u-boot/board/digsy_mtc
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
..
cmd_mtc.c Make sure that argv[] argument pointers are not modified. 2010-07-04 23:55:42 +02:00
cmd_mtc.h digsy_mtc: Add mtc state command. 2009-08-09 22:59:27 +02:00
config.mk Add support for the digsy MTC board. 2009-03-20 22:39:14 +01:00
digsy_mtc.c ppc: Remove board-specific command table relocation fixups 2009-10-03 10:17:56 +02:00
eeprom.h Add support for the digsy MTC board. 2009-03-20 22:39:14 +01:00
is42s16800a-7t.h Update CHANGELOG, coding style cleanup. 2009-04-05 00:27:57 +02:00
Makefile digsy MTC: Add 'mtc' command. 2009-06-14 23:04:37 +02:00