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Documentation for dvb-usb-framework module and its devices

Idea behind the dvb-usb-framework
=================================

In March 2005 I got the new Twinhan USB2.0 DVB-T device. They provided specs and a firmware.

Quite keen I wanted to put the driver (with some quirks of course) into dibusb.
After reading some specs and doing some USB snooping, it realized, that the
dibusb-driver would be a complete mess afterwards. So I decided to do it in a
different way: With the help of a dvb-usb-framework.

The framework provides generic functions (mostly kernel API calls), such as:

- Transport Stream URB handling in conjunction with dvb-demux-feed-control
  (bulk and isoc are supported)
- registering the device for the DVB-API
- registering an I2C-adapter if applicable
- remote-control/input-device handling
- firmware requesting and loading (currently just for the Cypress USB
  controllers)
- other functions/methods which can be shared by several drivers (such as
  functions for bulk-control-commands)
- TODO: a I2C-chunker. It creates device-specific chunks of register-accesses
  depending on length of a register and the number of values that can be
  multi-written and multi-read.

The source code of the particular DVB USB devices does just the communication
with the device via the bus. The connection between the DVB-API-functionality
is done via callbacks, assigned in a static device-description (struct
dvb_usb_device) each device-driver has to have.

For an example have a look in drivers/media/dvb/dvb-usb/vp7045*.

Objective is to migrate all the usb-devices (dibusb, cinergyT2, maybe the
ttusb; flexcop-usb already benefits from the generic flexcop-device) to use
the dvb-usb-lib.

TODO: dynamic enabling and disabling of the pid-filter in regard to number of
feeds requested.

Supported devices
========================

See the LinuxTV DVB Wiki at www.linuxtv.org for a complete list of
cards/drivers/firmwares:

http://www.linuxtv.org/wiki/index.php/DVB_USB

0. History & News:
  2005-06-30 - added support for WideView WT-220U (Thanks to Steve Chang)
  2005-05-30 - added basic isochronous support to the dvb-usb-framework
	       added support for Conexant Hybrid reference design and Nebula DigiTV USB
  2005-04-17 - all dibusb devices ported to make use of the dvb-usb-framework
  2005-04-02 - re-enabled and improved remote control code.
  2005-03-31 - ported the Yakumo/Hama/Typhoon DVB-T USB2.0 device to dvb-usb.
  2005-03-30 - first commit of the dvb-usb-module based on the dibusb-source. First device is a new driver for the
	       TwinhanDTV Alpha / MagicBox II USB2.0-only DVB-T device.

  (change from dvb-dibusb to dvb-usb)
  2005-03-28 - added support for the AVerMedia AverTV DVB-T USB2.0 device (Thanks to Glen Harris and Jiun-Kuei Jung, AVerMedia)
  2005-03-14 - added support for the Typhoon/Yakumo/HAMA DVB-T mobile USB2.0
  2005-02-11 - added support for the KWorld/ADSTech Instant DVB-T USB2.0. Thanks a lot to Joachim von Caron
  2005-02-02 - added support for the Hauppauge Win-TV Nova-T USB2
  2005-01-31 - distorted streaming is gone for USB1.1 devices
  2005-01-13 - moved the mirrored pid_filter_table back to dvb-dibusb
	     - first almost working version for HanfTek UMT-010
	     - found out, that Yakumo/HAMA/Typhoon are predecessors of the HanfTek UMT-010
  2005-01-10 - refactoring completed, now everything is very delightful
	     - tuner quirks for some weird devices (Artec T1 AN2235 device has sometimes a
	       Panasonic Tuner assembled). Tunerprobing implemented. Thanks a lot to Gunnar Wittich.
  2004-12-29 - after several days of struggling around bug of no returning URBs fixed.
  2004-12-26 - refactored the dibusb-driver, splitted into separate files
	     - i2c-probing enabled
  2004-12-06 - possibility for demod i2c-address probing
	     - new usb IDs (Compro, Artec)
  2004-11-23 - merged changes from DiB3000MC_ver2.1
	     - revised the debugging
	     - possibility to deliver the complete TS for USB2.0
  2004-11-21 - first working version of the dib3000mc/p frontend driver.
  2004-11-12 - added additional remote control keys. Thanks to Uwe Hanke.
  2004-11-07 - added remote control support. Thanks to David Matthews.
  2004-11-05 - added support for a new devices (Grandtec/Avermedia/Artec)
	     - merged my changes (for dib3000mb/dibusb) to the FE_REFACTORING, because it became HEAD
	     - moved transfer control (pid filter, fifo control) from usb driver to frontend, it seems
	       better settled there (added xfer_ops-struct)
	     - created a common files for frontends (mc/p/mb)
  2004-09-28 - added support for a new device (Unkown, vendor ID is Hyper-Paltek)
  2004-09-20 - added support for a new device (Compro DVB-U2000), thanks
	       to Amaury Demol for reporting
	     - changed usb TS transfer method (several urbs, stopping transfer
	       before setting a new pid)
  2004-09-13 - added support for a new device (Artec T1 USB TVBOX), thanks
	       to Christian Motschke for reporting
  2004-09-05 - released the dibusb device and dib3000mb-frontend driver

