/* * Helpers for getting linearized buffers from iov / filling buffers into iovs * * Copyright IBM, Corp. 2007, 2008 * Copyright (C) 2010 Red Hat, Inc. * * Author(s): * Anthony Liguori <aliguori@us.ibm.com> * 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. * * Contributions after 2012-01-13 are licensed under the terms of the * GNU GPL, version 2 or (at your option) any later version. */ #include "qemu/osdep.h" #include "qemu/iov.h" #include "qemu/sockets.h" #include "qemu/cutils.h" size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt, size_t offset, const void *buf, size_t bytes) { size_t done; unsigned int i; for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { if (offset < iov[i].iov_len) { size_t len = MIN(iov[i].iov_len - offset, bytes - done); memcpy(iov[i].iov_base + offset, buf + done, len); done += len; offset = 0; } else { offset -= iov[i].iov_len; } } assert(offset == 0); return done; } size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, size_t offset, void *buf, size_t bytes) { size_t done; unsigned int i; for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { if (offset < iov[i].iov_len) { size_t len = MIN(iov[i].iov_len - offset, bytes - done); memcpy(buf + done, iov[i].iov_base + offset, len); done += len; offset = 0; } else { offset -= iov[i].iov_len; } } assert(offset == 0); return done; } size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt, size_t offset, int fillc, size_t bytes) { size_t done; unsigned int i; for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { if (offset < iov[i].iov_len) { size_t len = MIN(iov[i].iov_len - offset, bytes - done); memset(iov[i].iov_base + offset, fillc, len); done += len; offset = 0; } else { offset -= iov[i].iov_len; } } assert(offset == 0); return done; } size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) { size_t len; unsigned int i; len = 0; for (i = 0; i < iov_cnt; i++) { len += iov[i].iov_len; } return len; } /* helper function for iov_send_recv() */ static ssize_t do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) { #ifdef CONFIG_POSIX ssize_t ret; struct msghdr msg; memset(&msg, 0, sizeof(msg)); msg.msg_iov = iov; msg.msg_iovlen = iov_cnt; do { ret = do_send ? sendmsg(sockfd, &msg, 0) : recvmsg(sockfd, &msg, 0); } while (ret < 0 && errno == EINTR); return ret; #else /* else send piece-by-piece */ /*XXX Note: windows has WSASend() and WSARecv() */ unsigned i = 0; ssize_t ret = 0; while (i < iov_cnt) { ssize_t r = do_send ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0) : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0); if (r > 0) { ret += r; } else if (!r) { break; } else if (errno == EINTR) { continue; } else { /* else it is some "other" error, * only return if there was no data processed. */ if (ret == 0) { ret = -1; } break; } i++; } return ret; #endif } ssize_t iov_send_recv(int sockfd, const struct iovec *_iov, unsigned iov_cnt, size_t offset, size_t bytes, bool do_send) { ssize_t total = 0; ssize_t ret; size_t orig_len, tail; unsigned niov; struct iovec *local_iov, *iov; if (bytes <= 0) { return 0; } local_iov = g_new0(struct iovec, iov_cnt); iov_copy(local_iov, iov_cnt, _iov, iov_cnt, offset, bytes); offset = 0; iov = local_iov; while (bytes > 0) { /* Find the start position, skipping `offset' bytes: * first, skip all full-sized vector elements, */ for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) { offset -= iov[niov].iov_len; } /* niov == iov_cnt would only be valid if bytes == 0, which * we already ruled out in the loop condition. */ assert(niov < iov_cnt); iov += niov; iov_cnt -= niov; if (offset) { /* second, skip `offset' bytes from the (now) first element, * undo it on exit */ iov[0].iov_base += offset; iov[0].iov_len -= offset; } /* Find the end position skipping `bytes' bytes: */ /* first, skip all full-sized elements */ tail = bytes; for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) { tail -= iov[niov].iov_len; } if (tail) { /* second, fixup the last element, and