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, 12 insertions, 12 deletions

diff --git a/board/trab/cmd_trab.c b/board/trab/cmd_trab.c
index 472d7d8..6d23470 100644
--- a/board/trab/cmd_trab.c
+++ b/board/trab/cmd_trab.c
@@ -109,16 +109,16 @@ extern s32 tsc2000_contact_temp (void);
 extern void tsc2000_spi_init(void);
 
 /* function declarations */
-int do_dip (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
-int do_vcc5v (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
-int do_burn_in (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
-int do_contact_temp (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
-int do_burn_in_status (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+int do_dip (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
+int do_vcc5v (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
+int do_burn_in (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
+int do_contact_temp (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
+int do_burn_in_status (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 int i2c_write_multiple (uchar chip, uint addr, int alen,
 			uchar *buffer, int len);
 int i2c_read_multiple (uchar chip, uint addr, int alen,
 			uchar *buffer, int len);
-int do_temp_log (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+int do_temp_log (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 
 /* helper functions */
 static void adc_init (void);
@@ -162,7 +162,7 @@ typedef struct test_function_s {
 test_function_t test_function[BIF_MAX];
 
 
-int do_burn_in (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_burn_in (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;
 	int cycle_status;
@@ -266,7 +266,7 @@ U_BOOT_CMD(
 );
 
 
-int do_dip (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_dip (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int i, dip;
 
@@ -299,7 +299,7 @@ U_BOOT_CMD(
 );
 
 
-int do_vcc5v (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_vcc5v (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int vcc5v;
 
@@ -327,7 +327,7 @@ U_BOOT_CMD(
 );
 
 
-int do_contact_temp (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_contact_temp (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int contact_temp;
 
@@ -352,7 +352,7 @@ U_BOOT_CMD(
 );
 
 
-int do_burn_in_status (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_burn_in_status (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc > 1) {
 		cmd_usage(cmdtp);
@@ -842,7 +842,7 @@ static int dummy(void)
 	return (0);
 }
 
-int do_temp_log (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_temp_log (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int contact_temp;
 	int delay = 0;