new file mode 100644
--- /dev/null
+++ b/src/core/ngx_write_chain.c
@@ -0,0 +1,203 @@
+
+#include <ngx_config.h>
+
+#include <ngx_core.h>
+#include <ngx_types.h>
+#include <ngx_alloc.h>
+#include <ngx_array.h>
+#include <ngx_hunk.h>
+#include <ngx_connection.h>
+#include <ngx_sendv.h>
+#include <ngx_sendfile.h>
+
+#include <ngx_write_chain.h>
+
+
+ngx_chain_t *ngx_write_chain(ngx_connection_t *c, ngx_chain_t *in, off_t flush)
+{
+    int           rc, i, last;
+    u_int         flags;
+    char         *prev;
+    off_t         sent;
+    ngx_iovec_t  *iov;
+    ngx_array_t   header, trailer;
+    ngx_hunk_t   *file;
+    ngx_chain_t  *ce;
+
+    ch = in;
+    file = NULL;
+    last = 0;
+
+    ngx_init_array(header, c->pool, 10, sizeof(ngx_iovec_t), NGX_CHAIN_ERROR);
+    ngx_init_array(trailer, c->pool, 10, sizeof(ngx_iovec_t), NGX_CHAIN_ERROR);
+
+    do {
+        header.nelts = 0;
+        trailer.nelts = 0;
+
+        if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
+            prev = NULL;
+            iov = NULL;
+
+            /* create iovec and coalesce the neighbouring chain entries */
+            while (ce && (ce->hunk->type & NGX_HUNK_IN_MEMORY))
+            {
+                if (prev == ce->hunk->pos.mem) {
+                    iov->ngx_iov_len += ce->hunk->last.mem - ce->hunk->pos.mem;
+
+                } else {
+                    ngx_test_null(iov, ngx_push_array(&header),
+                                  NGX_CHAIN_ERROR);
+                    iov->ngx_iov_base = ce->hunk->pos.mem;
+                    iov->ngx_iov_len = ce->hunk->last.mem - ce->hunk->pos.mem;
+                    prev = ce->hunk->last.mem;
+                }
+
+                if (ce->hunk->type & NGX_HUNK_LAST) {
+                    last = 1;
+                }
+
+                ce = ce->next;
+            }
+        }
+
+        if (ce && (ce->hunk->type & NGX_HUNK_FILE)) {
+            file = ce->hunk;
+            ce = ce->next;
+
+            if (ce->hunk->type & NGX_HUNK_LAST) {
+                last = 1;
+            }
+        }
+
+#if (HAVE_MAX_SENDFILE_IOVEC)
+        if (file && header->nelts > HAVE_MAX_SENDFILE_IOVEC) {
+            rc = ngx_sendv(c->fd, (ngx_iovec_t *) header->elts, header->nelts,
+                           &sent);
+        } else {
+#endif
+            if (ch && ch->hunk->type & NGX_HUNK_IN_MEMORY) {
+                prev = NULL;
+                iov = NULL;
+
+                while (ch && (ch->hunk->type & NGX_HUNK_IN_MEMORY)) {
+
+                    if (prev == ch->hunk->pos.mem) {
+                        iov->ngx_iov_len +=
+                                        ch->hunk->last.mem - ch->hunk->pos.mem;
+
+                    } else {
+                        ngx_test_null(iov, ngx_push_array(trailer),
+                                      NGX_CHAIN_ERROR);
+                        iov->ngx_iov_base = ch->hunk->pos.mem;
+                        iov->ngx_iov_len =
+                                        ch->hunk->last.mem - ch->hunk->pos.mem;
+                        prev = ch->hunk->last.mem;
+                    }
+
+                    if (ch->hunk->type & NGX_HUNK_LAST) {
+                        last = 1;
+                    }
+
+                    ch = ch->next;
+                }
+            }
+
+            if (file) {
+                flags = ngx_sendfile_flags;
+#if (HAVE_SENDFILE_DISCONNECT)
+                if (last && c->close) {
+                    flags |= NGX_SENDFILE_DISCONNECT;
+                }
+#endif
+                rc = ngx_sendfile(c,
+                                  (ngx_iovec_t *) header->elts, header->nelts,
+                                  file->file->fd, file->pos.file,
+                                  (size_t) (file->last.file - file->pos.file),
+                                  (ngx_iovec_t *) trailer->elts, trailer->nelts,
+                                  &sent, flags);
+
+#if (HAVE_AIO_EVENT) && !(HAVE_IOCP_EVENT)
+            } else if (ngx_event_flags & NGX_HAVE_AIO_EVENT) {
+
+                sent = 0;
+                rc = NGX_AGAIN;
+                iov = (ngx_iovec_t *) header->elts;
+                for (i = 0; i < header->nelts; i++) {
+                    rc = ngx_event_aio_write(c, iov[i].ngx_iov_base,
+                                             iov[i].ngx_iov_len);
+
+                    if (rc > 0) {
+                        sent += rc;
+                    } else {
+                        break;
+                    }
+
+                    if (rc < (int) iov->ngx_iov_len) {
+                        break;
+                    }
+                }
+#endif
+            } else {
+                rc = ngx_sendv(c, (ngx_iovec_t *) header->elts, header->nelts);
+
+                sent = rc > 0 ? rc: 0;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+                ngx_log_debug(c->log, "sendv: " OFF_FMT _ sent);
+#endif
+            }
+#if (HAVE_MAX_SENDFILE_IOVEC)
+        }
+#endif
+        if (rc == NGX_ERROR)
+            return (ngx_chain_t *) NGX_ERROR;
+
+        c->sent += sent;
+        flush -= sent;
+
+        for (ch = in; ch; ch = ch->next) {
+
+#if (NGX_DEBUG_EVENT_WRITE)
+            ngx_log_debug(c->log, "event write: %x " QX_FMT " " OFF_FMT _
+                          ch->hunk->type _
+                          ch->hunk->pos.file _
+                          ch->hunk->last.file - ch->hunk->pos.file);
+#endif
+
+            if (sent >= ch->hunk->last.file - ch->hunk->pos.file) {
+                sent -= ch->hunk->last.file - ch->hunk->pos.file;
+                ch->hunk->pos.file = ch->hunk->last.file;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+                ngx_log_debug(c->log, "event write: " QX_FMT " 0 " OFF_FMT _
+                              ch->hunk->pos.file _ sent);
+#endif
+
+/*
+                if (ch->hunk->type & NGX_HUNK_LAST)
+                   break;
+*/
+
+                continue;
+            }
+
+            ch->hunk->pos.file += sent;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+            ngx_log_debug(c->log, "event write: " QX_FMT " " OFF_FMT _
+                          ch->hunk->pos.file _
+                          ch->hunk->last.file - ch->hunk->pos.file);
+#endif
+
+            break;
+        }
+
+    /* flush hunks if threaded state */
+    } while (c->write->context && flush > 0);
+
+    ngx_destroy_array(&trailer);
+    ngx_destroy_array(&header);
+
+    return ch;
+}