unix_io.c revision 7e7bd3dccbfe8f79e25e5c1554b5bc3a9aaca321
/**
* unix_io.c - Unix style disk io functions. Part of the Linux-NTFS project.
*
* Copyright (c) 2000-2006 Anton Altaparmakov
*
* This program/include file 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program/include file 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 (in the main directory of the Linux-NTFS
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_LINUX_FD_H
#include <linux/fd.h>
#endif
#include "types.h"
#include "mst.h"
#include "debug.h"
#include "device.h"
#include "logging.h"
#define DEV_FD(dev) (*(int *)dev->d_private)
/* Define to nothing if not present on this system. */
#ifndef O_EXCL
# define O_EXCL 0
#endif
/**
* ntfs_device_unix_io_open - Open a device and lock it exclusively
* @dev:
* @flags:
*
* Description...
*
* Returns:
*/
static int ntfs_device_unix_io_open(struct ntfs_device *dev, int flags)
{
struct flock flk;
struct stat sbuf;
int err;
if (NDevOpen(dev)) {
errno = EBUSY;
return -1;
}
if (!(dev->d_private = ntfs_malloc(sizeof(int))))
return -1;
*(int*)dev->d_private = open(dev->d_name, flags);
if (*(int*)dev->d_private == -1) {
err = errno;
goto err_out;
}
/* Setup our read-only flag. */
if ((flags & O_RDWR) != O_RDWR)
NDevSetReadOnly(dev);
/* Acquire exclusive (mandatory) lock on the whole device. */
memset(&flk, 0, sizeof(flk));
if (NDevReadOnly(dev))
flk.l_type = F_RDLCK;
else
flk.l_type = F_WRLCK;
flk.l_whence = SEEK_SET;
flk.l_start = flk.l_len = 0LL;
if (fcntl(DEV_FD(dev), F_SETLK, &flk)) {
err = errno;
ntfs_log_debug("ntfs_device_unix_io_open: Could not lock %s "
"for %s\n", dev->d_name, NDevReadOnly(dev) ?
"reading" : "writing");
if (close(DEV_FD(dev)))
ntfs_log_perror("ntfs_device_unix_io_open: Warning: "
"Could not close %s", dev->d_name);
goto err_out;
}
/* Determine if device is a block device or not, ignoring errors. */
if (!fstat(DEV_FD(dev), &sbuf) && S_ISBLK(sbuf.st_mode))
NDevSetBlock(dev);
/* Set our open flag. */
NDevSetOpen(dev);
return 0;
err_out:
free(dev->d_private);
dev->d_private = NULL;
errno = err;
return -1;
}
/**
* ntfs_device_unix_io_close - Close the device, releasing the lock
* @dev:
*
* Description...
*
* Returns:
*/
static int ntfs_device_unix_io_close(struct ntfs_device *dev)
{
struct flock flk;
if (!NDevOpen(dev)) {
errno = EBADF;
return -1;
}
if (NDevDirty(dev))
fsync(DEV_FD(dev));
/* Release exclusive (mandatory) lock on the whole device. */
memset(&flk, 0, sizeof(flk));
flk.l_type = F_UNLCK;
flk.l_whence = SEEK_SET;
flk.l_start = flk.l_len = 0LL;
if (fcntl(DEV_FD(dev), F_SETLK, &flk))
ntfs_log_perror("ntfs_device_unix_io_close: Warning: Could not "
"unlock %s", dev->d_name);
/* Close the file descriptor and clear our open flag. */
if (close(DEV_FD(dev)))
return -1;
NDevClearOpen(dev);
free(dev->d_private);
dev->d_private = NULL;
return 0;
}
/**
* ntfs_device_unix_io_seek - Seek to a place on the device
* @dev:
* @offset:
* @whence:
*
* Description...
*
* Returns:
*/
static s64 ntfs_device_unix_io_seek(struct ntfs_device *dev, s64 offset,
int whence)
{
return lseek(DEV_FD(dev), offset, whence);
}
/**
* ntfs_device_unix_io_read - Read from the device, from the current location
* @dev:
* @buf:
* @count:
*
* Description...
*
* Returns:
*/
static s64 ntfs_device_unix_io_read(struct ntfs_device *dev, void *buf,
s64 count)
{
return read(DEV_FD(dev), buf, count);
}
/**
* ntfs_device_unix_io_write - Write to the device, at the current location
* @dev:
* @buf:
* @count:
*
* Description...
*
* Returns:
*/
static s64 ntfs_device_unix_io_write(struct ntfs_device *dev, const void *buf,
s64 count)
{
if (NDevReadOnly(dev)) {
errno = EROFS;
return -1;
}
NDevSetDirty(dev);
return write(DEV_FD(dev), buf, count);
}
/**
* ntfs_device_unix_io_pread - Perform a positioned read from the device
* @dev:
* @buf:
* @count:
* @offset:
*
* Description...
*
* Returns:
*/
static s64 ntfs_device_unix_io_pread(struct ntfs_device *dev, void *buf,
s64 count, s64 offset)
{
return pread(DEV_FD(dev), buf, count, offset);
}
/**
* ntfs_device_unix_io_pwrite - Perform a positioned write to the device
* @dev:
* @buf:
* @count:
* @offset:
*
* Description...
*
* Returns:
*/
static s64 ntfs_device_unix_io_pwrite(struct ntfs_device *dev, const void *buf,
s64 count, s64 offset)
{
if (NDevReadOnly(dev)) {
errno = EROFS;
return -1;
}
NDevSetDirty(dev);
return pwrite(DEV_FD(dev), buf, count, offset);
}
/**
* ntfs_device_unix_io_sync - Flush any buffered changes to the device
* @dev:
*
* Description...
*
* Returns:
*/
static int ntfs_device_unix_io_sync(struct ntfs_device *dev)
{
if (!NDevReadOnly(dev) && NDevDirty(dev)) {
int res = fsync(DEV_FD(dev));
if (!res)
NDevClearDirty(dev);
return res;
}
return 0;
}
/**
* ntfs_device_unix_io_stat - Get information about the device
* @dev:
* @buf:
*
* Description...
*
* Returns:
*/
static int ntfs_device_unix_io_stat(struct ntfs_device *dev, struct stat *buf)
{
return fstat(DEV_FD(dev), buf);
}
/**
* ntfs_device_unix_io_ioctl - Perform an ioctl on the device
* @dev:
* @request:
* @argp:
*
* Description...
*
* Returns:
*/
static int ntfs_device_unix_io_ioctl(struct ntfs_device *dev, int request,
void *argp)
{
return ioctl(DEV_FD(dev), request, argp);
}
/**
* Device operations for working with unix style devices and files.
*/
struct ntfs_device_operations ntfs_device_unix_io_ops = {
.open = ntfs_device_unix_io_open,
.close = ntfs_device_unix_io_close,
.seek = ntfs_device_unix_io_seek,
.read = ntfs_device_unix_io_read,
.write = ntfs_device_unix_io_write,
.pread = ntfs_device_unix_io_pread,
.pwrite = ntfs_device_unix_io_pwrite,
.sync = ntfs_device_unix_io_sync,
.stat = ntfs_device_unix_io_stat,
.ioctl = ntfs_device_unix_io_ioctl,
};