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-rw-r--r--util/iov.c422
1 files changed, 422 insertions, 0 deletions
diff --git a/util/iov.c b/util/iov.c
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+++ b/util/iov.c
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+/*
+ * 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)
+{
+#if defined CONFIG_IOVEC && defined 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 ret;
+ unsigned si, ei; /* start and end indexes */
+ if (bytes == 0) {
+ /* Catch the do-nothing case early, as otherwise we will pass an
+ * empty iovec to sendmsg/recvmsg(), and not all implementations
+ * accept this.
+ */
+ return 0;
+ }
+
+ /* Find the start position, skipping `offset' bytes:
+ * first, skip all full-sized vector elements, */
+ for (si = 0; si < iov_cnt && offset >= iov[si].iov_len; ++si) {
+ offset -= iov[si].iov_len;
+ }
+ if (offset) {
+ assert(si < iov_cnt);
+ /* second, skip `offset' bytes from the (now) first element,
+ * undo it on exit */
+ iov[si].iov_base += offset;
+ iov[si].iov_len -= offset;
+ }
+ /* Find the end position skipping `bytes' bytes: */
+ /* first, skip all full-sized elements */
+ for (ei = si; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) {
+ bytes -= iov[ei].iov_len;
+ }
+ if (bytes) {
+ /* second, fixup the last element, and remember
+ * the length we've cut from the end of it in `bytes' */
+ size_t tail;
+ assert(ei < iov_cnt);
+ assert(iov[ei].iov_len > bytes);
+ tail = iov[ei].iov_len - bytes;
+ iov[ei].iov_len = bytes;
+ bytes = tail; /* bytes is now equal to the tail size */
+ ++ei;
+ }
+
+ ret = do_send_recv(sockfd, iov + si, ei - si, do_send);
+
+ /* Undo the changes above */
+ if (offset) {
+ iov[si].iov_base -= offset;
+ iov[si].iov_len += offset;
+ }
+ if (bytes) {
+ iov[ei-1].iov_len += bytes;
+ }
+
+ return ret;
+}
+
+
+void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
+ FILE *fp, const char *prefix, size_t limit)
+{
+ unsigned int i, v, b;
+ uint8_t *c;
+
+ c = iov[0].iov_base;
+ for (i = 0, v = 0, b = 0; b < limit; i++, b++) {
+ if (i == iov[v].iov_len) {
+ i = 0; v++;
+ if (v == iov_cnt) {
+ break;
+ }
+ c = iov[v].iov_base;
+ }
+ if ((b % 16) == 0) {
+ fprintf(fp, "%s: %04x:", prefix, b);
+ }
+ if ((b % 4) == 0) {
+ fprintf(fp, " ");
+ }
+ fprintf(fp, " %02x", c[i]);
+ if ((b % 16) == 15) {
+ fprintf(fp, "\n");
+ }
+ }
+ if ((b % 16) != 0) {
+ fprintf(fp, "\n");
+ }
+}
+
+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;
+ 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;
+}
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