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
  34 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
  35                       int offset, int len)
  36 {
  37         int copy;
  38         for (; len > 0; ++iov) {
  39                 /* Skip over the finished iovecs */
  40                 if (unlikely(offset >= iov->iov_len)) {
  41                         offset -= iov->iov_len;
  42                         continue;
  43                 }
  44                 copy = min_t(unsigned int, iov->iov_len - offset, len);
  45                 if (copy_to_user(iov->iov_base + offset, kdata, copy))
  46                         return -EFAULT;
  47                 offset = 0;
  48                 kdata += copy;
  49                 len -= copy;
  50         }
  51
  52         return 0;
  53 }
  54 EXPORT_SYMBOL(memcpy_toiovecend);
  55
  56 /*
  57  *      Copy iovec to kernel. Returns -EFAULT on error.
  58  */
  59
  60 int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
  61                         int offset, int len)
  62 {
  63         /* No data? Done! */
  64         if (len == 0)
  65                 return 0;
  66
  67         /* Skip over the finished iovecs */
  68         while (offset >= iov->iov_len) {
  69                 offset -= iov->iov_len;
  70                 iov++;
  71         }
  72
  73         while (len > 0) {
  74                 u8 __user *base = iov->iov_base + offset;
  75                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
  76
  77                 offset = 0;
  78                 if (copy_from_user(kdata, base, copy))
  79                         return -EFAULT;
  80                 len -= copy;
  81                 kdata += copy;
  82                 iov++;
  83         }
  84
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(memcpy_fromiovecend);