
Previously, the prefixname field of struct cmd_list_element was manually
set for prefix commands. This seems verbose and error prone as it
required every single call to functions adding prefix commands to
specify the prefix name while the same information can be easily
generated.
Historically, this was not possible as the prefix field was null for
many commands, but this was fixed in commit
3f4d92ebdf
by Philippe Waroquiers, so
we can rely on the prefix field being set when generating the prefix
name.
This commit also fixes a use after free in this scenario:
* A command gets created via Python (using the gdb.Command class).
The prefix name member is dynamically allocated.
* An alias to the new command is created. The alias's prefixname is set
to point to the prefixname for the original command with a direct
assignment.
* A new command with the same name as the Python command is created.
* The object for the original Python command gets freed and its
prefixname gets freed as well.
* The alias is updated to point to the new command, but its prefixname
is not updated so it keeps pointing to the freed one.
gdb/ChangeLog:
* command.h (add_prefix_cmd): Remove the prefixname argument as
it can now be generated automatically. Update all callers.
(add_basic_prefix_cmd): Ditto.
(add_show_prefix_cmd): Ditto.
(add_prefix_cmd_suppress_notification): Ditto.
(add_abbrev_prefix_cmd): Ditto.
* cli/cli-decode.c (add_prefix_cmd): Ditto.
(add_basic_prefix_cmd): Ditto.
(add_show_prefix_cmd): Ditto.
(add_prefix_cmd_suppress_notification): Ditto.
(add_prefix_cmd_suppress_notification): Ditto.
(add_abbrev_prefix_cmd): Ditto.
* cli/cli-decode.h (struct cmd_list_element): Replace the
prefixname member variable with a method which generates the
prefix name at runtime. Update all code reading the prefix
name to use the method, and remove all code setting it.
* python/py-cmd.c (cmdpy_destroyer): Remove code to free the
prefixname member as it's now a method.
(cmdpy_function): Determine if the command is a prefix by
looking at prefixlist, not prefixname.
298 lines
10 KiB
C++
298 lines
10 KiB
C++
/* Header file for GDB command decoding library.
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Copyright (C) 2000-2021 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef CLI_CLI_DECODE_H
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#define CLI_CLI_DECODE_H
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/* This file defines the private interfaces for any code implementing
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command internals. */
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/* Include the public interfaces. */
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#include "command.h"
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#include "gdb_regex.h"
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#include "cli-script.h"
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#include "completer.h"
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/* Not a set/show command. Note that some commands which begin with
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"set" or "show" might be in this category, if their syntax does
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not fall into one of the following categories. */
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enum cmd_types
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{
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not_set_cmd,
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set_cmd,
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show_cmd
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};
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/* This structure records one command'd definition. */
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struct cmd_list_element
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{
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cmd_list_element (const char *name_, enum command_class theclass_,
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const char *doc_)
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: name (name_),
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theclass (theclass_),
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cmd_deprecated (0),
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deprecated_warn_user (0),
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malloced_replacement (0),
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doc_allocated (0),
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name_allocated (0),
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hook_in (0),
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allow_unknown (0),
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abbrev_flag (0),
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type (not_set_cmd),
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var_type (var_boolean),
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doc (doc_)
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{
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memset (&function, 0, sizeof (function));
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}
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~cmd_list_element ()
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{
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if (doc && doc_allocated)
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xfree ((char *) doc);
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if (name_allocated)
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xfree ((char *) name);
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}
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DISABLE_COPY_AND_ASSIGN (cmd_list_element);
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/* For prefix commands, return a string containing prefix commands to
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get here: this one plus any others needed to get to it. Ends in a
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space. It is used before the word "command" in describing the
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commands reached through this prefix.
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For non-prefix commands, an empty string is returned. */
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std::string prefixname ()
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{
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if (prefixlist == nullptr)
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/* Not a prefix command. */
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return "";
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std::string prefixname;
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if (prefix != nullptr)
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prefixname = prefix->prefixname ();
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prefixname += name;
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prefixname += " ";
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return prefixname;
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}
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/* Points to next command in this list. */
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struct cmd_list_element *next = nullptr;
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/* Name of this command. */
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const char *name;
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/* Command class; class values are chosen by application program. */
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enum command_class theclass;
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/* When 1 indicated that this command is deprecated. It may be
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removed from gdb's command set in the future. */
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unsigned int cmd_deprecated : 1;
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/* The user needs to be warned that this is a deprecated command.
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The user should only be warned the first time a command is
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used. */
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unsigned int deprecated_warn_user : 1;
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/* When functions are deprecated at compile time (this is the way
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it should, in general, be done) the memory containing the
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replacement string is statically allocated. In some cases it
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makes sense to deprecate commands at runtime (the testsuite is
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one example). In this case the memory for replacement is
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malloc'ed. When a command is undeprecated or re-deprecated at
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runtime we don't want to risk calling free on statically
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allocated memory, so we check this flag. */
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unsigned int malloced_replacement : 1;
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/* Set if the doc field should be xfree'd. */
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unsigned int doc_allocated : 1;
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/* Set if the name field should be xfree'd. */
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unsigned int name_allocated : 1;
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/* Flag that specifies if this command is already running its hook. */
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/* Prevents the possibility of hook recursion. */
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unsigned int hook_in : 1;
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/* For prefix commands only:
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nonzero means do not get an error if subcommand is not
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recognized; call the prefix's own function in that case. */
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unsigned int allow_unknown : 1;
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/* Nonzero says this is an abbreviation, and should not
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be mentioned in lists of commands.
