// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2024 Paulo Alcantara <pc@manguebit.com>
 */

#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include "cifsglob.h"
#include "smb2proto.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "fs_context.h"
#include "reparse.h"

static int mknod_nfs(unsigned int xid, struct inode *inode,
		     struct dentry *dentry, struct cifs_tcon *tcon,
		     const char *full_path, umode_t mode, dev_t dev,
		     const char *symname);

static int mknod_wsl(unsigned int xid, struct inode *inode,
		     struct dentry *dentry, struct cifs_tcon *tcon,
		     const char *full_path, umode_t mode, dev_t dev,
		     const char *symname);

static int create_native_symlink(const unsigned int xid, struct inode *inode,
				 struct dentry *dentry, struct cifs_tcon *tcon,
				 const char *full_path, const char *symname);

static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
					   const unsigned int xid,
					   const char *full_path,
					   const char *symname,
					   bool *directory);

int smb2_create_reparse_symlink(const unsigned int xid, struct inode *inode,
				struct dentry *dentry, struct cifs_tcon *tcon,
				const char *full_path, const char *symname)
{
	switch (get_cifs_symlink_type(CIFS_SB(inode->i_sb))) {
	case CIFS_SYMLINK_TYPE_NATIVE:
		return create_native_symlink(xid, inode, dentry, tcon, full_path, symname);
	case CIFS_SYMLINK_TYPE_NFS:
		return mknod_nfs(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname);
	case CIFS_SYMLINK_TYPE_WSL:
		return mknod_wsl(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname);
	default:
		return -EOPNOTSUPP;
	}
}

static int create_native_symlink(const unsigned int xid, struct inode *inode,
				 struct dentry *dentry, struct cifs_tcon *tcon,
				 const char *full_path, const char *symname)
{
	struct reparse_symlink_data_buffer *buf = NULL;
	struct cifs_open_info_data data = {};
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct inode *new;
	struct kvec iov;
	__le16 *path = NULL;
	bool directory;
	char *symlink_target = NULL;
	char *sym = NULL;
	char sep = CIFS_DIR_SEP(cifs_sb);
	u16 len, plen, poff, slen;
	int rc = 0;

	if (strlen(symname) > REPARSE_SYM_PATH_MAX)
		return -ENAMETOOLONG;

	symlink_target = kstrdup(symname, GFP_KERNEL);
	if (!symlink_target) {
		rc = -ENOMEM