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/i386/lib/board.c b/arch/i386/lib/board.c
index 3f849f6..0adc664 100644
--- a/arch/i386/lib/board.c
+++ b/arch/i386/lib/board.c
@@ -431,7 +431,7 @@ void hang (void)
 	for (;;);
 }
 
-unsigned long do_go_exec (ulong (*entry)(int, char *[]), int argc, char *argv[])
+unsigned long do_go_exec (ulong (*entry)(int, char *[]), int argc, char * const argv[])
 {
 	/*
 	 * x86 does not use a dedicated register to pass the pointer
diff --git a/arch/i386/lib/bootm.c b/arch/i386/lib/bootm.c
index f96d7bd..b36e58d 100644
--- a/arch/i386/lib/bootm.c
+++ b/arch/i386/lib/bootm.c
@@ -29,7 +29,7 @@
 #include <asm/zimage.h>
 
 /*cmd_boot.c*/
-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		*base_ptr;
 	ulong		os_data, os_len;
diff --git a/arch/i386/lib/interrupts.c b/arch/i386/lib/interrupts.c
index 51def59..5a28278 100644
--- a/arch/i386/lib/interrupts.c
+++ b/arch/i386/lib/interrupts.c
@@ -136,7 +136,7 @@ void do_irq(int hw_irq)
 }
 
 #if defined(CONFIG_CMD_IRQ)
-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[])
 {
 	int irq;
 
diff --git a/arch/i386/lib/zimage.c b/arch/i386/lib/zimage.c
index b39615a..89fe015 100644
--- a/arch/i386/lib/zimage.c
+++ b/arch/i386/lib/zimage.c
@@ -245,7 +245,7 @@ void boot_zimage(void *setup_base)
 	enter_realmode(((u32)setup_base+SETUP_START_OFFSET)>>4, 0, &regs, &regs);
 }
 
-int do_zboot (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_zboot (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	void *base_ptr;
 	void *bzImage_addr;