volume.c

添加linux下对NTFS格式文件系统访问支持的源代码ntfs-3g

		/* Get a pointer to the value of the attribute. */
		vname = (ntfschar*)(le16_to_cpu(a->value_offset) + (char*)a);
		u = le32_to_cpu(a->value_length) / 2;
		/*
		 * Convert Unicode volume name to current locale multibyte
		 * format.
		 */
		vol->vol_name = NULL;
		if (ntfs_ucstombs(vname, u, &vol->vol_name, 0) == -1) {
			ntfs_log_perror("Volume name could not be converted "
					"to current locale");
			ntfs_log_debug("Forcing name into ASCII by replacing "
				"non-ASCII characters with underscores.\n");
			vol->vol_name = ntfs_malloc(u + 1);
			if (!vol->vol_name) {
				ntfs_log_debug(FAILED);
				goto error_exit;
			}
			for (j = 0; j < (s32)u; j++) {
				ntfschar uc = le16_to_cpu(vname[j]);
				if (uc > 0xff)
					uc = (ntfschar)'_';
				vol->vol_name[j] = (char)uc;
			}
			vol->vol_name[u] = '\0';
		}
	}
	ntfs_log_debug(OK);
	ntfs_attr_put_search_ctx(ctx);
	ctx = NULL;
	/* Now load the attribute definitions from $AttrDef. */
	ntfs_log_debug("Loading $AttrDef... ");
	ni = ntfs_inode_open(vol, FILE_AttrDef);
	if (!ni) {
		ntfs_log_debug(FAILED);
		ntfs_log_perror("Failed to open $AttrDef");
		goto error_exit;
	}
	/* Get an ntfs attribute for $AttrDef/$DATA. */
	na = ntfs_attr_open(ni, AT_DATA, AT_UNNAMED, 0);
	if (!na) {
		ntfs_log_debug(FAILED);
		ntfs_log_perror("Failed to open ntfs attribute");
		goto error_exit;
	}
	/* Check we don't overflow 32-bits. */
	if (na->data_size > 0xffffffffLL) {
		ntfs_log_debug(FAILED);
		ntfs_log_error("Attribute definition table is too big (max "
			       "32-bit allowed).\n");
		errno = EINVAL;
		goto error_exit;
	}
	vol->attrdef_len = na->data_size;
	vol->attrdef = ntfs_malloc(na->data_size);
	if (!vol->attrdef) {
		ntfs_log_debug(FAILED);
		goto error_exit;
	}
	/* Read in the $DATA attribute value into the buffer. */
	l = ntfs_attr_pread(na, 0, na->data_size, vol->attrdef);
	if (l != na->data_size) {
		ntfs_log_debug(FAILED);
		ntfs_log_error("Failed to read $AttrDef, unexpected length "
			       "(%lld != %lld).\n", (long long)l,
			       (long long)na->data_size);
		errno = EIO;
		goto error_exit;
	}
	/* Done with the $AttrDef mft record. */
	ntfs_log_debug(OK);
	ntfs_attr_close(na);
	if (ntfs_inode_close(ni))
		ntfs_log_perror("Failed to close inode, leaking memory");
	/*
	 * Check for dirty logfile and hibernated Windows.
	 * We care only about read-write mounts.
	 */
	if (!(flags & MS_RDONLY)) {
		if (ntfs_volume_check_logfile(vol) < 0)
			goto error_exit;
		if (ntfs_volume_check_hiberfile(vol) < 0)
			goto error_exit;
	}

	return vol;
io_error_exit:
	errno = EIO;
error_exit:
	eo = errno;
	if (ctx)
		ntfs_attr_put_search_ctx(ctx);
	free(m);
	free(m2);
	__ntfs_volume_release(vol);
	errno = eo;
	return NULL;
}

/**
 * ntfs_mount - open ntfs volume
 * @name:	name of device/file to open
 * @flags:	optional mount flags
 *
 * This function mounts an ntfs volume. @name should contain the name of the
 * device/file to mount as the ntfs volume.
 *
 * @flags is an optional second parameter. The same flags are used as for
 * the mount system call (man 2 mount). Currently only the following flags
 * are implemented:
 *	MS_RDONLY	- mount volume read-only
 *	MS_NOATIME	- do not update access time
 *
 * The function opens the device or file @name and verifies that it contains a
 * valid bootsector. Then, it allocates an ntfs_volume structure and initializes
 * some of the values inside the structure from the information stored in the
 * bootsector. It proceeds to load the necessary system files and completes
 * setting up the structure.
 *
 * Return the allocated volume structure on success and NULL on error with
 * errno set to the error code.
 *
 * Note, that a copy is made of @name, and hence it can be discarded as
 * soon as the function returns.
 */
ntfs_volume *ntfs_mount(const char *name __attribute__((unused)),
		unsigned long flags __attribute__((unused)))
{
#ifndef NO_NTFS_DEVICE_DEFAULT_IO_OPS
	struct ntfs_device *dev;
	ntfs_volume *vol;

	/* Allocate an ntfs_device structure. */
	dev = ntfs_device_alloc(name, 0, &ntfs_device_default_io_ops, NULL);
	if (!dev)
		return NULL;
	/* Call ntfs_device_mount() to do the actual mount. */
	vol = ntfs_device_mount(dev, flags);
	if (!vol) {
		int eo = errno;
		ntfs_device_free(dev);
		errno = eo;
	}
	return vol;
#else
	/*
	 * ntfs_mount() makes no sense if NO_NTFS_DEVICE_DEFAULT_IO_OPS is
	 * defined as there are no device operations available in libntfs in
	 * this case.
	 */
	errno = EOPNOTSUPP;
	return NULL;
#endif
}

/**
 * ntfs_device_umount - close ntfs volume
 * @vol: address of ntfs_volume structure of volume to close
 * @force: if true force close the volume even if it is busy
 *
 * Deallocate all structures (including @vol itself) associated with the ntfs
 * volume @vol.
 *
 * Note it is up to the caller to destroy the device associated with the volume
 * being unmounted after this function returns.
 *
 * Return 0 on success. On error return -1 with errno set appropriately
 * (most likely to one of EAGAIN, EBUSY or EINVAL). The EAGAIN error means that
 * an operation is in progress and if you try the close later the operation
 * might be completed and the close succeed.
 *
 * If @force is true (i.e. not zero) this function will close the volume even
 * if this means that data might be lost.
 *
 * @vol must have previously been returned by a call to ntfs_device_mount().
 *
 * @vol itself is deallocated and should no longer be dereferenced after this
 * function returns success. If it returns an error then nothing has been done
 * so it is safe to continue using @vol.
 */
int ntfs_device_umount(ntfs_volume *vol,
		const BOOL force __attribute__((unused)))
{
	if (!vol) {
		errno = EINVAL;
		return -1;
	}
	__ntfs_volume_release(vol);
	return 0;
}

/**
 * ntfs_umount - close ntfs volume
 * @vol: address of ntfs_volume structure of volume to close
 * @force: if true force close the volume even if it is busy
 *
 * Deallocate all structures (including @vol itself) associated with the ntfs
 * volume @vol.
 *
 * Return 0 on success. On error return -1 with errno set appropriately
 * (most likely to one of EAGAIN, EBUSY or EINVAL). The EAGAIN error means that
 * an operation is in progress and if you try the close later the operation
 * might be completed and the close succeed.
 *
 * If @force is true (i.e. not zero) this function will close the volume even
 * if this means that data might be lost.
 *
 * @vol must have previously been returned by a call to ntfs_mount().
 *
 * @vol itself is deallocated and should no longer be dereferenced after this
 * function returns success. If it returns an error then nothing has been done
 * so it is safe to continue using @vol.
 */
int ntfs_umount(ntfs_volume *vol,
		const BOOL force __attribute__((unused)))
{
	struct ntfs_device *dev;

	if (!vol) {
		errno = EINVAL;
		return -1;
	}
	dev = vol->dev;
	__ntfs_volume_release(vol);
	ntfs_device_free(dev);
	return 0;
}

#ifdef HAVE_MNTENT_H

#ifndef HAVE_REALPATH
/**
 * realpath - If there is no realpath on the system
 */
static char *realpath(const char *path, char *resolved_path)
{
	strncpy(resolved_path, path, PATH_MAX);
	resolved_path[PATH_MAX] = '\0';
	return resolved_path;
}
#endif

