Linux kernel mirror (for testing)
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1/*
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 */
9#ifndef __LINUX_UIO_H
10#define __LINUX_UIO_H
11
12#include <linux/kernel.h>
13#include <uapi/linux/uio.h>
14
15struct page;
16
17struct kvec {
18 void *iov_base; /* and that should *never* hold a userland pointer */
19 size_t iov_len;
20};
21
22enum {
23 ITER_IOVEC = 0,
24 ITER_KVEC = 2,
25 ITER_BVEC = 4,
26};
27
28struct iov_iter {
29 int type;
30 size_t iov_offset;
31 size_t count;
32 union {
33 const struct iovec *iov;
34 const struct kvec *kvec;
35 const struct bio_vec *bvec;
36 };
37 unsigned long nr_segs;
38};
39
40/*
41 * Total number of bytes covered by an iovec.
42 *
43 * NOTE that it is not safe to use this function until all the iovec's
44 * segment lengths have been validated. Because the individual lengths can
45 * overflow a size_t when added together.
46 */
47static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
48{
49 unsigned long seg;
50 size_t ret = 0;
51
52 for (seg = 0; seg < nr_segs; seg++)
53 ret += iov[seg].iov_len;
54 return ret;
55}
56
57static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
58{
59 return (struct iovec) {
60 .iov_base = iter->iov->iov_base + iter->iov_offset,
61 .iov_len = min(iter->count,
62 iter->iov->iov_len - iter->iov_offset),
63 };
64}
65
66#define iov_for_each(iov, iter, start) \
67 if (!((start).type & ITER_BVEC)) \
68 for (iter = (start); \
69 (iter).count && \
70 ((iov = iov_iter_iovec(&(iter))), 1); \
71 iov_iter_advance(&(iter), (iov).iov_len))
72
73unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
74
75size_t iov_iter_copy_from_user_atomic(struct page *page,
76 struct iov_iter *i, unsigned long offset, size_t bytes);
77void iov_iter_advance(struct iov_iter *i, size_t bytes);
78int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
79size_t iov_iter_single_seg_count(const struct iov_iter *i);
80size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
81 struct iov_iter *i);
82size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
83 struct iov_iter *i);
84size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i);
85size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
86size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
87size_t iov_iter_zero(size_t bytes, struct iov_iter *);
88unsigned long iov_iter_alignment(const struct iov_iter *i);
89void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
90 unsigned long nr_segs, size_t count);
91void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *iov,
92 unsigned long nr_segs, size_t count);
93ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
94 size_t maxsize, unsigned maxpages, size_t *start);
95ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
96 size_t maxsize, size_t *start);
97int iov_iter_npages(const struct iov_iter *i, int maxpages);
98
99static inline size_t iov_iter_count(struct iov_iter *i)
100{
101 return i->count;
102}
103
104static inline bool iter_is_iovec(struct iov_iter *i)
105{
106 return !(i->type & (ITER_BVEC | ITER_KVEC));
107}
108
109/*
110 * Cap the iov_iter by given limit; note that the second argument is
111 * *not* the new size - it's upper limit for such. Passing it a value
112 * greater than the amount of data in iov_iter is fine - it'll just do
113 * nothing in that case.
114 */
115static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
116{
117 /*
118 * count doesn't have to fit in size_t - comparison extends both
119 * operands to u64 here and any value that would be truncated by
120 * conversion in assignement is by definition greater than all
121 * values of size_t, including old i->count.
122 */
123 if (i->count > count)
124 i->count = count;
125}
126
127/*
128 * reexpand a previously truncated iterator; count must be no more than how much
129 * we had shrunk it.
130 */
131static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
132{
133 i->count = count;
134}
135size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
136size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
137
138int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
139int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
140 int offset, int len);
141int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
142 int offset, int len);
143
144#endif