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>

3 files changed, 7 insertions, 7 deletions

diff --git a/board/amcc/taihu/lcd.c b/board/amcc/taihu/lcd.c
index c3dc983..595dee3 100644
--- a/board/amcc/taihu/lcd.c
+++ b/board/amcc/taihu/lcd.c
@@ -129,7 +129,7 @@ int lcd_init(void)
 	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[])
 {
 	out_8((u8 *) LCD_CMD_ADDR, 0x01);
 	udelay(2000);
@@ -137,7 +137,7 @@ static int do_lcd_clear (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	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);
@@ -148,7 +148,7 @@ static int do_lcd_puts (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	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);
@@ -159,7 +159,7 @@ static int do_lcd_putc (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	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;
diff --git a/board/amcc/taihu/taihu.c b/board/amcc/taihu/taihu.c
index be381d6..1682cf7 100644
--- a/board/amcc/taihu/taihu.c
+++ b/board/amcc/taihu/taihu.c
@@ -78,7 +78,7 @@ int checkboard(void)
 	return 0;
 }
 
-static int do_sw_stat(cmd_tbl_t* cmd_tp, int flags, int argc, char *argv[])
+static int do_sw_stat(cmd_tbl_t* cmd_tp, int flags, int argc, char * const argv[])
 {
 	char stat;
 	int i;
@@ -97,7 +97,7 @@ U_BOOT_CMD (
 	""
 );
 
-static int do_led_ctl(cmd_tbl_t* cmd_tp, int flags, int argc, char *argv[])
+static int do_led_ctl(cmd_tbl_t* cmd_tp, int flags, int argc, char * const argv[])
 {
 	int led_no;
 
diff --git a/board/amcc/taihu/update.c b/board/amcc/taihu/update.c
index f9c31b3..b87eac4 100644
--- a/board/amcc/taihu/update.c
+++ b/board/amcc/taihu/update.c
@@ -98,7 +98,7 @@ static uchar buf_66[] =
 	0x00
 };
 
-static int update_boot_eeprom(cmd_tbl_t* cmdtp, int flag, int argc, char *argv[])
+static int update_boot_eeprom(cmd_tbl_t* cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong len = 0x20;
 	uchar chip = CONFIG_SYS_I2C_EEPROM_ADDR;