| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748 |
- /*
- * 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[].
- */
- /* tbl has the following structure equivalent, but is C99 compliant:
- * struct {
- * struct type##_replace repl;
- * struct type##_standard entries[nhooks];
- * struct type##_error term;
- * } *tbl;
- */
- #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[]; \
- } *tbl; \
- struct type##_error *term; \
- size_t term_offset = (offsetof(typeof(*tbl), entries[nhooks]) + \
- __alignof__(*term) - 1) & ~(__alignof__(*term) - 1); \
- tbl = kzalloc(term_offset + sizeof(*term), GFP_KERNEL); \
- if (tbl == NULL) \
- return NULL; \
- term = (struct type##_error *)&(((char *)tbl)[term_offset]); \
- strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \
- *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; \
- })
|
