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, 3 insertions, 3 deletions

diff --git a/arch/mips/cpu/cpu.c b/arch/mips/cpu/cpu.c
index d5a1604..3ae397c 100644
--- a/arch/mips/cpu/cpu.c
+++ b/arch/mips/cpu/cpu.c
@@ -42,7 +42,7 @@ void __attribute__((weak)) _machine_restart(void)
 {
 }
 
-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[])
 {
 	_machine_restart();
 
diff --git a/arch/mips/lib/bootm.c b/arch/mips/lib/bootm.c
index 54af24c..40a5647 100644
--- a/arch/mips/lib/bootm.c
+++ b/arch/mips/lib/bootm.c
@@ -43,7 +43,7 @@ static int	linux_env_idx;
 static void linux_params_init (ulong start, char * commandline);
 static void linux_env_set (char * env_name, char * env_val);
 
-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)
 {
 	void	(*theKernel) (int, char **, char **, int *);
 	char	*commandline = getenv ("bootargs");
diff --git a/arch/mips/lib/bootm_qemu_mips.c b/arch/mips/lib/bootm_qemu_mips.c
index cc70fa9..f1906c6 100644
--- a/arch/mips/lib/bootm_qemu_mips.c
+++ b/arch/mips/lib/bootm_qemu_mips.c
@@ -29,7 +29,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-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)
 {
 	void	(*theKernel) (int, char **, char **, int *);
 	char	*bootargs = getenv ("bootargs");