new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_os.h
@@ -0,0 +1,58 @@
+#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 struct {
+    ssize_t       (*recv)(ngx_connection_t *c, char *buf, size_t size);
+    ssize_t       (*recv_chain)(ngx_connection_t *c, ngx_chain_t *in);
+    ssize_t       (*send)(ngx_connection_t *c, char *buf, size_t size);
+    ngx_chain_t  *(*send_chain)(ngx_connection_t *c, ngx_chain_t *in);
+    int             flags;
+} ngx_os_io_t;
+
+
+int ngx_os_init(ngx_log_t *log);
+int ngx_daemon(ngx_log_t *log);
+int ngx_posix_init(ngx_log_t *log);
+
+ssize_t ngx_unix_recv(ngx_connection_t *c, char *buf, size_t size);
+ssize_t ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *entry);
+ngx_chain_t *ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in);
+
+
+extern ngx_os_io_t  ngx_os_io;
+extern int          ngx_max_sockets;
+extern int          ngx_inherited_nonblocking;
+
+
+extern int          restart;
+extern int          rotate;
+
+
+#ifdef __FreeBSD__
+#include <ngx_freebsd.h>
+#endif
+
+
+#endif /* _NGX_OS_H_INCLUDED_ */