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>
93 lines
2.1 KiB
C
93 lines
2.1 KiB
C
/*
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* (C) Copyright 2007 OpenMoko, Inc.
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* Written by Harald Welte <laforge@openmoko.org>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* Boot support
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*/
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#include <common.h>
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#include <command.h>
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#include <stdio_dev.h>
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#include <serial.h>
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int do_terminal(cmd_tbl_t * cmd, int flag, int argc, char * const argv[])
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{
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int last_tilde = 0;
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struct stdio_dev *dev = NULL;
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if (argc < 1)
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return -1;
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/* Scan for selected output/input device */
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dev = stdio_get_by_name(argv[1]);
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if (!dev)
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return -1;
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serial_reinit_all();
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printf("Entering terminal mode for port %s\n", dev->name);
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puts("Use '~.' to leave the terminal and get back to u-boot\n");
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while (1) {
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int c;
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/* read from console and display on serial port */
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if (stdio_devices[0]->tstc()) {
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c = stdio_devices[0]->getc();
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if (last_tilde == 1) {
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if (c == '.') {
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putc(c);
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putc('\n');
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break;
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} else {
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last_tilde = 0;
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/* write the delayed tilde */
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dev->putc('~');
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/* fall-through to print current
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* character */
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}
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}
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if (c == '~') {
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last_tilde = 1;
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puts("[u-boot]");
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putc(c);
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}
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dev->putc(c);
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}
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/* read from serial port and display on console */
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if (dev->tstc()) {
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c = dev->getc();
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putc(c);
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}
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}
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return 0;
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}
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/***************************************************/
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U_BOOT_CMD(
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terminal, 3, 1, do_terminal,
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"start terminal emulator",
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""
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);
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