xt_repldata.h

Go to the documentation of this file.

/*
 * Today's hack: quantum tunneling in structs
 *
 * 'entries' and 'term' are never anywhere referenced by word in code. In fact,
 * they serve as the hanging-off data accessed through repl.data[].
 */

#define xt_alloc_initial_table(type, typ2) ({ \
    unsigned int hook_mask = info->valid_hooks; \
    unsigned int nhooks = hweight32(hook_mask); \
    unsigned int bytes = 0, hooknum = 0, i = 0; \
    struct { \
        struct type##_replace repl; \
        struct type##_standard entries[nhooks]; \
        struct type##_error term; \
    } *tbl = kzalloc(sizeof(*tbl), GFP_KERNEL); \
    if (tbl == NULL) \
        return NULL; \
    strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \
    tbl->term = (struct type##_error)typ2##_ERROR_INIT;  \
    tbl->repl.valid_hooks = hook_mask; \
    tbl->repl.num_entries = nhooks + 1; \
    tbl->repl.size = nhooks * sizeof(struct type##_standard) + \
                     sizeof(struct type##_error); \
    for (; hook_mask != 0; hook_mask >>= 1, ++hooknum) { \
        if (!(hook_mask & 1)) \
            continue; \
        tbl->repl.hook_entry[hooknum] = bytes; \
        tbl->repl.underflow[hooknum]  = bytes; \
        tbl->entries[i++] = (struct type##_standard) \
            typ2##_STANDARD_INIT(NF_ACCEPT); \
        bytes += sizeof(struct type##_standard); \
    } \
    tbl; \
})