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>
diff --git a/common/command.c b/common/command.c
index 67ad692..a1fc592 100644
--- a/common/command.c
+++ b/common/command.c
@@ -34,7 +34,7 @@
*/
int _do_help (cmd_tbl_t *cmd_start, int cmd_items, cmd_tbl_t * cmdtp, int
- flag, int argc, char *argv[])
+ flag, int argc, char * const argv[])
{
int i;
int rcode = 0;
@@ -158,7 +158,7 @@
#ifdef CONFIG_AUTO_COMPLETE
-int var_complete(int argc, char *argv[], char last_char, int maxv, char *cmdv[])
+int var_complete(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
{
static char tmp_buf[512];
int space;
@@ -175,7 +175,7 @@
}
static void install_auto_complete_handler(const char *cmd,
- int (*complete)(int argc, char *argv[], char last_char, int maxv, char *cmdv[]))
+ int (*complete)(int argc, char * const argv[], char last_char, int maxv, char *cmdv[]))
{
cmd_tbl_t *cmdtp;
@@ -200,7 +200,7 @@
/*************************************************************************************/
-static int complete_cmdv(int argc, char *argv[], char last_char, int maxv, char *cmdv[])
+static int complete_cmdv(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
{
cmd_tbl_t *cmdtp;
const char *p;
@@ -301,7 +301,7 @@
return argc;
}
-static void print_argv(const char *banner, const char *leader, const char *sep, int linemax, char *argv[])
+static void print_argv(const char *banner, const char *leader, const char *sep, int linemax, char * const argv[])
{
int ll = leader != NULL ? strlen(leader) : 0;
int sl = sep != NULL ? strlen(sep) : 0;
@@ -328,7 +328,7 @@
printf("\n");
}
-static int find_common_prefix(char *argv[])
+static int find_common_prefix(char * const argv[])
{
int i, len;
char *anchor, *s, *t;
