11de7afc9SPaolo Bonzini /* 21de7afc9SPaolo Bonzini * Helpers for using (partial) iovecs. 31de7afc9SPaolo Bonzini * 41de7afc9SPaolo Bonzini * Copyright (C) 2010 Red Hat, Inc. 51de7afc9SPaolo Bonzini * 61de7afc9SPaolo Bonzini * Author(s): 71de7afc9SPaolo Bonzini * Amit Shah <amit.shah@redhat.com> 81de7afc9SPaolo Bonzini * Michael Tokarev <mjt@tls.msk.ru> 91de7afc9SPaolo Bonzini * 101de7afc9SPaolo Bonzini * This work is licensed under the terms of the GNU GPL, version 2. See 111de7afc9SPaolo Bonzini * the COPYING file in the top-level directory. 121de7afc9SPaolo Bonzini */ 131de7afc9SPaolo Bonzini 141de7afc9SPaolo Bonzini #ifndef IOV_H 151de7afc9SPaolo Bonzini #define IOV_H 161de7afc9SPaolo Bonzini 171de7afc9SPaolo Bonzini /** 181de7afc9SPaolo Bonzini * count and return data size, in bytes, of an iovec 191de7afc9SPaolo Bonzini * starting at `iov' of `iov_cnt' number of elements. 201de7afc9SPaolo Bonzini */ 211de7afc9SPaolo Bonzini size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt); 221de7afc9SPaolo Bonzini 231de7afc9SPaolo Bonzini /** 241de7afc9SPaolo Bonzini * Copy from single continuous buffer to scatter-gather vector of buffers 251de7afc9SPaolo Bonzini * (iovec) and back like memcpy() between two continuous memory regions. 261de7afc9SPaolo Bonzini * Data in single continuous buffer starting at address `buf' and 271de7afc9SPaolo Bonzini * `bytes' bytes long will be copied to/from an iovec `iov' with 281de7afc9SPaolo Bonzini * `iov_cnt' number of elements, starting at byte position `offset' 291de7afc9SPaolo Bonzini * within the iovec. If the iovec does not contain enough space, 301de7afc9SPaolo Bonzini * only part of data will be copied, up to the end of the iovec. 311de7afc9SPaolo Bonzini * Number of bytes actually copied will be returned, which is 321de7afc9SPaolo Bonzini * min(bytes, iov_size(iov)-offset) 331de7afc9SPaolo Bonzini * `Offset' must point to the inside of iovec. 341de7afc9SPaolo Bonzini */ 35ad523bcaSPaolo Bonzini size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt, 361de7afc9SPaolo Bonzini size_t offset, const void *buf, size_t bytes); 37ad523bcaSPaolo Bonzini size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, 381de7afc9SPaolo Bonzini size_t offset, void *buf, size_t bytes); 391de7afc9SPaolo Bonzini 40ad523bcaSPaolo Bonzini static inline size_t 41ad523bcaSPaolo Bonzini iov_from_buf(const struct iovec *iov, unsigned int iov_cnt, 42ad523bcaSPaolo Bonzini size_t offset, const void *buf, size_t bytes) 43ad523bcaSPaolo Bonzini { 44ad523bcaSPaolo Bonzini if (__builtin_constant_p(bytes) && iov_cnt && 45ad523bcaSPaolo Bonzini offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) { 46ad523bcaSPaolo Bonzini memcpy(iov[0].iov_base + offset, buf, bytes); 47ad523bcaSPaolo Bonzini return bytes; 48ad523bcaSPaolo Bonzini } else { 49ad523bcaSPaolo Bonzini return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes); 50ad523bcaSPaolo Bonzini } 51ad523bcaSPaolo Bonzini } 52ad523bcaSPaolo Bonzini 53ad523bcaSPaolo Bonzini static inline size_t 54ad523bcaSPaolo Bonzini iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt, 55ad523bcaSPaolo Bonzini size_t offset, void *buf, size_t bytes) 56ad523bcaSPaolo Bonzini { 57ad523bcaSPaolo