/* * 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/iov.h" #ifdef _WIN32 # include <windows.h> # include <winsock2.h> #else # include <sys/types.h> # include <sys/socket.h> #endif size_t iov_from_buf(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(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, 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; 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); 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; } 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(buf, fp, prefix, 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 && 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_malloc(alloc_hint * sizeof(struct iovec)); 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_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec)); } 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. */ void 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; } 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 */ } /* * 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); } void qemu_iovec_destroy(QEMUIOVector *qiov) { assert(qiov->nalloc != -1); qemu_iovec_reset(qiov); g_free(qiov->iov); qiov->nalloc = 0; qiov->iov = NULL; } 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); } size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt, size_t bytes) { size_t total = 0; struct iovec *cur; for (cur = *iov; *iov_cnt > 0; cur++) { if (cur->iov_len > bytes) { 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_back(struct iovec *iov, unsigned int *iov_cnt, size_t bytes) { size_t total = 0; struct iovec *cur; if (*iov_cnt == 0) { return 0; } cur = iov + (*iov_cnt - 1); while (*iov_cnt > 0) { if (cur->iov_len > bytes) { cur->iov_len -= bytes; total += bytes; break; } bytes -= cur->iov_len; total += cur->iov_len; cur--; *iov_cnt -= 1; } return total; }