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>

4 files changed, 4 insertions, 4 deletions

diff --git a/arch/arm/cpu/arm_cortexa8/mx51/clock.c b/arch/arm/cpu/arm_cortexa8/mx51/clock.c
index 38480ac..a27227d 100644
--- a/arch/arm/cpu/arm_cortexa8/mx51/clock.c
+++ b/arch/arm/cpu/arm_cortexa8/mx51/clock.c
@@ -269,7 +269,7 @@ u32 imx_get_fecclk(void)
 /*
  * Dump some core clockes.
  */
-int do_mx51_showclocks(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_mx51_showclocks(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	u32 freq;
 
diff --git a/arch/arm/cpu/arm_cortexa8/omap3/board.c b/arch/arm/cpu/arm_cortexa8/omap3/board.c
index d2500ca..69e56f5 100644
--- a/arch/arm/cpu/arm_cortexa8/omap3/board.c
+++ b/arch/arm/cpu/arm_cortexa8/omap3/board.c
@@ -282,7 +282,7 @@ void abort(void)
 /******************************************************************************
  * OMAP3 specific command to switch between NAND HW and SW ecc
  *****************************************************************************/
-static int do_switch_ecc(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_switch_ecc(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc != 2)
 		goto usage;
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 5ac1302..3101321 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -50,7 +50,7 @@ static void setup_end_tag (bd_t *bd);
 static struct tag *params;
 #endif /* CONFIG_SETUP_MEMORY_TAGS || CONFIG_CMDLINE_TAG || CONFIG_INITRD_TAG */
 
-int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
+int do_bootm_linux(int flag, int argc, char * const argv[], bootm_headers_t *images)
 {
 	bd_t	*bd = gd->bd;
 	char	*s;
diff --git a/arch/arm/lib/reset.c b/arch/arm/lib/reset.c
index 4fcedfa..08e6acb 100644
--- a/arch/arm/lib/reset.c
+++ b/arch/arm/lib/reset.c
@@ -39,7 +39,7 @@
 
 #include <common.h>
 
-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[])
 {
 	puts ("resetting ...\n");