remember the original * length */ assert(niov < iov_cnt); assert(iov[niov].iov_len > tail); orig_len = iov[niov].iov_len; iov[niov++].iov_len = tail; ret = do_send_recv(sockfd, iov, niov, do_send); /* Undo the changes above before checking for errors */ iov[niov-1].iov_len = orig_len; } else { ret = do_send_recv(sockfd, iov, niov, do_send); } if (offset) { iov[0].iov_base -= offset; iov[0].iov_len += offset; } if (ret < 0) { assert(errno != EINTR); g_free(local_iov); if (errno == EAGAIN && total > 0) { return total; } return -1; } if (ret == 0 && !do_send) { /* recv returns 0 when the peer has performed an orderly * shutdown. */ break; } /* Prepare for the next iteration */ offset += ret; total += ret; bytes -= ret; } g_free(local_iov); return total; } void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, FILE *fp, const char *prefix, size_t limit) { int v; size_t size = 0; char *buf; for (v = 0; v < iov_cnt; v++) { size += iov[v].iov_len; } size = size > limit ? limit : size; buf = g_malloc(size); iov_to_buf(iov, iov_cnt, 0, buf, size); qemu_hexdump(fp, prefix, buf, size); g_free(buf); } 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) { size_t len; unsigned int i, j; for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && (offset || bytes); i++) { if (offset >= iov[i].iov_len) { offset -= iov[i].iov_len; continue; } len = MIN(bytes, iov[i].iov_len - offset); dst_iov[j].iov_base = iov[i].iov_base + offset; dst_iov[j].iov_len = len; j++; bytes -= len; offset = 0; } assert(offset == 0); return j; } /* io vectors */ void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint) { qiov->iov = g_new(struct iovec, alloc_hint); qiov->niov = 0; qiov->nalloc = alloc_hint; qiov->size = 0; } void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov) { int i; qiov->iov = iov; qiov->niov = niov; qiov->nalloc = -1; qiov->size = 0; for (i = 0; i < niov; i++) qiov->size += iov[i].iov_len; } void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) { assert(qiov->nalloc != -1); if (qiov->niov == qiov->nalloc) { qiov->nalloc = 2 * qiov->nalloc + 1; qiov->iov = g_renew(struct iovec, qiov->iov, qiov->nalloc); } qiov->iov[qiov->niov].iov_base = base; qiov->iov[qiov->niov].iov_len = len; qiov->size += len; ++qiov->niov; } /* * Concatenates (partial) iovecs from src_iov to the end of dst. * It starts copying after skipping `soffset' bytes at the * beginning of src and adds individual vectors from src to * dst copies up to `sbytes' bytes total, or up to the end * of src_iov if it comes first. This way, it is okay to specify * very large value for `sbytes' to indicate "up to the end * of src". * Only vector pointers are processed, not the actual data buffers. */ size_t qemu_iovec_concat_iov(QEMUIOVector *dst, struct iovec *src_iov, unsigned int src_cnt, size_t soffset, size_t sbytes) { int i; size_t done; if (!sbytes) { return 0; } assert(dst->nalloc != -1); for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { if (soffset < src_iov[i].iov_len) { size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); done += len; soffset = 0; } else { soffset -= src_iov[i].iov_len; } } assert(soffset == 0); /* offset beyond end of src */ return done; } /* * Concatenates (partial) iovecs from src to the end of dst. * It starts copying after skipping `soffset' bytes at the * beginning of src and adds individual vectors from src to * dst copies up to `sbytes' bytes total, or up to the end * of src if it comes first. This way, it is okay to specify * very large value for `sbytes' to indicate "up to the end * of src". * Only vector pointers are processed, not the actual data buffers. */ void qemu_iovec_concat(QEMUIOVector *dst, QEMUIOVector *src, size_t soffset, size_t sbytes) { qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); } /* * qiov_find_iov * * Return pointer to iovec structure, where byte at @offset in original vector * @iov exactly is. * Set @remaining_offset to be offset inside that iovec to the same byte. */ static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset, size_t *remaining_offset) { while (offset > 0 && offset >= iov->iov_len) { offset -= iov->iov_len; iov++; } *remaining_offset = offset; return iov; } /* * qiov_slice * * Find subarray of iovec's, containing requested range. @head would * be offset in first iov (returned by the function), @tail would be * count of extra bytes in last iovec (returned iov + @niov - 1). */ static struct iovec *qiov_slice(QEMUIOVector *qiov, size_t offset, size_t len, size_t *head, size_t *tail, int *niov) { struct iovec *iov, *end_iov; assert(offset + len <= qiov->size); iov = iov_skip_offset(qiov->iov, offset, head); end_iov = iov_skip_offset(iov, *head + len, tail); if (*tail > 0) { assert(*tail < end_iov->iov_len); *tail = end_iov->iov_len - *tail; end_iov++; } *niov = end_iov - iov; return iov; } int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len) { size_t head, tail; int niov; qiov_slice(qiov, offset, len, &head, &tail, &niov); return niov; } /* * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov, * and @tail_buf buffer into new qiov. */ int qemu_iovec_init_extended( QEMUIOVector *qiov, void *head_buf, size_t head_len, QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len, void *tail_buf, size_t tail_len) { size_t mid_head, mid_tail; int total_niov, mid_niov = 0; struct iovec *p, *mid_iov = NULL; assert(mid_qiov->niov <= IOV_MAX); if (SIZE_MAX - head_len < mid_len || SIZE_MAX - head_len - mid_len < tail_len) { return -EINVAL; } if (mid_len) { mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len, &mid_head, &mid_tail, &mid_niov); } total_niov = !!head_len + mid_niov + !!tail_len; if (total_niov > IOV_MAX) { return -EINVAL; } if (total_niov == 1) { qemu_iovec_init_buf(qiov, NULL, 0); p = &qiov->local_iov; } else { qiov->niov = qiov->nalloc = total_niov; qiov->size = head_len + mid_len + tail_len; p = qiov->iov = g_new(struct iovec, qiov->niov); } if (head_len) { p->iov_base = head_buf; p->iov_len = head_len; p++; } assert(!mid_niov == !mid_len); if (mid_niov) { memcpy(p, mid_iov, mid_niov * sizeof(*p)); p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head; p[0].iov_len -= mid_head; p[mid_niov - 1].iov_len -= mid_tail; p += mid_niov; } if (tail_len) { p->iov_base = tail_buf; p->iov_len = tail_len; } return 0; } /* * Check if the contents of subrange of qiov data is all zeroes. */ bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes) { struct iovec *iov; size_t current_offset; assert(offset + bytes <= qiov->size); iov = iov_skip_offset(qiov->iov, offset, ¤t_offset); while (bytes) { uint8_t *base = (uint8_t *)iov->iov_base + current_offset; size_t len = MIN(iov->iov_len - current_offset, bytes); if (!buffer_is_zero(base, len)) { return false; } current_offset = 0; bytes -= len; iov++; } return true; } void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source, size_t offset, size_t len) { int ret; assert(source->size >= len); assert(source->size - len >= offset); /* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */ ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0); assert(ret == 0); } void qemu_iovec_destroy(QEMUIOVector *qiov) { if (qiov->nalloc != -1) { g_free(qiov->iov); } memset(qiov, 0, sizeof(*qiov)); } void qemu_iovec_reset(QEMUIOVector *qiov) { assert(qiov->nalloc != -1); qiov->niov = 0; qiov->size = 0; } size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, void *buf, size_t bytes) { return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes); } size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset, const void *buf, size_t bytes) { return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes); } size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset, int fillc, size_t bytes) { return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes); } /** * Check that I/O vector contents are identical * * The IO vectors must have the same structure (same length of all parts). * A typical usage is to compare vectors