new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_linux_sendfile_chain.c
@@ -0,0 +1,285 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+
+
+/*
+ * On Linux up to 2.4.21 sendfile() (syscall #187) works with 32-bit
+ * offsets only and the including <sys/sendfile.h> breaks the compiling
+ * if off_t is 64 bit wide.  So we use own sendfile() definition where offset
+ * parameter is int32_t and use sendfile() with the file parts below 2G.
+ *
+ * Linux 2.4.21 has a new sendfile64() syscall #239.
+ */
+
+
+#define NGX_HEADERS   8
+
+
+ngx_chain_t *ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in,
+                                      off_t limit)
+{
+    int              rc;
+    u_char          *prev;
+    off_t            fprev, send, sprev, aligned;
+    size_t           fsize;
+    ssize_t          size, sent;
+    ngx_uint_t       eintr, complete;
+    ngx_err_t        err;
+    ngx_buf_t       *file;
+    ngx_array_t      header;
+    ngx_event_t     *wev;
+    ngx_chain_t     *cl;
+    struct iovec    *iov, headers[NGX_HEADERS];
+#if (HAVE_SENDFILE64)
+    off_t            offset;
+#else
+    int32_t          offset;
+#endif
+
+    wev = c->write;
+
+    if (!wev->ready) {
+        return in;
+    }
+
+    send = 0;
+
+    header.elts = headers;
+    header.size = sizeof(struct iovec);
+    header.nalloc = NGX_HEADERS;
+    header.pool = c->pool;
+
+    for ( ;; ) {
+        file = NULL;
+        fsize = 0;
+        eintr = 0;
+        complete = 0;
+        sprev = send;
+
+        header.nelts = 0;
+
+        prev = NULL;
+        iov = NULL;
+
+        /* create the iovec and coalesce the neighbouring bufs */
+
+        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;
+            send += size;
+        }
+
+        /* set TCP_CORK if there is a header before a file */
+
+        if (c->tcp_nopush == NGX_TCP_NOPUSH_UNSET
+            && header.nelts != 0
+            && cl
+            && cl->buf->in_file)
+        {
+            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_CORK
+                 */
+
+                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");
+            }
+        }
+
+        /* get the file buf */
+
+        if (header.nelts == 0 && 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) {
+#if (HAVE_SENDFILE64)
+            offset = file->file_pos;
+#else
+            offset = (int32_t) file->file_pos;
+#endif
+            rc = sendfile(c->fd, file->file->fd, &offset, fsize);
+
+            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,
+                                   "sendfile() is not ready");
+
+                } else {
+                    wev->error = 1;
+                    ngx_connection_error(c, err, "sendfile() failed");
+                    return NGX_CHAIN_ERROR;
+                }
+            }
+
+            sent = rc > 0 ? rc : 0;
+
+            ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                           "sendfile: %d, @" OFF_T_FMT " %d:%d",
+                           rc, file->file_pos, sent, fsize);
+
+        } else {
+            rc = writev(c->fd, header.elts, header.nelts);
+
+            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;
+
+            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "writev: %d", sent);
+        }
+
+        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 (eintr) {
+            continue; 
+        }
+
+        if (!complete) { 
+            wev->ready = 0;
+            return cl;
+        }
+
+        if (send >= limit || cl == NULL) {
+            return cl;
+        }
+
+        in = cl;
+    }
+}