Introduce functions to copy to/from a buffer from/to an iovec array,
to compute data length in in bytes of an iovec and to copy memory from
an iovec to another.
iov_from_buf(), iov_to_buf(), iov_size(), iov_copy().
Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
---
Notes:
v3:
- update copyright statement
(but keep it as proposed by Stefano)
- open code of iov_fill_from_buf()/iov_fill_to_buf()
into iov_frombuf()/iov_to_buf()
- coding style cleanup
- use size_t for the length of the vectors
v2:
- reorder added files in alphanetical order in Makefile
- update comments, cosmetic cleanup
- rename iov_from_buf_full/iov_to_buf_full to
iov_fill_from_buf/iov_fill_to_buf
- split loops that manage offset and bytes copy.
- move iov_from_buf()/iov_to_buf() to iov.c
Makefile | 8 +--
iov.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
iov.h | 29 ++++++++++
3 files changed, 204 insertions(+), 4 deletions(-)
create mode 100644 iov.c
create mode 100644 iov.h
diff --git a/Makefile b/Makefile
index af4fa87e7e13..156398b3844e 100644
--- a/Makefile
+++ b/Makefile
@@ -45,16 +45,16 @@ FLAGS += -DVERSION=\"$(VERSION)\"
FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c icmp.c \
- igmp.c isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c \
- passt.c pasta.c pcap.c pif.c port_fwd.c tap.c tcp.c tcp_splice.c udp.c \
- util.c
+ igmp.c iov.c isolation.c lineread.c log.c mld.c ndp.c netlink.c \
+ packet.c passt.c pasta.c pcap.c pif.c port_fwd.c tap.c tcp.c \
+ tcp_splice.c udp.c util.c
QRAP_SRCS = qrap.c
SRCS = $(PASST_SRCS) $(QRAP_SRCS)
MANPAGES = passt.1 pasta.1 qrap.1
PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h flow.h \
- flow_table.h icmp.h inany.h isolation.h lineread.h log.h ndp.h \
+ flow_table.h icmp.h inany.h iov.h isolation.h lineread.h log.h ndp.h \
netlink.h packet.h passt.h pasta.h pcap.h pif.h port_fwd.h siphash.h \
tap.h tcp.h tcp_conn.h tcp_splice.h udp.h util.h
HEADERS = $(PASST_HEADERS) seccomp.h
diff --git a/iov.c b/iov.c
new file mode 100644
index 000000000000..1135f87e2f45
--- /dev/null
+++ b/iov.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iov.h - helpers for using (partial) iovecs.
+ *
+ * Copyright Red Hat
+ * Author: Laurent Vivier <lvivier(a)redhat.com>
+ *
+ * This file also contains code originally from QEMU include/qemu/iov.h
+ * and licensed under the following terms:
+ *
+ * Copyright (C) 2010 Red Hat, Inc.
+ *
+ * Author(s):
+ * Amit Shah <amit.shah(a)redhat.com>
+ * Michael Tokarev <mjt(a)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 <sys/socket.h>
+
+#include "util.h"
+#include "iov.h"
+
+/**
+ * iov_from_buf - Copy data from a buffer to an I/O vector (struct iovec)
+ * efficiently.
+ *
+ * @iov: Pointer to the array of struct iovec describing the
+ * scatter/gather I/O vector.
+ * @iov_cnt: Number of elements in the iov array.
+ * @offset: Byte offset in the iov array where copying should start.
+ * @buf: Pointer to the source buffer containing the data to copy.
+ * @bytes: Total number of bytes to copy from buf to iov.
+ *
+ * Returns: The number of bytes successfully copied.
+ */
+size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
+ size_t offset, const void *buf, size_t bytes)
+{
+ unsigned int i;
+ size_t copied;
+
+ if (__builtin_constant_p(bytes) && iov_cnt &&
+ offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+ memcpy((char *)iov[0].iov_base + offset, buf, bytes);
+ return bytes;
+ }
+
+ /* skipping offset bytes in the iovec */
+ for (i = 0; offset >= iov[i].iov_len && i < iov_cnt; i++)
+ offset -= iov[i].iov_len;
+
+ /* copying data */
+ for (copied = 0; copied < bytes && i < iov_cnt; i++) {
+ size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
+
+ memcpy((char *)iov[i].iov_base + offset, (char *)buf + copied,
+ len);
+ copied += len;
+ offset = 0;
+ }
+
+ return copied;
+}
+
+/**
+ * iov_to_buf - Copy data from a scatter/gather I/O vector (struct iovec) to
+ * a buffer efficiently.
