Commit | Line | Data |
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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
e3eaa991 JE |
2 | /* |
3 | * Today's hack: quantum tunneling in structs | |
4 | * | |
5 | * 'entries' and 'term' are never anywhere referenced by word in code. In fact, | |
6 | * they serve as the hanging-off data accessed through repl.data[]. | |
7 | */ | |
8 | ||
066c6807 MC |
9 | /* tbl has the following structure equivalent, but is C99 compliant: |
10 | * struct { | |
11 | * struct type##_replace repl; | |
12 | * struct type##_standard entries[nhooks]; | |
13 | * struct type##_error term; | |
14 | * } *tbl; | |
15 | */ | |
16 | ||
e3eaa991 JE |
17 | #define xt_alloc_initial_table(type, typ2) ({ \ |
18 | unsigned int hook_mask = info->valid_hooks; \ | |
19 | unsigned int nhooks = hweight32(hook_mask); \ | |
20 | unsigned int bytes = 0, hooknum = 0, i = 0; \ | |
21 | struct { \ | |
22 | struct type##_replace repl; \ | |
066c6807 MC |
23 | struct type##_standard entries[]; \ |
24 | } *tbl; \ | |
25 | struct type##_error *term; \ | |
26 | size_t term_offset = (offsetof(typeof(*tbl), entries[nhooks]) + \ | |
27 | __alignof__(*term) - 1) & ~(__alignof__(*term) - 1); \ | |
28 | tbl = kzalloc(term_offset + sizeof(*term), GFP_KERNEL); \ | |
e3eaa991 JE |
29 | if (tbl == NULL) \ |
30 | return NULL; \ | |
066c6807 | 31 | term = (struct type##_error *)&(((char *)tbl)[term_offset]); \ |
e3eaa991 | 32 | strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \ |
066c6807 | 33 | *term = (struct type##_error)typ2##_ERROR_INIT; \ |
e3eaa991 JE |
34 | tbl->repl.valid_hooks = hook_mask; \ |
35 | tbl->repl.num_entries = nhooks + 1; \ | |
36 | tbl->repl.size = nhooks * sizeof(struct type##_standard) + \ | |
066c6807 | 37 | sizeof(struct type##_error); \ |
e3eaa991 JE |
38 | for (; hook_mask != 0; hook_mask >>= 1, ++hooknum) { \ |
39 | if (!(hook_mask & 1)) \ | |
40 | continue; \ | |
41 | tbl->repl.hook_entry[hooknum] = bytes; \ | |
42 | tbl->repl.underflow[hooknum] = bytes; \ | |
43 | tbl->entries[i++] = (struct type##_standard) \ | |
44 | typ2##_STANDARD_INIT(NF_ACCEPT); \ | |
45 | bytes += sizeof(struct type##_standard); \ | |
46 | } \ | |
47 | tbl; \ | |
48 | }) |