iov.c

   1 /*
   2  * Helpers for getting linearized buffers from iov / filling buffers into iovs
   3  *
   4  * Copyright IBM, Corp. 2007, 2008
   5  * Copyright (C) 2010 Red Hat, Inc.
   6  *
   7  * Author(s):
   8  *  Anthony Liguori <aliguori@us.ibm.com>
   9  *  Amit Shah <amit.shah@redhat.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.  See
  12  * the COPYING file in the top-level directory.
  13  */
  14
  15 #include "iov.h"
  16
  17 size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
  18                     const void *buf, size_t iov_off, size_t size)
  19 {
  20     size_t iovec_off, buf_off;
  21     unsigned int i;
  22
  23     iovec_off = 0;
  24     buf_off = 0;
  25     for (i = 0; i < iov_cnt && size; i++) {
  26         if (iov_off < (iovec_off + iov[i].iov_len)) {
  27             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off, size);
  28
  29             memcpy(iov[i].iov_base + (iov_off - iovec_off), buf + buf_off, len);
  30
  31             buf_off += len;
  32             iov_off += len;
  33             size -= len;
  34         }
  35         iovec_off += iov[i].iov_len;
  36     }
  37     return buf_off;
  38 }
  39
  40 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
  41                   void *buf, size_t iov_off, size_t size)
  42 {
  43     uint8_t *ptr;
  44     size_t iovec_off, buf_off;
  45     unsigned int i;
  46
  47     ptr = buf;
  48     iovec_off = 0;
  49     buf_off = 0;
  50     for (i = 0; i < iov_cnt && size; i++) {
  51         if (iov_off < (iovec_off + iov[i].iov_len)) {
  52             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
  53
  54             memcpy(ptr + buf_off, iov[i].iov_base + (iov_off - iovec_off), len);
  55
  56             buf_off += len;
  57             iov_off += len;
  58             size -= len;
  59         }
  60         iovec_off += iov[i].iov_len;
  61     }
  62     return buf_off;
  63 }
  64
  65 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
  66 {
  67     size_t len;
  68     unsigned int i;
  69
  70     len = 0;
  71     for (i = 0; i < iov_cnt; i++) {
  72         len += iov[i].iov_len;
  73     }
  74     return len;
  75 }