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/*
* Berkeley style UIO structures - Alan Cox 1994.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef __LINUX_UIO_H
#define __LINUX_UIO_H
#include <linux/kernel.h>
#include <uapi/linux/uio.h>
struct page;
struct kvec {
void *iov_base; /* and that should *never* hold a userland pointer */
size_t iov_len;
};
enum {
ITER_IOVEC = 0,
ITER_KVEC = 2,
ITER_BVEC = 4,
};
struct iov_iter {
int type;
size_t iov_offset;
size_t count;
union {
const struct iovec *iov;
const struct bio_vec *bvec;
};
unsigned long nr_segs;
};
/*
* Total number of bytes covered by an iovec.
*
* NOTE that it is not safe to use this function until all the iovec's
* segment lengths have been validated. Because the individual lengths can
* overflow a size_t when added together.
*/
static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
{
unsigned long seg;
size_t ret = 0;
for (seg = 0; seg < nr_segs; seg++)
ret += iov[seg].iov_len;
return ret;
}
static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
{
return (struct iovec) {
.iov_base = iter->iov->iov_base + iter->iov_offset,
.iov_len = min(iter->count,
iter->iov->iov_len - iter->iov_offset),
};
}
#define iov_for_each(iov, iter, start) \
if (!((start).type & ITER_BVEC)) \
for (iter = (start); \
(iter).count && \
((iov = iov_iter_iovec(&(iter))), 1); \
iov_iter_advance(&(iter), (iov).iov_len))
unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes);
void iov_iter_advance(struct iov_iter *i, size_t bytes);
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
unsigned long iov_iter_alignment(const struct iov_iter *i);
void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
unsigned long nr_segs, size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
static inline size_t iov_iter_count(struct iov_iter *i)
{
return i->count;
}
/*
* Cap the iov_iter by given limit; note that the second argument is
* *not* the new size - it's upper limit for such. Passing it a value
* greater than the amount of data in iov_iter is fine - it'll just do
* nothing in that case.
*/
static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
{
/*
* count doesn't have to fit in size_t - comparison extends both
* operands to u64 here and any value that would be truncated by
* conversion in assignement is by definition greater than all
* values of size_t, including old i->count.
*/
if (i->count > count)
i->count = count;
}
/*
* reexpand a previously truncated iterator; count must be no more than how much
* we had shrunk it.
*/
static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
{
i->count = count;
}
int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
int offset, int len);
int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
int offset, int len);
#endif
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