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>

1 files changed, 3 insertions, 3 deletions

diff --git a/board/freescale/common/pixis.c b/board/freescale/common/pixis.c
index 119eaf9..a35b5cf 100644
--- a/board/freescale/common/pixis.c
+++ b/board/freescale/common/pixis.c
@@ -284,7 +284,7 @@ static void set_px_go_with_watchdog(void)
  *
  */
 static int pixis_disable_watchdog_cmd(cmd_tbl_t *cmdtp, int flag, int argc,
-				      char *argv[])
+				      char * const argv[])
 {
 	/* Disable the VELA sequencer and the watchdog */
 	clrbits_8(pixis_base + PIXIS_VCTL, 9);
@@ -302,7 +302,7 @@ U_BOOT_CMD(
 
 /* Enable or disable SGMII mode for a TSEC
  */
-static int pixis_set_sgmii(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int pixis_set_sgmii(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int which_tsec = -1;
 	unsigned char mask;
@@ -430,7 +430,7 @@ static unsigned long strfractoint(char *strptr)
 	return intval + decval;
 }
 
-static int pixis_reset_cmd(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int pixis_reset_cmd(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned int i;
 	char *p_cf = NULL;