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, 7 insertions, 7 deletions

diff --git a/board/amcc/taishan/lcd.c b/board/amcc/taishan/lcd.c
index d432cc3..6a049df 100644
--- a/board/amcc/taishan/lcd.c
+++ b/board/amcc/taishan/lcd.c
@@ -152,19 +152,19 @@ int lcd_init(void)
 	return 0;
 }
 
-static int do_lcd_test(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_lcd_test(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	lcd_init();
 	return 0;
 }
 
-static int do_lcd_clear(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_lcd_clear(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	*LCD_CMD_ADDR = 0x01;
 	mdelay(LCD_DELAY_NORMAL_MS);
 	return 0;
 }
-static int do_lcd_puts(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_lcd_puts(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc < 2) {
 		cmd_usage(cmdtp);
@@ -173,7 +173,7 @@ static int do_lcd_puts(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	lcd_puts(argv[1]);
 	return 0;
 }
-static int do_lcd_putc(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_lcd_putc(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc < 2) {
 		cmd_usage(cmdtp);
@@ -182,7 +182,7 @@ static int do_lcd_putc(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	lcd_putc((char)argv[1][0]);
 	return 0;
 }
-static int do_lcd_cur(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_lcd_cur(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong count;
 	ulong dir;
@@ -356,7 +356,7 @@ void set_phy_normal_mode(void)
 }
 #endif	/* 0 - test only */
 
-static int do_led_test_off(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_led_test_off(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile unsigned int *GpioOr =
 		(volatile unsigned int *)(CONFIG_SYS_PERIPHERAL_BASE + 0x700);
@@ -364,7 +364,7 @@ static int do_led_test_off(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	return 0;
 }
 
-static int do_led_test_on(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_led_test_on(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile unsigned int *GpioOr =
 		(volatile unsigned int *)(CONFIG_SYS_PERIPHERAL_BASE + 0x700);