Bonzini if (__builtin_constant_p(bytes) && iov_cnt && 58ad523bcaSPaolo Bonzini offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) { 59ad523bcaSPaolo Bonzini memcpy(buf, iov[0].iov_base + offset, bytes); 60ad523bcaSPaolo Bonzini return bytes; 61ad523bcaSPaolo Bonzini } else { 62ad523bcaSPaolo Bonzini return iov_to_buf_full(iov, iov_cnt, offset, buf, bytes); 63ad523bcaSPaolo Bonzini } 64ad523bcaSPaolo Bonzini } 65ad523bcaSPaolo Bonzini 661de7afc9SPaolo Bonzini /** 671de7afc9SPaolo Bonzini * Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements, 681de7afc9SPaolo Bonzini * starting at byte offset `start', to value `fillc', repeating it 691de7afc9SPaolo Bonzini * `bytes' number of times. `Offset' must point to the inside of iovec. 701de7afc9SPaolo Bonzini * If `bytes' is large enough, only last bytes portion of iovec, 711de7afc9SPaolo Bonzini * up to the end of it, will be filled with the specified value. 721de7afc9SPaolo Bonzini * Function return actual number of bytes processed, which is 731de7afc9SPaolo Bonzini * min(size, iov_size(iov) - offset). 741de7afc9SPaolo Bonzini */ 751de7afc9SPaolo Bonzini size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, 761de7afc9SPaolo Bonzini size_t offset, int fillc, size_t bytes); 771de7afc9SPaolo Bonzini 781de7afc9SPaolo Bonzini /* 791de7afc9SPaolo Bonzini * Send/recv data from/to iovec buffers directly 801de7afc9SPaolo Bonzini * 811de7afc9SPaolo Bonzini * `offset' bytes in the beginning of iovec buffer are skipped and 821de7afc9SPaolo Bonzini * next `bytes' bytes are used, which must be within data of iovec. 831de7afc9SPaolo Bonzini * 841de7afc9SPaolo Bonzini * r = iov_send_recv(sockfd, iov, iovcnt, offset, bytes, true); 851de7afc9SPaolo Bonzini * 861de7afc9SPaolo Bonzini * is logically equivalent to 871de7afc9SPaolo Bonzini * 881de7afc9SPaolo Bonzini * char *buf = malloc(bytes); 891de7afc9SPaolo Bonzini * iov_to_buf(iov, iovcnt, offset, buf, bytes); 901de7afc9SPaolo Bonzini * r = send(sockfd, buf, bytes, 0); 911de7afc9SPaolo Bonzini * free(buf); 921de7afc9SPaolo Bonzini * 931de7afc9SPaolo Bonzini * For iov_send_recv() _whole_ area being sent or received 941de7afc9SPaolo Bonzini * should be within the iovec, not only beginning of it. 951de7afc9SPaolo Bonzini */ 966b64640dSWen Congyang ssize_t iov_send_recv(int sockfd, const struct iovec *iov, unsigned iov_cnt, 971de7afc9SPaolo Bonzini size_t offset, size_t bytes, bool do_send); 981de7afc9SPaolo Bonzini #define iov_recv(sockfd, iov, iov_cnt, offset, bytes) \ 991de7afc9SPaolo Bonzini iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, false) 1001de7afc9SPaolo Bonzini #define iov_send(sockfd, iov, iov_cnt, offset, bytes) \ 1011de7afc9SPaolo Bonzini iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, true) 1021de7afc9SPaolo Bonzini 1031de7afc9SPaolo Bonzini /** 1041de7afc9SPaolo Bonzini * Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements 1051de7afc9SPaolo Bonzini * in file `fp', prefixing each line with `prefix' and processing not more 1061de7afc9SPaolo Bonzini * than `limit' data bytes. 