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, 9 insertions, 9 deletions

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index d2ef21760..13325bc83 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -139,7 +139,7 @@ static int printenv(char *name, int state)
 	return i;
 }
 
-int do_printenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_printenv (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;
 	int rcode = 0;
@@ -173,7 +173,7 @@ int do_printenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  * This function will ONLY work with a in-RAM copy of the environment
  */
 
-int _do_setenv (int flag, int argc, char *argv[])
+int _do_setenv (int flag, int argc, char * const argv[])
 {
 	int   i, len, oldval;
 	int   console = -1;
@@ -390,7 +390,7 @@ int _do_setenv (int flag, int argc, char *argv[])
 
 int setenv (char *varname, char *varvalue)
 {
-	char *argv[4] = { "setenv", varname, varvalue, NULL };
+	char * const argv[4] = { "setenv", varname, varvalue, NULL };
 	if ((varvalue == NULL) || (varvalue[0] == '\0'))
 		return _do_setenv (0, 2, argv);
 	else
@@ -400,12 +400,12 @@ int setenv (char *varname, char *varvalue)
 #ifdef CONFIG_HAS_UID
 void forceenv (char *varname, char *varvalue)
 {
-	char *argv[4] = { "forceenv", varname, varvalue, NULL };
+	char * const argv[4] = { "forceenv", varname, varvalue, NULL };
 	_do_setenv (0xdeaf4add, 3, argv);
 }
 #endif
 
-int do_setenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_setenv (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc < 2) {
 		cmd_usage(cmdtp);
@@ -420,7 +420,7 @@ int do_setenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  */
 
 #if defined(CONFIG_CMD_ASKENV)
-int do_askenv ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_askenv ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	extern char console_buffer[CONFIG_SYS_CBSIZE];
 	char message[CONFIG_SYS_CBSIZE];
@@ -497,7 +497,7 @@ int do_askenv ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  * Interactively edit an environment variable
  */
 #if defined(CONFIG_CMD_EDITENV)
-int do_editenv(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_editenv(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	char buffer[CONFIG_SYS_CBSIZE];
 	char *init_val;
@@ -576,7 +576,7 @@ int getenv_r (char *name, char *buf, unsigned len)
 
 #if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
 
-int do_saveenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_saveenv (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	extern char * env_name_spec;
 
@@ -660,7 +660,7 @@ U_BOOT_CMD(
 #endif
 
 #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[]);
 U_BOOT_CMD(
 	run,	CONFIG_SYS_MAXARGS,	1,	do_run,
 	"run commands in an environment variable",