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binutils-gdb/gdb/python/py-prettyprint.c

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/* Python pretty-printing
Copyright (C) 2008-2018 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 "objfiles.h"
#include "symtab.h"
#include "language.h"
#include "valprint.h"
#include "extension-priv.h"
#include "python.h"
#include "python-internal.h"
#include "py-ref.h"
/* Return type of print_string_repr. */
enum string_repr_result
{
/* The string method returned None. */
string_repr_none,
/* The string method had an error. */
string_repr_error,
/* Everything ok. */
string_repr_ok
};
/* Helper function for find_pretty_printer which iterates over a list,
calls each function and inspects output. This will return a
printer object if one recognizes VALUE. If no printer is found, it
will return None. On error, it will set the Python error and
return NULL. */
static PyObject *
search_pp_list (PyObject *list, PyObject *value)
{
Py_ssize_t pp_list_size, list_index;
pp_list_size = PyList_Size (list);
for (list_index = 0; list_index < pp_list_size; list_index++)
{
PyObject *function = PyList_GetItem (list, list_index);
if (! function)
return NULL;
/* Skip if disabled. */
if (PyObject_HasAttr (function, gdbpy_enabled_cst))
{
gdbpy_ref<> attr (PyObject_GetAttr (function, gdbpy_enabled_cst));
int cmp;
if (attr == NULL)
return NULL;
cmp = PyObject_IsTrue (attr.get ());
if (cmp == -1)
return NULL;
if (!cmp)
continue;
}
gdbpy_ref<> printer (PyObject_CallFunctionObjArgs (function, value,
NULL));
if (printer == NULL)
return NULL;
else if (printer != Py_None)
return printer.release ();
}
Py_RETURN_NONE;
}
/* Subroutine of find_pretty_printer to simplify it.
Look for a pretty-printer to print VALUE in all objfiles.
The result is NULL if there's an error and the search should be terminated.
The result is Py_None, suitably inc-ref'd, if no pretty-printer was found.
Otherwise the result is the pretty-printer function, suitably inc-ref'd. */
static PyObject *
find_pretty_printer_from_objfiles (PyObject *value)
{
struct objfile *obj;
ALL_OBJFILES (obj)
{
PyObject *objf = objfile_to_objfile_object (obj);
if (!objf)
{
/* Ignore the error and continue. */
PyErr_Clear ();
continue;
}
gdbpy_ref<> pp_list (objfpy_get_printers (objf, NULL));
gdbpy_ref<> function (search_pp_list (pp_list.get (), value));
/* If there is an error in any objfile list, abort the search and exit. */
if (function == NULL)
return NULL;
if (function != Py_None)
return function.release ();
}
Py_RETURN_NONE;
}
/* Subroutine of find_pretty_printer to simplify it.
Look for a pretty-printer to print VALUE in the current program space.
The result is NULL if there's an error and the search should be terminated.
The result is Py_None, suitably inc-ref'd, if no pretty-printer was found.
Otherwise the result is the pretty-printer function, suitably inc-ref'd. */
static PyObject *
find_pretty_printer_from_progspace (PyObject *value)
{
PyObject *obj = pspace_to_pspace_object (current_program_space);
if (!obj)
return NULL;
gdbpy_ref<> pp_list (pspy_get_printers (obj, NULL));
return search_pp_list (pp_list.get (), value);
}
/* Subroutine of find_pretty_printer to simplify it.
Look for a pretty-printer to print VALUE in the gdb module.
The result is NULL if there's an error and the search should be terminated.
The result is Py_None, suitably inc-ref'd, if no pretty-printer was found.
