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 #define iov_iter_fault_in_multipages_readable iov_iter_fault_in_readable 86 size_t iov_iter_single_seg_count(const struct iov_iter *i); 87 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 88 struct iov_iter *i); 89 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 90 struct iov_iter *i); 91 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); 92 size_t copy_from_iter(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 size_t iov_iter_zero(size_t bytes, struct iov_iter *); 95 unsigned long iov_iter_alignment(const struct iov_iter *i); 96 unsigned long iov_iter_gap_alignment(const struct iov_iter *i); 97 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, 98 unsigned long nr_segs, size_t count); 99 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec, 100 unsigned long nr_segs, size_t count); 101 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec, 102 unsigned long nr_segs, size_t count); 103 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe, 104 size_t count); 105 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, 106 size_t maxsize, unsigned maxpages, size_t *start); 107 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, 108 size_t maxsize, size_t *start); 109 int iov_iter_npages(const struct iov_iter *i, int maxpages); 110 111 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags); 112 113 static inline size_t iov_iter_count(struct iov_iter *i) 114 { 115 return i->count; 116 } 117 118 static inline bool iter_is_iovec(struct iov_iter *i) 119 { 120 return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE)); 121 } 122 123 /* 124 * Get one of READ or WRITE out of iter->type without any other flags OR'd in 125 * with it. 126 * 127 * The ?: is just for type safety. 128 */ 129 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & RW_MASK) 130 131 /* 132 * Cap the iov_iter by given limit; note that the second argument is 133 * *not* the new size - it's upper limit for such. Passing it a value 134 * greater than the amount of data in iov_iter is fine - it'll just do 135 * nothing in that case. 136 */ 137 static inline void iov_iter_truncate(struct iov_iter *i, u64 count) 138 { 139 /* 140 * count doesn't have to fit in size_t - comparison extends both 141 * operands to u64 here and any value that would be truncated by 142 * conversion in assignement is by definition greater than all 143 * values of size_t, including old i->count. 144 */ 145 if (i->count > count) 146 i->count = count; 147 } 148 149 /* 150 * reexpand a previously truncated iterator; count must be no more than how much 151 * we had shrunk it. 152 */ 153 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) 154 { 155 i->count = count; 156 } 157 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 158 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); 159 160 int import_iovec(int type, const struct iovec __user * uvector, 161 unsigned nr_segs, unsigned fast_segs, 162 struct iovec **iov, struct iov_iter *i); 163 164 #ifdef CONFIG_COMPAT 165 struct compat_iovec; 166 int compat_import_iovec(int type, const struct compat_iovec __user * uvector, 167 unsigned nr_segs, unsigned fast_segs, 168 struct iovec **iov, struct iov_iter *i); 169 #endif 170 171 int import_single_range(int type, void __user *buf, size_t len, 172 struct iovec *iov, struct iov_iter *i); 173 174 #endif 175