Commit 066c6807 authored by Mark Charlebois's avatar Mark Charlebois Committed by Behan Webster

net: netfilter: LLVMLinux: vlais-netfilter

Replaced non-standard C use of Variable Length Arrays In Structs (VLAIS) in
xt_repldata.h with a C99 compliant flexible array member and then calculated
offsets to the other struct members. These other members aren't referenced by
name in this code, however this patch maintains the same memory layout and
padding as was previously accomplished using VLAIS.

Had the original structure been ordered differently, with the entries VLA at
the end, then it could have been a flexible member, and this patch would have
been a lot simpler. However since the data stored in this structure is
ultimately exported to userspace, the order of this structure can't be changed.

This patch makes no attempt to change the existing behavior, merely the way in
which the current layout is accomplished using standard C99 constructs. As such
the code can now be compiled with either gcc or clang.

This version of the patch removes the trailing alignment that the VLAIS
structure would allocate in order to simplify the patch.

Author: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: default avatarMark Charlebois <charlebm@gmail.com>
Signed-off-by: default avatarBehan Webster <behanw@converseincode.com>
Signed-off-by: default avatarVinícius Tinti <viniciustinti@gmail.com>
parent 66d8ea57
...@@ -5,23 +5,35 @@ ...@@ -5,23 +5,35 @@
* they serve as the hanging-off data accessed through repl.data[]. * 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) ({ \ #define xt_alloc_initial_table(type, typ2) ({ \
unsigned int hook_mask = info->valid_hooks; \ unsigned int hook_mask = info->valid_hooks; \
unsigned int nhooks = hweight32(hook_mask); \ unsigned int nhooks = hweight32(hook_mask); \
unsigned int bytes = 0, hooknum = 0, i = 0; \ unsigned int bytes = 0, hooknum = 0, i = 0; \
struct { \ struct { \
struct type##_replace repl; \ struct type##_replace repl; \
struct type##_standard entries[nhooks]; \ struct type##_standard entries[]; \
struct type##_error term; \ } *tbl; \
} *tbl = kzalloc(sizeof(*tbl), GFP_KERNEL); \ 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) \ if (tbl == NULL) \
return NULL; \ return NULL; \
term = (struct type##_error *)&(((char *)tbl)[term_offset]); \
strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \ strncpy(tbl->repl.name, info->name, sizeof(tbl->repl.name)); \
tbl->term = (struct type##_error)typ2##_ERROR_INIT; \ *term = (struct type##_error)typ2##_ERROR_INIT; \
tbl->repl.valid_hooks = hook_mask; \ tbl->repl.valid_hooks = hook_mask; \
tbl->repl.num_entries = nhooks + 1; \ tbl->repl.num_entries = nhooks + 1; \
tbl->repl.size = nhooks * sizeof(struct type##_standard) + \ tbl->repl.size = nhooks * sizeof(struct type##_standard) + \
sizeof(struct type##_error); \ sizeof(struct type##_error); \
for (; hook_mask != 0; hook_mask >>= 1, ++hooknum) { \ for (; hook_mask != 0; hook_mask >>= 1, ++hooknum) { \
if (!(hook_mask & 1)) \ if (!(hook_mask & 1)) \
continue; \ continue; \
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment