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/main.c b/common/main.c
index 3760ba3..20090ee 100644
--- a/common/main.c
+++ b/common/main.c
@@ -51,10 +51,10 @@ void inline __show_boot_progress (int val) {}
 void show_boot_progress (int val) __attribute__((weak, alias("__show_boot_progress")));
 
 #if defined(CONFIG_BOOT_RETRY_TIME) && defined(CONFIG_RESET_TO_RETRY)
-extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);		/* for do_reset() prototype */
+extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);		/* for do_reset() prototype */
 #endif
 
-extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 
 #if defined(CONFIG_UPDATE_TFTP)
 void update_tftp (void);
@@ -1414,7 +1414,7 @@ int run_command (const char *cmd, int flag)
 /****************************************************************************/
 
 #if defined(CONFIG_CMD_RUN)
-int do_run (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_run (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;