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	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>
		
	
			
		
			
				
	
	
		
			174 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			174 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * Copyright 2000-2009
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 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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 *
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 * See file CREDITS for list of people who contributed to this
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 * project.
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 *
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 * This program is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU General Public License as
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 * published by the Free Software Foundation; either version 2 of
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 * the License, or (at your option) any later version.
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 *
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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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 *
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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, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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 * MA 02111-1307 USA
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 */
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#include <common.h>
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#include <command.h>
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int do_test(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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{
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	char * const *ap;
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	int left, adv, expr, last_expr, neg, last_cmp;
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	/* args? */
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	if (argc < 3)
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		return 1;
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#if 0
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	{
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		printf("test:");
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		left = 1;
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		while (argv[left])
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			printf(" %s", argv[left++]);
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	}
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#endif
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	last_expr = 0;
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	left = argc - 1; ap = argv + 1;
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	if (left > 0 && strcmp(ap[0], "!") == 0) {
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		neg = 1;
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		ap++;
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		left--;
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	} else
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		neg = 0;
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	expr = -1;
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	last_cmp = -1;
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	last_expr = -1;
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	while (left > 0) {
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		if (strcmp(ap[0], "-o") == 0 || strcmp(ap[0], "-a") == 0)
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			adv = 1;
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		else if (strcmp(ap[0], "-z") == 0 || strcmp(ap[0], "-n") == 0)
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			adv = 2;
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		else
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			adv = 3;
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		if (left < adv) {
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			expr = 1;
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			break;
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		}
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		if (adv == 1) {
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			if (strcmp(ap[0], "-o") == 0) {
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				last_expr = expr;
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				last_cmp = 0;
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			} else if (strcmp(ap[0], "-a") == 0) {
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				last_expr = expr;
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				last_cmp = 1;
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			} else {
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				expr = 1;
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				break;
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			}
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		}
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		if (adv == 2) {
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			if (strcmp(ap[0], "-z") == 0)
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				expr = strlen(ap[1]) == 0 ? 1 : 0;
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			else if (strcmp(ap[0], "-n") == 0)
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				expr = strlen(ap[1]) == 0 ? 0 : 1;
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			else {
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				expr = 1;
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				break;
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			}
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			if (last_cmp == 0)
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				expr = last_expr || expr;
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			else if (last_cmp == 1)
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				expr = last_expr && expr;
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			last_cmp = -1;
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		}
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		if (adv == 3) {
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			if (strcmp(ap[1], "=") == 0)
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				expr = strcmp(ap[0], ap[2]) == 0;
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			else if (strcmp(ap[1], "!=") == 0)
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				expr = strcmp(ap[0], ap[2]) != 0;
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			else if (strcmp(ap[1], ">") == 0)
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				expr = strcmp(ap[0], ap[2]) > 0;
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			else if (strcmp(ap[1], "<") == 0)
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				expr = strcmp(ap[0], ap[2]) < 0;
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			else if (strcmp(ap[1], "-eq") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) == simple_strtol(ap[2], NULL, 10);
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			else if (strcmp(ap[1], "-ne") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) != simple_strtol(ap[2], NULL, 10);
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			else if (strcmp(ap[1], "-lt") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) < simple_strtol(ap[2], NULL, 10);
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			else if (strcmp(ap[1], "-le") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) <= simple_strtol(ap[2], NULL, 10);
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			else if (strcmp(ap[1], "-gt") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) > simple_strtol(ap[2], NULL, 10);
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			else if (strcmp(ap[1], "-ge") == 0)
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				expr = simple_strtol(ap[0], NULL, 10) >= simple_strtol(ap[2], NULL, 10);
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			else {
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				expr = 1;
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				break;
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			}
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			if (last_cmp == 0)
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				expr = last_expr || expr;
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			else if (last_cmp == 1)
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				expr = last_expr && expr;
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			last_cmp = -1;
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		}
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		ap += adv; left -= adv;
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	}
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	if (neg)
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		expr = !expr;
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	expr = !expr;
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	debug (": returns %d\n", expr);
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	return expr;
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}
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U_BOOT_CMD(
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	test,	CONFIG_SYS_MAXARGS,	1,	do_test,
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	"minimal test like /bin/sh",
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	"[args..]"
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);
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int do_false(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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{
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	return 1;
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}
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U_BOOT_CMD(
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	false,	CONFIG_SYS_MAXARGS,	1,	do_false,
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	"do nothing, unsuccessfully",
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	NULL
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);
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int do_true(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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{
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	return 0;
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}
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U_BOOT_CMD(
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	true,	CONFIG_SYS_MAXARGS,	1,	do_true,
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	"do nothing, successfully",
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	NULL
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);
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