On Fri, Feb 02, 2024 at 03:11:28PM +0100, Laurent Vivier wrote: > Signed-off-by: Laurent Vivier > --- > Makefile | 4 +-- > iov.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > iov.h | 46 +++++++++++++++++++++++++++++++++ > 3 files changed, 126 insertions(+), 2 deletions(-) > create mode 100644 iov.c > create mode 100644 iov.h > > diff --git a/Makefile b/Makefile > index af4fa87e7e13..c1138fb91d26 100644 > --- a/Makefile > +++ b/Makefile > @@ -47,7 +47,7 @@ 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 > + util.c iov.c I think we've been maintaining these in alphabetical order so far. > QRAP_SRCS = qrap.c > SRCS = $(PASST_SRCS) $(QRAP_SRCS) > > @@ -56,7 +56,7 @@ 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 \ > 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 > + tap.h tcp.h tcp_conn.h tcp_splice.h udp.h util.h iov.h > HEADERS = $(PASST_HEADERS) seccomp.h > > C := \#include \nstruct tcp_info x = { .tcpi_snd_wnd = 0 }; > diff --git a/iov.c b/iov.c > new file mode 100644 > index 000000000000..38a8e7566021 > --- /dev/null > +++ b/iov.c > @@ -0,0 +1,78 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later I believe we need an actual copyright / authorship notice as well as the SPDX comment. > + > +/* some parts copied from QEMU util/iov.c */ > + > +#include > +#include "util.h" > +#include "iov.h" > + Function comments would be really helpful here. It took me a while to figure out what this does from just the name and implementation. > +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; passt style is to order local declarations from longest to shortest. > + for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) { Not immediately seeing why you need the 'offset ||' part of the condition. > + if (offset < iov[i].iov_len) { > + size_t len = MIN(iov[i].iov_len - offset, bytes - done); > + memcpy((char *)iov[i].iov_base + offset, (char *)buf + done, len); > + done += len; > + offset = 0; > + } else { > + offset -= iov[i].iov_len; > + } > + } > + return done; > +} > + > +size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, const modifier on an int isn't very useful. > + 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((char *)buf + done, (char *)iov[i].iov_base + offset, len); > + done += len; > + offset = 0; > + } else { > + offset -= iov[i].iov_len; > + } > + } > + return done; > +} > + > +size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt) > +{ > + size_t len; > + unsigned int i; > + > + len = 0; Can be an initialiser. > + for (i = 0; i < iov_cnt; i++) { > + len += iov[i].iov_len; > + } > + return len; > +} > + > +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 = (char *)iov[i].iov_base + offset; > + dst_iov[j].iov_len = len; > + j++; > + bytes -= len; > + offset = 0; > + } > + return j; > +} Small concern about the interface to iov_copy(). If dst_iov_cnt < iov_cnt and the chunk of the input iovec you want doesn't fit in the destination it will silently truncate - you can't tell if this has happened from the return value. If the assumption is that dst_iov_cnt >= iov_cnt, then there's not really any need to pass it. > diff --git a/iov.h b/iov.h > new file mode 100644 > index 000000000000..31fbf6d0e1cf > --- /dev/null > +++ b/iov.h > @@ -0,0 +1,46 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > + > +/* some parts copied from QEMU include/qemu/iov.h */ > + > +#ifndef IOVEC_H > +#define IOVEC_H > + > +#include > +#include > + > +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 iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt, > + size_t offset, void *buf, size_t bytes); > + > +static inline 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; Do you have an idea of how much difference this optimized path makes? > + } else { > + return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes); > + } > +} > + > +static inline size_t iov_to_buf(const struct iovec *iov, > + const 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; > + } else { > + return iov_to_buf_full(iov, iov_cnt, offset, buf, 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 Normal to put a /* IOVEC_H */ comment on the final #endif. -- 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