/* $Id$
 * Detect media size of given GIOChannel for libcaptive
 * Copyright (C) 2002 Jan Kratochvil <project-captive@jankratochvil.net>
 * 
 * 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; exactly version 2 of June 1991 is required
 * 
 * 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
 */


#include "config.h"

#include "captive/storage.h"	/* self */
#include "../client/giochannel-blind.h"	/* for captive_giochannel_blind_get_size() */
#include "../sandbox/client-CaptiveIOChannel.h"	/* for captive_io_channel_get_size() */
#include <glib/gmessages.h>
#include <glib/gtypes.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
/* Do not: #include <linux/fs.h>	* for 'BLKGETSIZE64' *
 * as including any Linux kernel include files is too much incompatible.
 */
#include <sys/mount.h>	/* for 'BLKGETSIZE' */


static guint64 size_blind(GIOChannel *iochannel)
{
guint64 r;

	g_return_val_if_fail(iochannel!=NULL,0);

	if (!captive_giochannel_blind_get_size(iochannel,&r))
		return 0;

	return r;
}


static guint64 size_sandbox(GIOChannel *iochannel)
{
guint64 r;

	g_return_val_if_fail(iochannel!=NULL,0);

	if (!captive_io_channel_get_size(iochannel,&r))
		return 0;

	return r;
}


static GIOChannel *iochannel_null;

static int iounixchannel_get_fd(GIOChannel *iochannel)
{
int r;

	g_return_val_if_fail(iochannel!=NULL,-1);

	if (!iochannel_null) {
int fd;

		fd=open("/dev/null",O_RDONLY);
		g_return_val_if_fail(fd!=-1,-1);
		iochannel_null=g_io_channel_unix_new(fd);
		g_return_val_if_fail(iochannel_null!=NULL,-1);
		}

	if (iochannel->funcs!=iochannel_null->funcs) {
		/* Not a UNIX file descriptor */
		return -1;
		}

	/* It is forbidden to callg_io_channel_unix_get_fd()
	 * if you are not sure it is a 'GIOUnixChannel'.
	 */
	r=g_io_channel_unix_get_fd(iochannel);
	g_return_val_if_fail(r!=-1,-1);

	return r;
}


static guint64 size_ioctl(GIOChannel *iochannel)
{
int fd;
guint64 r;
long r_long;

	g_return_val_if_fail(iochannel!=NULL,0);

	if (-1==(fd=iounixchannel_get_fd(iochannel)))
		return 0;

#ifdef BLKGETSIZE64
	if (!ioctl(fd,BLKGETSIZE64,&r))
		return r;
#endif
	if (ioctl(fd,BLKGETSIZE,&r_long))
		return 0;
	if (r_long<0)
		return 0;
	r=((guint64)512)*r_long;

	return r;
}


static guint64 size_seek(GIOChannel *iochannel)
{
int fd;
off_t offset_orig,offset;

	g_return_val_if_fail(iochannel!=NULL,0);

	/* We may need '_FILE_OFFSET_BITS=64'.
	 * Setting '__USE_FILE_OFFSET64' did not help.
	 * Done by 'AC_SYS_LARGEFILE' of configure.in.
	 */
	g_return_val_if_fail(sizeof(offset)==sizeof(guint64),0);

	if (-1==(fd=iounixchannel_get_fd(iochannel)))
		return 0;

	if (-1==(offset_orig=lseek(fd,0,SEEK_CUR)))
		return 0;
	g_return_val_if_fail(offset_orig>=0,0);
	offset=lseek(fd,0,SEEK_END);
	if (offset_orig!=lseek(fd,offset_orig,SEEK_SET))
		g_assert_not_reached();

	if (-1==offset)
		return 0;
	g_return_val_if_fail(offset>=0,0);

	return offset;
}



static guint64 size_read(GIOChannel *iochannel)
{
gint64 low,high,mid;
GIOStatus erriostatus;
gchar bufchar;
gsize bufchargot;

	g_return_val_if_fail(iochannel!=NULL,0);
	/* Default "UTF-8" encoding is not much usable for us */
	g_return_val_if_fail(g_io_channel_get_encoding(iochannel)==NULL,0);

	/* low  ==high: low (high)
	 * low+1==high: mid==low; NORMAL: no change: high
	 * low+1==high: mid==low; EOF   : high=mid => 'low==high' case
	 */
	for (low=0,
			high=
					G_MAXINT64;
			low+1<high;) {
		mid=low+(high-low)/2;	/* beware of 'gint64' overflow! */

		erriostatus=g_io_channel_seek_position(iochannel,mid,G_SEEK_SET,
				NULL);	/* error */
		/* During seek in block device such as on URL file:///dev/hda1#captive-fastfat.sys-ro:/
		 * we will do llseek(2) on "/dev/hda1" device from captive_giochannel_size().
		 * Although we are allowed to seek behind EOF on regular files
		 * at least linux-kernel-2.4.19-ac4/fs/block_dev.c/block_llseek() will give
		 * EINVAL on seek behind EOF therefore it must be accepted without complaints by us.
		 */
		if (erriostatus!=G_IO_STATUS_NORMAL) {
			erriostatus=G_IO_STATUS_EOF;
			bufchargot=0;
			}
		else {
			g_assert(sizeof(bufchar)==1);
			erriostatus=g_io_channel_read_chars(iochannel,
					&bufchar, /* buf */
					sizeof(bufchar),	/* count */
					&bufchargot,	/* bytes_read */
					NULL);	/* error */
			/* During read on the end boundary of Linux kernel block device we will
			 * get GNOME_VFS_ERROR_IO at least from linux-kernel-2.4.19-ac4
			 * which will get mapped to G_IO_STATUS_ERROR by captive_gnomevfs_giognomevfs_io_read().
			 */
			g_assert(0
					|| erriostatus==G_IO_STATUS_NORMAL
					|| erriostatus==G_IO_STATUS_EOF
					|| erriostatus==G_IO_STATUS_ERROR);
			g_assert(0
					|| (erriostatus==G_IO_STATUS_NORMAL && bufchargot==1)
					|| (erriostatus==G_IO_STATUS_EOF    && bufchargot==0)
					|| (erriostatus==G_IO_STATUS_ERROR  && bufchargot==0));
			}

		if (erriostatus==G_IO_STATUS_NORMAL)
			low=mid;
		else
			high=mid;
		}
	
	g_assert(high>=0);
	return high;
}


guint64 captive_giochannel_size(GIOChannel *iochannel)
{
guint64 r;

	if ((r=size_blind(iochannel)))
		return r;
	if ((r=size_sandbox(iochannel)))
		return r;
	if ((r=size_ioctl(iochannel)))
		return r;
	if ((r=size_seek(iochannel)))
		return r;
	if ((r=size_read(iochannel)))
		return r;

	return r;
}