lseek.c

Newlib 嵌入式 C库 标准实现代码

/*#######################################################################
# RDOS operating system
# Copyright (C) 1988-2006, Leif Ekblad
#
# This library is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# This library 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
#
# The author of this program may be contacted at [e-mail]
#
# lseek.c                                                                
# lseek function implementation
#
##########################################################################*/

#include "config.h"
#include <_ansi.h>
#include <_syslist.h>
#include <unistd.h>
#include <errno.h>
#include <rdos.h>

off_t lseek(int file, off_t pos, int whence)
{
	off_t temp;

	switch (whence)
	{
		case SEEK_CUR:
			temp = RdosGetFilePos(file);
			temp += pos;
			RdosSetFilePos(file, temp);
			return temp;

		case SEEK_SET:
			RdosSetFilePos(file, pos);
			return pos;

		case SEEK_END:
			temp = RdosGetFilePos(file);
			temp += pos;
			RdosSetFilePos(file, temp);
			return temp;

		default:
			errno = EINVAL;
			return - 1;
	}
}