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, 15 insertions, 15 deletions

diff --git a/common/cmd_i2c.c b/common/cmd_i2c.c
index 8b9c2c9490e..fb9d3b038fa 100644
--- a/common/cmd_i2c.c
+++ b/common/cmd_i2c.c
@@ -178,7 +178,7 @@ static uint get_alen(char *arg)
  *	i2c read {i2c_chip} {devaddr}{.0, .1, .2} {len} {memaddr}
  */
 
-static int do_i2c_read ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_read ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	u_char	chip;
 	uint	devaddr, alen, length;
@@ -226,7 +226,7 @@ static int do_i2c_read ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  * Syntax:
  *	i2c md {i2c_chip} {addr}{.0, .1, .2} {len}
  */
-static int do_i2c_md ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_md ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	u_char	chip;
 	uint	addr, alen, length;
@@ -324,7 +324,7 @@ static int do_i2c_md ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  * Syntax:
  *	i2c mw {i2c_chip} {addr}{.0, .1, .2} {data} [{count}]
  */
-static int do_i2c_mw ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_mw ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	uchar	chip;
 	ulong	addr;
@@ -388,7 +388,7 @@ static int do_i2c_mw ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  * Syntax:
  *	i2c crc32 {i2c_chip} {addr}{.0, .1, .2} {count}
  */
-static int do_i2c_crc (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_crc (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	uchar	chip;
 	ulong	addr;
@@ -452,7 +452,7 @@ static int do_i2c_crc (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  */
 
 static int
-mod_i2c_mem(cmd_tbl_t *cmdtp, int incrflag, int flag, int argc, char *argv[])
+mod_i2c_mem(cmd_tbl_t *cmdtp, int incrflag, int flag, int argc, char * const argv[])
 {
 	uchar	chip;
 	ulong	addr;
@@ -575,7 +575,7 @@ mod_i2c_mem(cmd_tbl_t *cmdtp, int incrflag, int flag, int argc, char *argv[])
  * Syntax:
  *	i2c probe {addr}{.0, .1, .2}
  */
-static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int j;
 #if defined(CONFIG_SYS_I2C_NOPROBES)
@@ -619,7 +619,7 @@ static int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
  *	{length} - Number of bytes to read
  *	{delay}  - A DECIMAL number and defaults to 1000 uSec
  */
-static int do_i2c_loop(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_loop(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	u_char	chip;
 	ulong	alen;
@@ -731,7 +731,7 @@ static void decode_bits (u_char const b, char const *str[], int const do_once)
  * Syntax:
  *	i2c sdram {i2c_chip}
  */
-static int do_sdram (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_sdram (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	enum { unknown, EDO, SDRAM, DDR2 } type;
 
@@ -1208,7 +1208,7 @@ static int do_sdram (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 #endif
 
 #if defined(CONFIG_I2C_MUX)
-static int do_i2c_add_bus(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_add_bus(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int ret=0;
 
@@ -1239,7 +1239,7 @@ static int do_i2c_add_bus(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 #endif  /* CONFIG_I2C_MUX */
 
 #if defined(CONFIG_I2C_MULTI_BUS)
-static int do_i2c_bus_num(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_bus_num(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int bus_idx, ret=0;
 
@@ -1257,7 +1257,7 @@ static int do_i2c_bus_num(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 }
 #endif  /* CONFIG_I2C_MULTI_BUS */
 
-static int do_i2c_bus_speed(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_bus_speed(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int speed, ret=0;
 
@@ -1274,17 +1274,17 @@ static int do_i2c_bus_speed(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	return ret;
 }
 
-static int do_i2c_mm(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_mm(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	return mod_i2c_mem (cmdtp, 1, flag, argc, argv);
 }
 
-static int do_i2c_nm(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_nm(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	return mod_i2c_mem (cmdtp, 0, flag, argc, argv);
 }
 
-static int do_i2c_reset(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c_reset(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
 	return 0;
@@ -1312,7 +1312,7 @@ static cmd_tbl_t cmd_i2c_sub[] = {
 	U_BOOT_CMD_MKENT(speed, 1, 1, do_i2c_bus_speed, "", ""),
 };
 
-static int do_i2c(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+static int do_i2c(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	cmd_tbl_t *c;