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>

2 files changed, 2 insertions, 2 deletions

diff --git a/board/eltec/bab7xx/bab7xx.c b/board/eltec/bab7xx/bab7xx.c
index 1f78f8d..f5c9777 100644
--- a/board/eltec/bab7xx/bab7xx.c
+++ b/board/eltec/bab7xx/bab7xx.c
@@ -184,7 +184,7 @@ void after_reloc (ulong dest_addr)
  * do_reset is done here because in this case it is board specific, since the
  * 7xx CPUs can only be reset by external HW (the RTC in this case).
  */
-void do_reset (cmd_tbl_t * cmdtp, bd_t * bd, int flag, int argc, char *argv[])
+void do_reset (cmd_tbl_t * cmdtp, bd_t * bd, int flag, int argc, char * const argv[])
 {
 #if defined(CONFIG_RTC_MK48T59)
 	/* trigger watchdog immediately */
diff --git a/board/eltec/elppc/elppc.c b/board/eltec/elppc/elppc.c
index e73c712..cb9ab86 100644
--- a/board/eltec/elppc/elppc.c
+++ b/board/eltec/elppc/elppc.c
@@ -117,7 +117,7 @@ phys_size_t initdram (int board_type)
  * Register PI in the MPC 107 (at offset 0x41090 of the Embedded Utilities
  * Memory Block).
  */
-int do_reset (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_reset (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	out8 (MPC107_EUMB_PI, 1);
 	return (0);