Otherwise the result is the pretty-printer function, suitably inc-ref'd. */
static PyObject *
find_pretty_printer_from_gdb (PyObject *value)
{
/* Fetch the global pretty printer list. */
if (gdb_python_module == NULL
|| ! PyObject_HasAttrString (gdb_python_module, "pretty_printers"))
Py_RETURN_NONE;
gdbpy_ref<> pp_list (PyObject_GetAttrString (gdb_python_module,
"pretty_printers"));
if (pp_list == NULL || ! PyList_Check (pp_list.get ()))
Py_RETURN_NONE;
return search_pp_list (pp_list.get (), value);
}
/* Find the pretty-printing constructor function for VALUE. If no
pretty-printer exists, return None. If one exists, return a new
reference. On error, set the Python error and return NULL. */
static PyObject *
find_pretty_printer (PyObject *value)
{
/* Look at the pretty-printer list for each objfile
in the current program-space. */
gdbpy_ref<> function (find_pretty_printer_from_objfiles (value));
if (function == NULL || function != Py_None)
return function.release ();
/* Look at the pretty-printer list for the current program-space. */
function.reset (find_pretty_printer_from_progspace (value));
if (function == NULL || function != Py_None)
return function.release ();
/* Look at the pretty-printer list in the gdb module. */
return find_pretty_printer_from_gdb (value);
}
/* Pretty-print a single value, via the printer object PRINTER.
If the function returns a string, a PyObject containing the string
is returned. If the function returns Py_NONE that means the pretty
printer returned the Python None as a value. Otherwise, if the
function returns a value, *OUT_VALUE is set to the value, and NULL
is returned. On error, *OUT_VALUE is set to NULL, NULL is
returned, with a python exception set. */
static PyObject *
pretty_print_one_value (PyObject *printer, struct value **out_value)
{
gdbpy_ref<> result;
*out_value = NULL;
TRY
{
result.reset (PyObject_CallMethodObjArgs (printer, gdbpy_to_string_cst,
NULL));
if (result != NULL)
{
if (! gdbpy_is_string (result.get ())
&& ! gdbpy_is_lazy_string (result.get ())
&& result != Py_None)
{
*out_value = convert_value_from_python (result.get ());
if (PyErr_Occurred ())
*out_value = NULL;
result = NULL;
}
}
}
CATCH (except, RETURN_MASK_ALL)
{
}
END_CATCH
return result.release ();
}
/* Return the display hint for the object printer, PRINTER. Return
NULL if there is no display_hint method, or if the method did not
return a string. On error, print stack trace and return NULL. On
success, return an xmalloc()d string. */
gdb::unique_xmalloc_ptr<char>
gdbpy_get_display_hint (PyObject *printer)
{
gdb::unique_xmalloc_ptr<char> result;
if (! PyObject_HasAttr (printer, gdbpy_display_hint_cst))
return NULL;
gdbpy_ref<> hint (PyObject_CallMethodObjArgs (printer, gdbpy_display_hint_cst,
NULL));
if (hint != NULL)
{
if (gdbpy_is_string (hint.get ()))
{
result = python_string_to_host_string (hint.get ());
if (result == NULL)
gdbpy_print_stack ();
}
}
else
gdbpy_print_stack ();
return result;
}
/* A wrapper for gdbpy_print_stack that ignores MemoryError. */
static void
print_stack_unless_memory_error (struct ui_file *stream)
{
if (PyErr_ExceptionMatches (gdbpy_gdb_memory_error))
{
PyObject *type, *value, *trace;
PyErr_Fetch (&type, &value, &trace);
gdbpy_ref<> type_ref (type);
gdbpy_ref<> value_ref (value);
gdbpy_ref<> trace_ref (trace);
gdb::unique_xmalloc_ptr<char>
msg (gdbpy_exception_to_string (type, value));
if (msg == NULL || *msg == '\0')
fprintf_filtered (stream, _("<error reading variable>"));
else
fprintf_filtered (stream, _("<error reading variable: %s>"),
msg.get ());
}
else
gdbpy_print_stack ();
}
/* Helper for gdbpy_apply_val_pretty_printer which calls to_string and
formats the result. */
static enum string_repr_result
print_string_repr (PyObject *printer, const char *hint,
struct ui_file *stream, int recurse,
