dir.c

linux环境下基于FAT的文件系统的通用代码

EXPORT_SYMBOL_GPL(fat_search_long);

struct fat_ioctl_filldir_callback {
	void __user *dirent;
	int result;
	/* for dir ioctl */
	const char *longname;
	int long_len;
	const char *shortname;
	int short_len;
};

static int __fat_readdir(struct inode *inode, struct file *filp, void *dirent,
			 filldir_t filldir, int short_only, int both)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	struct nls_table *nls_disk = sbi->nls_disk;
	unsigned char nr_slots;
	wchar_t bufuname[14];
	wchar_t *unicode = NULL;
	unsigned char c, work[MSDOS_NAME];
	unsigned char bufname[FAT_MAX_SHORT_SIZE], *ptname = bufname;
	unsigned short opt_shortname = sbi->options.shortname;
	int isvfat = sbi->options.isvfat;
	int nocase = sbi->options.nocase;
	const char *fill_name = NULL;
	unsigned long inum;
	unsigned long lpos, dummy, *furrfu = &lpos;
	loff_t cpos;
	int chi, chl, i, i2, j, last, last_u, dotoffset = 0, fill_len = 0;
	int ret = 0;

	lock_super(sb);

	cpos = filp->f_pos;
	/* Fake . and .. for the root directory. */
	if (inode->i_ino == MSDOS_ROOT_INO) {
		while (cpos < 2) {
			if (filldir(dirent, "..", cpos+1, cpos, MSDOS_ROOT_INO, DT_DIR) < 0)
				goto out;
			cpos++;
			filp->f_pos++;
		}
		if (cpos == 2) {
			dummy = 2;
			furrfu = &dummy;
			cpos = 0;
		}
	}
	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
		ret = -ENOENT;
		goto out;
	}

	bh = NULL;
get_new:
	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
		goto end_of_dir;
parse_record:
	nr_slots = 0;
	/*
	 * Check for long filename entry, but if short_only, we don't
	 * need to parse long filename.
	 */
	if (isvfat && !short_only) {
		if (de->name[0] == DELETED_FLAG)
			goto record_end;
		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
			goto record_end;
		if (de->attr != ATTR_EXT && IS_FREE(de->name))
			goto record_end;
	} else {
		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
			goto record_end;
	}

	if (isvfat && de->attr == ATTR_EXT) {
		int status = fat_parse_long(inode, &cpos, &bh, &de,
					    &unicode, &nr_slots);
		if (status < 0) {
			filp->f_pos = cpos;
			ret = status;
			goto out;
		} else if (status == PARSE_INVALID)
			goto record_end;
		else if (status == PARSE_NOT_LONGNAME)
			goto parse_record;
		else if (status == PARSE_EOF)
			goto end_of_dir;

		if (nr_slots) {
			void *longname = unicode + FAT_MAX_UNI_CHARS;
			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
			int len = fat_uni_to_x8(sbi, unicode, longname, size);

			fill_name = longname;
			fill_len = len;
			/* !both && !short_only, so we don't need shortname. */
			if (!both)
				goto start_filldir;
		}
	}

	if (sbi->options.dotsOK) {
		ptname = bufname;
		dotoffset = 0;
		if (de->attr & ATTR_HIDDEN) {
			*ptname++ = '.';
			dotoffset = 1;
		}
	}

	memcpy(work, de->name, sizeof(de->name));
	/* see namei.c, msdos_format_name */
	if (work[0] == 0x05)
		work[0] = 0xE5;
	for (i = 0, j = 0, last = 0, last_u = 0; i < 8;) {
		if (!(c = work[i]))
			break;
		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
					&bufuname[j++], opt_shortname,
					de->lcase & CASE_LOWER_BASE);
		if (chl <= 1) {
			ptname[i++] = (!nocase && c>='A' && c<='Z') ? c+32 : c;
			if (c != ' ') {
				last = i;
				last_u = j;
			}
		} else {
			last_u = j;
			for (chi = 0; chi < chl && i < 8; chi++) {
				ptname[i] = work[i];
				i++; last = i;
			}
		}
	}
	i = last;
	j = last_u;
	fat_short2uni(nls_disk, ".", 1, &bufuname[j++]);
	ptname[i++] = '.';
	for (i2 = 8; i2 < MSDOS_NAME;) {
		if (!(c = work[i2]))
			break;
		chl = fat_shortname2uni(nls_disk, &work[i2], MSDOS_NAME - i2,
					&bufuname[j++], opt_shortname,
					de->lcase & CASE_LOWER_EXT);
		if (chl <= 1) {
			i2++;
			ptname[i++] = (!nocase && c>='A' && c<='Z') ? c+32 : c;
			if (c != ' ') {
				last = i;
				last_u = j;
			}
		} else {
			last_u = j;
			for (chi = 0; chi < chl && i2 < MSDOS_NAME; chi++) {
				ptname[i++] = work[i2++];
				last = i;
			}
		}
	}
	if (!last)
		goto record_end;

