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/sh/cpu/sh2/cpu.c b/arch/sh/cpu/sh2/cpu.c
index e0cb04752de..6bbedd9d48d 100644
--- a/arch/sh/cpu/sh2/cpu.c
+++ b/arch/sh/cpu/sh2/cpu.c
@@ -59,7 +59,7 @@ int cleanup_before_linux(void)
 	return 0;
 }
 
-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[])
 {
 	disable_interrupts();
 	reset_cpu(0);
diff --git a/arch/sh/cpu/sh3/cpu.c b/arch/sh/cpu/sh3/cpu.c
index 8261d29d481..3e9caad8d24 100644
--- a/arch/sh/cpu/sh3/cpu.c
+++ b/arch/sh/cpu/sh3/cpu.c
@@ -45,7 +45,7 @@ int cleanup_before_linux(void)
 	return 0;
 }
 
-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[])
 {
 	disable_interrupts();
 	reset_cpu(0);
diff --git a/arch/sh/cpu/sh4/cpu.c b/arch/sh/cpu/sh4/cpu.c
index be410abf00a..f1367583345 100644
--- a/arch/sh/cpu/sh4/cpu.c
+++ b/arch/sh/cpu/sh4/cpu.c
@@ -44,7 +44,7 @@ int cleanup_before_linux (void)
 	return 0;
 }
 
-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[])
 {
 	disable_interrupts();
 	reset_cpu (0);
diff --git a/arch/sh/lib/bootm.c b/arch/sh/lib/bootm.c
index ae1f869f10d..9c58ed7ec8c 100644
--- a/arch/sh/lib/bootm.c
+++ b/arch/sh/lib/bootm.c
@@ -43,7 +43,7 @@ static void hexdump(unsigned char *buf, int len)
 }
 #endif
 
-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)
 {
 	/* Linux kernel load address */
 	void (*kernel) (void) = (void (*)(void))images->ep;