const struct value_print_options *options,
const struct language_defn *language,
struct gdbarch *gdbarch)
{
struct value *replacement = NULL;
enum string_repr_result result = string_repr_ok;
gdbpy_ref<> py_str (pretty_print_one_value (printer, &replacement));
if (py_str != NULL)
{
if (py_str == Py_None)
result = string_repr_none;
else if (gdbpy_is_lazy_string (py_str.get ()))
{
CORE_ADDR addr;
long length;
struct type *type;
gdb::unique_xmalloc_ptr<char> encoding;
struct value_print_options local_opts = *options;
gdbpy_extract_lazy_string (py_str.get (), &addr, &type,
&length, &encoding);
local_opts.addressprint = 0;
val_print_string (type, encoding.get (), addr, (int) length,
stream, &local_opts);
}
else
{
gdbpy_ref<> string
(python_string_to_target_python_string (py_str.get ()));
if (string != NULL)
{
char *output;
long length;
struct type *type;
#ifdef IS_PY3K
output = PyBytes_AS_STRING (string.get ());
length = PyBytes_GET_SIZE (string.get ());
#else
output = PyString_AsString (string.get ());
length = PyString_Size (string.get ());
#endif
type = builtin_type (gdbarch)->builtin_char;
if (hint && !strcmp (hint, "string"))
LA_PRINT_STRING (stream, type, (gdb_byte *) output,
length, NULL, 0, options);
else
fputs_filtered (output, stream);
}
else
{
result = string_repr_error;
print_stack_unless_memory_error (stream);
}
}
}
else if (replacement)
{
struct value_print_options opts = *options;
opts.addressprint = 0;
common_val_print (replacement, stream, recurse, &opts, language);
}
else
{
result = string_repr_error;
print_stack_unless_memory_error (stream);
}
return result;
}
#ifndef IS_PY3K
/* Create a dummy PyFrameObject, needed to work around
a Python-2.4 bug with generators. */
class dummy_python_frame
{
public:
dummy_python_frame ();
~dummy_python_frame ()
{
if (m_valid)
m_tstate->frame = m_saved_frame;
}
bool failed () const
{
return !m_valid;
}
private:
bool m_valid;
PyFrameObject *m_saved_frame;
gdbpy_ref<> m_frame;
PyThreadState *m_tstate;
};
dummy_python_frame::dummy_python_frame ()
: m_valid (false),
m_saved_frame (NULL),
m_tstate (NULL)
{
PyCodeObject *code;
PyFrameObject *frame;
gdbpy_ref<> empty_string (PyString_FromString (""));
if (empty_string == NULL)
return;
gdbpy_ref<> null_tuple (PyTuple_New (0));
if (null_tuple == NULL)
return;
code = PyCode_New (0, /* argcount */
0, /* locals */
0, /* stacksize */
0, /* flags */
empty_string.get (), /* code */
null_tuple.get (), /* consts */
null_tuple.get (), /* names */
null_tuple.get (), /* varnames */
#if PYTHON_API_VERSION >= 1010
null_tuple.get (), /* freevars */
null_tuple.get (), /* cellvars */
#endif
empty_string.get (), /* filename */
empty_string.get (), /* name */
1, /* firstlineno */
empty_string.get () /* lnotab */
);
if (code == NULL)
return;
gdbpy_ref<> code_holder ((PyObject *) code);
gdbpy_ref<> globals (PyDict_New ());
if (globals == NULL)
return;
m_tstate = PyThreadState_GET ();
frame = PyFrame_New (m_tstate, code, globals.get (), NULL);
if (frame == NULL)
return;
m_frame.reset ((PyObject *) frame);
m_tstate->frame = frame;
m_saved_frame = frame->f_back;
m_valid = true;
}
#endif
/* Helper for gdbpy_apply_val_pretty_printer that formats children of the
printer, if any exist. If is_py_none is true, then nothing has
been printed by to_string, and format output accordingly. */
static void
print_children (PyObject *printer, const char *hint,
struct ui_file *stream, int recurse,
const struct value_print_options *options,
const struct language_defn *language,
int is_py_none)
{
int is_map, is_array, done_flag, pretty;
unsigned int i;
if (! PyObject_HasAttr (printer, gdbpy_children_cst))
return;
/* If we are printing a map or an array, we want some special
formatting. */
is_map = hint && ! strcmp (hint, "map");
is_array = hint && ! strcmp (hint, "array");
