]>
Commit | Line | Data |
---|---|---|
e3eaa991 JE |
1 | /* |
2 | * Today's hack: quantum tunneling in structs | |
3 | * | |
4 | * 'entries' and 'term' are never anywhere referenced by word in code. In fact, | |
5 | * they serve as the hanging-off data accessed through repl.data[]. | |
6 | */ | |
7 | ||
066c6807 MC |
8 | /* tbl has the following structure equivalent, but is C99 compliant: |
9 | * struct { | |
10 | * struct type##_replace repl; | |
11 | * struct type##_standard entries[nhooks]; | |
12 | * struct type##_error term; | |
13 | * } *tbl; | |
14 | */ | |
15 | ||
e3eaa991 JE |
16 | #define xt_alloc_initial_table(type, typ2) ({ \ |
17 | unsigned int hook_mask = info->valid_hooks; \ | |
18 | unsigned int nhooks = hweight32(hook_mask); \ | |
19 | unsigned int bytes = 0, hooknum = 0, i = 0; \ | |
20 | struct { \ | |
21 | struct type##_replace repl; \ | |
066c6807 MC |
22 | struct type##_standard entries[]; \ |
23 | } *tbl; \ | |
24 | struct type##_error *term; \ | |
25 | size_t term_offset = (offsetof(typeof(*tbl), entries[nhooks]) + \ | |
26 | __alignof__(*term) - 1) & ~(__alignof__(*term) - 1); \ | |
27 | tbl = kzalloc(term_offset + sizeof(*term), GFP_KERNEL); \ | |
e3eaa991 JE |
28 | if (tbl == NULL) \ |
29 | return NULL; \ | |
066c6807 | 30 | term = (struct type##_error *)&(((char *)tbl)[term_offset]); \ |
e3eaa991 | 31 | strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \ |
066c6807 | 32 | *term = (struct type##_error)typ2##_ERROR_INIT; \ |
e3eaa991 JE |
33 | tbl->repl.valid_hooks = hook_mask; \ |
34 | tbl->repl.num_entries = nhooks + 1; \ | |
35 | tbl->repl.size = nhooks * sizeof(struct type##_standard) + \ | |
066c6807 | 36 | sizeof(struct type##_error); \ |
e3eaa991 JE |
37 | for (; hook_mask != 0; hook_mask >>= 1, ++hooknum) { \ |
38 | if (!(hook_mask & 1)) \ | |
39 | continue; \ | |
40 | tbl->repl.hook_entry[hooknum] = bytes; \ | |
41 | tbl->repl.underflow[hooknum] = bytes; \ | |
42 | tbl->entries[i++] = (struct type##_standard) \ | |
43 | typ2##_STANDARD_INIT(NF_ACCEPT); \ | |
44 | bytes += sizeof(struct type##_standard); \ | |
45 | } \ | |
46 | tbl; \ | |
47 | }) |