  (old news for vp7041.c)
  2004-07-15 - found out, by accident, that the device has a TUA6010XS for
	       PLL
  2004-07-12 - figured out, that the driver should also work with the
	       CTS Portable (Chinese Television System)
  2004-07-08 - firmware-extraction-2.422-problem solved, driver is now working
	       properly with firmware extracted from 2.422
	     - #if for 2.6.4 (dvb), compile issue
	     - changed firmware handling, see vp7041.txt sec 1.1
  2004-07-02 - some tuner modifications, v0.1, cleanups, first public
  2004-06-28 - now using the dvb_dmx_swfilter_packets, everything
	       runs fine now
  2004-06-27 - able to watch and switching channels (pre-alpha)
	     - no section filtering yet
  2004-06-06 - first TS received, but kernel oops :/
  2004-05-14 - firmware loader is working
  2004-05-11 - start writing the driver

1. How to use?
1.1. Firmware

Most of the USB drivers need to download a firmware to the device before start
working.

Have a look at the Wikipage for the DVB-USB-drivers to find out, which firmware
you need for your device:

http://www.linuxtv.org/wiki/index.php/DVB_USB

1.2. Compiling

Since the driver is in the linux kernel, activating the driver in
your favorite config-environment should sufficient. I recommend
to compile the driver as module. Hotplug does the rest.

If you use dvb-kernel enter the build-2.6 directory run 'make' and 'insmod.sh
load' afterwards.

1.3. Loading the drivers

Hotplug is able to load the driver, when it is needed (because you plugged
in the device).

If you want to enable debug output, you have to load the driver manually and
from withing the dvb-kernel cvs repository.

first have a look, which debug level are available:

modinfo dvb-usb
modinfo dvb-usb-vp7045
etc.

modprobe dvb-usb debug=<level>
modprobe dvb-usb-vp7045 debug=<level>
etc.

should do the trick.

When the driver is loaded successfully, the firmware file was in
the right place and the device is connected, the "Power"-LED should be
turned on.

At this point you should be able to start a dvb-capable application. I'm use
(t|s)zap, mplayer and dvbscan to test the basics. VDR-xine provides the
long-term test scenario.

2. Known problems and bugs

- Don't remove the USB device while running an DVB application, your system
  will go crazy or die most likely.

2.1. Adding support for devices

TODO

2.2. USB1.1 Bandwidth limitation

A lot of the currently supported devices are USB1.1 and thus they have a
maximum bandwidth of about 5-6 MBit/s when connected to a USB2.0 hub.
This is not enough for receiving the complete transport stream of a
DVB-T channel (which is about 16 MBit/s). Normally this is not a
problem, if you only want to watch TV (this does not apply for HDTV),
but watching a channel while recording another channel on the same
frequency simply does not work very well. This applies to all USB1.1
DVB-T devices, not just the dvb-usb-devices)

The bug, where the TS is distorted by a heavy usage of the device is gone
definitely. All dvb-usb-devices I was using (Twinhan, Kworld, DiBcom) are
working like charm now with VDR. Sometimes I even was able to record a channel
and watch another one.

2.3. Comments

Patches, comments and suggestions are very very welcome.

3. Acknowledgements
   Amaury Demol (ademol@dibcom.fr) and Francois Kanounnikoff from DiBcom for
    providing specs, code and help, on which the dvb-dibusb, dib3000mb and
    dib3000mc are based.

   David Matthews for identifying a new device type (Artec T1 with AN2235)
    and for extending dibusb with remote control event handling. Thank you.

   Alex Woods for frequently answering question about usb and dvb
    stuff, a big thank you.