gdbpy_ref<> children (PyObject_CallMethodObjArgs (printer, gdbpy_children_cst,
NULL));
if (children == NULL)
{
print_stack_unless_memory_error (stream);
return;
}
gdbpy_ref<> iter (PyObject_GetIter (children.get ()));
if (iter == NULL)
{
print_stack_unless_memory_error (stream);
return;
}
/* Use the prettyformat_arrays option if we are printing an array,
and the pretty option otherwise. */
if (is_array)
pretty = options->prettyformat_arrays;
else
{
if (options->prettyformat == Val_prettyformat)
pretty = 1;
else
pretty = options->prettyformat_structs;
}
/* Manufacture a dummy Python frame to work around Python 2.4 bug,
where it insists on having a non-NULL tstate->frame when
a generator is called. */
#ifndef IS_PY3K
dummy_python_frame frame;
if (frame.failed ())
{
gdbpy_print_stack ();
return;
}
#endif
done_flag = 0;
for (i = 0; i < options->print_max; ++i)
{
PyObject *py_v;
const char *name;
gdbpy_ref<> item (PyIter_Next (iter.get ()));
if (item == NULL)
{
if (PyErr_Occurred ())
print_stack_unless_memory_error (stream);
/* Set a flag so we can know whether we printed all the
available elements. */
else
done_flag = 1;
break;
}
if (! PyTuple_Check (item.get ()) || PyTuple_Size (item.get ()) != 2)
{
PyErr_SetString (PyExc_TypeError,
_("Result of children iterator not a tuple"
" of two elements."));
gdbpy_print_stack ();
continue;
}
if (! PyArg_ParseTuple (item.get (), "sO", &name, &py_v))
{
/* The user won't necessarily get a stack trace here, so provide
more context. */
if (gdbpy_print_python_errors_p ())
fprintf_unfiltered (gdb_stderr,
_("Bad result from children iterator.\n"));
gdbpy_print_stack ();
continue;
}
/* Print initial "{". For other elements, there are three
cases:
1. Maps. Print a "," after each value element.
2. Arrays. Always print a ",".
3. Other. Always print a ",". */
if (i == 0)
{
if (is_py_none)
fputs_filtered ("{", stream);
else
fputs_filtered (" = {", stream);
}
else if (! is_map || i % 2 == 0)
fputs_filtered (pretty ? "," : ", ", stream);
/* In summary mode, we just want to print "= {...}" if there is
a value. */
if (options->summary)
{
/* This increment tricks the post-loop logic to print what
we want. */
++i;
/* Likewise. */
pretty = 0;
break;
}
if (! is_map || i % 2 == 0)
{
if (pretty)
{
fputs_filtered ("\n", stream);
print_spaces_filtered (2 + 2 * recurse, stream);
}
else
wrap_here (n_spaces (2 + 2 *recurse));
}
if (is_map && i % 2 == 0)
fputs_filtered ("[", stream);
else if (is_array)
{
/* We print the index, not whatever the child method
returned as the name. */
if (options->print_array_indexes)
fprintf_filtered (stream, "[%d] = ", i);
}
else if (! is_map)
{
fputs_filtered (name, stream);
fputs_filtered (" = ", stream);
}
if (gdbpy_is_lazy_string (py_v))
{
CORE_ADDR addr;
struct type *type;
long length;
gdb::unique_xmalloc_ptr<char> encoding;
struct value_print_options local_opts = *options;
gdbpy_extract_lazy_string (py_v, &addr, &type, &length, &encoding);
local_opts.addressprint = 0;
val_print_string (type, encoding.get (), addr, (int) length, stream,
&local_opts);
}
else if (gdbpy_is_string (py_v))
{
gdb::unique_xmalloc_ptr<char> output;
output = python_string_to_host_string (py_v);
if (!output)
gdbpy_print_stack ();
else
fputs_filtered (output.get (), stream);
}
else
{
struct value *value = convert_value_from_python (py_v);
if (value == NULL)
{
gdbpy_print_stack ();
error (_("Error while executing Python code."));
}
else
common_val_print (value, stream, recurse + 1, options, language);
}
if (is_map && i % 2 == 0)
fputs_filtered ("] = ", stream);
}
if (i)
{
if (!done_flag)
{
if (pretty)
{
fputs_filtered ("\n", stream);
print_spaces_filtered (2 + 2 * recurse, stream);
}
fputs_filtered ("...", stream);
}
if (pretty)
{
fputs_filtered ("\n", stream);
print_spaces_filtered (2 * recurse, stream);
}
