new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_os.h
@@ -0,0 +1,84 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#ifndef _NGX_OS_H_INCLUDED_
+#define _NGX_OS_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+#define NGX_IO_SENDFILE    1
+#define NGX_IO_ZEROCOPY    2
+
+#if (HAVE_SENDFILE)
+#define NGX_HAVE_SENDFILE  NGX_IO_SENDFILE
+#else
+#define NGX_HAVE_SENDFILE  0
+#endif
+
+#if (HAVE_ZEROCOPY)
+#define NGX_HAVE_ZEROCOPY  NGX_IO_ZEROCOPY
+#else
+#define NGX_HAVE_ZEROCOPY  0
+#endif
+
+
+typedef ssize_t (*ngx_recv_pt)(ngx_connection_t *c, u_char *buf, size_t size);
+typedef ssize_t (*ngx_recv_chain_pt)(ngx_connection_t *c, ngx_chain_t *in);
+typedef ssize_t (*ngx_send_pt)(ngx_connection_t *c, u_char *buf, size_t size);
+typedef ngx_chain_t *(*ngx_send_chain_pt)(ngx_connection_t *c, ngx_chain_t *in,
+                                          off_t limit);
+
+typedef struct {
+    ngx_recv_pt        recv;
+    ngx_recv_chain_pt  recv_chain;
+    ngx_send_pt        send;
+    ngx_send_chain_pt  send_chain;
+    ngx_uint_t         flags;
+} ngx_os_io_t;
+
+
+void ngx_debug_init();
+ngx_int_t ngx_os_init(ngx_log_t *log);
+void ngx_os_status(ngx_log_t *log);
+ngx_int_t ngx_daemon(ngx_log_t *log);
+ngx_int_t ngx_posix_init(ngx_log_t *log);
+void ngx_posix_status(ngx_log_t *log);
+ngx_int_t ngx_posix_post_conf_init(ngx_log_t *log);
+
+
+ssize_t ngx_unix_recv(ngx_connection_t *c, u_char *buf, size_t size);
+ssize_t ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *entry);
+ssize_t ngx_unix_send(ngx_connection_t *c, u_char *buf, size_t size);
+ngx_chain_t *ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in,
+                              off_t limit);
+
+
+extern ngx_os_io_t  ngx_os_io;
+extern ngx_int_t    ngx_ncpu;
+extern ngx_int_t    ngx_max_sockets;
+extern ngx_int_t    ngx_inherited_nonblocking;
+
+#define ngx_stderr_fileno  STDERR_FILENO
+
+#ifdef __FreeBSD__
+#include <ngx_freebsd.h>
+#endif
+
+
+#ifdef __linux__
+#include <ngx_linux.h>
+#endif
+
+
+#ifdef SOLARIS
+#include <ngx_solaris.h>
+#endif
+
+
+#endif /* _NGX_OS_H_INCLUDED_ */