u-boot/common/cmd_test.c
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

174 lines
3.9 KiB
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
*/
#include <common.h>
#include <command.h>
int do_test(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
char * const *ap;
int left, adv, expr, last_expr, neg, last_cmp;
/* args? */
if (argc < 3)
return 1;
#if 0
{
printf("test:");
left = 1;
while (argv[left])
printf(" %s", argv[left++]);
}
#endif
last_expr = 0;
left = argc - 1; ap = argv + 1;
if (left > 0 && strcmp(ap[0], "!") == 0) {
neg = 1;
ap++;
left--;
} else
neg = 0;
expr = -1;
last_cmp = -1;
last_expr = -1;
while (left > 0) {
if (strcmp(ap[0], "-o") == 0 || strcmp(ap[0], "-a") == 0)
adv = 1;
else if (strcmp(ap[0], "-z") == 0 || strcmp(ap[0], "-n") == 0)
adv = 2;
else
adv = 3;
if (left < adv) {
expr = 1;
break;
}
if (adv == 1) {
if (strcmp(ap[0], "-o") == 0) {
last_expr = expr;
last_cmp = 0;
} else if (strcmp(ap[0], "-a") == 0) {
last_expr = expr;
last_cmp = 1;
} else {
expr = 1;
break;
}
}
if (adv == 2) {
if (strcmp(ap[0], "-z") == 0)
expr = strlen(ap[1]) == 0 ? 1 : 0;
else if (strcmp(ap[0], "-n") == 0)
expr = strlen(ap[1]) == 0 ? 0 : 1;
else {
expr = 1;
break;
}
if (last_cmp == 0)
expr = last_expr || expr;
else if (last_cmp == 1)
expr = last_expr && expr;
last_cmp = -1;
}
if (adv == 3) {
if (strcmp(ap[1], "=") == 0)
expr = strcmp(ap[0], ap[2]) == 0;
else if (strcmp(ap[1], "!=") == 0)
expr = strcmp(ap[0], ap[2]) != 0;
else if (strcmp(ap[1], ">") == 0)
expr = strcmp(ap[0], ap[2]) > 0;
else if (strcmp(ap[1], "<") == 0)
expr = strcmp(ap[0], ap[2]) < 0;
else if (strcmp(ap[1], "-eq") == 0)
expr = simple_strtol(ap[0], NULL, 10) == simple_strtol(ap[2], NULL, 10);
else if (strcmp(ap[1], "-ne") == 0)
expr = simple_strtol(ap[0], NULL, 10) != simple_strtol(ap[2], NULL, 10);
else if (strcmp(ap[1], "-lt") == 0)
expr = simple_strtol(ap[0], NULL, 10) < simple_strtol(ap[2], NULL, 10);
else if (strcmp(ap[1], "-le") == 0)
expr = simple_strtol(ap[0], NULL, 10) <= simple_strtol(ap[2], NULL, 10);
else if (strcmp(ap[1], "-gt") == 0)
expr = simple_strtol(ap[0], NULL, 10) > simple_strtol(ap[2], NULL, 10);
else if (strcmp(ap[1], "-ge") == 0)
expr = simple_strtol(ap[0], NULL, 10) >= simple_strtol(ap[2], NULL, 10);
else {
expr = 1;
break;
}
if (last_cmp == 0)
expr = last_expr || expr;
else if (last_cmp == 1)
expr = last_expr && expr;
last_cmp = -1;
}
ap += adv; left -= adv;
}
if (neg)
expr = !expr;
expr = !expr;
debug (": returns %d\n", expr);
return expr;
}
U_BOOT_CMD(
test, CONFIG_SYS_MAXARGS, 1, do_test,
"minimal test like /bin/sh",
"[args..]"
);
int do_false(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
return 1;
}
U_BOOT_CMD(
false, CONFIG_SYS_MAXARGS, 1, do_false,
"do nothing, unsuccessfully",
NULL
);
int do_true(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
return 0;
}
U_BOOT_CMD(
true, CONFIG_SYS_MAXARGS, 1, do_true,
"do nothing, successfully",
NULL
);