// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 */

#include <linux/fs.h>
#include <linux/nls.h>
#include <linux/ctype.h>
#include <linux/posix_acl.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"

/*
 * fill_name_de - Format NTFS_DE in @buf.
 */
int fill_name_de(struct ntfs_sb_info *sbi, void *buf, const struct qstr *name,
                 const struct cpu_str *uni)
{
        int err;
        struct NTFS_DE *e = buf;
        u16 data_size;
        struct ATTR_FILE_NAME *fname = (struct ATTR_FILE_NAME *)(e + 1);

#ifndef CONFIG_NTFS3_64BIT_CLUSTER
        e->ref.high = fname->home.high = 0;
#endif
        if (uni) {
#ifdef __BIG_ENDIAN
                int ulen = uni->len;
                __le16 *uname = fname->name;
                const u16 *name_cpu = uni->name;

                while (ulen--)
                        *uname++ = cpu_to_le16(*name_cpu++);
#else
                memcpy(fname->name, uni->name, uni->len * sizeof(u16));
#endif
                fname->name_len = uni->len;

        } else {
                /* Convert input string to unicode. */
                err = ntfs_nls_to_utf16(sbi, name->name, name->len,
                                        (struct cpu_str *)&fname->name_len,
                                        NTFS_NAME_LEN, UTF16_LITTLE_ENDIAN);
                if (err < 0)
                        return err;
        }

        fname->type = FILE_NAME_POSIX;
        data_size = fname_full_size(fname);

        e->size = cpu_to_le16(ALIGN(data_size, 8) + sizeof(struct NTFS_DE));
        e->key_size = cpu_to_le16(data_size);
        e->flags = 0;
        e->res = 0;

        return 0;
}

/*
 * ntfs_lookup - inode_operations::lookup
 */
static struct dentry *ntfs_lookup(struct inode *dir, struct dentry *dentry,
                                  u32 flags)
{
        struct ntfs_inode *ni = ntfs_i(dir);
        struct cpu_str *uni = kmalloc(PATH_MAX, GFP_KERNEL);
        struct inode *inode;
        int err;

        if (!uni)
                inode = ERR_PTR(-ENOMEM);
        else {
                err = ntfs_nls_to_utf16(ni->mi.sbi, dentry->d_name.name,
                                        dentry->d_name.len, uni, NTFS_NAME_LEN,
                                        UTF16_HOST_ENDIAN);
                if (err < 0)
                        inode = ERR_PTR(err);
                else {
                        ni_lock_dir(ni);
                        inode = dir_search_u(dir, uni, NULL);
                        ni_unlock(ni);
                }
                kfree(uni);
        }

        /*
         * Check for a null pointer
         * If the MFT record of ntfs inode is not a base record, inode->i_op can be NULL.
         * This causes null pointer dereference in d_splice_alias().
         */
        if (!IS_ERR_OR_NULL(inode) && !inode->i_op) {
                iput(inode);
                inode = ERR_PTR(-EINVAL);
        }

        return d_splice_alias(inode, dentry);
}

/*
 * ntfs_create - inode_operations::create
 */
static int ntfs_create(struct mnt_idmap *idmap, struct inode *dir,
                       struct dentry *dentry, umode_t mode, bool excl)
{
        return ntfs_create_inode(idmap, dir, dentry, NULL, S_IFREG | mode, 0,
                                 NULL, 0, NULL);
}

/*
 * ntfs_mknod - inode_operations::mknod
 */
static int ntfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
                      struct dentry *dentry, umode_t mode, dev_t rdev)
{
        return ntfs_create_inode(idmap, dir, dentry, NULL, mode, rdev, NULL, 0,
                                 NULL);
}

/*
 * ntfs_link - inode_operations::link
 */
static int ntfs_link(struct dentry *ode, struct inode *dir, struct dentry *de)
{
        int err;
        struct inode *inode = d_inode(ode);
        struct ntfs_inode *ni = ntfs_i(inode);

        if (S_ISDIR(inode->i_mode))
                return -EPERM;

        if (inode->i_nlink >= NTFS_LINK_MAX)
                return -EMLINK;

        ni_lock_dir(ntfs_i(dir));
        if (inode != dir)
                ni_lock(ni);

        inc_nlink(inode);
        ihold(inode);

        err = ntfs_link_inode(inode, de);

        if (!err) {
                inode_set_ctime_current(inode);
                inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
                mark_inode_dirty(inode);
                mark_inode_dirty(dir);
                d_instantiate(de, inode);
        } else {
                drop_nlink(inode);
                iput(inode);
        }

        if (inode != dir)
                ni_unlock(ni);
        ni_unlock(ntfs_i(dir));

        return err;
}

/*
 * ntfs_unlink - inode_operations::unlink
 */
static int ntfs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct ntfs_inode *ni = ntfs_i(dir);
        int err;

