[PATCH] dhcpc.c: fix found_opts

[Denys Vlasenko]

2011/10/11 Lambrecht Jürgen <J.Lambrecht at televic.com>:
> Hello,
>
> The patch below fixes a bug in networking/udhcp/dhcpc.c. Here my reasoning:
> There are 256 dhcp options supported, so 256 bits to store.
> You want to store that in an unsigned (BITMAP define), 32b in my case.
> So you need an unsigned array of 256/sizeoff(unsigned) == 8 elements.

sizeof(unsigned) is 4, because sizeof() measures size in bytes, not bits.

256/4 = 64.

> In
> the code, the define BBITS is used for this, and the bug is that *8 is
> added to that define, resulting in an array of only 1 element (32b) to
> store 256 bits.

I disassembled this:

        memset(found_opts, 0, sizeof(found_opts));

and I see that this memset fills 8 words, not 1 word:

   f:   b9 08 00 00 00          mov    $0x8,%ecx
  14:   31 c0                   xor    %eax,%eax
  16:   f3 ab                   rep stos %eax,%es:(%edi)

-- 
vda