5))" "yay" "check evaluation of true integer value in expression"
+
+ gdb_test "py test_bool (gdb.Value (0))" "nay" "check evaluation of false integer value in expression"
+
+ gdb_test "py test_bool (gdb.Value (5.2))" "yay" "check evaluation of true integer value in expression"
+
+ gdb_test "py test_bool (gdb.Value (0.0))" "nay" "check evaluation of false integer value in expression"
+}
+
+proc test_value_compare {} {
+ gdb_test "py print gdb.Value (1) < gdb.Value (1)" "False" "less than, equal"
+ gdb_test "py print gdb.Value (1) < gdb.Value (2)" "True" "less than, less"
+ gdb_test "py print gdb.Value (2) < gdb.Value (1)" "False" "less than, greater"
+ gdb_test "py print gdb.Value (2) < None" "False" "less than, None"
+
+ gdb_test "py print gdb.Value (1) <= gdb.Value (1)" "True" "less or equal, equal"
+ gdb_test "py print gdb.Value (1) <= gdb.Value (2)" "True" "less or equal, less"
+ gdb_test "py print gdb.Value (2) <= gdb.Value (1)" "False" "less or equal, greater"
+ gdb_test "py print gdb.Value (2) <= None" "False" "less or equal, None"
+
+ gdb_test "py print gdb.Value (1) == gdb.Value (1)" "True" "equality of gdb.Values"
+ gdb_test "py print gdb.Value (1) == gdb.Value (2)" "False" "inequality of gdb.Values"
+ gdb_test "py print gdb.Value (1) == 1.0" "True" "equality of gdb.Value with Python value"
+ gdb_test "py print gdb.Value (1) == 2" "False" "inequality of gdb.Value with Python value"
+ gdb_test "py print gdb.Value (1) == None" "False" "inequality of gdb.Value with None"
+
+ gdb_test "py print gdb.Value (1) != gdb.Value (1)" "False" "inequality, false"
+ gdb_test "py print gdb.Value (1) != gdb.Value (2)" "True" "inequality, true"
+ gdb_test "py print gdb.Value (1) != None" "True" "inequality, None"
+
+ gdb_test "py print gdb.Value (1) > gdb.Value (1)" "False" "greater than, equal"
+ gdb_test "py print gdb.Value (1) > gdb.Value (2)" "False" "greater than, less"
+ gdb_test "py print gdb.Value (2) > gdb.Value (1)" "True" "greater than, greater"
+ gdb_test "py print gdb.Value (2) > None" "True" "greater than, None"
+
+ gdb_test "py print gdb.Value (1) >= gdb.Value (1)" "True" "greater or equal, equal"
+ gdb_test "py print gdb.Value (1) >= gdb.Value (2)" "False" "greater or equal, less"
+ gdb_test "py print gdb.Value (2) >= gdb.Value (1)" "True" "greater or equal, greater"
+ gdb_test "py print gdb.Value (2) >= None" "True" "greater or equal, None"
+}
+
+proc test_value_in_inferior {} {
+ global gdb_prompt
+ global testfile
+
+ gdb_breakpoint [gdb_get_line_number "break to inspect struct and union"]
+ gdb_start_cmd
+
+ # Avoid race condition where a continue command in gdb_continue_to_breakpoint
+ # is issued too early.
+ gdb_test "" "$gdb_prompt"
+
+ gdb_continue_to_breakpoint "break to inspect struct and union"
+
+ # Just get inferior variable s in the value history, available to python.
+ gdb_test "print s" " = {a = 3, b = 5}" ""
+
+ gdb_test_multiple "python s = gdb.get_value_from_history (0)" "get value from history" {
+ -re "Traceback.*$gdb_prompt $" {fail "get value from history"}
+ -re "$gdb_prompt $" {pass "get value from history"}
+ }
+
+ gdb_test "python print 'result = ' + str(s\['a'\])" " = 3" "acess element inside struct using 8-bit string name"
+ gdb_test "python print 'result = ' + str(s\[u'a'\])" " = 3" "acess element inside struct using unicode name"
+
+ # Test dereferencing the argv pointer
+
+ # Just get inferior variable argv the value history, available to python.
+ gdb_test "print argv" " = \\(char \\*\\*\\) 0x.*" ""
+
+ gdb_test_multiple "python argv = gdb.get_value_from_history (0)" "" {
+ -re "Traceback.*$gdb_prompt $" {fail "get value from history"}
+ -re "$gdb_prompt $" {}
+ }
+
+ gdb_test_multiple "python arg0 = argv.dereference ()" "" {
+ -re "Traceback.*$gdb_prompt $" {fail "dereference value"}
+ -re "$gdb_prompt $" {pass "dereference value"}
+ }
+
+ # Check that the dereferenced value is sane
+ gdb_test "python print arg0" "0x.*$testfile\"" "verify dereferenced value"
+}
+
+
+# Start with a fresh gdb.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+gdb_test_multiple "python print 'hello, world!'" "verify python support" {
+ -re "not supported.*$gdb_prompt $" {
+ unsupported "python support is disabled"
+ return -1
+ }
+ -re "$gdb_prompt $" {}
+}
+
+test_value_creation
+test_value_numeric_ops
+test_value_boolean
+test_value_compare
+test_value_in_inferior
diff --git a/gdb/value.c b/gdb/value.c
index b38bae0..b652174 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -37,6 +37,8 @@
#include "dfp.h"
#include "objfiles.h"

