before i make a fool of myself on the main LKML, perhaps someone can
verify that some code is as strange as i think it is.
from include/linux/netfilter/xt_sctp.h
...
#define ELEMCOUNT(x) (sizeof(x)/sizeof(x[0]))
...
#define SCTP_CHUNKMAP_IS_CLEAR(chunkmap) \
({ \
int i; \
int flag = 1; \
for (i = 0; i < ELEMCOUNT(chunkmap); i++) { \
if (chunkmap[i]) { \
flag = 0; \
break; \
} \
} \
flag; \
})
...
so ELEMCOUNT() is clearly just an alternative to the more common
ARRAY_SIZE() macro. but calling the macro SCTP_CHUNKMAP_IS_CLEAR()
pretty clearly assumes that you can determine the array size of the
macro parameter "chunkmap". however, from the source file
net/netfilter/xt_sctp.c, we have:
...
static inline bool
match_packet(const struct sk_buff *skb,
unsigned int offset,
const u_int32_t *chunkmap, <----- only a *pointer*
...
switch (chunk_match_type) {
case SCTP_CHUNK_MATCH_ALL:
return SCTP_CHUNKMAP_IS_CLEAR(chunkmap);
...
>i don't see how you can reasonably call the macro
>SCTP_CHUNKMAP_IS_CLEAR() with a *pointer* to an array and expect that
>macro to be able to determine the "size" of that array. AFAIK,
>wouldn't you just get the answer "1" as the alleged size?
> or is it a bad idea that i've been up all night again?
>rday
Boy this is basic C....
Just try out the code snippet
int i_arr[10];
char c_arr[30];
printf("chunk size(i_arr) = %d\n", sizeof(i_arr)/sizeof(i_arr[0]);
printf("chunk size (c_arr)= %d\n", sizeof(c_arr)/sizeof(c_arr[0]);
Guess you got the point..
And never go for a structure for such silly things Avishay , this is a classic programming I say..:) Just enjoy the
beauty of this code piece and see how generic the code piece has been made.
