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-rw-r--r--util/iov.c764
1 files changed, 764 insertions, 0 deletions
diff --git a/util/iov.c b/util/iov.c
new file mode 100644
index 000000000..58c7b3eee
--- /dev/null
+++ b/util/iov.c
@@ -0,0 +1,764 @@
+/*
+ * 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-common.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, &current_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;
+}