iov.h

   1 /*
   2  * Helpers for getting linearized buffers from iov / filling buffers into iovs
   3  *
   4  * Copyright (C) 2010 Red Hat, Inc.
   5  *
   6  * Author(s):
   7  *  Amit Shah <amit.shah@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu-common.h"
  14
  15 /**
  16  * count and return data size, in bytes, of an iovec
  17  * starting at `iov' of `iov_cnt' number of elements.
  18  */
  19 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
  20
  21 /**
  22  * Copy from single continuous buffer to scatter-gather vector of buffers
  23  * (iovec) and back like memcpy() between two continuous memory regions.
  24  * Data in single continuous buffer starting at address `buf' and
  25  * `bytes' bytes long will be copied to/from an iovec `iov' with
  26  * `iov_cnt' number of elements, starting at byte position `offset'
  27  * within the iovec.  If the iovec does not contain enough space,
  28  * only part of data will be copied, up to the end of the iovec.
  29  * Number of bytes actually copied will be returned, which is
  30  *  min(bytes, iov_size(iov)-offset)
  31  */
  32 size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
  33                     size_t offset, const void *buf, size_t bytes);
  34 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
  35                   size_t offset, void *buf, size_t bytes);
  36
  37 /**
  38  * Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
  39  * starting at byte offset `start', to value `fillc', repeating it
  40  * `bytes' number of times.
  41  * If `bytes' is large enough, only last bytes portion of iovec,
  42  * up to the end of it, will be filled with the specified value.
  43  * Function return actual number of bytes processed, which is
  44  * min(size, iov_size(iov) - offset).
  45  */
  46 size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
  47                   size_t offset, int fillc, size_t bytes);
  48
  49 /**
  50  * Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements
  51  * in file `fp', prefixing each line with `prefix' and processing not more
  52  * than `limit' data bytes.
  53  */
  54 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
  55                  FILE *fp, const char *prefix, size_t limit);