On Sat, Feb 17, 2024 at 04:07:17PM +0100, Laurent Vivier wrote: > 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 Reviewed-by: David Gibson > --- > > 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 > + * > + * 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 > + * Michael Tokarev > + * > + * 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 > + > +#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 > + * > + * This file also contains code originally from QEMU include/qemu/iov.h: > + * > + * Author(s): > + * Amit Shah > + * Michael Tokarev > + */ > + > +#ifndef IOVEC_H > +#define IOVEC_H > + > +#include > +#include > + > +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 */ -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson