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54841ab50c
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>
The TRAB keyboard implementation is similar to that for LWMON and R360MPI boards. The only difference concerns key naming. There are 4 keys on TRAB: 1, 2, 3, 4. 1) The "kbd" command provides information about the current state of the keys. For example, TRAB # kbd Keys: 1 0 1 0 means that keys 1 and 3 are pressed. The keyboard status is also stored in the "keybd" environment variable. In this example we get keybd=1010 2) The "preboot" variable is set according to current environment settings and keys pressed. This is an example: TRAB # setenv magic_keys XY TRAB # setenv key_magicX 12 TRAB # setenv key_cmdX echo ## Keys 1 + 2 pressed ##\;echo TRAB # setenv key_magicY 13 TRAB # setenv key_cmdY echo ## Keys 1 + 3 pressed ##\;echo Here "magic_keys=XY" means that the "key_magicX" and "key_magicY" variables will be checked for a match. Each variable "key_magic*" defines a set of keys. In the our example, if keys 1 and 3 are pressed during reset, then "key_magicY" matches, so the "preboot" variable will be set to the contents of "key_cmdY": preboot=echo ## Keys 1 + 3 pressed ##;echo 3) The TRAB board has optional modem support. When a certain key combination is pressed on the keyboard at power-on, the firmware performs the necessary initialization of the modem and allows for dial-in. The key combination is specified in the "include/configs/trab.h" file. For example: #define CONFIG_MODEM_KEY_MAGIC "23" means that modem will be initialized if and only if both keys 2, 3 are pressed. Note that the format of this string is similar to the format of "key_magic*" environment variables described above.