1071de7afc9SPaolo Bonzini */ 1081de7afc9SPaolo Bonzini void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, 1091de7afc9SPaolo Bonzini FILE *fp, const char *prefix, size_t limit); 1101de7afc9SPaolo Bonzini 1111de7afc9SPaolo Bonzini /* 1121de7afc9SPaolo Bonzini * Partial copy of vector from iov to dst_iov (data is not copied). 1131de7afc9SPaolo Bonzini * dst_iov overlaps iov at a specified offset. 1141de7afc9SPaolo Bonzini * size of dst_iov is at most bytes. dst vector count is returned. 1151de7afc9SPaolo Bonzini */ 1161de7afc9SPaolo Bonzini unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, 1171de7afc9SPaolo Bonzini const struct iovec *iov, unsigned int iov_cnt, 1181de7afc9SPaolo Bonzini size_t offset, size_t bytes); 1191de7afc9SPaolo Bonzini 120d0277635SStefan Hajnoczi /* 121d0277635SStefan Hajnoczi * Remove a given number of bytes from the front or back of a vector. 122d0277635SStefan Hajnoczi * This may update iov and/or iov_cnt to exclude iovec elements that are 123d0277635SStefan Hajnoczi * no longer required. 124d0277635SStefan Hajnoczi * 125d0277635SStefan Hajnoczi * The number of bytes actually discarded is returned. This number may be 126d0277635SStefan Hajnoczi * smaller than requested if the vector is too small. 127d0277635SStefan Hajnoczi */ 128d0277635SStefan Hajnoczi size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, 129d0277635SStefan Hajnoczi size_t bytes); 130d0277635SStefan Hajnoczi size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, 131d0277635SStefan Hajnoczi size_t bytes); 132d0277635SStefan Hajnoczi 133*9dd6f7c2SStefan Hajnoczi /* Information needed to undo an iov_discard_*() operation */ 134*9dd6f7c2SStefan Hajnoczi typedef struct { 135*9dd6f7c2SStefan Hajnoczi struct iovec *modified_iov; 136*9dd6f7c2SStefan Hajnoczi struct iovec orig; 137*9dd6f7c2SStefan Hajnoczi } IOVDiscardUndo; 138*9dd6f7c2SStefan Hajnoczi 139*9dd6f7c2SStefan Hajnoczi /* 140*9dd6f7c2SStefan Hajnoczi * Undo an iov_discard_front_undoable() or iov_discard_back_undoable() 141*9dd6f7c2SStefan Hajnoczi * operation. If multiple operations are made then each one needs a separate 142*9dd6f7c2SStefan Hajnoczi * IOVDiscardUndo and iov_discard_undo() must be called in the reverse order 143*9dd6f7c2SStefan Hajnoczi * that the operations were made. 144*9dd6f7c2SStefan Hajnoczi */ 145*9dd6f7c2SStefan Hajnoczi void iov_discard_undo(IOVDiscardUndo *undo); 146*9dd6f7c2SStefan Hajnoczi 147*9dd6f7c2SStefan Hajnoczi /* 148*9dd6f7c2SStefan Hajnoczi * Undoable versions of iov_discard_front() and iov_discard_back(). Use 149*9dd6f7c2SStefan Hajnoczi * iov_discard_undo() to reset to the state before the discard operations. 150*9dd6f7c2SStefan Hajnoczi */ 151*9dd6f7c2SStefan Hajnoczi size_t iov_discard_front_undoable(struct iovec **iov, unsigned int *iov_cnt, 152*9dd6f7c2SStefan Hajnoczi size_t bytes, IOVDiscardUndo *undo); 153*9dd6f7c2SStefan Hajnoczi size_t iov_discard_back_undoable(struct iovec *iov, unsigned int *iov_cnt, 154*9dd6f7c2SStefan Hajnoczi size_t bytes, IOVDiscardUndo *undo); 155*9dd6f7c2SStefan Hajnoczi 156daf015efSMarkus Armbruster typedef struct QEMUIOVector { 157daf015efSMarkus Armbruster struct iovec *iov; 158daf015efSMarkus Armbruster int niov; 159a1ca3ed5SVladimir Sementsov-Ogievskiy 160a1ca3ed5SVladimir Sementsov-Ogievskiy /* 161a1ca3ed5SVladimir Sementsov-Ogievskiy * For external @iov (qemu_iovec_init_external()) or allocated @iov 162a1ca3ed5SVladimir Sementsov-Ogievskiy * (qemu_iovec_init()), @size is the cumulative size of iovecs and 163a1ca3ed5SVladimir Sementsov-Ogievskiy * @local_iov is invalid and unused. 