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, 3 insertions, 3 deletions

diff --git a/common/image.c b/common/image.c
index 2b6007e..6d8833e 100644
--- a/common/image.c
+++ b/common/image.c
@@ -60,7 +60,7 @@ static int fit_check_ramdisk (const void *fit, int os_noffset,
 #endif
 
 #ifdef CONFIG_CMD_BDI
-extern int do_bdinfo(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+extern int do_bdinfo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 #endif
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -756,7 +756,7 @@ int genimg_has_config (bootm_headers_t *images)
  *     1, if ramdisk image is found but corrupted, or invalid
  *     rd_start and rd_end are set to 0 if no ramdisk exists
  */
-int boot_get_ramdisk (int argc, char *argv[], bootm_headers_t *images,
+int boot_get_ramdisk (int argc, char * const argv[], bootm_headers_t *images,
 		uint8_t arch, ulong *rd_start, ulong *rd_end)
 {
 	ulong rd_addr, rd_load;
@@ -1279,7 +1279,7 @@ error:
  *     1, if fdt image is found but corrupted
  *     of_flat_tree and of_size are set to 0 if no fdt exists
  */
-int boot_get_fdt (int flag, int argc, char *argv[], bootm_headers_t *images,
+int boot_get_fdt (int flag, int argc, char * const argv[], bootm_headers_t *images,
 		char **of_flat_tree, ulong *of_size)
 {
 	const image_header_t *fdt_hdr;