u-boot/arch/nios2/cpu/sysid.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

58 lines
1.5 KiB
C

/*
* (C) Copyright 2004, Psyent Corporation <www.psyent.com>
* Scott McNutt <smcnutt@psyent.com>
*
* 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>
#if defined (CONFIG_SYS_NIOS_SYSID_BASE)
#include <command.h>
#include <asm/io.h>
#include <nios2-io.h>
#include <linux/time.h>
void display_sysid (void)
{
struct nios_sysid_t *sysid = (struct nios_sysid_t *)CONFIG_SYS_NIOS_SYSID_BASE;
struct tm t;
char asc[32];
time_t stamp;
stamp = readl (&sysid->timestamp);
localtime_r (&stamp, &t);
asctime_r (&t, asc);
printf ("SYSID : %08lx, %s", readl (&sysid->id), asc);
}
int do_sysid (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
display_sysid ();
return (0);
}
U_BOOT_CMD(
sysid, 1, 1, do_sysid,
"display Nios-II system id",
""
);
#endif /* CONFIG_SYS_NIOS_SYSID_BASE */