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/powerpc/cpu/mpc86xx/cpu.c b/arch/powerpc/cpu/mpc86xx/cpu.c
index 1887575..9064e78 100644
--- a/arch/powerpc/cpu/mpc86xx/cpu.c
+++ b/arch/powerpc/cpu/mpc86xx/cpu.c
@@ -124,7 +124,7 @@ checkcpu(void)
 
 
 void
-do_reset(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_reset(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *)CONFIG_SYS_IMMR;
 	volatile ccsr_gur_t *gur = &immap->im_gur;
diff --git a/arch/powerpc/cpu/mpc86xx/interrupts.c b/arch/powerpc/cpu/mpc86xx/interrupts.c
index c78fc72..d8ad6d3 100644
--- a/arch/powerpc/cpu/mpc86xx/interrupts.c
+++ b/arch/powerpc/cpu/mpc86xx/interrupts.c
@@ -101,7 +101,7 @@ void irq_free_handler(int vec)
 /*
  * irqinfo - print information about PCI devices,not implemented.
  */
-int do_irqinfo(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_irqinfo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	return 0;
 }
diff --git a/arch/powerpc/cpu/mpc86xx/mp.c b/arch/powerpc/cpu/mpc86xx/mp.c
index b4a0faa..24eb30a 100644
--- a/arch/powerpc/cpu/mpc86xx/mp.c
+++ b/arch/powerpc/cpu/mpc86xx/mp.c
@@ -66,7 +66,7 @@ int cpu_disable(int nr)
 	return 0;
 }
 
-int cpu_release(int nr, int argc, char *argv[])
+int cpu_release(int nr, int argc, char * const argv[])
 {
 	/* dummy function so common/cmd_mp.c will build
 	 * should be implemented in the future */