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, 7 insertions, 7 deletions

diff --git a/board/esd/tasreg/tasreg.c b/board/esd/tasreg/tasreg.c
index bd9fb2fc2b..270caac08c 100644
--- a/board/esd/tasreg/tasreg.c
+++ b/board/esd/tasreg/tasreg.c
@@ -29,7 +29,7 @@
 
 
 /* Prototypes */
-int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len);
 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len);
 
@@ -219,7 +219,7 @@ int i2c_probe(uchar addr);
 
 /*
  */
-int do_iploop(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_iploop(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;
 
@@ -254,7 +254,7 @@ U_BOOT_CMD(
 
 /*
  */
-int do_codec(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_codec(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	uchar buf[8];
 
@@ -307,7 +307,7 @@ U_BOOT_CMD(
 
 /*
  */
-int do_saa(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_saa(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;
 	ulong instr;
@@ -340,7 +340,7 @@ U_BOOT_CMD(
 
 /*
  */
-int do_iwrite(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_iwrite(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;
 	ulong data0;
@@ -379,7 +379,7 @@ U_BOOT_CMD(
 
 /*
  */
-int do_iread(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_iread(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;
 	ulong cnt;
@@ -411,7 +411,7 @@ U_BOOT_CMD(
 
 /*
  */
-int do_ireadl(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_ireadl(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;
 	uchar buf[32];