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From: Laurent Vivier <lvivier@redhat.com>
To: passt-dev@passt.top
Cc: Laurent Vivier <lvivier@redhat.com>
Subject: [PATCH v2 1/8] iov: add some functions to manage iovec
Date: Wed, 14 Feb 2024 09:56:21 +0100	[thread overview]
Message-ID: <20240214085628.210783-2-lvivier@redhat.com> (raw)
In-Reply-To: <20240214085628.210783-1-lvivier@redhat.com>

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@redhat.com>
---

Notes:
    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    | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 iov.h    |  43 +++++++++++
 3 files changed, 259 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..73dd5cf25d0d
--- /dev/null
+++ b/iov.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iov.h - helpers for using (partial) iovecs.
+ *
+ * Copyrigh (c) 2024 Red Hat
+ * Author: Laurent Vivier <lvivier@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@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 <sys/socket.h>
+
+#include "util.h"
+#include "iov.h"
+
+/**
+ * iov_from_buf - Copy data from a buffer to a scatter/gather
+ *                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, unsigned int iov_cnt,
+		    size_t offset, const void *buf, size_t bytes)
+{
+	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;
+	}
+
+	return iov_fill_from_buf(iov, iov_cnt, offset, buf, bytes);
+}
+
+/**
+ * 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, unsigned int iov_cnt,
+		  size_t offset, void *buf, size_t bytes)
+{
+	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;
+	}
+
+	return iov_fill_to_buf(iov, iov_cnt, offset, buf, bytes);
+}
+
+/**
+ * iov_fill_from_buf - Copy data from a buffer to a scatter/gather
+ *                     I/O vector (struct iovec) until either all bytes
+ *                     are copied or all elements in the vector are filled.
+ *
+ * @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 total number of bytes successfully copied
+ *
+ */
+size_t iov_fill_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes)
+{
+	unsigned int i;
+	size_t copied;
+
+	/* 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_fill_to_buf - Copy data from a scatter/gather I/O vector (struct iovec)
+ *                   to a buffer until either all bytes are copied or all
+ *                   elements in the vector are read.
+ *
+ * @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 destination buffer where data will be copied.
+ * @bytes:     Total number of bytes to copy from iov to buf.
+ *
+ * Returns:    The total number of bytes successfully copied
+ */
+size_t iov_fill_to_buf(const struct iovec *iov, unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes)
+{
+	unsigned int i;
+	size_t copied;
+
+	/* 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, const unsigned int iov_cnt)
+{
+	size_t len;
+	unsigned int i;
+
+	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, unsigned int dst_iov_cnt,
+		  const struct iovec *iov, unsigned int 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..0153acca9e62
--- /dev/null
+++ b/iov.h
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iov.c - helpers for using (partial) iovecs.
+ *
+ * Copyrigh (c) 2024 Red Hat
+ * Author: Laurent Vivier <lvivier@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@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.
+ */
+
+#ifndef IOVEC_H
+#define IOVEC_H
+
+#include <unistd.h>
+#include <string.h>
+
+size_t iov_fill_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes);
+size_t iov_fill_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes);
+size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+                    size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf(const struct iovec *iov, unsigned int iov_cnt,
+                  size_t offset, void *buf, size_t bytes);
+
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
+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);
+#endif /* IOVEC_H */
-- 
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iov.c - helpers for using (partial) iovecs.
+ *
+ * Copyrigh (c) 2024 Red Hat
+ * Author: Laurent Vivier <lvivier@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@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.
+ */
+
+#ifndef IOVEC_H
+#define IOVEC_H
+
+#include <unistd.h>
+#include <string.h>
+
+size_t iov_fill_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+			 size_t offset, const void *buf, size_t bytes);
+size_t iov_fill_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
+		       size_t offset, void *buf, size_t bytes);
+size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+                    size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf(const struct iovec *iov, unsigned int iov_cnt,
+                  size_t offset, void *buf, size_t bytes);
+
+size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
+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);
+#endif /* IOVEC_H */
-- 
2.42.0


  reply	other threads:[~2024-02-14  8:56 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-14  8:56 [PATCH v2 0/8] Add vhost-user support to passt (part 1) Laurent Vivier
2024-02-14  8:56 ` Laurent Vivier [this message]
2024-02-15  0:24   ` [PATCH v2 1/8] iov: add some functions to manage iovec David Gibson
2024-02-15  0:32     ` David Gibson
2024-02-16  5:29     ` Stefano Brivio
2024-02-14  8:56 ` [PATCH v2 2/8] pcap: add pcap_iov() Laurent Vivier
2024-02-15  0:35   ` David Gibson
2024-02-16  5:30   ` Stefano Brivio
2024-02-14  8:56 ` [PATCH v2 3/8] checksum: align buffers Laurent Vivier
2024-02-15  0:40   ` David Gibson
2024-02-14  8:56 ` [PATCH v2 4/8] checksum: add csum_iov() Laurent Vivier
2024-02-15  0:44   ` David Gibson
2024-02-14  8:56 ` [PATCH v2 5/8] util: move IP stuff from util.[ch] to ip.[ch] Laurent Vivier
2024-02-15  2:29   ` David Gibson
2024-02-14  8:56 ` [PATCH v2 6/8] checksum: use csum_ip4_header() in udp.c and tcp.c Laurent Vivier
2024-02-15  2:51   ` David Gibson
2024-02-16  9:08   ` Stefano Brivio
2024-02-16 14:17     ` Laurent Vivier
2024-02-16 14:54       ` Stefano Brivio
2024-02-16 18:05         ` Laurent Vivier
2024-02-16 18:24           ` Stefano Brivio
2024-02-17 14:22             ` Laurent Vivier
2024-02-17 14:37               ` Stefano Brivio
2024-02-19  2:06               ` David Gibson
2024-02-14  8:56 ` [PATCH v2 7/8] checksum: introduce functions to compute the header part checksum for TCP/UDP Laurent Vivier
2024-02-15  3:12   ` David Gibson
2024-02-14  8:56 ` [PATCH v2 8/8] tap: make tap_update_mac() generic Laurent Vivier
2024-02-15  3:13   ` David Gibson

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