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, 5 insertions, 5 deletions

diff --git a/board/cm5200/cmd_cm5200.c b/board/cm5200/cmd_cm5200.c
index cd98ae2..df372d9 100644
--- a/board/cm5200/cmd_cm5200.c
+++ b/board/cm5200/cmd_cm5200.c
@@ -29,7 +29,7 @@
 
 #ifdef CONFIG_CMD_BSP
 
-static int do_i2c_test(char *argv[])
+static int do_i2c_test(char * const argv[])
 {
 	unsigned char temp, temp1;
 
@@ -57,7 +57,7 @@ static int do_i2c_test(char *argv[])
 	return 0;
 }
 
-static int do_usb_test(char *argv[])
+static int do_usb_test(char * const argv[])
 {
 	int i;
 	static int usb_stor_curr_dev = -1; /* current device */
@@ -90,7 +90,7 @@ static int do_usb_test(char *argv[])
 	return 0;
 }
 
-static int do_led_test(char *argv[])
+static int do_led_test(char * const argv[])
 {
 	int i = 0;
 	struct mpc5xxx_gpt_0_7 *gpt = (struct mpc5xxx_gpt_0_7 *)MPC5XXX_GPT;
@@ -134,7 +134,7 @@ static int do_led_test(char *argv[])
 	return 0;
 }
 
-static int do_rs232_test(char *argv[])
+static int do_rs232_test(char * const argv[])
 {
 	int error_status = 0;
 	struct mpc5xxx_gpio *gpio = (struct mpc5xxx_gpio *)MPC5XXX_GPIO;
@@ -397,7 +397,7 @@ static int do_rs232_test(char *argv[])
 	return error_status;
 }
 
-static int cmd_fkt(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int cmd_fkt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int rcode = -1;