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binutils-gdb/gdb/command.h
Sergio Durigan Junior 7d793aa9f0 PR python/16699: GDB Python command completion with overriden complete vs. completer class 
This PR came from a Red Hat bug that was filed recently.  I checked and
it still exists on HEAD, so here's a proposed fix.  Although this is
marked as a Python backend bug, this is really about the completion
mechanism used by GDB.  Since this code reminds me of my first attempt
to make a good noodle, it took me quite some time to fix it in a
non-intrusive way.

The problem is triggered when one registers a completion method inside a
class in a Python script, rather than registering the command using a
completer class directly.  For example, consider the following script:

    class MyFirstCommand(gdb.Command):
          def __init__(self):
              gdb.Command.__init__(self,'myfirstcommand',gdb.COMMAND_USER,gdb.COMPLETE_FILENAME)

              def invoke(self,argument,from_tty):
                  raise gdb.GdbError('not implemented')

    class MySecondCommand(gdb.Command):
          def __init__(self):
              gdb.Command.__init__(self,'mysecondcommand',gdb.COMMAND_USER)

              def invoke(self,argument,from_tty):
                  raise gdb.GdbError('not implemented')

                  def complete(self,text,word):
                      return gdb.COMPLETE_FILENAME

    MyFirstCommand ()
    MySecondCommand ()

When one loads this into GDB and tries to complete filenames for both
myfirstcommand and mysecondcommand, she gets:

    (gdb) myfirstcommand /hom<TAB>
    (gdb) myfirstcommand /home/
                               ^
    ...
    (gdb) mysecondcommand /hom<TAB>
    (gdb) mysecondcommand /home
                                ^

(The "^" marks the final position of the cursor after the TAB).

So we see that myfirstcommand honors the COMPLETE_FILENAME class (as
specified in the command creation), but mysecondcommand does not.  After
some investigation, I found that the problem lies with the set of word
break characters that is used for each case.  The set should be the same
for both commands, but it is not.

During the process of deciding which type of completion should be used,
the code in gdb/completer.c:complete_line_internal analyses the command
that requested the completion and tries to determine the type of
completion wanted by checking which completion function will be called
(e.g., filename_completer for filenames, location_completer for
locations, etc.).

This all works fine for myfirstcommand, because immediately after the
command registration the Python backend already sets its completion
function to filename_completer (which then causes the
complete_line_internal function to choose the right set of word break
chars).  However, for mysecondcommand, this decision is postponed to
when the completer function is evaluated, and the Python backend uses an
internal completer (called cmdpy_completer).  complete_line_internal
doesn't know about this internal completer, and can't choose the right
set of word break chars in time, which then leads to a bad decision when
completing the "/hom" word.

So, after a few attempts, I decided to create another callback in
"struct cmd_list_element" that will be responsible for handling the case
when there is an unknown completer function for complete_line_internal
to work with.  So far, only the Python backend uses this callback, and
only when the user provides a completer method instead of registering
the command directly with a completer class.  I think this is the best
option because it not very intrusive (all the other commands will still
work normally), but especially because the whole completion code is so
messy that it would be hard to fix this without having to redesign
things.

I have regtested this on Fedora 18 x86_64, without regressions.  I also
included a testcase.

gdb/ChangeLog:
2014-09-03  Sergio Durigan Junior  <sergiodj@redhat.com>

	PR python/16699
	* cli/cli-decode.c (set_cmd_completer_handle_brkchars): New
	function.
	(add_cmd): Set "completer_handle_brkchars" to NULL.
	* cli/cli-decode.h (struct cmd_list_element)
	<completer_handle_brkchars>: New field.
	* command.h (completer_ftype_void): New typedef.
	(set_cmd_completer_handle_brkchars): New prototype.
	* completer.c (set_gdb_completion_word_break_characters): New
	function.
	(complete_line_internal): Call "completer_handle_brkchars"
	callback from command.
	* completer.h: Include "command.h".
	(set_gdb_completion_word_break_characters): New prototype.
	* python/py-cmd.c (cmdpy_completer_helper): New function.
	(cmdpy_completer_handle_brkchars): New function.
	(cmdpy_completer): Adjust to use cmdpy_completer_helper.
	(cmdpy_init): Set completer_handle_brkchars to
	cmdpy_completer_handle_brkchars.

gdb/testsuite/ChangeLog:
2014-09-03  Sergio Durigan Junior  <sergiodj@redhat.com>

	PR python/16699
	* gdb.python/py-completion.exp: New file.
	* gdb.python/py-completion.py: Likewise.
2014-09-03 16:30:28 -04:00