/**
 * ntfs_mntent_check - desc
 *
 * If you are wanting to use this, you actually wanted to use
 * ntfs_check_if_mounted(), you just didn't realize. (-:
 *
 * See description of ntfs_check_if_mounted(), below.
 */
static int ntfs_mntent_check(const char *file, unsigned long *mnt_flags)
{
	struct mntent *mnt;
	char *real_file = NULL, *real_fsname = NULL;
	FILE *f;
	int err = 0;

	real_file = ntfs_malloc(PATH_MAX + 1);
	if (!real_file)
		return -1;
	real_fsname = ntfs_malloc(PATH_MAX + 1);
	if (!real_fsname) {
		err = errno;
		goto exit;
	}
	if (!realpath(file, real_file)) {
		err = errno;
		goto exit;
	}
	if (!(f = setmntent(MOUNTED, "r"))) {
		err = errno;
		goto exit;
	}
	while ((mnt = getmntent(f))) {
		if (!realpath(mnt->mnt_fsname, real_fsname))
			continue;
		if (!strcmp(real_file, real_fsname))
			break;
	}
	endmntent(f);
	if (!mnt)
		goto exit;
	*mnt_flags = NTFS_MF_MOUNTED;
	if (!strcmp(mnt->mnt_dir, "/"))
		*mnt_flags |= NTFS_MF_ISROOT;
#ifdef HAVE_HASMNTOPT
	if (hasmntopt(mnt, "ro") && !hasmntopt(mnt, "rw"))
		*mnt_flags |= NTFS_MF_READONLY;
#endif
exit:
	free(real_file);
	free(real_fsname);
	if (err) {
		errno = err;
		return -1;
	}
	return 0;
}
#endif /* HAVE_MNTENT_H */

/**
 * ntfs_check_if_mounted - check if an ntfs volume is currently mounted
 * @file:	device file to check
 * @mnt_flags:	pointer into which to return the ntfs mount flags (see volume.h)
 *
 * If the running system does not support the {set,get,end}mntent() calls,
 * just return 0 and set *@mnt_flags to zero.
 *
 * When the system does support the calls, ntfs_check_if_mounted() first tries
 * to find the device @file in /etc/mtab (or wherever this is kept on the
 * running system). If it is not found, assume the device is not mounted and
 * return 0 and set *@mnt_flags to zero.
 *
 * If the device @file is found, set the NTFS_MF_MOUNTED flags in *@mnt_flags.
 *
 * Further if @file is mounted as the file system root ("/"), set the flag
 * NTFS_MF_ISROOT in *@mnt_flags.
 *
 * Finally, check if the file system is mounted read-only, and if so set the
 * NTFS_MF_READONLY flag in *@mnt_flags.
 *
 * On success return 0 with *@mnt_flags set to the ntfs mount flags.
 *
 * On error return -1 with errno set to the error code.
 */
int ntfs_check_if_mounted(const char *file __attribute__((unused)),
		unsigned long *mnt_flags)
{
	*mnt_flags = 0;
#ifdef HAVE_MNTENT_H
	return ntfs_mntent_check(file, mnt_flags);
#else
	return 0;
#endif
}

/**
 * ntfs_version_is_supported - check if NTFS version is supported.
 * @vol:	ntfs volume whose version we're interested in.
 *
 * The function checks if the NTFS volume version is known or not.
 * Version 1.1 and 1.2 are used by Windows NT3.x and NT4.
 * Version 2.x is used by Windows 2000 Betas.
 * Version 3.0 is used by Windows 2000.
 * Version 3.1 is used by Windows XP, Windows Server 2003 and Longhorn.
 *
 * Return 0 if NTFS version is supported otherwise -1 with errno set.
 *
 * The following error codes are defined:
 *	EOPNOTSUPP - Unknown NTFS version
 *	EINVAL	   - Invalid argument
 */
int ntfs_version_is_supported(ntfs_volume *vol)
{
	u8 major, minor;

	if (!vol) {
		errno = EINVAL;
		return -1;
	}

	major = vol->major_ver;
	minor = vol->minor_ver;

	if (NTFS_V1_1(major, minor) || NTFS_V1_2(major, minor))
		return 0;

	if (NTFS_V2_X(major, minor))
		return 0;

	if (NTFS_V3_0(major, minor) || NTFS_V3_1(major, minor))
		return 0;

