lib/iovec.c

   1 #include <linux/uaccess.h>
   2 #include <linux/export.h>
   3 #include <linux/uio.h>
   4
   5 /*
   6  *      Copy iovec to kernel. Returns -EFAULT on error.
   7  *
   8  *      Note: this modifies the original iovec.
   9  */
  10
  11 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
  12 {
  13         while (len > 0) {
  14                 if (iov->iov_len) {
  15                         int copy = min_t(unsigned int, len, iov->iov_len);
  16                         if (copy_from_user(kdata, iov->iov_base, copy))
  17                                 return -EFAULT;
  18                         len -= copy;
  19                         kdata += copy;
  20                         iov->iov_base += copy;
  21                         iov->iov_len -= copy;
  22                 }
  23                 iov++;
  24         }
  25
  26         return 0;
  27 }
  28 EXPORT_SYMBOL(memcpy_fromiovec);
  29
  30 /*
  31  *      Copy kernel to iovec. Returns -EFAULT on error.
  32  *
  33  *      Note: this modifies the original iovec.
  34  */
  35
  36 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
  37 {
  38         while (len > 0) {
  39                 if (iov->iov_len) {
  40                         int copy = min_t(unsigned int, iov->iov_len, len);
  41                         if (copy_to_user(iov->iov_base, kdata, copy))
  42                                 return -EFAULT;
  43                         kdata += copy;
  44                         len -= copy;
  45                         iov->iov_len -= copy;
  46                         iov->iov_base += copy;
  47                 }
  48                 iov++;
  49         }
  50
  51         return 0;
  52 }
  53 EXPORT_SYMBOL(memcpy_toiovec);
  54
  55 /*
  56  *      Copy kernel to iovec. Returns -EFAULT on error.
  57  */
  58
  59 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
  60                       int offset, int len)
  61 {
  62         int copy;
  63         for (; len > 0; ++iov) {
  64                 /* Skip over the finished iovecs */
  65                 if (unlikely(offset >= iov->iov_len)) {
  66                         offset -= iov->iov_len;
  67                         continue;
  68                 }
  69                 copy = min_t(unsigned int, iov->iov_len - offset, len);
  70                 if (copy_to_user(iov->iov_base + offset, kdata, copy))
  71                         return -EFAULT;
  72                 offset = 0;
  73                 kdata += copy;
  74                 len -= copy;
  75         }
  76
  77         return 0;
  78 }
  79 EXPORT_SYMBOL(memcpy_toiovecend);
  80
  81 /*
  82  *      Copy iovec to kernel. Returns -EFAULT on error.
  83  */
  84
  85 int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
  86                         int offset, int len)
  87 {
  88         /* No data? Done! */
  89         if (len == 0)
  90                 return 0;
  91
  92         /* Skip over the finished iovecs */
  93         while (offset >= iov->iov_len) {
  94                 offset -= iov->iov_len;
  95                 iov++;
  96         }
  97
  98         while (len > 0) {
  99                 u8 __user *base = iov->iov_base + offset;
 100                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
 101
 102                 offset = 0;
 103                 if (copy_from_user(kdata, base, copy))
 104                         return -EFAULT;
 105                 len -= copy;
 106                 kdata += copy;
 107                 iov++;
 108         }
 109
 110         return 0;
 111 }
 112 EXPORT_SYMBOL(memcpy_fromiovecend);