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>

2 files changed, 4 insertions, 4 deletions

diff --git a/board/esd/cpci750/cpci750.c b/board/esd/cpci750/cpci750.c
index a199d46182..f9f7c7fdf1 100644
--- a/board/esd/cpci750/cpci750.c
+++ b/board/esd/cpci750/cpci750.c
@@ -562,7 +562,7 @@ int display_mem_map (void)
 /*
  * Command loadpci: wait for signal from host and boot image.
  */
-int do_loadpci(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_loadpci(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile unsigned int *ptr;
 	int count = 0;
@@ -1056,7 +1056,7 @@ void board_prebootm_init ()
 	dcache_disable ();
 }
 
-int do_show_config(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_show_config(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned int reset_sample_low;
 	unsigned int reset_sample_high;
@@ -1091,7 +1091,7 @@ U_BOOT_CMD(
 	"Show Marvell strapping register (ResetSampleLow ResetSampleHigh)"
 );
 
-int do_pldver(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_pldver(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	printf("PLD version:0x%02x\n", in_8((void *)CONFIG_SYS_PLD_VER));
 
diff --git a/board/esd/cpci750/sdram_init.c b/board/esd/cpci750/sdram_init.c
index 5347958085..615e32af9f 100644
--- a/board/esd/cpci750/sdram_init.c
+++ b/board/esd/cpci750/sdram_init.c
@@ -1811,7 +1811,7 @@ int set_dfcdlInit (void)
 	return (0);
 }
 
-int do_show_ecc(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_show_ecc(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned int ecc_counter;
 	unsigned int ecc_addr;