   Bernd Wagner for helping with huge bug reports and discussions.

   Gunnar Wittich and Joachim von Caron for their trust for providing
    root-shells on their machines to implement support for new devices.

   Allan Third and Michael Hutchinson for their help to write the Nebula
    digitv-driver.

   Glen Harris for bringing up, that there is a new dibusb-device and Jiun-Kuei
    Jung from AVerMedia who kindly provided a special firmware to get the device
    up and running in Linux.

   Jennifer Chen, Jeff and Jack from Twinhan for kindly supporting by
	writing the vp7045-driver.

   Steve Chang from WideView for providing information for new devices and
	firmware files.

   Michael Paxton for submitting remote control keymaps.

   Some guys on the linux-dvb mailing list for encouraging me.

   Peter Schildmann >peter.schildmann-nospam-at-web.de< for his
    user-level firmware loader, which saves a lot of time
    (when writing the vp7041 driver)

   Ulf Hermenau for helping me out with traditional chinese.

   André Smoktun and Christian Frömmel for supporting me with
    hardware and listening to my problems very patiently.
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/*
 *  linux/fs/open.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/string.h>
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/quotaops.h>
#include <linux/fsnotify.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
#include <linux/capability.h>
#include <linux/securebits.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/fcntl.h>
#include <asm/uaccess.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/rcupdate.h>
#include <linux/audit.h>
#include <linux/falloc.h>
#include <linux/fs_struct.h>

int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	int retval = -ENODEV;

	if (dentry) {
		retval = -ENOSYS;
		if (dentry->d_sb->s_op->statfs) {
			memset(buf, 0, sizeof(*buf));
			retval = security_sb_statfs(dentry);
			if (retval)
				return retval;
			retval = dentry->d_sb->s_op->statfs(dentry, buf);
			if (retval == 0 && buf->f_frsize == 0)
				buf->f_frsize = buf->f_bsize;
		}
	}
	return retval;
}

EXPORT_SYMBOL(vfs_statfs);

static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
{
	struct kstatfs st;
	int retval;

	retval = vfs_statfs(dentry, &st);
	if (retval)
		return retval;

	if (sizeof(*buf) == sizeof(st))
		memcpy(buf, &st, sizeof(st));
	else {
		if (sizeof buf->f_blocks == 4) {
			if ((st.f_blocks | st.f_bfree | st.f_bavail |
			     st.f_bsize | st.f_frsize) &
			    0xffffffff00000000ULL)
				return -EOVERFLOW;
			/*
			 * f_files and f_ffree may be -1; it's okay to stuff
			 * that into 32 bits
			 */
			if (st.f_files != -1 &&
			    (st.f_files & 0xffffffff00000000ULL))
				return -EOVERFLOW;
			if (st.f_ffree != -1 &&
			    (st.f_ffree & 0xffffffff00000000ULL))
				return -EOVERFLOW;
		}

		buf->f_type = st.f_type;
		buf->f_bsize = st.f_bsize;
		buf->f_blocks = st.f_blocks;
		buf->f_bfree = st.f_bfree;
		buf->f_bavail = st.f_bavail;
		buf->f_files = st.f_files;
		buf->f_ffree = st.f_ffree;
		buf->f_fsid = st.f_fsid;
		buf->f_namelen = st.f_namelen;
		buf->f_frsize = st.f_frsize;
		memset(buf->f_spare, 0, sizeof(buf->f_spare));
	}
	return 0;
}

static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
{
	struct kstatfs st;
	int retval;

	retval = vfs_statfs(dentry, &st);
	if (retval)
		return retval;

	if (sizeof(*buf) == sizeof(st))
		memcpy(buf, &st, sizeof(st));
	else {
		buf->f_type = st.f_type;
		buf->f_bsize = st.f_bsize;
		buf->f_blocks = st.f_blocks;
		buf->f_bfree = st.f_bfree;
		buf->f_bavail = st.f_bavail;
		buf->f_files = st.f_files;
		buf->f_ffree = st.f_ffree;
		buf->f_fsid = st.f_fsid;
		buf->f_namelen = st.f_namelen;
		buf->f_frsize = st.f_frsize;
		memset(buf->f_spare, 0, sizeof(buf->f_spare));
	}
	return 0;
}

SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
{
	struct path path;
	int error;

	error = user_path(pathname, &path);
	if (!error) {
		struct statfs tmp;
		error = vfs_statfs_native(path.dentry, &tmp);
		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
			error = -EFAULT;
		path_put(&path);
	}
	return error;
}

SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
{
	struct path path;
	long error;

	if (sz != sizeof(*buf))
		return -EINVAL;
	error = user_path(pathname, &path);
	if (!error) {
		struct statfs64 tmp;
		error = vfs_statfs64(path.dentry, &tmp);
		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
			error = -EFAULT;
		path_put(&path);
	}
	return error;
}

SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
{
	struct file * file;
	struct statfs tmp;
	int error;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;
	error = vfs_statfs_native(file->f_path.dentry, &tmp);
	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
		error = -EFAULT;
	fput(file);
out:
	return error;
}

SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
{
	struct file * file;
	struct statfs64 tmp;
	int error;

	if (sz != sizeof(*buf))
		return -EINVAL;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;
	error = vfs_statfs64(file->f_path.dentry, &tmp);
	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
		error = -EFAULT;
	fput(file);
out:
	return error;
}

int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
	struct file *filp)
{
	int err;
	struct iattr newattrs;

	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
	if (length < 0)
		return -EINVAL;

	newattrs.ia_size = length;
	newattrs.ia_valid = ATTR_SIZE | time_attrs;
	if (filp) {
		newattrs.ia_file = filp;
		newattrs.ia_valid |= ATTR_FILE;
	}

	/* Remove suid/sgid on truncate too */
	newattrs.ia_valid |= should_remove_suid(dentry);

	mutex_lock(&dentry->d_inode->i_mutex);
	err = notify_change(dentry, &newattrs);
	mutex_unlock(&dentry->d_inode->i_mutex);
	return err;
}

static long do_sys_truncate(const char __user *pathname, loff_t length)
{
	struct path path;
	struct inode *inode;
	int error;

	error = -EINVAL;
	if (length < 0)	/* sorry, but loff_t says... */
		goto out;

	error = user_path(pathname, &path);
	if (error)
		goto out;
	inode = path.dentry->d_inode;

	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
	error = -EISDIR;
	if (S_ISDIR(inode->i_mode))
		goto dput_and_out;

	error = -EINVAL;
	if (!S_ISREG(inode->i_mode))
		goto dput_and_out;

	error = mnt_want_write(path.mnt);
	if (error)
		goto dput_and_out;

	error = inode_permission(inode, MAY_WRITE);
	if (error)
		goto mnt_drop_write_and_out;

	error = -EPERM;
	if (IS_APPEND(inode))
		goto mnt_drop_write_and_out;

	error = get_write_access(inode);
	if (error)
		goto mnt_drop_write_and_out;

	/*
	 * Make sure that there are no leases.  get_write_access() protects
	 * against the truncate racing with a lease-granting setlease().
	 */
	error = break_lease(inode, FMODE_WRITE);
	if (error)
		goto put_write_and_out;

	error = locks_verify_truncate(inode, NULL, length);
	if (!error)
		error = security_path_truncate(&path, length, 0);
	if (!error) {
		vfs_dq_init(inode);
		error = do_truncate(path.dentry, length, 0, NULL);
	}

put_write_and_out:
	put_write_access(inode);
mnt_drop_write_and_out:
	mnt_drop_write(path.mnt);
dput_and_out:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE2(truncate, const char __user *, path, unsigned long, length)
{
	/* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
	return do_sys_truncate(path, (long)length);
}

static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
{
	struct inode * inode;
	struct dentry *dentry;
	struct file * file;
	int error;

	error = -EINVAL;
	if (length < 0)
		goto out;
	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;

	/* explicitly opened as large or we are on 64-bit box */
	if (file->f_flags & O_LARGEFILE)
		small = 0;

	dentry = file->f_path.dentry;
	inode = dentry->d_inode;
	error = -EINVAL;
	if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
		goto out_putf;

	error = -EINVAL;
	/* Cannot ftruncate over 2^31 bytes without large file support */
	if (small && length > MAX_NON_LFS)
		goto out_putf;

	error = -EPERM;
	if (IS_APPEND(inode))
		goto out_putf;

	error = locks_verify_truncate(inode, file, length);
	if (!error)
		error = security_path_truncate(&file->f_path, length,
					       ATTR_MTIME|ATTR_CTIME);
	if (!error)
		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
out_putf:
	fput(file);
out:
	return error;
}

SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
{
	long ret = do_sys_ftruncate(fd, length, 1);
	/* avoid REGPARM breakage on x86: */
	asmlinkage_protect(2, ret, fd, length);
	return ret;
}

/* LFS versions of truncate are only needed on 32 bit machines */
#if BITS_PER_LONG == 32
SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
{
	return do_sys_truncate(path, length);
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_truncate64(long path, loff_t length)
{
	return SYSC_truncate64((const char __user *) path, length);
}
SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
#endif

SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
{
	long ret = do_sys_ftruncate(fd, length, 0);
	/* avoid REGPARM breakage on x86: */
	asmlinkage_protect(2, ret, fd, length);
	return ret;
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_ftruncate64(long fd, loff_t length)
{
	return SYSC_ftruncate64((unsigned int) fd, length);
}
SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
#endif
#endif /* BITS_PER_LONG == 32 */


int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
{
	struct inode *inode = file->f_path.dentry->d_inode;
	long ret;

	if (offset < 0 || len <= 0)
		return -EINVAL;

	/* Return error if mode is not supported */
	if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
		return -EOPNOTSUPP;

	if (!(file->f_mode & FMODE_WRITE))
		return -EBADF;
	/*
	 * Revalidate the write permissions, in case security policy has
	 * changed since the files were opened.
	 */
	ret = security_file_permission(file, MAY_WRITE);
	if (ret)
		return ret;

	if (S_ISFIFO(inode->i_mode))
		return -ESPIPE;

	/*
	 * Let individual file system decide if it supports preallocation
	 * for directories or not.
	 */
	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
		return -ENODEV;

	/* Check for wrap through zero too */
	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
		return -EFBIG;

	if (!inode->i_op->fallocate)
		return -EOPNOTSUPP;

	return inode->i_op->fallocate(inode, mode, offset, len);
}

SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
{
	struct file *file;
	int error = -EBADF;

	file = fget(fd);
	if (file) {
		error = do_fallocate(file, mode, offset, len);
		fput(file);
	}

	return error;
}

#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
{
	return SYSC_fallocate((int)fd, (int)mode, offset, len);
}
SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
#endif

/*
 * access() needs to use the real uid/gid, not the effective uid/gid.
 * We do this by temporarily clearing all FS-related capabilities and
 * switching the fsuid/fsgid around to the real ones.
 */
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
{
	const struct cred *old_cred;
	struct cred *override_cred;
	struct path path;
	struct inode *inode;
	int res;

	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
		return -EINVAL;

	override_cred = prepare_creds();
	if (!override_cred)
		return -ENOMEM;

	override_cred->fsuid = override_cred->uid;
	override_cred->fsgid = override_cred->gid;

	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
		/* Clear the capabilities if we switch to a non-root user */
		if (override_cred->uid)
			cap_clear(override_cred->cap_effective);
		else
			override_cred->cap_effective =
				override_cred->cap_permitted;
	}

	old_cred = override_creds(override_cred);

	res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
	if (res)
		goto out;

	inode = path.dentry->d_inode;

	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
		/*
		 * MAY_EXEC on regular files is denied if the fs is mounted
		 * with the "noexec" flag.
		 */
		res = -EACCES;
		if (path.mnt->mnt_flags & MNT_NOEXEC)
			goto out_path_release;
	}

	res = inode_permission(inode, mode | MAY_ACCESS);
	/* SuS v2 requires we report a read only fs too */
	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
		goto out_path_release;
	/*
	 * This is a rare case where using __mnt_is_readonly()
	 * is OK without a mnt_want/drop_write() pair.  Since
	 * no actual write to the fs is performed here, we do
	 * not need to telegraph to that to anyone.
	 *
	 * By doing this, we accept that this access is
	 * inherently racy and know that the fs may change
	 * state before we even see this result.
	 */
	if (__mnt_is_readonly(path.mnt))
		res = -EROFS;

out_path_release:
	path_put(&path);
out:
	revert_creds(old_cred);
	put_cred(override_cred);
	return res;
}

SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
{
	return sys_faccessat(AT_FDCWD, filename, mode);
}

SYSCALL_DEFINE1(chdir, const char __user *, filename)
{
	struct path path;
	int error;

	error = user_path_dir(filename, &path);
	if (error)
		goto out;

