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 int idx; 43 }; 44 }; 45 46 /* 47 * Total number of bytes covered by an iovec. 48 * 49 * NOTE that it is not safe to use this function until all the iovec's 50 * segment lengths have been validated. Because the individual lengths can 51 * overflow a size_t when added together. 52 */ 53 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) 54 { 55 unsigned long seg; 56 size_t ret = 0; 57 58 for (seg = 0; seg < nr_segs; seg++) 59 ret += iov[seg].iov_len; 60 return ret; 61 } 62 63 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter) 64 { 65 return (struct iovec) { 66 .iov_base = iter->iov->iov_base + iter->iov_offset, 67 .iov_len = min(iter->count, 68 iter->iov->iov_len - iter->iov_offset), 69 }; 70 } 71 72 #define iov_for_each(iov, iter, start) \ 73 if (!((start).type & (ITER_BVEC | ITER_PIPE))) \ 74 for (iter = (start); \ 75 (iter).count && \ 76 ((iov = iov_iter_iovec(&(iter))), 1); \ 77 iov_iter_advance(&(iter), (iov).iov_len)) 78 79 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to); 80 81 size_t iov_iter_copy_from_user_atomic(struct page *page, 82 struct iov_iter *i, unsigned long offset, size_t bytes); 83 void iov_iter_advance(struct iov_iter *i, size_t bytes); 84 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); 85 size_t iov_iter_single_seg_count(const struct iov_iter *i); 86 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 87 struct iov_iter *i); 88 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 89 struct iov_iter *i); 90 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); 91 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); 92 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i); 93 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i); 94 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i); 95 size_t iov_iter_zero(size_t bytes, struct iov_iter *); 96 unsigned long iov_iter_alignment(const struct iov_iter *i); 97 unsigned long iov_iter_gap_alignment(const struct iov_iter *i); 98 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, 99 unsigned long nr_segs, size_t count); 100 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec, 101 unsigned long nr_segs, size_t count); 102 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec, 103 unsigned long nr_segs, size_t count); 104 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe, 105 size_t count); 106 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, 107 size_t maxsize, unsigned maxpages, size_t *start); 108 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, 109 size_t maxsize, size_t *start); 110 int iov_iter_npages(const struct iov_iter *i, int maxpages); 111 112 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags); 113 114 static inline size_t iov_iter_count(const struct iov_iter *i) 115 { 116 return i->count; 117 } 118 119 static inline bool iter_is_iovec(const struct iov_iter *i) 120 { 121 return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE)); 122 } 123 124 /* 125 * Get one of READ or WRITE out of iter->type without any other flags OR'd in 126 * with it. 127 * 128 * The ?: is just for type safety. 129 */ 130 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE)) 131 132 /* 133 * Cap the iov_iter by given limit; note that the second argument is 134 * *not* the new size - it's upper limit for such. Passing it a value 135 * greater than the amount of data in iov_iter is fine - it'll just do 136 * nothing in that case. 137 */ 138 static inline void iov_iter_truncate(struct iov_iter *i, u64 count) 139 { 140 /* 141 * count doesn't have to fit in size_t - comparison extends both 142 * operands to u64 here and any value that would be truncated by 143 * conversion in assignement is by definition greater than all 144 * values of size_t, including old i->count. 145 */ 146 if (i->count > count) 147 i->count = count; 148 } 149 150 /* 151 * reexpand a previously truncated iterator; count must be no more than how much 152 * we had shrunk it. 153 */ 154 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) 155 { 156 i->count = count; 157 } 158 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 159 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 160 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 161 162 int import_iovec(int type, const struct iovec __user * uvector, 163 unsigned nr_segs, unsigned fast_segs, 164 struct iovec **iov, struct iov_iter *i); 165 166 #ifdef CONFIG_COMPAT 167 struct compat_iovec; 168 int compat_import_iovec(int type, const struct compat_iovec __user * uvector, 169 unsigned nr_segs, unsigned fast_segs, 170 struct iovec **iov, struct iov_iter *i); 171 #endif 172 173 int import_single_range(int type, void __user *buf, size_t len, 174 struct iovec *iov, struct iov_iter *i); 175 176 #endif 177