sandbox: Add OS dependent layer

We want to keep all OS-dependent code in once place, with a simple interface
to U-Boot. For now, this is that place.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/os.h

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * Operating System Interface
+ *
+ * This provides access to useful OS routines from the sandbox architecture
+ */
+
+/**
+ * Access to the OS read() system call
+ *
+ * \param fd	File descriptor as returned by os_open()
+ * \param buf	Buffer to place data
+ * \param count	Number of bytes to read
+ * \return number of bytes read, or -1 on error
+ */
+ssize_t os_read(int fd, void *buf, size_t count);
+
+/**
+ * Access to the OS write() system call
+ *
+ * \param fd	File descriptor as returned by os_open()
+ * \param buf	Buffer containing data to write
+ * \param count	Number of bytes to write
+ * \return number of bytes written, or -1 on error
+ */
+ssize_t os_write(int fd, const void *buf, size_t count);
+
+/**
+ * Access to the OS open() system call
+ *
+ * \param pathname	Pathname of file to open
+ * \param flags		Flags, like O_RDONLY, O_RDWR
+ * \return file descriptor, or -1 on error
+ */
+int os_open(const char *pathname, int flags);
+
+/**
+ * Access to the OS close() system call
+ *
+ * \param fd	File descriptor to close
+ * \return 0 on success, -1 on error
+ */
+int os_close(int fd);
+
+/**
+ * Access to the OS exit() system call
+ *
+ * This exits with the supplied return code, which should be 0 to indicate
+ * success.
+ *
+ * @param exit_code	exit code for U-Boot
+ */
+void os_exit(int exit_code);