created with qemu_iovec_clone(). * * @a: I/O vector * @b: I/O vector * @ret: Offset to first mismatching byte or -1 if match */ ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b) { int i; ssize_t offset = 0; assert(a->niov == b->niov); for (i = 0; i < a->niov; i++) { size_t len = 0; uint8_t *p = (uint8_t *)a->iov[i].iov_base; uint8_t *q = (uint8_t *)b->iov[i].iov_base; assert(a->iov[i].iov_len == b->iov[i].iov_len); while (len < a->iov[i].iov_len && *p++ == *q++) { len++; } offset += len; if (len != a->iov[i].iov_len) { return offset; } } return -1; } typedef struct { int src_index; struct iovec *src_iov; void *dest_base; } IOVectorSortElem; static int sortelem_cmp_src_base(const void *a, const void *b) { const IOVectorSortElem *elem_a = a; const IOVectorSortElem *elem_b = b; /* Don't overflow */ if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) { return -1; } else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) { return 1; } else { return 0; } } static int sortelem_cmp_src_index(const void *a, const void *b) { const IOVectorSortElem *elem_a = a; const IOVectorSortElem *elem_b = b; return elem_a->src_index - elem_b->src_index; } /** * Copy contents of I/O vector * * The relative relationships of overlapping iovecs are preserved. This is * necessary to ensure identical semantics in the cloned I/O vector. */ void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf) { IOVectorSortElem sortelems[src->niov]; void *last_end; int i; /* Sort by source iovecs by base address */ for (i = 0; i < src->niov; i++) { sortelems[i].src_index = i; sortelems[i].src_iov = &src->iov[i]; } qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base); /* Allocate buffer space taking into account overlapping iovecs */ last_end = NULL; for (i = 0; i < src->niov; i++) { struct iovec *cur = sortelems[i].src_iov; ptrdiff_t rewind = 0; /* Detect overlap */ if (last_end && last_end > cur->iov_base) { rewind = last_end - cur->iov_base; } sortelems[i].dest_base = buf - rewind; buf += cur->iov_len - MIN(rewind, cur->iov_len); last_end = MAX(cur->iov_base + cur->iov_len, last_end); } /* Sort by source iovec index and build destination iovec */ qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index); for (i = 0; i < src->niov; i++) { qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len); } } void iov_discard_undo(IOVDiscardUndo *undo) { /* Restore original iovec if it was modified */ if (undo->modified_iov) { *undo->modified_iov = undo->orig; } } size_t iov_discard_front_undoable(struct iovec **iov, unsigned int *iov_cnt, size_t bytes, IOVDiscardUndo *undo) { size_t total = 0; struct iovec *cur; if (undo) { undo->modified_iov = NULL; } for (cur = *iov; *iov_cnt > 0; cur++) { if (cur->iov_len > bytes) { if (undo) { undo->modified_iov = cur; undo->orig = *cur; } cur->iov_base += bytes; cur->iov_len -= bytes; total += bytes; break; } bytes -= cur->iov_len; total += cur->iov_len; *iov_cnt -= 1; } *iov = cur; return total; } size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, size_t bytes) { return iov_discard_front_undoable(iov, iov_cnt, bytes, NULL); } size_t iov_discard_back_undoable(struct iovec *iov, unsigned int *iov_cnt, size_t bytes, IOVDiscardUndo *undo) { size_t total = 0; struct iovec *cur; if (undo) { undo->modified_iov = NULL; } if (*iov_cnt == 0) { return 0; } cur = iov + (*iov_cnt - 1); while (*iov_cnt > 0) { if (cur->iov_len > bytes) { if (undo) { undo->modified_iov = cur; undo->orig = *cur; } cur->iov_len -= bytes; total += bytes; break; } bytes -= cur->iov_len; total += cur->iov_len; cur--; *iov_cnt -= 1; } return total; } size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt, size_t bytes) { return iov_discard_back_undoable(iov, iov_cnt, bytes, NULL); } void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes) { size_t total; unsigned int niov = qiov->niov; assert(qiov->size >= bytes); total = iov_discard_back(qiov->iov, &niov, bytes); assert(total == bytes); qiov->niov = niov; qiov->size -= bytes; }