new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_freebsd_sendfile_chain.c
@@ -0,0 +1,380 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+
+
+/*
+ * Although FreeBSD sendfile() allows to pass a header and a trailer
+ * it can not send a header with a part of the file in one packet until
+ * FreeBSD 5.3.  Besides over the fast ethernet connection sendfile()
+ * may send the partially filled packets, i.e. the 8 file pages may be sent
+ * as the 11 full 1460-bytes packets, then one incomplete 324-bytes packet,
+ * and then again the 11 full 1460-bytes packets.
+ *
+ * So we use the TCP_NOPUSH option (similar to Linux's TCP_CORK)
+ * to postpone the sending - it not only sends a header and the first part
+ * of the file in one packet but also sends the file pages in the full packets.
+ *
+ * But until FreeBSD 4.5 the turning TCP_NOPUSH off does not flush a pending
+ * data that less than MSS so that data may be sent with 5 second delay.
+ * So we do not use TCP_NOPUSH on FreeBSD prior to 4.5 although it can be used
+ * for non-keepalive HTTP connections.
+ */
+
+
+#define NGX_HEADERS   8
+#define NGX_TRAILERS  4
+
+
+ngx_chain_t *ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in,
+                                        off_t limit)
+{
+    int              rc;
+    u_char          *prev;
+    off_t            fprev, sent, send, sprev, aligned;
+    size_t           hsize, fsize;
+    ssize_t          size;
+    ngx_uint_t       eintr, eagain, complete;
+    ngx_err_t        err;
+    ngx_buf_t       *file;
+    ngx_array_t      header, trailer;
+    ngx_event_t     *wev;
+    ngx_chain_t     *cl;
+    struct sf_hdtr   hdtr;
+    struct iovec    *iov, headers[NGX_HEADERS], trailers[NGX_TRAILERS];
+
+    wev = c->write;
+
+    if (!wev->ready) {
+        return in;
+    }
+
+#if (HAVE_KQUEUE)
+
+    if ((ngx_event_flags & NGX_HAVE_KQUEUE_EVENT) && wev->pending_eof) {
+        ngx_log_error(NGX_LOG_INFO, c->log, wev->kq_errno,
+                      "kevent() reported about an closed connection");
+
+        wev->error = 1;
+        return NGX_CHAIN_ERROR;
+    }
+
+#endif
+
+    send = 0;
+    eagain = 0;
+
+    header.elts = headers;
+    header.size = sizeof(struct iovec);
+    header.nalloc = NGX_HEADERS;
+    header.pool = c->pool;
+
+    trailer.elts = trailers;
+    trailer.size = sizeof(struct iovec);
+    trailer.nalloc = NGX_TRAILERS;
+    trailer.pool = c->pool;
+
+    for ( ;; ) {
+        file = NULL;
+        fsize = 0;
+        hsize = 0;
+        eintr = 0;
+        complete = 0;
+        sprev = send;
+
+        header.nelts = 0;
+        trailer.nelts = 0;
+
+        /* create the header iovec and coalesce the neighbouring bufs */
+
+        prev = NULL;
+        iov = NULL;
+
+        for (cl = in;
+             cl && header.nelts < IOV_MAX && send < limit;
+             cl = cl->next)
+        {
+            if (ngx_buf_special(cl->buf)) {
+                continue;
+            }
+
+            if (!ngx_buf_in_memory_only(cl->buf)) {
+                break;
+            }
+
+            size = cl->buf->last - cl->buf->pos;
+
+            if (send + size > limit) {
+                size = limit - send;
+            }
+
+            if (prev == cl->buf->pos) {
+                iov->iov_len += size;
+
+            } else {
+                if (!(iov = ngx_array_push(&header))) {
+                    return NGX_CHAIN_ERROR;
+                }
+
+                iov->iov_base = (void *) cl->buf->pos;
+                iov->iov_len = size;
+            }
+
+            prev = cl->buf->pos + size;
+            hsize += size;
+            send += size;
+        }
+
+        /* get the file buf */
+
+        if (cl && cl->buf->in_file && send < limit) {
+            file = cl->buf;
+
+            /* coalesce the neighbouring file bufs */
+
+            do {
+                size = (size_t) (cl->buf->file_last - cl->buf->file_pos);
+
+                if (send + size > limit) {
+                    size = limit - send;
+
+                    aligned = (cl->buf->file_pos + size + ngx_pagesize - 1)
+                                                      & ~(ngx_pagesize - 1);
+
+                    if (aligned <= cl->buf->file_last) {
+                        size = aligned - cl->buf->file_pos;
+                    }
+                }
+
+                fsize += size;
+                send += size;
+                fprev = cl->buf->file_pos + size;
+                cl = cl->next;
+
+            } while (cl
+                     && cl->buf->in_file
+                     && send < limit
+                     && file->file->fd == cl->buf->file->fd
+                     && fprev == cl->buf->file_pos);
+        }
+
+        if (file) {
+            /* create the tailer iovec and coalesce the neighbouring bufs */
+
+            prev = NULL;
+            iov = NULL;
+
+            for (/* void */;
+                 cl && header.nelts < IOV_MAX && send < limit;
+                 cl = cl->next)
+            {
+                if (ngx_buf_special(cl->buf)) {
+                    continue;
+                }
+
+                if (!ngx_buf_in_memory_only(cl->buf)) {
+                    break;
+                }
+
+                size = cl->buf->last - cl->buf->pos;
+
+                if (send + size > limit) {
+                    size = limit - send;
+                }
+
+                if (prev == cl->buf->pos) {