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ni)))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(dir->i_sb)))
                return -EIO;

        ni_lock_dir(ni);

        err = ntfs_unlink_inode(dir, dentry);

        ni_unlock(ni);

        return err;
}

/*
 * ntfs_symlink - inode_operations::symlink
 */
static int ntfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
                        struct dentry *dentry, const char *symname)
{
        u32 size = strlen(symname);

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ntfs_i(dir))))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(dir->i_sb)))
                return -EIO;

        return ntfs_create_inode(idmap, dir, dentry, NULL, S_IFLNK | 0777, 0,
                                 symname, size, NULL);
}

/*
 * ntfs_mkdir - inode_operations::mkdir
 */
static struct dentry *ntfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
                                 struct dentry *dentry, umode_t mode)
{
        return ERR_PTR(ntfs_create_inode(idmap, dir, dentry, NULL,
                                         S_IFDIR | mode, 0, NULL, 0, NULL));
}

/*
 * ntfs_rmdir - inode_operations::rmdir
 */
static int ntfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct ntfs_inode *ni = ntfs_i(dir);
        int err;

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ni)))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(dir->i_sb)))
                return -EIO;

        ni_lock_dir(ni);

        err = ntfs_unlink_inode(dir, dentry);

        ni_unlock(ni);

        return err;
}

/*
 * ntfs_rename - inode_operations::rename
 */
static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
                       struct dentry *dentry, struct inode *new_dir,
                       struct dentry *new_dentry, u32 flags)
{
        int err;
        struct super_block *sb = dir->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        struct ntfs_inode *dir_ni = ntfs_i(dir);
        struct ntfs_inode *new_dir_ni = ntfs_i(new_dir);
        struct inode *inode = d_inode(dentry);
        struct ntfs_inode *ni = ntfs_i(inode);
        struct inode *new_inode = d_inode(new_dentry);
        struct NTFS_DE *de, *new_de;
        bool is_same;
        /*
         * de           - memory of PATH_MAX bytes:
         * [0-1024)     - original name (dentry->d_name)
         * [1024-2048)  - paired to original name, usually DOS variant of dentry->d_name
         * [2048-3072)  - new name (new_dentry->d_name)
         */
        static_assert(SIZEOF_ATTRIBUTE_FILENAME_MAX + SIZEOF_RESIDENT < 1024);
        static_assert(SIZEOF_ATTRIBUTE_FILENAME_MAX + sizeof(struct NTFS_DE) <
                      1024);
        static_assert(PATH_MAX >= 4 * 1024);

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ni)))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(sb)))
                return -EIO;

        if (flags & ~RENAME_NOREPLACE)
                return -EINVAL;

        is_same = dentry->d_name.len == new_dentry->d_name.len &&
                  !memcmp(dentry->d_name.name, new_dentry->d_name.name,
                          dentry->d_name.len);

        if (is_same && dir == new_dir) {
                /* Nothing to do. */
                return 0;
        }

        if (ntfs_is_meta_file(sbi, inode->i_ino)) {
                /* Should we print an error? */
                return -EINVAL;
        }

        if (new_inode) {
                /* Target name exists. Unlink it. */
                dget(new_dentry);
                ni_lock_dir(new_dir_ni);
                err = ntfs_unlink_inode(new_dir, new_dentry);
                ni_unlock(new_dir_ni);
                dput(new_dentry);
                if (err)
                        return err;
        }

        de = kmalloc(PATH_MAX, GFP_KERNEL);
        if (!de)
                return -ENOMEM;

        /* Translate dentry->d_name into unicode form. */
        err = fill_name_de(sbi, de, &dentry->d_name, NULL);
        if (err < 0)
                goto out;

        if (is_same) {
                /* Reuse 'de'. */
                new_de = de;
        } else {
                /* Translate new_dentry->d_name into unicode form. */
                new_de = Add2Ptr(de, 2048);
                err = fill_name_de(sbi, new_de, &new_dentry->d_name, NULL);
                if (err < 0)
                        goto out;
        }

        ni_lock_dir(dir_ni);
        ni_lock(ni);
        if (dir_ni != new_dir_ni)
                ni_lock_dir2(new_dir_ni);

        err = ni_rename(dir_ni, new_dir_ni, ni, de, new_de);
        if (!err) {
                simple_rename_timestamp(dir, dentry, new_dir, new_dentry);
                mark_inode_dirty(inode);
                mark_inode_dirty(dir);
                if (dir != new_dir)
                        mark_inode_dirty(new_dir);

                if (IS_DIRSYNC(dir))
                        ntfs_sync_inode(dir);

                if (IS_DIRSYNC(new_dir))
                        ntfs_sync_inode(inode);
        }

        if (dir_ni != new_dir_ni)
                ni_unlock(new_dir_ni);
        ni_unlock(ni);
        ni_unlock(dir_ni);
out:
        kfree(de);
        return err;
}

struct dentry *ntfs3_get_parent(struct dentry *child)
{
        struct inode *inode = d_inode(child);
        struct ntfs_inode *ni = ntfs_i(inode);

