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 iovcnt,
  18                     const void *buf, size_t size)
  19 {
  20     size_t offset;
  21     unsigned int i;
  22
  23     offset = 0;
  24     for (i = 0; offset < size && i < iovcnt; i++) {
  25         size_t len;
  26
  27         len = MIN(iov[i].iov_len, size - offset);
  28
  29         memcpy(iov[i].iov_base, buf + offset, len);
  30         offset += len;
  31     }
  32     return offset;
  33 }
  34
  35 size_t iov_to_buf(const struct iovec *iov, const unsigned int iovcnt,
  36                   void *buf, size_t offset, size_t size)
  37 {
  38     uint8_t *ptr;
  39     size_t iov_off, buf_off;
  40     unsigned int i;
  41
  42     ptr = buf;
  43     iov_off = 0;
  44     buf_off = 0;
  45     for (i = 0; i < iovcnt && size; i++) {
  46         if (offset < (iov_off + iov[i].iov_len)) {
  47             size_t len = MIN((iov_off + iov[i].iov_len) - offset , size);
  48
  49             memcpy(ptr + buf_off, iov[i].iov_base + (offset - iov_off), len);
  50
  51             buf_off += len;
  52             offset += len;
  53             size -= len;
  54         }
  55         iov_off += iov[i].iov_len;
  56     }
  57     return buf_off;
  58 }
  59
  60 size_t iov_size(const struct iovec *iov, const unsigned int iovcnt)
  61 {
  62     size_t len;
  63     unsigned int i;
  64
  65     len = 0;
  66     for (i = 0; i < iovcnt; i++) {
  67         len += iov[i].iov_len;
  68     }
  69     return len;
  70 }