exfat_xattr.c

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/dcache.h>
#include "exfat.h"

#ifndef CONFIG_EXFAT_VIRTUAL_XATTR_SELINUX_LABEL
#define CONFIG_EXFAT_VIRTUAL_XATTR_SELINUX_LABEL	("undefined")
#endif

static const char default_xattr[] = CONFIG_EXFAT_VIRTUAL_XATTR_SELINUX_LABEL;

static int can_support(const char *name)
{
	if (!name || strcmp(name, "security.selinux"))
		return -1;
	return 0;
}

ssize_t exfat_listxattr(struct dentry *dentry, char *list, size_t size)
{
	return 0;
}
EXPORT_SYMBOL(exfat_listxattr);

/*************************************************************************
 * INNER FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
 *************************************************************************/
static int __exfat_xattr_check_support(const char *name)
{
	if (can_support(name))
		return -EOPNOTSUPP;

	return 0;
}

ssize_t __exfat_getxattr(const char *name, void *value, size_t size)
{
	if (can_support(name))
		return -EOPNOTSUPP;

	if ((size > strlen(default_xattr)+1) && value)
		strcpy(value, default_xattr);

	return strlen(default_xattr);
}


/*************************************************************************
 * FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
 *************************************************************************/
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 9, 0)
static int exfat_xattr_get(const struct xattr_handler *handler,
		struct dentry *dentry, struct inode *inode,
		const char *name, void *buffer, size_t size)
{
	return __exfat_getxattr(name, buffer, size);
}

static int exfat_xattr_set(const struct xattr_handler *handler,
		struct dentry *dentry, struct inode *inode,
		const char *name, const void *value, size_t size,
		int flags)
{
	return __exfat_xattr_check_support(name);
}

const struct xattr_handler exfat_xattr_handler = {
	.prefix = "",  /* match anything */
	.get = exfat_xattr_get,
	.set = exfat_xattr_set,
};

const struct xattr_handler *exfat_xattr_handlers[] = {
	&exfat_xattr_handler,
	NULL
};

void setup_exfat_xattr_handler(struct super_block *sb)
{
	sb->s_xattr = exfat_xattr_handlers;
}
EXPORT_SYMBOL(setup_exfat_xattr_handler);
#else /* LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0) */
int exfat_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
{
	return __exfat_xattr_check_support(name);
}

ssize_t exfat_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
{
	return __exfat_getxattr(name, value, size);
}

int exfat_removexattr(struct dentry *dentry, const char *name)
{
	return __exfat_xattr_check_support(name);
}

void setup_exfat_xattr_handler(struct super_block *sb)
{
	/* DO NOTHING */
}
EXPORT_SYMBOL(setup_exfat_xattr_handler);
#endif