	errno = EOPNOTSUPP;
	return -1;
}

/**
 * ntfs_logfile_reset - "empty" $LogFile data attribute value
 * @vol:	ntfs volume whose $LogFile we intend to reset.
 *
 * Fill the value of the $LogFile data attribute, i.e. the contents of
 * the file, with 0xff's, thus marking the journal as empty.
 *
 * FIXME(?): We might need to zero the LSN field of every single mft
 * record as well. (But, first try without doing that and see what
 * happens, since chkdsk might pickup the pieces and do it for us...)
 *
 * On success return 0.
 *
 * On error return -1 with errno set to the error code.
 */
int ntfs_logfile_reset(ntfs_volume *vol)
{
	ntfs_inode *ni;
	ntfs_attr *na;
	int eo;

	if (!vol) {
		errno = EINVAL;
		return -1;
	}

	if ((ni = ntfs_inode_open(vol, FILE_LogFile)) == NULL) {
		ntfs_log_perror("Failed to open inode FILE_LogFile.");
		return -1;
	}

	if ((na = ntfs_attr_open(ni, AT_DATA, AT_UNNAMED, 0)) == NULL) {
		eo = errno;
		ntfs_log_perror("Failed to open $FILE_LogFile/$DATA");
		goto error_exit;
	}

	if (ntfs_empty_logfile(na)) {
		eo = errno;
		ntfs_log_perror("Failed to empty $FILE_LogFile/$DATA");
		ntfs_attr_close(na);
		goto error_exit;
	}
	ntfs_attr_close(na);
	return ntfs_inode_close(ni);

error_exit:
	ntfs_inode_close(ni);
	errno = eo;
	return -1;
}

/**
 * ntfs_volume_write_flags - set the flags of an ntfs volume
 * @vol:	ntfs volume where we set the volume flags
 * @flags:	new flags
 *
 * Set the on-disk volume flags in the mft record of $Volume and
 * on volume @vol to @flags.
 *
 * Return 0 if successful and -1 if not with errno set to the error code.
 */
int ntfs_volume_write_flags(ntfs_volume *vol, const u16 flags)
{
	ATTR_RECORD *a;
	VOLUME_INFORMATION *c;
	ntfs_attr_search_ctx *ctx;
	int ret = -1;	/* failure */

	if (!vol || !vol->vol_ni) {
		errno = EINVAL;
		return -1;
	}
	/* Get a pointer to the volume information attribute. */
	ctx = ntfs_attr_get_search_ctx(vol->vol_ni, NULL);
	if (!ctx) {
		ntfs_log_perror("Failed to allocate attribute search context");
		return -1;
	}
	if (ntfs_attr_lookup(AT_VOLUME_INFORMATION, AT_UNNAMED, 0, 0, 0, NULL,
			0, ctx)) {
		ntfs_log_error("Attribute $VOLUME_INFORMATION was not found "
			       "in $Volume!\n");
		goto err_out;
	}
	a = ctx->attr;
	/* Sanity check. */
	if (a->non_resident) {
		ntfs_log_error("Attribute $VOLUME_INFORMATION must be resident "
			       "but it isn't.\n");
		errno = EIO;
		goto err_out;
	}
	/* Get a pointer to the value of the attribute. */
	c = (VOLUME_INFORMATION*)(le16_to_cpu(a->value_offset) + (char*)a);
	/* Sanity checks. */
	if ((char*)c + le32_to_cpu(a->value_length) > (char*)ctx->mrec +
			le32_to_cpu(ctx->mrec->bytes_in_use) ||
			le16_to_cpu(a->value_offset) +
			le32_to_cpu(a->value_length) > le32_to_cpu(a->length)) {
		ntfs_log_error("Attribute $VOLUME_INFORMATION in $Volume is "
			       "corrupt!\n");
		errno = EIO;
		goto err_out;
	}
	/* Set the volume flags. */
	vol->flags = c->flags = flags & VOLUME_FLAGS_MASK;
	/* Write them to disk. */
	ntfs_inode_mark_dirty(vol->vol_ni);
	if (ntfs_inode_sync(vol->vol_ni)) {
		ntfs_log_perror("Error writing $Volume");
		goto err_out;
	}
	ret = 0; /* success */
err_out:
	ntfs_attr_put_search_ctx(ctx);
	return ret;
}