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diff --git a/source3/lib/asys/asys.h b/source3/lib/asys/asys.h
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+/*
+ * Async syscalls
+ * Copyright (C) Volker Lendecke 2012
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ASYS_H__
+#define __ASYS_H__
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/**
+ * @defgroup asys The async syscall library
+ *
+ * This module contains a set of asynchronous functions that directly
+ * wrap normally synchronous posix system calls. The reason for this
+ * module's existence is the limited set of operations the posix async
+ * I/O API provides.
+ *
+ * The basic flow of operations is:
+ *
+ * The application creates a asys_context structure using
+ * asys_context_create()
+ *
+ * The application triggers a call to the library by calling for
+ * example asys_ftruncate(). asys_ftruncate() takes a private_data
+ * argument that will be returned later by asys_result. The calling
+ * application should hand a pointer representing the async operation
+ * to the private_data argument.
+ *
+ * The application puts the fd returned by asys_signalfd() into its
+ * event loop. When the signal fd becomes readable, the application
+ * calls asys_result() to grab the final result of one of the system
+ * calls that were issued in the meantime.
+ *
+ * For multi-user applications it is necessary to create different
+ * credential contexts, as it is not clear when exactly the real
+ * system call will be issued. The application might have called
+ * seteuid(2) or something equivalent in the meantime. Thus, all
+ * system calls doing access checks, in particular all calls doing
+ * path-based operations, require a struct auth_creds_context
+ * parameter. asys_creds_context_create() creates such a context. All
+ * credential-checking operations take a struct asys_creds_context as
+ * an argument. It can be NULL if the application never changes
+ * credentials.
+ *
+ * @{
+ */
+
+struct asys_context;
+struct asys_creds_context;
+
+enum asys_log_level {
+	ASYS_LOG_FATAL = 0,
+	ASYS_DEBUG_ERROR,
+	ASYS_DEBUG_WARNING,
+	ASYS_DEBUG_TRACE
+};
+
+#ifndef PRINTF_ATTRIBUTE
+#if (__GNUC__ >= 3)
+/** Use gcc attribute to check printf fns.  a1 is the 1-based index of
+ * the parameter containing the format, and a2 the index of the first
+ * argument. Note that some gcc 2.x versions don't handle this
+ * properly **/
+#define PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format (__printf__, a1, a2)))
+#else
+#define PRINTF_ATTRIBUTE(a1, a2)
+#endif
+#endif
+
+typedef void (*asys_log_fn)(struct asys_context *ctx, void *private_data,
+			    enum asys_log_level level,
+			    const char *fmt, ...) PRINTF_ATTRIBUTE(4, 5);
+
+int asys_context_init(struct asys_context **ctx, unsigned max_parallel);
+int asys_context_destroy(struct asys_context *ctx);
+void asys_set_log_fn(struct asys_context *ctx, asys_log_fn fn,
+		     void *private_data);
+
+/**
+ * @brief Get the the signal fd
+ *
+ * asys_signalfd() returns a file descriptor that will become readable
+ * whenever an asynchronous request has finished. When the signalfd is
+ * readable, calling asys_result() will not block.
+ *
+ * @param[in]	ctx	The asys context
+ * @return		A file descriptor indicating a finished operation
+ */
+
+int asys_signalfd(struct asys_context *ctx);
+
+/**
+ * @brief Pull the result from an async operation
+ *
+ * Whe the fd returned from asys_signalfd() is readable, an async
+ * operation has finished. The result from the async operation can be
+ * pulled with asys_result().
+ *
+ * @param[in]	ctx	The asys context
+ * @return		success: 0, failure: errno
+ */
+int asys_result(struct asys_context *ctx, ssize_t *pret, int *perrno,
+		void *pdata);
+void asys_cancel(struct asys_context *ctx, void *private_data);
+
+int asys_pread(struct asys_context *ctx, int fildes, void *buf, size_t nbyte,
+	       off_t offset, void *private_data);
+int asys_pwrite(struct asys_context *ctx, int fildes, const void *buf,
+		size_t nbyte, off_t offset, void *private_data);
+int asys_ftruncate(struct asys_context *ctx, int filedes, off_t length,
+		   void *private_data);
+int asys_fsync(struct asys_context *ctx, int fd, void *private_data);
+int asys_close(struct asys_context *ctx, int fd, void *private_data);
+
+struct asys_creds_context *asys_creds_context_create(
+	struct asys_context *ctx,
+	uid_t uid, gid_t gid, unsigned num_gids, gid_t *gids);
+
+int asys_creds_context_delete(struct asys_creds_context *ctx);
+
+int asys_open(struct asys_context *ctx, struct asys_creds_context *cctx,
+	      const char *pathname, int flags, mode_t mode,
+	      void *private_data);
+int asys_unlink(struct asys_context *ctx, struct asys_creds_context *cctx,
+		const char *pathname, void *private_data);
+
+/* @} */
+
+#endif /* __ASYS_H__ */