diff options
Diffstat (limited to 'iov.h')
| -rw-r--r-- | iov.h | 77 |
1 files changed, 71 insertions, 6 deletions
@@ -1,10 +1,11 @@ /* - * Helpers for getting linearized buffers from iov / filling buffers into iovs + * 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. @@ -12,12 +13,76 @@ #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, - const void *buf, size_t iov_off, size_t size); + size_t offset, const void *buf, size_t bytes); size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, - void *buf, size_t iov_off, size_t size); -size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt); -size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt, - size_t iov_off, size_t size); + 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); |