+#include "python/python.h"
+
/* Prototypes for exported functions. */

void _initialize_values (void);
@@ -130,8 +132,8 @@ struct value

/* Values are stored in a chain, so that they can be deleted easily
over calls to the inferior. Values assigned to internal
- variables or put into the value history are taken off this
- list. */
+ variables, put into the value history or exposed to Python are
+ taken off this list. */
struct value *next;

/* Register number if the value is from a register. */
@@ -257,6 +259,31 @@ allocate_repeat_value (struct type *type, int count)
type, range_type));
}

+/* Needed if another module needs to maintain its on list of values. */
+void
+value_prepend_to_list (struct value **head, struct value *val)
+{
+ val->next = *head;
+ *head = val;
+}
+
+/* Needed if another module needs to maintain its on list of values. */
+void
+value_remove_from_list (struct value **head, struct value *val)
+{
+ struct value *prev;
+
+ if (*head == val)
+ *head = (*head)->next;
+ else
+ for (prev = *head; prev->next; prev = prev->next)
+ if (prev->next == val)
+ {
+ prev->next = val->next;
+ break;
+ }
+}
+
/* Accessor methods. */

struct value *
@@ -916,6 +943,7 @@ preserve_values (struct objfile *objfile)
htab_t copied_types;
struct value_history_chunk *cur;
struct internalvar *var;
+ struct value *val;
int i;

/* Create the hash table. We allocate on the objfile's obstack, since
@@ -930,6 +958,9 @@ preserve_values (struct objfile *objfile)
for (var = internalvars; var; var = var->next)
preserve_one_value (var->value, objfile, copied_types);

+ for (val = values_in_python; val; val = val->next)
+ preserve_one_value (val, objfile, copied_types);
+
htab_delete (copied_types);
}

diff --git a/gdb/value.h b/gdb/value.h
index 2aac9b2..45a6ced 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -40,9 +40,15 @@ struct language_defn;

struct value;

+/* Needed if another module needs to maintain its on list of values. */
+
+void value_prepend_to_list (struct value **head, struct value *val);
+void value_remove_from_list (struct value **head, struct value *val);
+
/* Values are stored in a chain, so that they can be deleted easily
- over calls to the inferior. Values assigned to internal variables
- or put into the value history are taken off this list. */
+ over calls to the inferior. Values assigned to internal variables,
+ put into the value history or exposed to Python are taken off this
+ list. */

struct value *value_next (struct value *);