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https://github.com/tmux/tmux.git
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Switch tmux to use imsg. This is the last major change to make the
client-server protocol more resilient and make the protocol versioning work properly. In future, the only things requiring a protocol version bump will be changes in the message structs, and (when both client and server have this change) mixing different versions should nicely report an error message. As a side effect this also makes the code tidier, fixes a problem with the way errors reported during server startup were handled, and supports fd passing (which will be used in future). Looked over by eric@, thanks. Please note that mixing a client with this change with an older server or vice versa may cause tmux to crash or hang - tmux should be completely exited before upgrading.
This commit is contained in:
Nicholas Marriott
305
imsg-buffer.c
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305
imsg-buffer.c
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@@ -0,0 +1,305 @@
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/* $OpenBSD$ */
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/*
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* Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/param.h>
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#include <sys/queue.h>
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#include <sys/socket.h>
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#include <sys/uio.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "imsg.h"
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int buf_realloc(struct buf *, size_t);
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void buf_enqueue(struct msgbuf *, struct buf *);
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void buf_dequeue(struct msgbuf *, struct buf *);
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struct buf *
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buf_open(size_t len)
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{
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struct buf *buf;
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if ((buf = calloc(1, sizeof(struct buf))) == NULL)
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return (NULL);
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if ((buf->buf = malloc(len)) == NULL) {
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free(buf);
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return (NULL);
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}
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buf->size = buf->max = len;
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buf->fd = -1;
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return (buf);
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}
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struct buf *
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buf_dynamic(size_t len, size_t max)
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{
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struct buf *buf;
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if (max < len)
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return (NULL);
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if ((buf = buf_open(len)) == NULL)
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return (NULL);
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if (max > 0)
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buf->max = max;
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return (buf);
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}
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int
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buf_realloc(struct buf *buf, size_t len)
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{
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u_char *b;
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/* on static buffers max is eq size and so the following fails */
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if (buf->wpos + len > buf->max) {
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errno = ENOMEM;
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return (-1);
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}
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b = realloc(buf->buf, buf->wpos + len);
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if (b == NULL)
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return (-1);
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buf->buf = b;
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buf->size = buf->wpos + len;
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return (0);
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}
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int
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buf_add(struct buf *buf, const void *data, size_t len)
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{
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if (buf->wpos + len > buf->size)
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if (buf_realloc(buf, len) == -1)
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return (-1);
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memcpy(buf->buf + buf->wpos, data, len);
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buf->wpos += len;
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return (0);
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}
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void *
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buf_reserve(struct buf *buf, size_t len)
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{
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void *b;
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if (buf->wpos + len > buf->size)
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if (buf_realloc(buf, len) == -1)
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return (NULL);
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b = buf->buf + buf->wpos;
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buf->wpos += len;
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return (b);
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}
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void *
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buf_seek(struct buf *buf, size_t pos, size_t len)
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{
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/* only allowed to seek in already written parts */
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if (pos + len > buf->wpos)
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return (NULL);
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return (buf->buf + pos);
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}
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size_t
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buf_size(struct buf *buf)
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{
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return (buf->wpos);
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}
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size_t
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buf_left(struct buf *buf)
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{
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return (buf->max - buf->wpos);
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}
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void
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buf_close(struct msgbuf *msgbuf, struct buf *buf)
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{
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buf_enqueue(msgbuf, buf);
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}
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int
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buf_write(struct msgbuf *msgbuf)
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{
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struct iovec iov[IOV_MAX];
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struct buf *buf, *next;
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unsigned int i = 0;
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ssize_t n;
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bzero(&iov, sizeof(iov));
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TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
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if (i >= IOV_MAX)
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break;
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iov[i].iov_base = buf->buf + buf->rpos;
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iov[i].iov_len = buf->wpos - buf->rpos;
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i++;
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}
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if ((n = writev(msgbuf->fd, iov, i)) == -1) {
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if (errno == EAGAIN || errno == ENOBUFS ||
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errno == EINTR) /* try later */
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return (0);
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else
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return (-1);
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}
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if (n == 0) { /* connection closed */
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errno = 0;
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return (-2);
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}
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for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
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buf = next) {
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next = TAILQ_NEXT(buf, entry);
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if (buf->rpos + n >= buf->wpos) {
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n -= buf->wpos - buf->rpos;
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buf_dequeue(msgbuf, buf);
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} else {
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buf->rpos += n;
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n = 0;
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}
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}
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return (0);
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}
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void
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buf_free(struct buf *buf)
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{
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free(buf->buf);
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free(buf);
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}
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void
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msgbuf_init(struct msgbuf *msgbuf)
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{
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msgbuf->queued = 0;
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msgbuf->fd = -1;
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TAILQ_INIT(&msgbuf->bufs);
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}
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void
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msgbuf_clear(struct msgbuf *msgbuf)
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{
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struct buf *buf;
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while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
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buf_dequeue(msgbuf, buf);
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}
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int
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msgbuf_write(struct msgbuf *msgbuf)
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{
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struct iovec iov[IOV_MAX];
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struct buf *buf, *next;
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unsigned int i = 0;
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ssize_t n;
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struct msghdr msg;
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struct cmsghdr *cmsg;
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union {
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struct cmsghdr hdr;
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char buf[CMSG_SPACE(sizeof(int))];
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} cmsgbuf;
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bzero(&iov, sizeof(iov));
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bzero(&msg, sizeof(msg));
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TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
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if (i >= IOV_MAX)
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break;
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iov[i].iov_base = buf->buf + buf->rpos;
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iov[i].iov_len = buf->wpos - buf->rpos;
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i++;
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if (buf->fd != -1)
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break;
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}
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msg.msg_iov = iov;
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msg.msg_iovlen = i;
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if (buf != NULL && buf->fd != -1) {
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msg.msg_control = (caddr_t)&cmsgbuf.buf;
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msg.msg_controllen = sizeof(cmsgbuf.buf);
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cmsg = CMSG_FIRSTHDR(&msg);
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cmsg->cmsg_len = CMSG_LEN(sizeof(int));
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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*(int *)CMSG_DATA(cmsg) = buf->fd;
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}
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if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
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if (errno == EAGAIN || errno == ENOBUFS ||
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errno == EINTR) /* try later */
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return (0);
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else
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return (-1);
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}
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if (n == 0) { /* connection closed */
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errno = 0;
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return (-2);
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}
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/*
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* assumption: fd got sent if sendmsg sent anything
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* this works because fds are passed one at a time
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*/
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if (buf != NULL && buf->fd != -1) {
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close(buf->fd);
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buf->fd = -1;
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}
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for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
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buf = next) {
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next = TAILQ_NEXT(buf, entry);
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if (buf->rpos + n >= buf->wpos) {
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n -= buf->wpos - buf->rpos;
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buf_dequeue(msgbuf, buf);
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} else {
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buf->rpos += n;
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n = 0;
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}
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}
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return (0);
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}
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void
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buf_enqueue(struct msgbuf *msgbuf, struct buf *buf)
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{
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TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
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msgbuf->queued++;
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}
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void
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buf_dequeue(struct msgbuf *msgbuf, struct buf *buf)
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{
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TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
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if (buf->fd != -1)
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close(buf->fd);
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msgbuf->queued--;
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buf_free(buf);
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}
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