164a1ca3ed5SVladimir Sementsov-Ogievskiy * 165a1ca3ed5SVladimir Sementsov-Ogievskiy * For embedded @iov (QEMU_IOVEC_INIT_BUF() or qemu_iovec_init_buf()), 166a1ca3ed5SVladimir Sementsov-Ogievskiy * @iov is equal to &@local_iov, and @size is valid, as it has same 167a1ca3ed5SVladimir Sementsov-Ogievskiy * offset and type as @local_iov.iov_len, which is guaranteed by 168a1ca3ed5SVladimir Sementsov-Ogievskiy * static assertion below. 169a1ca3ed5SVladimir Sementsov-Ogievskiy * 170a1ca3ed5SVladimir Sementsov-Ogievskiy * @nalloc is always valid and is -1 both for embedded and external 171a1ca3ed5SVladimir Sementsov-Ogievskiy * cases. It is included in the union only to ensure the padding prior 172a1ca3ed5SVladimir Sementsov-Ogievskiy * to the @size field will not result in a 0-length array. 173a1ca3ed5SVladimir Sementsov-Ogievskiy */ 174a1ca3ed5SVladimir Sementsov-Ogievskiy union { 175a1ca3ed5SVladimir Sementsov-Ogievskiy struct { 176daf015efSMarkus Armbruster int nalloc; 177a1ca3ed5SVladimir Sementsov-Ogievskiy struct iovec local_iov; 178a1ca3ed5SVladimir Sementsov-Ogievskiy }; 179a1ca3ed5SVladimir Sementsov-Ogievskiy struct { 180a1ca3ed5SVladimir Sementsov-Ogievskiy char __pad[sizeof(int) + offsetof(struct iovec, iov_len)]; 181daf015efSMarkus Armbruster size_t size; 182a1ca3ed5SVladimir Sementsov-Ogievskiy }; 183a1ca3ed5SVladimir Sementsov-Ogievskiy }; 184daf015efSMarkus Armbruster } QEMUIOVector; 185daf015efSMarkus Armbruster 186a1ca3ed5SVladimir Sementsov-Ogievskiy QEMU_BUILD_BUG_ON(offsetof(QEMUIOVector, size) != 187a1ca3ed5SVladimir Sementsov-Ogievskiy offsetof(QEMUIOVector, local_iov.iov_len)); 188a1ca3ed5SVladimir Sementsov-Ogievskiy 189a1ca3ed5SVladimir Sementsov-Ogievskiy #define QEMU_IOVEC_INIT_BUF(self, buf, len) \ 190a1ca3ed5SVladimir Sementsov-Ogievskiy { \ 191a1ca3ed5SVladimir Sementsov-Ogievskiy .iov = &(self).local_iov, \ 192a1ca3ed5SVladimir Sementsov-Ogievskiy .niov = 1, \ 193a1ca3ed5SVladimir Sementsov-Ogievskiy .nalloc = -1, \ 194a1ca3ed5SVladimir Sementsov-Ogievskiy .local_iov = { \ 195a1ca3ed5SVladimir Sementsov-Ogievskiy .iov_base = (void *)(buf), /* cast away const */ \ 196a1ca3ed5SVladimir Sementsov-Ogievskiy .iov_len = (len), \ 197a1ca3ed5SVladimir Sementsov-Ogievskiy }, \ 198a1ca3ed5SVladimir Sementsov-Ogievskiy } 199a1ca3ed5SVladimir Sementsov-Ogievskiy 200a1ca3ed5SVladimir Sementsov-Ogievskiy /* 201a1ca3ed5SVladimir Sementsov-Ogievskiy * qemu_iovec_init_buf 202a1ca3ed5SVladimir Sementsov-Ogievskiy * 203a1ca3ed5SVladimir Sementsov-Ogievskiy * Initialize embedded QEMUIOVector. 204a1ca3ed5SVladimir Sementsov-Ogievskiy * 205a1ca3ed5SVladimir Sementsov-Ogievskiy * Note: "const" is used over @buf pointer to make it simple to pass 206a1ca3ed5SVladimir Sementsov-Ogievskiy * const pointers, appearing in read functions. Then this "const" is 207a1ca3ed5SVladimir Sementsov-Ogievskiy * cast away by QEMU_IOVEC_INIT_BUF(). 