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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Berkeley style UIO structures - Alan Cox 1994.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
David Howells607ca462012-10-13 10:46:48 +01009#ifndef __LINUX_UIO_H
10#define __LINUX_UIO_H
Linus Torvalds1da177e2005-04-16 15:20:36 -070011
Kent Overstreet92236872013-11-27 16:29:46 -080012#include <linux/kernel.h>
David Howells607ca462012-10-13 10:46:48 +010013#include <uapi/linux/uio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
Kent Overstreet92236872013-11-27 16:29:46 -080015struct page;
Jiri Slaby812ed032009-07-29 15:04:19 -070016
17struct kvec {
18 void *iov_base; /* and that should *never* hold a userland pointer */
19 size_t iov_len;
20};
21
Kent Overstreet92236872013-11-27 16:29:46 -080022struct iov_iter {
Al Viro71d8e532014-03-05 19:28:09 -050023 int type;
Kent Overstreet92236872013-11-27 16:29:46 -080024 const struct iovec *iov;
25 unsigned long nr_segs;
26 size_t iov_offset;
27 size_t count;
28};
29
Linus Torvalds1da177e2005-04-16 15:20:36 -070030/*
31 * Total number of bytes covered by an iovec.
32 *
33 * NOTE that it is not safe to use this function until all the iovec's
34 * segment lengths have been validated. Because the individual lengths can
35 * overflow a size_t when added together.
36 */
37static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
38{
39 unsigned long seg;
40 size_t ret = 0;
41
42 for (seg = 0; seg < nr_segs; seg++)
43 ret += iov[seg].iov_len;
44 return ret;
45}
46
Kent Overstreet92236872013-11-27 16:29:46 -080047static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
48{
49 return (struct iovec) {
50 .iov_base = iter->iov->iov_base + iter->iov_offset,
51 .iov_len = min(iter->count,
52 iter->iov->iov_len - iter->iov_offset),
53 };
54}
55
56#define iov_for_each(iov, iter, start) \
57 for (iter = (start); \
58 (iter).count && \
59 ((iov = iov_iter_iovec(&(iter))), 1); \
60 iov_iter_advance(&(iter), (iov).iov_len))
61
Linus Torvalds1da177e2005-04-16 15:20:36 -070062unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
Rusty Russelld2f83e92013-05-17 09:05:21 +093063
Kent Overstreet92236872013-11-27 16:29:46 -080064size_t iov_iter_copy_from_user_atomic(struct page *page,
65 struct iov_iter *i, unsigned long offset, size_t bytes);
Kent Overstreet92236872013-11-27 16:29:46 -080066void iov_iter_advance(struct iov_iter *i, size_t bytes);
67int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
68size_t iov_iter_single_seg_count(const struct iov_iter *i);
Al Viro6e58e792014-02-03 17:07:03 -050069size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
70 struct iov_iter *i);
Al Virof0d1bec2014-04-03 15:05:18 -040071size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
72 struct iov_iter *i);
Al Viro886a3912014-03-05 13:50:45 -050073unsigned long iov_iter_alignment(const struct iov_iter *i);
Al Viro71d8e532014-03-05 19:28:09 -050074void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
75 unsigned long nr_segs, size_t count);
Al Viro7b2c99d2014-03-15 04:05:57 -040076ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
77 size_t maxsize, size_t *start);
Al Viro91f79c42014-03-21 04:58:33 -040078ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
79 size_t maxsize, size_t *start);
Al Virof67da302014-03-19 01:16:16 -040080int iov_iter_npages(const struct iov_iter *i, int maxpages);
Kent Overstreet92236872013-11-27 16:29:46 -080081
82static inline size_t iov_iter_count(struct iov_iter *i)
83{
84 return i->count;
85}
86
Al Viro0c949332014-03-22 06:51:37 -040087static inline void iov_iter_truncate(struct iov_iter *i, size_t count)
88{
89 if (i->count > count)
90 i->count = count;
91}
92
Rusty Russelld2f83e92013-05-17 09:05:21 +093093int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
94int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
Kent Overstreet92236872013-11-27 16:29:46 -080095
Al Viro886a3912014-03-05 13:50:45 -050096
Jiri Slaby812ed032009-07-29 15:04:19 -070097#endif