u-boot/include/command.h
Wolfgang Denk 54841ab50c Make sure that argv[] argument pointers are not modified.
The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands.  Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".

This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:

int main (int argc, char **argv)
{
	while (--argc > 0 && **++argv == '-') {
/* ====> */	while (*++*argv) {
			switch (**argv) {
			case 'd':
				debug++;
				break;
			...
			default:
				usage ();
			}
		}
	}
	...
}

The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell.  With the modification, the compiler will prevent this with
an
	error: increment of read-only location '*argv'

N.B.: The code above can be trivially rewritten like this:

	while (--argc > 0 && **++argv == '-') {
		char *arg = *argv;
		while (*++arg) {
			switch (*arg) {
			...

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
2010-07-04 23:55:42 +02:00

129 lines
3.6 KiB
C

/*
* (C) Copyright 2000-2009
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* Definitions for Command Processor
*/
#ifndef __COMMAND_H
#define __COMMAND_H
#include <config.h>
#ifndef NULL
#define NULL 0
#endif
/* Default to a width of 8 characters for help message command width */
#ifndef CONFIG_SYS_HELP_CMD_WIDTH
#define CONFIG_SYS_HELP_CMD_WIDTH 8
#endif
#ifndef __ASSEMBLY__
/*
* Monitor Command Table
*/
struct cmd_tbl_s {
char *name; /* Command Name */
int maxargs; /* maximum number of arguments */
int repeatable; /* autorepeat allowed? */
/* Implementation function */
int (*cmd)(struct cmd_tbl_s *, int, int, char * const []);
char *usage; /* Usage message (short) */
#ifdef CONFIG_SYS_LONGHELP
char *help; /* Help message (long) */
#endif
#ifdef CONFIG_AUTO_COMPLETE
/* do auto completion on the arguments */
int (*complete)(int argc, char * const argv[], char last_char, int maxv, char *cmdv[]);
#endif
};
typedef struct cmd_tbl_s cmd_tbl_t;
extern cmd_tbl_t __u_boot_cmd_start;
extern cmd_tbl_t __u_boot_cmd_end;
/* common/command.c */
int _do_help (cmd_tbl_t *cmd_start, int cmd_items, cmd_tbl_t * cmdtp, int
flag, int argc, char * const argv[]);
cmd_tbl_t *find_cmd(const char *cmd);
cmd_tbl_t *find_cmd_tbl (const char *cmd, cmd_tbl_t *table, int table_len);
extern int cmd_usage(cmd_tbl_t *cmdtp);
#ifdef CONFIG_AUTO_COMPLETE
extern void install_auto_complete(void);
extern int cmd_auto_complete(const char *const prompt, char *buf, int *np, int *colp);
#endif
/*
* Monitor Command
*
* All commands use a common argument format:
*
* void function (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
*/
typedef void command_t (cmd_tbl_t *, int, int, char *[]);
#if defined(CONFIG_CMD_MEMORY) \
|| defined(CONFIG_CMD_I2C) \
|| defined(CONFIG_CMD_ITEST) \
|| defined(CONFIG_CMD_PCI) \
|| defined(CONFIG_CMD_PORTIO)
#define CMD_DATA_SIZE
extern int cmd_get_data_size(char* arg, int default_size);
#endif
#endif /* __ASSEMBLY__ */
/*
* Command Flags:
*/
#define CMD_FLAG_REPEAT 0x0001 /* repeat last command */
#define CMD_FLAG_BOOTD 0x0002 /* command is from bootd */
#define Struct_Section __attribute__ ((unused,section (".u_boot_cmd")))
#ifdef CONFIG_SYS_LONGHELP
#define U_BOOT_CMD(name,maxargs,rep,cmd,usage,help) \
cmd_tbl_t __u_boot_cmd_##name Struct_Section = {#name, maxargs, rep, cmd, usage, help}
#define U_BOOT_CMD_MKENT(name,maxargs,rep,cmd,usage,help) \
{#name, maxargs, rep, cmd, usage, help}
#else /* no long help info */
#define U_BOOT_CMD(name,maxargs,rep,cmd,usage,help) \
cmd_tbl_t __u_boot_cmd_##name Struct_Section = {#name, maxargs, rep, cmd, usage}
#define U_BOOT_CMD_MKENT(name,maxargs,rep,cmd,usage,help) \
{#name, maxargs, rep, cmd, usage}
#endif /* CONFIG_SYS_LONGHELP */
#endif /* __COMMAND_H */