Re: [RFA][python] Add gdb.Value.string method.

[Thiago Jung Bauermann <bauerman@br.ibm.com>]

Hi Eli,

I'm not sure if you're aware, this patch didn't get a documentation
review/approval yet.

Thanks for your speedy review on the other Python patches, by the way.
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


El sáb, 03-01-2009 a las 00:27 -0200, Thiago Jung Bauermann escribió:
> Hi,
> 
> This patch adds a method to the Value python class which returns the
> value as a Python Unicode string. It depends on the patch I just posted
> in the "Add la_getstr member to language_defn", and assumes that the
> "Fixes and improvements to gdb.Value" patch has been applied. Ok?
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> gdb/
> 2009-01-03  Thiago Jung Bauermann  <bauerman@br.ibm.com>
> 	    Tom Tromey  <tromey@redhat.com>
> 
> 	* python/python-utils.c (target_string_to_unicode): New function.
> 	* python/python-internal.h (target_string_to_unicode): New prototype.
> 	* python/python-value.c (valpy_string): New function.
> 	(value_object_methods): Add `string' entry.
> 
> gdb/doc/
> 2009-01-03  Tom Tromey  <tromey@redhat.com>
>  
> 	* gdb.texinfo (Values From Inferior): Document Value.string.
> 
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 030d4b3..3b1cd91 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -18202,6 +18202,31 @@ The result @code{bar} will be a @code{gdb.Value} object holding the
>  value pointed to by @code{foo}.
>  @end defmethod
>  
> +@defmethod Value string @r{[}encoding @r{[}errors@r{]}@r{]}
> +If this @code{gdb.Value} represents a string, then this method
> +converts the contents to a Python string.  Otherwise, this method will
> +throw an exception.
> +
> +Strings are recognized in a language-specific way; whether a given
> +@code{gdb.Value} represents a string is determined by the current
> +language.
> +
> +For C-like languages, a value is a string if it is a pointer to or an
> +array of characters or ints.  The string is assumed to be terminated
> +by a zero of the appropriate width.
> +
> +If the optional @var{encoding} argument is given, it must be a string
> +naming the encoding of the string in the @code{gdb.Value}.  The Python
> +codec machinery will be used to convert the string.  If @var{encoding}
> +is not given, or if @var{encoding} is the empty string, then either
> +the @code{target-charset} (@pxref{Character Sets}) will be used, or a
> +language-specific encoding will be used, if the current language is
> +able to supply one.
> +
> +The optional @var{errors} argument is the same as the corresponding
> +argument to Python's @code{string.decode} method.
> +@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 bcd37e4..9c2e8c6 100644
> --- a/gdb/python/python-internal.h
> +++ b/gdb/python/python-internal.h
> @@ -88,6 +88,7 @@ PyObject *python_string_to_unicode (PyObject *obj);
>  char *unicode_to_target_string (PyObject *unicode_str);
>  char *python_string_to_target_string (PyObject *obj);
>  char *python_string_to_host_string (PyObject *obj);
> +PyObject *target_string_to_unicode (const gdb_byte *str, int length);
>  int gdbpy_is_string (PyObject *obj);
>  
>  #endif /* GDB_PYTHON_INTERNAL_H */
> diff --git a/gdb/python/python-utils.c b/gdb/python/python-utils.c
> index c27a930..1e6d952 100644
> --- a/gdb/python/python-utils.c
> +++ b/gdb/python/python-utils.c
> @@ -160,6 +160,19 @@ python_string_to_host_string (PyObject *obj)
>    return unicode_to_encoded_string (str, host_charset ());
>  }
>  
> +/* Converts a target string of LENGTH bytes in the target's charset to a
> +   Python Unicode string. If LENGTH is -1, convert until a null byte is found.
> +
> +   Returns NULL on error, with a python exception set.  */
> +PyObject *
> +target_string_to_unicode (const gdb_byte *str, int length)
> +{
> +  if (length == -1)
> +    length = strlen (str);
> +
> +  return PyUnicode_Decode (str, length, target_charset (), NULL);
> +}
> +
>  /* Return true if OBJ is a Python string or unicode object, false
>     otherwise.  */
>  
> diff --git a/gdb/python/python-value.c b/gdb/python/python-value.c
> index 4d1f864..c6775b2 100644
> --- a/gdb/python/python-value.c
> +++ b/gdb/python/python-value.c
> @@ -148,6 +148,47 @@ valpy_address (PyObject *self, PyObject *args)
>    return value_to_value_object (res_val);
>  }
>  
> +/* Return Unicode string with value contents (assumed to be encoded in the
> +   target's charset).  */
> +static PyObject *
> +valpy_string (PyObject *self, PyObject *args)
> +{
> +  int length, ret = 0;
> +  gdb_byte *buffer;
> +  struct value *value = ((value_object *) self)->value;
> +  volatile struct gdb_exception except;
> +  PyObject *unicode;
> +  const char *encoding = NULL;
> +  const char *errors = NULL;
> +  const char *user_encoding = NULL;
> +  const char *la_encoding = NULL;
> +
> +  if (!PyArg_ParseTuple (args, "|ss", &user_encoding, &errors))
> +    return NULL;
> +
> +  TRY_CATCH (except, RETURN_MASK_ALL)
> +    {
> +      ret = LA_GET_STRING (value, &buffer, &length, &la_encoding);
> +    }
> +  GDB_PY_HANDLE_EXCEPTION (except);
> +
> +  if (ret != 0)
> +    {
> +      /* We may have read a partial string before the error happened, but
> +         we will ignore it and throw an exception anyway.  */
> +      PyErr_SetString (PyExc_RuntimeError, safe_strerror (ret));
> +      xfree (buffer);
> +
> +      return NULL;
> +    }
> +
> +  encoding = (user_encoding && *user_encoding) ? user_encoding : la_encoding;
> +  unicode = PyUnicode_Decode (buffer, length, encoding, errors);
> +  xfree (buffer);
> +
> +  return unicode;
> +}
> +
>  static Py_ssize_t
>  valpy_length (PyObject *self)
>  {
> @@ -773,6 +814,8 @@ gdbpy_initialize_values (void)
>  static PyMethodDef value_object_methods[] = {
>    { "address", valpy_address, METH_NOARGS, "Return the address of the value." },
>    { "dereference", valpy_dereference, METH_NOARGS, "Dereferences the value." },
> +  { "string", valpy_string, METH_VARARGS,
> +    "Return Unicode string representation of the value." },
>    {NULL}  /* Sentinel */
>  };
>  
> 
>