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Diffstat (limited to 'contrib/qemu/util/iov.c')
| -rw-r--r-- | contrib/qemu/util/iov.c | 426 |
1 files changed, 426 insertions, 0 deletions
diff --git a/contrib/qemu/util/iov.c b/contrib/qemu/util/iov.c new file mode 100644 index 00000000000..cc6e837c836 --- /dev/null +++ b/contrib/qemu/util/iov.c @@ -0,0 +1,426 @@ +/* + * 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 */ + if (tail) { + iov[niov-1].iov_len = orig_len; + } + 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; + } + + /* 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; +} |