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, 2 insertions, 2 deletions

diff --git a/arch/powerpc/cpu/ppc4xx/bedbug_405.c b/arch/powerpc/cpu/ppc4xx/bedbug_405.c
index ef11cb6..e1500cc 100644
--- a/arch/powerpc/cpu/ppc4xx/bedbug_405.c
+++ b/arch/powerpc/cpu/ppc4xx/bedbug_405.c
@@ -17,7 +17,7 @@
 extern CPU_DEBUG_CTX bug_ctx;
 
 void bedbug405_init __P ((void));
-void bedbug405_do_break __P ((cmd_tbl_t *, int, int, char *[]));
+void bedbug405_do_break __P ((cmd_tbl_t *, int, int, char * const []));
 void bedbug405_break_isr __P ((struct pt_regs *));
 int bedbug405_find_empty __P ((void));
 int bedbug405_set __P ((int, unsigned long));
@@ -63,7 +63,7 @@ void bedbug405_init (void)
  * set routine which will assign a breakpoint number.
  * ====================================================================== */
 
-void bedbug405_do_break (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+void bedbug405_do_break (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	long addr = 0;		/* Address to break at  */
 	int which_bp;		/* Breakpoint number    */