208a1ca3ed5SVladimir Sementsov-Ogievskiy */ 209a1ca3ed5SVladimir Sementsov-Ogievskiy static inline void qemu_iovec_init_buf(QEMUIOVector *qiov, 210a1ca3ed5SVladimir Sementsov-Ogievskiy const void *buf, size_t len) 211a1ca3ed5SVladimir Sementsov-Ogievskiy { 212a1ca3ed5SVladimir Sementsov-Ogievskiy *qiov = (QEMUIOVector) QEMU_IOVEC_INIT_BUF(*qiov, buf, len); 213a1ca3ed5SVladimir Sementsov-Ogievskiy } 214a1ca3ed5SVladimir Sementsov-Ogievskiy 215a1ca3ed5SVladimir Sementsov-Ogievskiy static inline void *qemu_iovec_buf(QEMUIOVector *qiov) 216a1ca3ed5SVladimir Sementsov-Ogievskiy { 217a1ca3ed5SVladimir Sementsov-Ogievskiy /* Only supports embedded iov */ 218a1ca3ed5SVladimir Sementsov-Ogievskiy assert(qiov->nalloc == -1 && qiov->iov == &qiov->local_iov); 219a1ca3ed5SVladimir Sementsov-Ogievskiy 220a1ca3ed5SVladimir Sementsov-Ogievskiy return qiov->local_iov.iov_base; 221a1ca3ed5SVladimir Sementsov-Ogievskiy } 222a1ca3ed5SVladimir Sementsov-Ogievskiy 223daf015efSMarkus Armbruster void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint); 224daf015efSMarkus Armbruster void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov); 225d953169dSVladimir Sementsov-Ogievskiy void qemu_iovec_init_extended( 226d953169dSVladimir Sementsov-Ogievskiy QEMUIOVector *qiov, 227d953169dSVladimir Sementsov-Ogievskiy void *head_buf, size_t head_len, 228d953169dSVladimir Sementsov-Ogievskiy QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len, 229d953169dSVladimir Sementsov-Ogievskiy void *tail_buf, size_t tail_len); 230d953169dSVladimir Sementsov-Ogievskiy void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source, 231d953169dSVladimir Sementsov-Ogievskiy size_t offset, size_t len); 2325396234bSVladimir Sementsov-Ogievskiy int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len); 233daf015efSMarkus Armbruster void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len); 234daf015efSMarkus Armbruster void qemu_iovec_concat(QEMUIOVector *dst, 235daf015efSMarkus Armbruster QEMUIOVector *src, size_t soffset, size_t sbytes); 236daf015efSMarkus Armbruster size_t qemu_iovec_concat_iov(QEMUIOVector *dst, 237daf015efSMarkus Armbruster struct iovec *src_iov, unsigned int src_cnt, 238daf015efSMarkus Armbruster size_t soffset, size_t sbytes); 239f76889e7SVladimir Sementsov-Ogievskiy bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t qiov_offeset, size_t bytes); 240daf015efSMarkus Armbruster void qemu_iovec_destroy(QEMUIOVector *qiov); 241daf015efSMarkus Armbruster void qemu_iovec_reset(QEMUIOVector *qiov); 242daf015efSMarkus Armbruster size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, 243daf015efSMarkus Armbruster void *buf, size_t bytes); 244daf015efSMarkus Armbruster size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, 245daf015efSMarkus Armbruster const void *buf, size_t bytes); 246daf015efSMarkus Armbruster size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, 247daf015efSMarkus Armbruster int fillc, size_t bytes); 248daf015efSMarkus Armbruster ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b); 249daf015efSMarkus Armbruster void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf); 250daf015efSMarkus Armbruster void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes); 251daf015efSMarkus Armbruster 2521de7afc9SPaolo Bonzini #endif 253