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 15 struct page; 16 struct pipe_inode_info; 17 18 struct kvec { 19 void *iov_base; /* and that should *never* hold a userland pointer */ 20 size_t iov_len; 21 }; 22 23 enum { 24 ITER_IOVEC = 0, 25 ITER_KVEC = 2, 26 ITER_BVEC = 4, 27 ITER_PIPE = 8, 28 }; 29 30 struct iov_iter { 31 int type; 32 size_t iov_offset; 33 size_t count; 34 union { 35 const struct iovec *iov; 36 const struct kvec *kvec; 37 const struct bio_vec *bvec; 38 struct pipe_inode_info *pipe; 39 }; 40 union { 41 unsigned long nr_segs; 42 struct { 43 int idx; 44 int start_idx; 45 }; 46 }; 47 }; 48 49 /* 50 * Total number of bytes covered by an iovec. 51 * 52 * NOTE that it is not safe to use this function until all the iovec's 53 * segment lengths have been validated. Because the individual lengths can 54 * overflow a size_t when added together. 55 */ 56 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) 57 { 58 unsigned long seg; 59 size_t ret = 0; 60 61 for (seg = 0; seg < nr_segs; seg++) 62 ret += iov[seg].iov_len; 63 return ret; 64 } 65 66 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter) 67 { 68 return (struct iovec) { 69 .iov_base = iter->iov->iov_base + iter->iov_offset, 70 .iov_len = min(iter->count, 71 iter->iov->iov_len - iter->iov_offset), 72 }; 73 } 74 75 #define iov_for_each(iov, iter, start) \ 76 if (!((start).type & (ITER_BVEC | ITER_PIPE))) \ 77 for (iter = (start); \ 78 (iter).count && \ 79 ((iov = iov_iter_iovec(&(iter))), 1); \ 80 iov_iter_advance(&(iter), (iov).iov_len)) 81 82 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to); 83 84 size_t iov_iter_copy_from_user_atomic(struct page *page, 85 struct iov_iter *i, unsigned long offset, size_t bytes); 86 void iov_iter_advance(struct iov_iter *i, size_t bytes); 87 void iov_iter_revert(struct iov_iter *i, size_t bytes); 88 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); 89 size_t iov_iter_single_seg_count(const struct iov_iter *i); 90 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 91 struct iov_iter *i); 92 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 93 struct iov_iter *i); 94 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); 95 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); 96 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i); 97 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i); 98 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i); 99 size_t iov_iter_zero(size_t bytes, struct iov_iter *); 100 unsigned long iov_iter_alignment(const struct iov_iter *i); 101 unsigned long iov_iter_gap_alignment(const struct iov_iter *i); 102 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, 103 unsigned long nr_segs, size_t count); 104 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec, 105 unsigned long nr_segs, size_t count); 106 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec, 107 unsigned long nr_segs, size_t count); 108 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe, 109 size_t count); 110 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, 111 size_t maxsize, unsigned maxpages, size_t *start); 112 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, 113 size_t maxsize, size_t *start); 114 int iov_iter_npages(const struct iov_iter *i, int maxpages); 115 116 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags); 117 118 static inline size_t iov_iter_count(const struct iov_iter *i) 119 { 120 return i->count; 121 } 122 123 static inline bool iter_is_iovec(const struct iov_iter *i) 124 { 125 return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE)); 126 } 127 128 /* 129 * Get one of READ or WRITE out of iter->type without any other flags OR'd in 130 * with it. 131 * 132 * The ?: is just for type safety. 133 */ 134 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE)) 135 136 /* 137 * Cap the iov_iter by given limit; note that the second argument is 138 * *not* the new size - it's upper limit for such. Passing it a value 139 * greater than the amount of data in iov_iter is fine - it'll just do 140 * nothing in that case. 141 */ 142 static inline void iov_iter_truncate(struct iov_iter *i, u64 count) 143 { 144 /* 145 * count doesn't have to fit in size_t - comparison extends both 146 * operands to u64 here and any value that would be truncated by 147 * conversion in assignement is by definition greater than all 148 * values of size_t, including old i->count. 149 */ 150 if (i->count > count) 151 i->count = count; 152 } 153 154 /* 155 * reexpand a previously truncated iterator; count must be no more than how much 156 * we had shrunk it. 157 */ 158 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) 159 { 160 i->count = count; 161 } 162 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 163 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 164 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 165 166 int import_iovec(int type, const struct iovec __user * uvector, 167 unsigned nr_segs, unsigned fast_segs, 168 struct iovec **iov, struct iov_iter *i); 169 170 #ifdef CONFIG_COMPAT 171 struct compat_iovec; 172 int compat_import_iovec(int type, const struct compat_iovec __user * uvector, 173 unsigned nr_segs, unsigned fast_segs, 174 struct iovec **iov, struct iov_iter *i); 175 #endif 176 177 int import_single_range(int type, void __user *buf, size_t len, 178 struct iovec *iov, struct iov_iter *i); 179 180 #endif 181