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/* Header file for command creation.
Copyright (C) 1986-2014 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/>. */
#if !defined (COMMAND_H)
#define COMMAND_H 1
#include "gdb_vecs.h"
/* This file defines the public interface for any code wanting to
create commands. */
/* Command classes are top-level categories into which commands are
broken down for "help" purposes.
Notes on classes: class_alias is for alias commands which are not
abbreviations of the original command. class-pseudo is for
commands which are not really commands nor help topics ("stop"). */
enum command_class
{
/* Special args to help_list */
class_deprecated = -3, all_classes = -2, all_commands = -1,
/* Classes of commands */
no_class = -1, class_run = 0, class_vars, class_stack, class_files,
class_support, class_info, class_breakpoint, class_trace,
class_alias, class_bookmark, class_obscure, class_maintenance,
class_pseudo, class_tui, class_user, class_xdb,
no_set_class /* Used for "show" commands that have no corresponding
"set" command. */
};
/* FIXME: cagney/2002-03-17: Once cmd_type() has been removed, ``enum
cmd_types'' can be moved from "command.h" to "cli-decode.h". */
/* Not a set/show command. Note that some commands which begin with
"set" or "show" might be in this category, if their syntax does
not fall into one of the following categories. */
typedef enum cmd_types
{
not_set_cmd,
set_cmd,
show_cmd
}
cmd_types;
/* Types of "set" or "show" command. */
typedef enum var_types
{
/* "on" or "off". *VAR is an integer which is nonzero for on,
zero for off. */
var_boolean,
/* "on" / "true" / "enable" or "off" / "false" / "disable" or
"auto. *VAR is an ``enum auto_boolean''. NOTE: In general a
custom show command will need to be implemented - one that for
"auto" prints both the "auto" and the current auto-selected
value. */
var_auto_boolean,
/* Unsigned Integer. *VAR is an unsigned int. The user can type
0 to mean "unlimited", which is stored in *VAR as UINT_MAX. */
var_uinteger,
/* Like var_uinteger but signed. *VAR is an int. The user can
type 0 to mean "unlimited", which is stored in *VAR as
INT_MAX. The only remaining use of it is the Python API.
Don't use it elsewhere. */
var_integer,
/* String which the user enters with escapes (e.g. the user types
\n and it is a real newline in the stored string).
*VAR is a malloc'd string, or NULL if the string is empty. */
var_string,
/* String which stores what the user types verbatim.
*VAR is a malloc'd string, or NULL if the string is empty. */
var_string_noescape,
/* String which stores a filename. (*VAR) is a malloc'd string,
or "" if the string was empty. */
var_optional_filename,
/* String which stores a filename. (*VAR) is a malloc'd
string. */
var_filename,
/* ZeroableInteger. *VAR is an int. Like var_integer except
that zero really means zero. */
var_zinteger,
/* ZeroableUnsignedInteger. *VAR is an unsigned int. Zero really
means zero. */
var_zuinteger,
/* ZeroableUnsignedInteger with unlimited value. *VAR is an int,
but its range is [0, INT_MAX]. -1 stands for unlimited and
other negative numbers are not allowed. */
var_zuinteger_unlimited,
/* Enumerated type. Can only have one of the specified values.
*VAR is a char pointer to the name of the element that we
find. */
var_enum
}
var_types;
/* This structure records one command'd definition. */
struct cmd_list_element;
typedef void cmd_cfunc_ftype (char *args, int from_tty);
/* Forward-declarations of the entry-points of cli/cli-decode.c. */
/* API to the manipulation of command lists. */
extern int valid_user_defined_cmd_name_p (const char *name);
extern struct cmd_list_element *add_cmd (const char *, enum command_class,
cmd_cfunc_ftype *fun,
const char *,
struct cmd_list_element **);
extern struct cmd_list_element *add_alias_cmd (const char *, const char *,
enum command_class, int,
struct cmd_list_element **);
extern struct cmd_list_element *add_prefix_cmd (const char *, enum command_class,
cmd_cfunc_ftype *fun,
const char *,
struct cmd_list_element **,
const char *, int,
struct cmd_list_element **);
extern struct cmd_list_element *add_abbrev_prefix_cmd (const char *,
enum command_class,
cmd_cfunc_ftype *fun,
const char *,
struct cmd_list_element
**, const char *, int,
struct cmd_list_element
**);
/* Set the commands corresponding callback. */
extern void set_cmd_cfunc (struct cmd_list_element *cmd,
cmd_cfunc_ftype *cfunc);
typedef void cmd_sfunc_ftype (char *args, int from_tty,
struct cmd_list_element *c);
extern void set_cmd_sfunc (struct cmd_list_element *cmd,
cmd_sfunc_ftype *sfunc);
typedef VEC (char_ptr) *completer_ftype (struct cmd_list_element *,
const char *, const char *);
typedef void completer_ftype_void (struct cmd_list_element *,
const char *, const char *);
extern void set_cmd_completer (struct cmd_list_element *, completer_ftype *);
/* Set the completer_handle_brkchars callback. */
extern void set_cmd_completer_handle_brkchars (struct cmd_list_element *,
completer_ftype_void *);
/* HACK: cagney/2002-02-23: Code, mostly in tracepoints.c, grubs
around in cmd objects to test the value of the commands sfunc(). */