	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
	if (error)
		goto dput_and_out;

	set_fs_pwd(current->fs, &path);

dput_and_out:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE1(fchdir, unsigned int, fd)
{
	struct file *file;
	struct inode *inode;
	int error;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;

	inode = file->f_path.dentry->d_inode;

	error = -ENOTDIR;
	if (!S_ISDIR(inode->i_mode))
		goto out_putf;

	error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
	if (!error)
		set_fs_pwd(current->fs, &file->f_path);
out_putf:
	fput(file);
out:
	return error;
}

SYSCALL_DEFINE1(chroot, const char __user *, filename)
{
	struct path path;
	int error;

	error = user_path_dir(filename, &path);
	if (error)
		goto out;

	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
	if (error)
		goto dput_and_out;

	error = -EPERM;
	if (!capable(CAP_SYS_CHROOT))
		goto dput_and_out;

	set_fs_root(current->fs, &path);
	error = 0;
dput_and_out:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
{
	struct inode * inode;
	struct dentry * dentry;
	struct file * file;
	int err = -EBADF;
	struct iattr newattrs;

	file = fget(fd);
	if (!file)
		goto out;

	dentry = file->f_path.dentry;
	inode = dentry->d_inode;

	audit_inode(NULL, dentry);

	err = mnt_want_write_file(file);
	if (err)
		goto out_putf;
	mutex_lock(&inode->i_mutex);
	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
	err = notify_change(dentry, &newattrs);
	mutex_unlock(&inode->i_mutex);
	mnt_drop_write(file->f_path.mnt);
out_putf:
	fput(file);
out:
	return err;
}

SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
{
	struct path path;
	struct inode *inode;
	int error;
	struct iattr newattrs;

	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
	if (error)
		goto out;
	inode = path.dentry->d_inode;

	error = mnt_want_write(path.mnt);
	if (error)
		goto dput_and_out;
	mutex_lock(&inode->i_mutex);
	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
	error = notify_change(path.dentry, &newattrs);
	mutex_unlock(&inode->i_mutex);
	mnt_drop_write(path.mnt);
dput_and_out:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
{
	return sys_fchmodat(AT_FDCWD, filename, mode);
}

static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
	struct inode *inode = dentry->d_inode;
	int error;
	struct iattr newattrs;

	newattrs.ia_valid =  ATTR_CTIME;
	if (user != (uid_t) -1) {
		newattrs.ia_valid |= ATTR_UID;
		newattrs.ia_uid = user;
	}
	if (group != (gid_t) -1) {
		newattrs.ia_valid |= ATTR_GID;
		newattrs.ia_gid = group;
	}
	if (!S_ISDIR(inode->i_mode))
		newattrs.ia_valid |=
			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
	mutex_lock(&inode->i_mutex);
	error = notify_change(dentry, &newattrs);
	mutex_unlock(&inode->i_mutex);

	return error;
}

SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
{
	struct path path;
	int error;

	error = user_path(filename, &path);
	if (error)
		goto out;
	error = mnt_want_write(path.mnt);
	if (error)
		goto out_release;
	error = chown_common(path.dentry, user, group);
	mnt_drop_write(path.mnt);
out_release:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
		gid_t, group, int, flag)
{
	struct path path;
	int error = -EINVAL;
	int follow;

	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
		goto out;

	follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
	error = user_path_at(dfd, filename, follow, &path);
	if (error)
		goto out;
	error = mnt_want_write(path.mnt);
	if (error)
		goto out_release;
	error = chown_common(path.dentry, user, group);
	mnt_drop_write(path.mnt);
out_release:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
{
	struct path path;
	int error;

	error = user_lpath(filename, &path);
	if (error)
		goto out;
	error = mnt_want_write(path.mnt);
	if (error)
		goto out_release;
	error = chown_common(path.dentry, user, group);
	mnt_drop_write(path.mnt);
out_release:
	path_put(&path);
out:
	return error;
}

SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
{
	struct file * file;
	int error = -EBADF;
	struct dentry * dentry;

	file = fget(fd);
	if (!file)
		goto out;

	error = mnt_want_write_file(file);
	if (error)
		goto out_fput;
	dentry = file->f_path.dentry;
	audit_inode(NULL, dentry);
	error = chown_common(dentry, user, group);
	mnt_drop_write(file->f_path.mnt);
out_fput:
	fput(file);
out:
	return error;
}

