After years of unsuccessful research I've finally shamelessly stolen other
peoples intellectual properties to present the all-new and world-changing
updated version command:
-
U-Boot>> version
U-Boot 2010.12-00014-g7435056-dirty (Jan 18 2011 - 23:19:38)
MyBoard
gcc (GCC) 0.42 (Distro foobar)
GNU ld (GNU Binutils) 0.314159265
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May the toolchain bugs rest in peace.
Signed-off-by: Alexander Holler <holler@ahsoftware.de>
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>
Alexander Holler
Wolfgang Denk
Peter Tyser