extern int cmd_cfunc_eq (struct cmd_list_element *cmd,
cmd_cfunc_ftype *cfun);
/* Each command object has a local context attached to it. */
extern void set_cmd_context (struct cmd_list_element *cmd,
void *context);
extern void *get_cmd_context (struct cmd_list_element *cmd);
/* Execute CMD's pre/post hook. Throw an error if the command fails.
If already executing this pre/post hook, or there is no pre/post
hook, the call is silently ignored. */
extern void execute_cmd_pre_hook (struct cmd_list_element *cmd);
extern void execute_cmd_post_hook (struct cmd_list_element *cmd);
/* Return the type of the command. */
extern enum cmd_types cmd_type (struct cmd_list_element *cmd);
/* Flag for an ambiguous cmd_list result. */
#define CMD_LIST_AMBIGUOUS ((struct cmd_list_element *) -1)
extern struct cmd_list_element *lookup_cmd (const char **,
struct cmd_list_element *, char *,
int, int);
extern struct cmd_list_element *lookup_cmd_1 (const char **,
struct cmd_list_element *,
struct cmd_list_element **,
int);
extern struct cmd_list_element *deprecate_cmd (struct cmd_list_element *,
const char * );
extern void deprecated_cmd_warning (const char *);
extern int lookup_cmd_composition (const char *text,
struct cmd_list_element **alias,
struct cmd_list_element **prefix_cmd,
struct cmd_list_element **cmd);
extern struct cmd_list_element *add_com (const char *, enum command_class,
cmd_cfunc_ftype *fun,
const char *);
extern struct cmd_list_element *add_com_alias (const char *, const char *,
enum command_class, int);
extern struct cmd_list_element *add_info (const char *,
cmd_cfunc_ftype *fun,
const char *);
extern struct cmd_list_element *add_info_alias (const char *, const char *,
int);
extern VEC (char_ptr) *complete_on_cmdlist (struct cmd_list_element *,
const char *, const char *, int);
extern VEC (char_ptr) *complete_on_enum (const char *const *enumlist,
const char *, const char *);
/* Functions that implement commands about CLI commands. */
extern void help_list (struct cmd_list_element *, const char *,
enum command_class, struct ui_file *);
/* Method for show a set/show variable's VALUE on FILE. If this
method isn't supplied deprecated_show_value_hack() is called (which
is not good). */
typedef void (show_value_ftype) (struct ui_file *file,
int from_tty,
struct cmd_list_element *cmd,
const char *value);
/* NOTE: i18n: This function is not i18n friendly. Callers should
instead print the value out directly. */
extern show_value_ftype deprecated_show_value_hack;
extern void add_setshow_enum_cmd (const char *name,
enum command_class class,
const char *const *enumlist,
const char **var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_auto_boolean_cmd (const char *name,
enum command_class class,
enum auto_boolean *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_boolean_cmd (const char *name,
enum command_class class,
int *var,
const char *set_doc, const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_filename_cmd (const char *name,
enum command_class class,
char **var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_string_cmd (const char *name,
enum command_class class,
char **var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern struct cmd_list_element *add_setshow_string_noescape_cmd
(const char *name,
enum command_class class,
char **var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_optional_filename_cmd (const char *name,
enum command_class class,
char **var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_integer_cmd (const char *name,
enum command_class class,
int *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_uinteger_cmd (const char *name,
enum command_class class,
unsigned int *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_zinteger_cmd (const char *name,
enum command_class class,
int *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void add_setshow_zuinteger_cmd (const char *name,
enum command_class class,
unsigned int *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
extern void
add_setshow_zuinteger_unlimited_cmd (const char *name,
enum command_class class,
int *var,
const char *set_doc,
const char *show_doc,
const char *help_doc,
cmd_sfunc_ftype *set_func,
show_value_ftype *show_func,
struct cmd_list_element **set_list,
struct cmd_list_element **show_list);
/* Do a "show" command for each thing on a command list. */
extern void cmd_show_list (struct cmd_list_element *, int, const char *);
/* Used everywhere whenever at least one parameter is required and
none is specified. */
extern void error_no_arg (const char *) ATTRIBUTE_NORETURN;
extern void dont_repeat (void);
extern struct cleanup *prevent_dont_repeat (void);
/* Used to mark commands that don't do anything. If we just leave the
function field NULL, the command is interpreted as a help topic, or
as a class of commands. */
extern void not_just_help_class_command (char *, int);
/* Check function pointer. */
extern int cmd_func_p (struct cmd_list_element *cmd);
/* Call the command function. */
extern void cmd_func (struct cmd_list_element *cmd,
char *args, int from_tty);
#endif /* !defined (COMMAND_H) */
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