+                    iov->iov_len += size;
+
+                } else {
+                    if (!(iov = ngx_array_push(&trailer))) {
+                        return NGX_CHAIN_ERROR;
+                    }
+
+                    iov->iov_base = (void *) cl->buf->pos;
+                    iov->iov_len = size;
+                }
+
+                prev = cl->buf->pos + size;
+                send += size;
+            }
+        }
+
+        if (file) {
+
+            if (ngx_freebsd_use_tcp_nopush
+                && c->tcp_nopush == NGX_TCP_NOPUSH_UNSET)
+            {
+
+                if (ngx_tcp_nopush(c->fd) == NGX_ERROR) {
+                    err = ngx_errno;
+
+                    /*
+                     * there is a tiny chance to be interrupted, however
+                     * we continue a processing without the TCP_NOPUSH
+                     */
+
+                    if (err != NGX_EINTR) {
+                        wev->error = 1;
+                        ngx_connection_error(c, err,
+                                             ngx_tcp_nopush_n " failed");
+                        return NGX_CHAIN_ERROR;
+                    }
+
+                } else {
+                    c->tcp_nopush = NGX_TCP_NOPUSH_SET;
+
+                    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                                   "tcp_nopush");
+                }
+            }
+
+            hdtr.headers = (struct iovec *) header.elts;
+            hdtr.hdr_cnt = header.nelts;
+            hdtr.trailers = (struct iovec *) trailer.elts;
+            hdtr.trl_cnt = trailer.nelts;
+
+            /*
+             * the "nbytes bug" of the old sendfile() syscall:
+             * http://www.freebsd.org/cgi/query-pr.cgi?pr=33771
+             */
+
+            if (ngx_freebsd_sendfile_nbytes_bug == 0) {
+                hsize = 0;
+            }
+
+            sent = 0;
+
+            rc = sendfile(file->file->fd, c->fd, file->file_pos,
+                          fsize + hsize, &hdtr, &sent, 0);
+
+            if (rc == -1) {
+                err = ngx_errno;
+
+                if (err == NGX_EAGAIN || err == NGX_EINTR) {
+                    if (err == NGX_EINTR) {
+                        eintr = 1;
+
+                    } else {
+                        eagain = 1;
+                    }
+
+                    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, err,
+                                   "sendfile() sent only " OFF_T_FMT " bytes",
+                                   sent);
+
+                } else {
+                    wev->error = 1;
+                    ngx_connection_error(c, err, "sendfile() failed");
+                    return NGX_CHAIN_ERROR;
+                }
+            }
+
+            ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                           "sendfile: %d, @" OFF_T_FMT " " OFF_T_FMT ":%d",
+                           rc, file->file_pos, sent, fsize + hsize);
+
+        } else {
+            rc = writev(c->fd, header.elts, header.nelts);
+
+            ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                           "writev: %d of " SIZE_T_FMT, rc, hsize);
+
+            if (rc == -1) {
+                err = ngx_errno;
+
+                if (err == NGX_EAGAIN || err == NGX_EINTR) {
+                    if (err == NGX_EINTR) {
+                        eintr = 1;
+                    }
+
+                    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
+                                   "writev() not ready");
+
+                } else {
+                    wev->error = 1;
+                    ngx_connection_error(c, err, "writev() failed");
+                    return NGX_CHAIN_ERROR;
+                }
+            }
+
+            sent = rc > 0 ? rc : 0;
+        }
+
+        if (send - sprev == sent) {
+            complete = 1;
+        }
+
+        c->sent += sent;
+
+        for (cl = in; cl; cl = cl->next) {
+
+            if (ngx_buf_special(cl->buf)) {
+                continue;
+            }
+
+            if (sent == 0) {
+                break;
+            }
+
+            size = ngx_buf_size(cl->buf);
+
+            if (sent >= size) {
+                sent -= size;
+
+                if (ngx_buf_in_memory(cl->buf)) {
+                    cl->buf->pos = cl->buf->last;
+                }
+
+                if (cl->buf->in_file) {
+                    cl->buf->file_pos = cl->buf->file_last;
+                }
+
+                continue;
+            }
+
+            if (ngx_buf_in_memory(cl->buf)) {
+                cl->buf->pos += sent;
+            }
+
+            if (cl->buf->in_file) {
+                cl->buf->file_pos += sent;
+            }
+
+            break;
+        }
+
+        if (eagain) {
+
+            /*
+             * sendfile() can return EAGAIN even if it has sent
+             * a whole file part but the successive sendfile() call would
+             * return EAGAIN right away and would not send anything.
+             * We use it as a hint.
+             */
+
+            wev->ready = 0;
+            return cl;
+        }
+
+        if (eintr) {
+            continue;
+        }
+
+        if (!complete) {
+            wev->ready = 0;
+            return cl;
+        }
+
+        if (send >= limit || cl == NULL) {
+            return cl;
+        }
+
+        in = cl;
+    }
+}