+ *
+ * @iov: Pointer to the array of struct iovec describing the scatter/gather
+ * I/O vector.
+ * @iov_cnt: Number of elements in the iov array.
+ * @offset: Offset within the first element of iov from where copying should start.
+ * @buf: Pointer to the destination buffer where data will be copied.
+ * @bytes: Total number of bytes to copy from iov to buf.
+ *
+ * Returns: The number of bytes successfully copied.
+ */
+size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
+ size_t offset, void *buf, size_t bytes)
+{
+ unsigned int i;
+ size_t copied;
+
+ if (__builtin_constant_p(bytes) && iov_cnt &&
+ offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
+ memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
+ return bytes;
+ }
+
+ /* skipping offset bytes in the iovec */
+ for (i = 0; offset >= iov[i].iov_len && i < iov_cnt; i++)
+ offset -= iov[i].iov_len;
+
+ /* copying data */
+ for (copied = 0; copied < bytes && i < iov_cnt; i++) {
+ size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
+ memcpy((char *)buf + copied, (char *)iov[i].iov_base + offset,
+ len);
+ copied += len;
+ offset = 0;
+ }
+
+ return copied;
+}
+
+/**
+ * iov_size - Calculate the total size of a scatter/gather I/O vector
+ * (struct iovec).
+ *
+ * @iov: Pointer to the array of struct iovec describing the
+ * scatter/gather I/O vector.
+ * @iov_cnt: Number of elements in the iov array.
+ *
+ * Returns: The total size in bytes.
+ */
+size_t iov_size(const struct iovec *iov, size_t iov_cnt)
+{
+ unsigned int i;
+ size_t len;
+
+ for (i = 0, len = 0; i < iov_cnt; i++)
+ len += iov[i].iov_len;
+
+ return len;
+}
+
+/**
+ * iov_copy - Copy data from one scatter/gather I/O vector (struct iovec) to
+ * another.
+ *
+ * @dst_iov: Pointer to the destination array of struct iovec describing
+ * the scatter/gather I/O vector to copy to.
+ * @dst_iov_cnt: Number of elements in the destination iov array.
+ * @iov: Pointer to the source array of struct iovec describing
+ * the scatter/gather I/O vector to copy from.
+ * @iov_cnt: Number of elements in the source iov array.
+ * @offset: Offset within the source iov from where copying should start.
+ * @bytes: Total number of bytes to copy from iov to dst_iov.
+ *
+ * Returns: The number of elements successfully copied to the destination
+ * iov array.
+ */
+unsigned iov_copy(struct iovec *dst_iov, size_t dst_iov_cnt,
+ const struct iovec *iov, size_t iov_cnt,
+ size_t offset, size_t bytes)
+{
+ unsigned int i, j;
+ size_t len;
+
+ /* skipping offset bytes in the iovec */
+ for (i = 0; offset >= iov[i].iov_len && i < iov_cnt; i++)
+ offset -= iov[i].iov_len;
+
+ /* copying data */
+ for (j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) {
+ len = MIN(bytes, iov[i].iov_len - offset);
+
+ dst_iov[j].iov_base = (char *)iov[i].iov_base + offset;
+ dst_iov[j].iov_len = len;
+ j++;
+ bytes -= len;
+ offset = 0;
+ }
+
+ return j;
+}
diff --git a/iov.h b/iov.h
new file mode 100644
index 000000000000..ee35a75d0870
--- /dev/null
+++ b/iov.h
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iov.c - helpers for using (partial) iovecs.
+ *
+ * Copyrigh Red Hat
+ * Author: Laurent Vivier <lvivier(a)redhat.com>
+ *
+ * This file also contains code originally from QEMU include/qemu/iov.h:
+ *
+ * Author(s):
+ * Amit Shah <amit.shah(a)redhat.com>
+ * Michael Tokarev <mjt(a)tls.msk.ru>
+ */
+
+#ifndef IOVEC_H
+#define IOVEC_H
+
+#include <unistd.h>
+#include <string.h>
+
+size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
+ size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
+ size_t offset, void *buf, size_t bytes);
+size_t iov_size(const struct iovec *iov, size_t iov_cnt);
+unsigned iov_copy(struct iovec *dst_iov, size_t dst_iov_cnt,
+ const struct iovec *iov, size_t iov_cnt,
+ size_t offset, size_t bytes);
+#endif /* IOVEC_H */
--
2.42.0