mirror of
https://github.com/xemu-project/xemu.git
synced 2024-11-27 05:20:50 +00:00
25e5e4c7e9
Make it much more understandable, add a missing iov_cnt argument (number of iovs in the iov), and add comments to it. The new implementation has been extensively tested by splitting a large buffer into many small randomly-sized chunks, sending it over socket to another, slow process and verifying the receiving data is the same. Also add a unit test for iov_send_recv(), sending/ receiving data between two processes over a socketpair using random vectors and random sizes. Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
89 lines
3.5 KiB
C
89 lines
3.5 KiB
C
/*
|
|
* Helpers for using (partial) iovecs.
|
|
*
|
|
* Copyright (C) 2010 Red Hat, Inc.
|
|
*
|
|
* Author(s):
|
|
* Amit Shah <amit.shah@redhat.com>
|
|
* Michael Tokarev <mjt@tls.msk.ru>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2. See
|
|
* the COPYING file in the top-level directory.
|
|
*/
|
|
|
|
#include "qemu-common.h"
|
|
|
|
/**
|
|
* count and return data size, in bytes, of an iovec
|
|
* starting at `iov' of `iov_cnt' number of elements.
|
|
*/
|
|
size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
|
|
|
|
/**
|
|
* Copy from single continuous buffer to scatter-gather vector of buffers
|
|
* (iovec) and back like memcpy() between two continuous memory regions.
|
|
* Data in single continuous buffer starting at address `buf' and
|
|
* `bytes' bytes long will be copied to/from an iovec `iov' with
|
|
* `iov_cnt' number of elements, starting at byte position `offset'
|
|
* within the iovec. If the iovec does not contain enough space,
|
|
* only part of data will be copied, up to the end of the iovec.
|
|
* Number of bytes actually copied will be returned, which is
|
|
* min(bytes, iov_size(iov)-offset)
|
|
* `Offset' must point to the inside of iovec.
|
|
* It is okay to use very large value for `bytes' since we're
|
|
* limited by the size of the iovec anyway, provided that the
|
|
* buffer pointed to by buf has enough space. One possible
|
|
* such "large" value is -1 (sinice size_t is unsigned),
|
|
* so specifying `-1' as `bytes' means 'up to the end of iovec'.
|
|
*/
|
|
size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
|
|
size_t offset, const void *buf, size_t bytes);
|
|
size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
|
|
size_t offset, void *buf, size_t bytes);
|
|
|
|
/**
|
|
* Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
|
|
* starting at byte offset `start', to value `fillc', repeating it
|
|
* `bytes' number of times. `Offset' must point to the inside of iovec.
|
|
* If `bytes' is large enough, only last bytes portion of iovec,
|
|
* up to the end of it, will be filled with the specified value.
|
|
* Function return actual number of bytes processed, which is
|
|
* min(size, iov_size(iov) - offset).
|
|
* Again, it is okay to use large value for `bytes' to mean "up to the end".
|
|
*/
|
|
size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
|
|
size_t offset, int fillc, size_t bytes);
|
|
|
|
/*
|
|
* Send/recv data from/to iovec buffers directly
|
|
*
|
|
* `offset' bytes in the beginning of iovec buffer are skipped and
|
|
* next `bytes' bytes are used, which must be within data of iovec.
|
|
*
|
|
* r = iov_send_recv(sockfd, iov, iovcnt, offset, bytes, true);
|
|
*
|
|
* is logically equivalent to
|
|
*
|
|
* char *buf = malloc(bytes);
|
|
* iov_to_buf(iov, iovcnt, offset, buf, bytes);
|
|
* r = send(sockfd, buf, bytes, 0);
|
|
* free(buf);
|
|
*
|
|
* For iov_send_recv() _whole_ area being sent or received
|
|
* should be within the iovec, not only beginning of it.
|
|
*/
|
|
ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
|
|
size_t offset, size_t bytes, bool do_send);
|
|
#define iov_recv(sockfd, iov, iov_cnt, offset, bytes) \
|
|
iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, false)
|
|
#define iov_send(sockfd, iov, iov_cnt, offset, bytes) \
|
|
iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, true)
|
|
|
|
/**
|
|
* Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements
|
|
* in file `fp', prefixing each line with `prefix' and processing not more
|
|
* than `limit' data bytes.
|
|
*/
|
|
void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
|
|
FILE *fp, const char *prefix, size_t limit);
|