/*
 * You have to be very careful that these write
 * counts get cleaned up in error cases and
 * upon __fput().  This should probably never
 * be called outside of __dentry_open().
 */
static inline int __get_file_write_access(struct inode *inode,
					  struct vfsmount *mnt)
{
	int error;
	error = get_write_access(inode);
	if (error)
		return error;
	/*
	 * Do not take mount writer counts on
	 * special files since no writes to
	 * the mount itself will occur.
	 */
	if (!special_file(inode->i_mode)) {
		/*
		 * Balanced in __fput()
		 */
		error = mnt_want_write(mnt);
		if (error)
			put_write_access(inode);
	}
	return error;
}

static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
					int flags, struct file *f,
					int (*open)(struct inode *, struct file *),
					const struct cred *cred)
{
	struct inode *inode;
	int error;

	f->f_flags = flags;
	f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;
	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = __get_file_write_access(inode, mnt);
		if (error)
			goto cleanup_file;
		if (!special_file(inode->i_mode))
			file_take_write(f);
	}

	f->f_mapping = inode->i_mapping;
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
	f->f_pos = 0;
	f->f_op = fops_get(inode->i_fop);
	file_move(f, &inode->i_sb->s_files);

	error = security_dentry_open(f, cred);
	if (error)
		goto cleanup_all;

	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	/* NB: we're sure to have correct a_ops only after f_op->open */
	if (f->f_flags & O_DIRECT) {
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
		    (!f->f_mapping->a_ops->get_xip_mem))) {
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITE) {
		put_write_access(inode);
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
			mnt_drop_write(mnt);
		}
	}
	file_kill(f);
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

/**
 * lookup_instantiate_filp - instantiates the open intent filp
 * @nd: pointer to nameidata
 * @dentry: pointer to dentry
 * @open: open callback
 *
 * Helper for filesystems that want to use lookup open intents and pass back
 * a fully instantiated struct file to the caller.
 * This function is meant to be called from within a filesystem's
 * lookup method.
 * Beware of calling it for non-regular files! Those ->open methods might block
 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
 * leading to a deadlock, as nobody can open that fifo anymore, because
 * another process to open fifo will block on locked parent when doing lookup).
 * Note that in case of error, nd->intent.open.file is destroyed, but the
 * path information remains valid.
 * If the open callback is set to NULL, then the standard f_op->open()
 * filesystem callback is substituted.
 */
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
		int (*open)(struct inode *, struct file *))
{
	const struct cred *cred = current_cred();

	if (IS_ERR(nd->intent.open.file))
		goto out;
	if (IS_ERR(dentry))
		goto out_err;
	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
					     nd->intent.open.flags - 1,
					     nd->intent.open.file,
					     open, cred);
out:
	return nd->intent.open.file;
out_err:
	release_open_intent(nd);
	nd->intent.open.file = (struct file *)dentry;
	goto out;
}
EXPORT_SYMBOL_GPL(lookup_instantiate_filp);

/**
 * nameidata_to_filp - convert a nameidata to an open filp.
 * @nd: pointer to nameidata
 * @flags: open flags
 *
 * Note that this function destroys the original nameidata
 */
struct file *nameidata_to_filp(struct nameidata *nd, int flags)
{
	const struct cred *cred = current_cred();
	struct file *filp;

	/* Pick up the filp from the open intent */
	filp = nd->intent.open.file;
	/* Has the filesystem initialised the file for us? */
	if (filp->f_path.dentry == NULL)
		filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
				     NULL, cred);
	else
		path_put(&nd->path);
	return filp;
}

/*
 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 * error.
 */
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
			 const struct cred *cred)
{
	int error;
	struct file *f;

	/*
	 * We must always pass in a valid mount pointer.   Historically
	 * callers got away with not passing it, but we must enforce this at
	 * the earliest possible point now to avoid strange problems deep in the
	 * filesystem stack.
	 */
	if (!mnt) {
		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
		dump_stack();
		return ERR_PTR(-EINVAL);
	}

	error = -ENFILE;
	f = get_empty_filp();
	if (f == NULL) {
		dput(dentry);
		mntput(mnt);
		return ERR_PTR(error);
	}

	return __dentry_open(dentry, mnt, flags, f, NULL, cred);
}
EXPORT_SYMBOL(dentry_open);

static void __put_unused_fd(struct files_struct *files, unsigned int fd)
{
	struct fdtable *fdt = files_fdtable(files);
	__FD_CLR(fd, fdt->open_fds);
	if (fd < files->next_fd)
		files->next_fd = fd;
}

void put_unused_fd(unsigned int fd)
{
	struct files_struct *files = current->files;
	spin_lock(&files->file_lock);
	__put_unused_fd(files, fd);
	spin_unlock(&files->file_lock);
}