fputs_filtered ("}", stream);
}
}
enum ext_lang_rc
gdbpy_apply_val_pretty_printer (const struct extension_language_defn *extlang,
struct type *type,
LONGEST embedded_offset, CORE_ADDR address,
struct ui_file *stream, int recurse,
struct value *val,
const struct value_print_options *options,
const struct language_defn *language)
{
struct gdbarch *gdbarch = get_type_arch (type);
struct value *value;
enum string_repr_result print_result;
const gdb_byte *valaddr = value_contents_for_printing (val);
/* No pretty-printer support for unavailable values. */
if (!value_bytes_available (val, embedded_offset, TYPE_LENGTH (type)))
return EXT_LANG_RC_NOP;
if (!gdb_python_initialized)
return EXT_LANG_RC_NOP;
gdbpy_enter enter_py (gdbarch, language);
/* Instantiate the printer. */
value = value_from_component (val, type, embedded_offset);
gdbpy_ref<> val_obj (value_to_value_object (value));
if (val_obj == NULL)
{
print_stack_unless_memory_error (stream);
return EXT_LANG_RC_ERROR;
}
/* Find the constructor. */
gdbpy_ref<> printer (find_pretty_printer (val_obj.get ()));
if (printer == NULL)
{
print_stack_unless_memory_error (stream);
return EXT_LANG_RC_ERROR;
}
if (printer == Py_None)
return EXT_LANG_RC_NOP;
/* If we are printing a map, we want some special formatting. */
gdb::unique_xmalloc_ptr<char> hint (gdbpy_get_display_hint (printer.get ()));
/* Print the section */
print_result = print_string_repr (printer.get (), hint.get (), stream,
recurse, options, language, gdbarch);
if (print_result != string_repr_error)
print_children (printer.get (), hint.get (), stream, recurse, options,
language, print_result == string_repr_none);
if (PyErr_Occurred ())
print_stack_unless_memory_error (stream);
return EXT_LANG_RC_OK;
}
/* Apply a pretty-printer for the varobj code. PRINTER_OBJ is the
print object. It must have a 'to_string' method (but this is
checked by varobj, not here) which takes no arguments and
returns a string. The printer will return a value and in the case
of a Python string being returned, this function will return a
PyObject containing the string. For any other type, *REPLACEMENT is
set to the replacement value and this function returns NULL. On
error, *REPLACEMENT is set to NULL and this function also returns
NULL. */
PyObject *
apply_varobj_pretty_printer (PyObject *printer_obj,
struct value **replacement,
struct ui_file *stream)
{
PyObject *py_str = NULL;
*replacement = NULL;
py_str = pretty_print_one_value (printer_obj, replacement);
if (*replacement == NULL && py_str == NULL)
print_stack_unless_memory_error (stream);
return py_str;
}
/* Find a pretty-printer object for the varobj module. Returns a new
reference to the object if successful; returns NULL if not. VALUE
is the value for which a printer tests to determine if it
can pretty-print the value. */
PyObject *
gdbpy_get_varobj_pretty_printer (struct value *value)
{
TRY
{
value = value_copy (value);
}
CATCH (except, RETURN_MASK_ALL)
{
GDB_PY_HANDLE_EXCEPTION (except);
}
END_CATCH
gdbpy_ref<> val_obj (value_to_value_object (value));
if (val_obj == NULL)
return NULL;
return find_pretty_printer (val_obj.get ());
}
/* A Python function which wraps find_pretty_printer and instantiates
the resulting class. This accepts a Value argument and returns a
pretty printer instance, or None. This function is useful as an
argument to the MI command -var-set-visualizer. */
PyObject *
gdbpy_default_visualizer (PyObject *self, PyObject *args)
{
PyObject *val_obj;
PyObject *cons;
struct value *value;
if (! PyArg_ParseTuple (args, "O", &val_obj))
return NULL;
value = value_object_to_value (val_obj);
if (! value)
{
PyErr_SetString (PyExc_TypeError,
_("Argument must be a gdb.Value."));
return NULL;
}
cons = find_pretty_printer (val_obj);
return cons;
}
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