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This allows "br<tab>" to complete to "break", which it
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otherwise wouldn't. */
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unsigned int abbrev_flag : 1;
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/* Type of "set" or "show" command (or SET_NOT_SET if not "set"
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or "show"). */
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ENUM_BITFIELD (cmd_types) type : 2;
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/* What kind of variable is *VAR? */
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ENUM_BITFIELD (var_types) var_type : 4;
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/* Function definition of this command. NULL for command class
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names and for help topics that are not really commands. NOTE:
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cagney/2002-02-02: This function signature is evolving. For
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the moment suggest sticking with either set_cmd_cfunc() or
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set_cmd_sfunc(). */
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void (*func) (struct cmd_list_element *c, const char *args, int from_tty)
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= nullptr;
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/* The command's real callback. At present func() bounces through
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to one of the below. */
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union
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{
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/* If type is not_set_cmd, call it like this: */
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cmd_const_cfunc_ftype *const_cfunc;
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/* If type is set_cmd or show_cmd, first set the variables,
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and then call this: */
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cmd_const_sfunc_ftype *sfunc;
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}
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function;
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/* Local state (context) for this command. This can be anything. */
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void *context = nullptr;
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/* Documentation of this command (or help topic).
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First line is brief documentation; remaining lines form, with it,
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the full documentation. First line should end with a period.
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Entire string should also end with a period, not a newline. */
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const char *doc;
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/* For set/show commands. A method for printing the output to the
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specified stream. */
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show_value_ftype *show_value_func = nullptr;
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/* If this command is deprecated, this is the replacement name. */
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const char *replacement = nullptr;
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/* If this command represents a show command, then this function
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is called before the variable's value is examined. */
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void (*pre_show_hook) (struct cmd_list_element *c) = nullptr;
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/* Hook for another command to be executed before this command. */
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struct cmd_list_element *hook_pre = nullptr;
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/* Hook for another command to be executed after this command. */
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struct cmd_list_element *hook_post = nullptr;
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/* Default arguments to automatically prepend to the user
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provided arguments when running this command or alias. */
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std::string default_args;
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/* Nonzero identifies a prefix command. For them, the address
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of the variable containing the list of subcommands. */
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struct cmd_list_element **prefixlist = nullptr;
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/* The prefix command of this command. */
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struct cmd_list_element *prefix = nullptr;
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/* Completion routine for this command. */
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completer_ftype *completer = symbol_completer;
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/* Handle the word break characters for this completer. Usually
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this function need not be defined, but for some types of
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completers (e.g., Python completers declared as methods inside
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a class) the word break chars may need to be redefined
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depending on the completer type (e.g., for filename
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completers). */
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completer_handle_brkchars_ftype *completer_handle_brkchars = nullptr;
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/* Destruction routine for this command. If non-NULL, this is
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called when this command instance is destroyed. This may be
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used to finalize the CONTEXT field, if needed. */
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void (*destroyer) (struct cmd_list_element *self, void *context) = nullptr;
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/* Pointer to variable affected by "set" and "show". Doesn't
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matter if type is not_set. */
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void *var = nullptr;
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/* Pointer to NULL terminated list of enumerated values (like
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argv). */
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const char *const *enums = nullptr;
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/* Pointer to command strings of user-defined commands */
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counted_command_line user_commands;
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/* Pointer to command that is hooked by this one, (by hook_pre)
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so the hook can be removed when this one is deleted. */
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struct cmd_list_element *hookee_pre = nullptr;
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/* Pointer to command that is hooked by this one, (by hook_post)
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so the hook can be removed when this one is deleted. */
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struct cmd_list_element *hookee_post = nullptr;
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/* Pointer to command that is aliased by this one, so the
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aliased command can be located in case it has been hooked. */
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struct cmd_list_element *cmd_pointer = nullptr;
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/* Start of a linked list of all aliases of this command. */
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struct cmd_list_element *aliases = nullptr;
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/* Link pointer for aliases on an alias list. */
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struct cmd_list_element *alias_chain = nullptr;
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/* If non-null, the pointer to a field in 'struct
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cli_suppress_notification', which will be set to true in cmd_func
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when this command is being executed. It will be set back to false
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when the command has been executed. */
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int *suppress_notification = nullptr;
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};
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/* Functions that implement commands about CLI commands. */
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extern void help_cmd (const char *, struct ui_file *);
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extern void apropos_cmd (struct ui_file *, struct cmd_list_element *,
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bool verbose, compiled_regex &, const char *);
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/* Used to mark commands that don't do anything. If we just leave the
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function field NULL, the command is interpreted as a help topic, or
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as a class of commands. */
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extern void not_just_help_class_command (const char *arg, int from_tty);
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/* Print only the first line of STR on STREAM.
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FOR_VALUE_PREFIX true indicates that the first line is output
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to be a prefix to show a value (see deprecated_show_value_hack):
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the first character is printed in uppercase, and the trailing
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dot character is not printed. */
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extern void print_doc_line (struct ui_file *stream, const char *str,
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bool for_value_prefix);
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/* The enums of boolean commands. */
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extern const char * const boolean_enums[];
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/* The enums of auto-boolean commands. */
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extern const char * const auto_boolean_enums[];
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/* Verify whether a given cmd_list_element is a user-defined command.
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Return 1 if it is user-defined. Return 0 otherwise. */
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extern int cli_user_command_p (struct cmd_list_element *);
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extern int find_command_name_length (const char *);
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#endif /* CLI_CLI_DECODE_H */
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