/*
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright © 2019 Keith Packard
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials provided
 *    with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "semihost-private.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

off_t lseek(int fd, off_t offset, int whence)
{
	if (whence == SEEK_CUR && offset == 0)
		return 0;

	if (whence == SEEK_END) {
		int flen = sys_semihost_flen(fd);
		if (flen != -1) {
			whence = SEEK_SET;
			offset += flen;
		}
	}

        fd = _map_stdio(fd);

	if (whence != SEEK_SET || fd < 0) {
		errno = EINVAL;
		return (off_t) -1;
	}

	struct {
		sh_param_t	field1;
		sh_param_t	field2;
	} arg = {
		.field1 = fd,
		.field2 = offset
	};

	uintptr_t ret = sys_semihost(SYS_SEEK, (uintptr_t) &arg);
	if (ret == 0)
		return offset;
	errno = sys_semihost_errno();
	return -1;
}