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Diffstat (limited to 'contrib/qemu/include/qemu/iov.h')
| -rw-r--r-- | contrib/qemu/include/qemu/iov.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/contrib/qemu/include/qemu/iov.h b/contrib/qemu/include/qemu/iov.h new file mode 100644 index 00000000000..68d25f29b76 --- /dev/null +++ b/contrib/qemu/include/qemu/iov.h @@ -0,0 +1,115 @@ +/* + * 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. + */ + +#ifndef IOV_H +#define IOV_H + +#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(const 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); + +/* + * Partial copy of vector from iov to dst_iov (data is not copied). + * dst_iov overlaps iov at a specified offset. + * size of dst_iov is at most bytes. dst vector count is returned. + */ +unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, + const struct iovec *iov, unsigned int iov_cnt, + size_t offset, size_t bytes); + +/* + * Remove a given number of bytes from the front or back of a vector. + * This may update iov and/or iov_cnt to exclude iovec elements that are + * no longer required. + * + * The number of bytes actually discarded is returned. This number may be + * smaller than requested if the vector is too small. + */ +size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, + size_t bytes); +size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, + size_t bytes); + +#endif |