EXPORT_SYMBOL(put_unused_fd);

/*
 * Install a file pointer in the fd array.
 *
 * The VFS is full of places where we drop the files lock between
 * setting the open_fds bitmap and installing the file in the file
 * array.  At any such point, we are vulnerable to a dup2() race
 * installing a file in the array before us.  We need to detect this and
 * fput() the struct file we are about to overwrite in this case.
 *
 * It should never happen - if we allow dup2() do it, _really_ bad things
 * will follow.
 */

void fd_install(unsigned int fd, struct file *file)
{
	struct files_struct *files = current->files;
	struct fdtable *fdt;
	spin_lock(&files->file_lock);
	fdt = files_fdtable(files);
	BUG_ON(fdt->fd[fd] != NULL);
	rcu_assign_pointer(fdt->fd[fd], file);
	spin_unlock(&files->file_lock);
}

EXPORT_SYMBOL(fd_install);

long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
{
	char *tmp = getname(filename);
	int fd = PTR_ERR(tmp);

	if (!IS_ERR(tmp)) {
		fd = get_unused_fd_flags(flags);
		if (fd >= 0) {
			struct file *f = do_filp_open(dfd, tmp, flags, mode, 0);
			if (IS_ERR(f)) {
				put_unused_fd(fd);
				fd = PTR_ERR(f);
			} else {
				fsnotify_open(f->f_path.dentry);
				fd_install(fd, f);
			}
		}
		putname(tmp);
	}
	return fd;
}

SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
{
	long ret;

	if (force_o_largefile())
		flags |= O_LARGEFILE;

	ret = do_sys_open(AT_FDCWD, filename, flags, mode);
	/* avoid REGPARM breakage on x86: */
	asmlinkage_protect(3, ret, filename, flags, mode);
	return ret;
}

SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
		int, mode)
{
	long ret;

	if (force_o_largefile())
		flags |= O_LARGEFILE;

	ret = do_sys_open(dfd, filename, flags, mode);
	/* avoid REGPARM breakage on x86: */
	asmlinkage_protect(4, ret, dfd, filename, flags, mode);
	return ret;
}

#ifndef __alpha__

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
{
	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
}

#endif

/*
 * "id" is the POSIX thread ID. We use the
 * files pointer for this..
 */
int filp_close(struct file *filp, fl_owner_t id)
{
	int retval = 0;

	if (!file_count(filp)) {
		printk(KERN_ERR "VFS: Close: file count is 0\n");
		return 0;
	}

	if (filp->f_op && filp->f_op->flush)
		retval = filp->f_op->flush(filp, id);

	dnotify_flush(filp, id);
	locks_remove_posix(filp, id);
	fput(filp);
	return retval;
}

EXPORT_SYMBOL(filp_close);

/*
 * Careful here! We test whether the file pointer is NULL before
 * releasing the fd. This ensures that one clone task can't release
 * an fd while another clone is opening it.
 */
SYSCALL_DEFINE1(close, unsigned int, fd)
{
	struct file * filp;
	struct files_struct *files = current->files;
	struct fdtable *fdt;
	int retval;

	spin_lock(&files->file_lock);
	fdt = files_fdtable(files);
	if (fd >= fdt->max_fds)
		goto out_unlock;
	filp = fdt->fd[fd];
	if (!filp)
		goto out_unlock;
	rcu_assign_pointer(fdt->fd[fd], NULL);
	FD_CLR(fd, fdt->close_on_exec);
	__put_unused_fd(files, fd);
	spin_unlock(&files->file_lock);
	retval = filp_close(filp, files);

	/* can't restart close syscall because file table entry was cleared */
	if (unlikely(retval == -ERESTARTSYS ||
		     retval == -ERESTARTNOINTR ||
		     retval == -ERESTARTNOHAND ||
		     retval == -ERESTART_RESTARTBLOCK))
		retval = -EINTR;

	return retval;

out_unlock:
	spin_unlock(&files->file_lock);
	return -EBADF;
}
EXPORT_SYMBOL(sys_close);

/*
 * This routine simulates a hangup on the tty, to arrange that users
 * are given clean terminals at login time.
 */
SYSCALL_DEFINE0(vhangup)
{
	if (capable(CAP_SYS_TTY_CONFIG)) {
		tty_vhangup_self();