1 #ifndef __LINUX_UIO_H 2 #define __LINUX_UIO_H 3 4 #include <linux/compiler.h> 5 #include <linux/types.h> 6 7 /* 8 * Berkeley style UIO structures - Alan Cox 1994. 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 16 17 /* A word of warning: Our uio structure will clash with the C library one (which is now obsolete). Remove the C 18 library one from sys/uio.h if you have a very old library set */ 19 20 struct iovec 21 { 22 void __user *iov_base; /* BSD uses caddr_t (1003.1g requires void *) */ 23 __kernel_size_t iov_len; /* Must be size_t (1003.1g) */ 24 }; 25 26 #ifdef __KERNEL__ 27 28 struct kvec { 29 void *iov_base; /* and that should *never* hold a userland pointer */ 30 size_t iov_len; 31 }; 32 33 #endif 34 35 /* 36 * UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1) 37 */ 38 39 #define UIO_FASTIOV 8 40 #define UIO_MAXIOV 1024 41 #if 0 42 #define UIO_MAXIOV 16 /* Maximum iovec's in one operation 43 16 matches BSD */ 44 /* Beg pardon: BSD has 1024 --ANK */ 45 #endif 46 47 /* 48 * Total number of bytes covered by an iovec. 49 * 50 * NOTE that it is not safe to use this function until all the iovec's 51 * segment lengths have been validated. Because the individual lengths can 52 * overflow a size_t when added together. 53 */ 54 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) 55 { 56 unsigned long seg; 57 size_t ret = 0; 58 59 for (seg = 0; seg < nr_segs; seg++) 60 ret += iov[seg].iov_len; 61 return ret; 62 } 63 64 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to); 65 66 #endif 67
