/*
??CUSE?example:?Character?device?in?Userspace
??Copyright?（C）?2008-2009??SUSE?Linux?Products?GmbH
??Copyright?（C）?2008-2009??Tejun?Heo?

??This?program?can?be?distributed?under?the?terms?of?the?GNU?GPL.
??See?the?file?COPYING.

??gcc?-Wall?cusexmp.c?‘pkg-config?fuse?--cflags?--libs‘?-o?cusexmp
*/

#define?FUSE_USE_VERSION?29

#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?

#include?“fioc.h“

static?void?*cusexmp_buf;
static?size_t?cusexmp_size;

static?const?char?*usage?=
“usage:?cusexmp?[options]\n“
“\n“
“options:\n“
“????--help|-h?????????????print?this?help?message\n“
“????--maj=MAJ|-M?MAJ??????device?major?number\n“
“????--min=MIN|-m?MIN??????device?minor?number\n“
“????--name=NAME|-n?NAME???device?name?（mandatory）\n“
“\n“;

static?int?cusexmp_resize（size_t?new_size）
{
	void?*new_buf;

	if?（new_size?==?cusexmp_size）
		return?0;

	new_buf?=?realloc（cusexmp_buf?new_size）;
	if?（!new_buf?&&?new_size）
		return?-ENOMEM;

	if?（new_size?>?cusexmp_size）
		memset（new_buf?+?cusexmp_size?0?new_size?-?cusexmp_size）;

	cusexmp_buf?=?new_buf;
	cusexmp_size?=?new_size;

	return?0;
}

static?int?cusexmp_expand（size_t?new_size）
{
	if?（new_size?>?cusexmp_size）
		return?cusexmp_resize（new_size）;
	return?0;
}

static?void?cusexmp_open（fuse_req_t?req?struct?fuse_file_info?*fi）
{
	fuse_reply_open（req?fi）;
}

static?void?cusexmp_read（fuse_req_t?req?size_t?size?off_t?off
			?struct?fuse_file_info?*fi）
{
	（void）fi;

	if?（off?>=?cusexmp_size）
		off?=?cusexmp_size;
	if?（size?>?cusexmp_size?-?off）
		size?=?cusexmp_size?-?off;

	fuse_reply_buf（req?cusexmp_buf?+?off?size）;
}

static?void?cusexmp_write（fuse_req_t?req?const?char?*buf?size_t?size
			??off_t?off?struct?fuse_file_info?*fi）
{
	（void）fi;

	if?（cusexmp_expand（off?+?size））?{
		fuse_reply_err（req?ENOMEM）;
		return;
	}

	memcpy（cusexmp_buf?+?off?buf?size）;
	fuse_reply_write（req?size）;
}

static?void?fioc_do_rw（fuse_req_t?req?void?*addr?const?void?*in_buf
		???????size_t?in_bufsz?size_t?out_bufsz?int?is_read）
{
	const?struct?fioc_rw_arg?*arg;
	struct?iovec?in_iov[2]?out_iov[3]?iov[3];
	size_t?cur_size;

	/*?read?in?arg?*/
	in_iov[0].iov_base?=?addr;
	in_iov[0].iov_len?=?sizeof（*arg）;
	if?（!in_bufsz）?{
		fuse_reply_ioctl_retry（req?in_iov?1?NULL?0）;
		return;
	}
	arg?=?in_buf;
	in_buf?+=?sizeof（*arg）;
	in_bufsz?-=?sizeof（*arg）;

	/*?prepare?size?outputs?*/
	out_iov[0].iov_base?=
		addr?+?（unsigned?long）&（（（struct?fioc_rw_arg?*）0）->prev_size）;
	out_iov[0].iov_len?=?sizeof（arg->prev_size）;

	out_iov[1].iov_base?=
		addr?+?（unsigned?long）&（（（struct?fioc_rw_arg?*）0）->new_size）;
	out_iov[1].iov_len?=?sizeof（arg->new_size）;

	/*?prepare?client?buf?*/
	if?（is_read）?{
		out_iov[2].iov_base?=?arg->buf;
		out_iov[2].iov_len?=?arg->size;
		if?（!out_bufsz）?{
			fuse_reply_ioctl_retry（req?in_iov?1?out_iov?3）;
			return;
		}
	}?else?{
		in_iov[1].iov_base?=?arg->buf