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>
51 lines
1.5 KiB
C
51 lines
1.5 KiB
C
/*
|
|
* Copyright 2000-2009
|
|
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
|
|
*
|
|
* See file CREDITS for list of people who contributed to this
|
|
* project.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of
|
|
* the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
|
|
* MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <common.h>
|
|
#include <command.h>
|
|
|
|
int do_help(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
|
|
{
|
|
return _do_help(&__u_boot_cmd_start,
|
|
&__u_boot_cmd_end - &__u_boot_cmd_start,
|
|
cmdtp, flag, argc, argv);
|
|
}
|
|
|
|
U_BOOT_CMD(
|
|
help, CONFIG_SYS_MAXARGS, 1, do_help,
|
|
"print command description/usage",
|
|
"\n"
|
|
" - print brief description of all commands\n"
|
|
"help command ...\n"
|
|
" - print detailed usage of 'command'"
|
|
);
|
|
|
|
/* This does not use the U_BOOT_CMD macro as ? can't be used in symbol names */
|
|
cmd_tbl_t __u_boot_cmd_question_mark Struct_Section = {
|
|
"?", CONFIG_SYS_MAXARGS, 1, do_help,
|
|
"alias for 'help'",
|
|
#ifdef CONFIG_SYS_LONGHELP
|
|
""
|
|
#endif /* CONFIG_SYS_LONGHELP */
|
|
};
|