u-boot/common/cmd_vfd.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

104 lines
2.7 KiB
C

/*
* (C) Copyright 2001
* 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
*/
/*
* Command to load a splash screen to the VFDs.
* NOTE that this will be controlled by a key combination when
* the keyboard stuff works. For now the user has to enter a
* bitmap number (only VFD_TEST_LOGO is supported now - 16.10.2002).
* Added VFD_REMOTE_LOGO (same as VFD_TEST_LOGO but a different color)
* on 20.10.2002.
*
* This rather crudely requires that each bitmap be included as a
* header file.
*/
#include <common.h>
#include <command.h>
#if defined(CONFIG_CMD_VFD)
#include <vfd_logo.h>
#define VFD_TEST_LOGO_BMPNR 0
#define VFD_REMOTE_LOGO_BMPNR 1
extern int transfer_pic(unsigned char, unsigned char *, int, int);
int trab_vfd (ulong bitmap);
int do_vfd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
ulong bitmap;
if (argc != 2) {
cmd_usage(cmdtp);
return 1;
}
if (argv[1][0] == '/') { /* select bitmap by number */
bitmap = simple_strtoul(argv[1]+1, NULL, 10);
return (trab_vfd(bitmap));
}
/* display bitmap at given address */
bitmap = simple_strtoul(argv[1], NULL, 16);
transfer_pic(3, (uchar *)bitmap, VFD_LOGO_HEIGHT, VFD_LOGO_WIDTH);
return 0;
}
U_BOOT_CMD(
vfd, 2, 0, do_vfd,
"load a bitmap to the VFDs on TRAB",
"/N\n"
" - load bitmap N to the VFDs (N is _decimal_ !!!)\n"
"vfd ADDR\n"
" - load bitmap at address ADDR"
);
#endif
int trab_vfd (ulong bitmap)
{
uchar *addr;
char *s;
switch (bitmap) {
case VFD_TEST_LOGO_BMPNR:
if ((s = getenv ("bitmap0")) != NULL) {
addr = (uchar *)simple_strtoul (s, NULL, 16);
} else {
addr = &vfd_test_logo_bitmap[0];
}
break;
case VFD_REMOTE_LOGO_BMPNR:
if ((s = getenv ("bitmap1")) != NULL) {
addr = (uchar *)simple_strtoul (s, NULL, 16);
} else {
addr = &vfd_remote_logo_bitmap[0];
}
break;
default:
printf("Unknown bitmap %ld\n", bitmap);
return 1;
}
transfer_pic(3, addr, VFD_LOGO_HEIGHT, VFD_LOGO_WIDTH);
return 0;
}