-/* Unfortunately this function is not exported so this is a verbatim copy
- * from net/core/datagram.c in 2.6.30. */
-static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
- u8 __user *to, int len,
- __wsum *csump)
-{
- int start = skb_headlen(skb);
- int pos = 0;
- int i, copy = start - offset;
-
- /* Copy header. */
- if (copy > 0) {
- int err = 0;
- if (copy > len)
- copy = len;
- *csump = csum_and_copy_to_user(skb->data + offset, to, copy,
- *csump, &err);
- if (err)
- goto fault;
- if ((len -= copy) == 0)
- return 0;
- offset += copy;
- to += copy;
- pos = copy;
- }
-
- for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
- int end;
-
- WARN_ON(start > offset + len);
-
- end = start + skb_shinfo(skb)->frags[i].size;
- if ((copy = end - offset) > 0) {
- __wsum csum2;
- int err = 0;
- u8 *vaddr;
- skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
- struct page *page = frag->page;
-
- if (copy > len)
- copy = len;
- vaddr = kmap(page);
- csum2 = csum_and_copy_to_user(vaddr +
- frag->page_offset +
- offset - start,
- to, copy, 0, &err);
- kunmap(page);
- if (err)
- goto fault;
- *csump = csum_block_add(*csump, csum2, pos);
- if (!(len -= copy))
- return 0;
- offset += copy;
- to += copy;
- pos += copy;
- }
- start = end;
- }
-
- if (skb_shinfo(skb)->frag_list) {
- struct sk_buff *list = skb_shinfo(skb)->frag_list;
-
- for (; list; list=list->next) {
- int end;
-
- WARN_ON(start > offset + len);
-
- end = start + list->len;
- if ((copy = end - offset) > 0) {
- __wsum csum2 = 0;
- if (copy > len)
- copy = len;
- if (skb_copy_and_csum_datagram(list,
- offset - start,
- to, copy,
- &csum2))
- goto fault;
- *csump = csum_block_add(*csump, csum2, pos);
- if ((len -= copy) == 0)
- return 0;
- offset += copy;
- to += copy;
- pos += copy;
- }
- start = end;
- }
- }
- if (!len)
- return 0;
-
-fault:
- return -EFAULT;
-}
-