        struct ATTR_LIST_ENTRY *le = NULL;
        struct ATTRIB *attr = NULL;
        struct ATTR_FILE_NAME *fname;

        while ((attr = ni_find_attr(ni, attr, &le, ATTR_NAME, NULL, 0, NULL,
                                    NULL))) {
                fname = resident_data_ex(attr, SIZEOF_ATTRIBUTE_FILENAME);
                if (!fname)
                        continue;

                return d_obtain_alias(
                        ntfs_iget5(inode->i_sb, &fname->home, NULL));
        }

        return ERR_PTR(-ENOENT);
}

/*
 * dentry_operations::d_hash
 */
static int ntfs_d_hash(const struct dentry *dentry, struct qstr *name)
{
        struct ntfs_sb_info *sbi;
        const char *n = name->name;
        unsigned int len = name->len;
        unsigned long hash;
        struct cpu_str *uni;
        unsigned int c;
        int err;

        /* First try fast implementation. */
        hash = init_name_hash(dentry);

        for (;;) {
                if (!len--) {
                        name->hash = end_name_hash(hash);
                        return 0;
                }

                c = *n++;
                if (c >= 0x80)
                        break;

                hash = partial_name_hash(toupper(c), hash);
        }

        /*
         * Try slow way with current upcase table
         */
        uni = kmalloc(PATH_MAX, GFP_NOWAIT);
        if (!uni)
                return -ENOMEM;

        sbi = dentry->d_sb->s_fs_info;

        err = ntfs_nls_to_utf16(sbi, name->name, name->len, uni, NTFS_NAME_LEN,
                                UTF16_HOST_ENDIAN);
        if (err < 0)
                goto out;

        if (!err) {
                err = -EINVAL;
                goto out;
        }

        hash = ntfs_names_hash(uni->name, uni->len, sbi->upcase,
                               init_name_hash(dentry));
        name->hash = end_name_hash(hash);
        err = 0;

out:
        kfree(uni);
        return err;
}

/*
 * dentry_operations::d_compare
 */
static int ntfs_d_compare(const struct dentry *dentry, unsigned int len1,
                          const char *str, const struct qstr *name)
{
        struct ntfs_sb_info *sbi;
        int ret;
        const char *n1 = str;
        const char *n2 = name->name;
        unsigned int len2 = name->len;
        unsigned int lm = min(len1, len2);
        unsigned char c1, c2;
        struct cpu_str *uni1;
        struct le_str *uni2;

        /* First try fast implementation. */
        for (;;) {
                if (!lm--)
                        return len1 != len2;

                if ((c1 = *n1++) == (c2 = *n2++))
                        continue;

                if (c1 >= 0x80 || c2 >= 0x80)
                        break;

                if (toupper(c1) != toupper(c2))
                        return 1;
        }

        /*
         * Try slow way with current upcase table
         */
        sbi = dentry->d_sb->s_fs_info;
        uni1 = kmalloc(PATH_MAX, GFP_NOWAIT);
        if (!uni1)
                return -ENOMEM;

        ret = ntfs_nls_to_utf16(sbi, str, len1, uni1, NTFS_NAME_LEN,
                                UTF16_HOST_ENDIAN);
        if (ret < 0)
                goto out;

        if (!ret) {
                ret = -EINVAL;
                goto out;
        }

        uni2 = Add2Ptr(uni1, 2048);

        ret = ntfs_nls_to_utf16(sbi, name->name, name->len,
                                (struct cpu_str *)uni2, NTFS_NAME_LEN,
                                UTF16_LITTLE_ENDIAN);
        if (ret < 0)
                goto out;

        if (!ret) {
                ret = -EINVAL;
                goto out;
        }

        ret = !ntfs_cmp_names_cpu(uni1, uni2, sbi->upcase, false) ? 0 : 1;

out:
        kfree(uni1);
        return ret;
}

// clang-format off
const struct inode_operations ntfs_dir_inode_operations = {
        .lookup         = ntfs_lookup,
        .create         = ntfs_create,
        .link           = ntfs_link,
        .unlink         = ntfs_unlink,
        .symlink        = ntfs_symlink,
        .mkdir          = ntfs_mkdir,
        .rmdir          = ntfs_rmdir,
        .mknod          = ntfs_mknod,
        .rename         = ntfs_rename,
        .get_acl        = ntfs_get_acl,
        .set_acl        = ntfs_set_acl,
        .setattr        = ntfs_setattr,
        .getattr        = ntfs_getattr,
        .listxattr      = ntfs_listxattr,
        .fiemap         = ntfs_fiemap,
};

const struct inode_operations ntfs_special_inode_operations = {
        .setattr        = ntfs_setattr,
        .getattr        = ntfs_getattr,
        .listxattr      = ntfs_listxattr,
        .get_acl        = ntfs_get_acl,
        .set_acl        = ntfs_set_acl,
};

const struct dentry_operations ntfs_dentry_ops = {
        .d_hash         = ntfs_d_hash,
        .d_compare      = ntfs_d_compare,
};

// clang-format on