	i = last + dotoffset;
	j = last_u;

	if (isvfat) {
		bufuname[j] = 0x0000;
		i = fat_uni_to_x8(sbi, bufuname, bufname, sizeof(bufname));
	}
	if (nr_slots) {
		/* hack for fat_ioctl_filldir() */
		struct fat_ioctl_filldir_callback *p = dirent;

		p->longname = fill_name;
		p->long_len = fill_len;
		p->shortname = bufname;
		p->short_len = i;
		fill_name = NULL;
		fill_len = 0;
	} else {
		fill_name = bufname;
		fill_len = i;
	}

start_filldir:
	lpos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME))
		inum = inode->i_ino;
	else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
		inum = parent_ino(filp->f_path.dentry);
	} else {
		loff_t i_pos = fat_make_i_pos(sb, bh, de);
		struct inode *tmp = fat_iget(sb, i_pos);
		if (tmp) {
			inum = tmp->i_ino;
			iput(tmp);
		} else
			inum = iunique(sb, MSDOS_ROOT_INO);
	}

	if (filldir(dirent, fill_name, fill_len, *furrfu, inum,
		    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG) < 0)
		goto fill_failed;

record_end:
	furrfu = &lpos;
	filp->f_pos = cpos;
	goto get_new;
end_of_dir:
	filp->f_pos = cpos;
fill_failed:
	brelse(bh);
	if (unicode)
		__putname(unicode);
out:
	unlock_super(sb);
	return ret;
}

static int fat_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
	struct inode *inode = filp->f_path.dentry->d_inode;
	return __fat_readdir(inode, filp, dirent, filldir, 0, 0);
}

#define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
static int func(void *__buf, const char *name, int name_len,		   \
			     loff_t offset, u64 ino, unsigned int d_type)  \
{									   \
	struct fat_ioctl_filldir_callback *buf = __buf;			   \
	struct dirent_type __user *d1 = buf->dirent;			   \
	struct dirent_type __user *d2 = d1 + 1;				   \
									   \
	if (buf->result)						   \
		return -EINVAL;						   \
	buf->result++;							   \
									   \
	if (name != NULL) {						   \
		/* dirent has only short name */			   \
		if (name_len >= sizeof(d1->d_name))			   \
			name_len = sizeof(d1->d_name) - 1;		   \
									   \
		if (put_user(0, d2->d_name)			||	   \
		    put_user(0, &d2->d_reclen)			||	   \
		    copy_to_user(d1->d_name, name, name_len)	||	   \
		    put_user(0, d1->d_name + name_len)		||	   \
		    put_user(name_len, &d1->d_reclen))			   \
			goto efault;					   \
	} else {							   \
		/* dirent has short and long name */			   \
		const char *longname = buf->longname;			   \
		int long_len = buf->long_len;				   \
		const char *shortname = buf->shortname;			   \
		int short_len = buf->short_len;				   \
									   \
		if (long_len >= sizeof(d1->d_name))			   \
			long_len = sizeof(d1->d_name) - 1;		   \
		if (short_len >= sizeof(d1->d_name))			   \
			short_len = sizeof(d1->d_name) - 1;		   \
									   \
		if (copy_to_user(d2->d_name, longname, long_len)	|| \
		    put_user(0, d2->d_name + long_len)			|| \
		    put_user(long_len, &d2->d_reclen)			|| \
		    put_user(ino, &d2->d_ino)				|| \
		    put_user(offset, &d2->d_off)			|| \
		    copy_to_user(d1->d_name, shortname, short_len)	|| \
		    put_user(0, d1->d_name + short_len)			|| \
		    put_user(short_len, &d1->d_reclen))			   \
			goto efault;					   \
	}								   \
	return 0;							   \
efault:									   \
	buf->result = -EFAULT;						   \
	return -EFAULT;							   \
}

FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)

static int fat_ioctl_readdir(struct inode *inode, struct file *filp,
			     void __user *dirent, filldir_t filldir,
			     int short_only, int both)
{
	struct fat_ioctl_filldir_callback buf;
	int ret;

	buf.dirent = dirent;
	buf.result = 0;
	mutex_lock(&inode->i_mutex);
	ret = -ENOENT;
	if (!IS_DEADDIR(inode)) {
		ret = __fat_readdir(inode, filp, &buf, filldir,
				    short_only, both);
	}
	mutex_unlock(&inode->i_mutex);
	if (ret >= 0)
		ret = buf.result;
	return ret;
}

static int fat_dir_ioctl(struct inode *inode, struct file *filp,
			 unsigned int cmd, unsigned long arg)
{
	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
	int short_only, both;

	switch (cmd) {
	case VFAT_IOCTL_READDIR_SHORT:
		short_only = 1;
		both = 0;
		break;
	case VFAT_IOCTL_READDIR_BOTH:
		short_only = 0;
		both = 1;
		break;
	default:
		return fat_generic_ioctl(inode, filp, cmd, arg);
	}

	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct __fat_dirent[2])))
		return -EFAULT;
	/*
	 * Yes, we don't need this put_user() absolutely. However old
	 * code didn't return the right value. So, app use this value,
	 * in order to check whether it is EOF.
	 */
	if (put_user(0, &d1->d_reclen))
		return -EFAULT;

	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
				 short_only, both);
}

#ifdef CONFIG_COMPAT
#define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
#define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])

FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)

static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
				 unsigned long arg)
{
	struct inode *inode = filp->f_path.dentry->d_inode;
	struct compat_dirent __user *d1 = compat_ptr(arg);
	int short_only, both;

	switch (cmd) {
	case VFAT_IOCTL_READDIR_SHORT32:
		short_only = 1;
		both = 0;
		break;
	case VFAT_IOCTL_READDIR_BOTH32:
		short_only = 0;
		both = 1;
		break;
	default:
		return -ENOIOCTLCMD;
	}

	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct compat_dirent[2])))
		return -EFAULT;
	/*
	 * Yes, we don't need this put_user() absolutely. However old
	 * code didn't return the right value. So, app use this value,
	 * in order to check whether it is EOF.
	 */
	if (put_user(0, &d1->d_reclen))
		return -EFAULT;

	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
				 short_only, both);
}
#endif /* CONFIG_COMPAT */

const struct file_operations fat_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.readdir	= fat_readdir,
	.ioctl		= fat_dir_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= fat_compat_dir_ioctl,
#endif
	.fsync		= file_fsync,
};

static int fat_get_short_entry(struct inode *dir, loff_t *pos,
			       struct buffer_head **bh,
			       struct msdos_dir_entry **de)
{
	while (fat_get_entry(dir, pos, bh, de) >= 0) {
		/* free entry or long name entry or volume label */
		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
			return 0;
	}
	return -ENOENT;
}

/*
 * The ".." entry can not provide the "struct fat_slot_info" informations
 * for inode. So, this function provide the some informations only.
 */
int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
			 struct msdos_dir_entry **de, loff_t *i_pos)
{
	loff_t offset;

	offset = 0;
	*bh = NULL;
	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME)) {
			*i_pos = fat_make_i_pos(dir->i_sb, *bh, *de);
			return 0;
		}
	}
	return -ENOENT;
}

EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);

/* See if directory is empty */
int fat_dir_empty(struct inode *dir)
{
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	loff_t cpos;
	int result = 0;

	bh = NULL;
	cpos = 0;
	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
			result = -ENOTEMPTY;
			break;
		}
	}
	brelse(bh);
	return result;
}

EXPORT_SYMBOL_GPL(fat_dir_empty);

/*
 * fat_subdirs counts the number of sub-directories of dir. It can be run
 * on directories being created.
 */
int fat_subdirs(struct inode *dir)
{
	struct buffer_head *bh;
	struct msdos_dir_entry *de;