/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include "reiserfs.h"
#include <linux/stat.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <asm/uaccess.h>

extern const struct reiserfs_key MIN_KEY;

static int reiserfs_readdir(struct file *, struct dir_context *);
static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
                              int datasync);

const struct file_operations reiserfs_dir_operations = {
        .llseek = generic_file_llseek,
        .read = generic_read_dir,
        .iterate = reiserfs_readdir,
        .fsync = reiserfs_dir_fsync,
        .unlocked_ioctl = reiserfs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = reiserfs_compat_ioctl,
#endif
};

static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
                              int datasync)
{
        struct inode *inode = filp->f_mapping->host;
        int err;

        err = filemap_write_and_wait_range(inode->i_mapping, start, end);
        if (err)
                return err;

        mutex_lock(&inode->i_mutex);
        reiserfs_write_lock(inode->i_sb);
        err = reiserfs_commit_for_inode(inode);
        reiserfs_write_unlock(inode->i_sb);
        mutex_unlock(&inode->i_mutex);
        if (err < 0)
                return err;
        return 0;
}

#define store_ih(where,what) copy_item_head (where, what)

static inline bool is_privroot_deh(struct inode *dir, struct reiserfs_de_head *deh)
{
        struct dentry *privroot = REISERFS_SB(dir->i_sb)->priv_root;
        return (privroot->d_inode &&
                deh->deh_objectid == INODE_PKEY(privroot->d_inode)->k_objectid);
}

int reiserfs_readdir_inode(struct inode *inode, struct dir_context *ctx)
{
        struct cpu_key pos_key; /* key of current position in the directory (key of directory entry) */
        INITIALIZE_PATH(path_to_entry);
        struct buffer_head *bh;
        int item_num, entry_num;
        const struct reiserfs_key *rkey;
        struct item_head *ih, tmp_ih;
        int search_res;
        char *local_buf;
        loff_t next_pos;
        char small_buf[32];     /* avoid kmalloc if we can */
        struct reiserfs_dir_entry de;
        int ret = 0;

        reiserfs_write_lock(inode->i_sb);

        reiserfs_check_lock_depth(inode->i_sb, "readdir");

        /* form key for search the next directory entry using f_pos field of
           file structure */
        make_cpu_key(&pos_key, inode, ctx->pos ?: DOT_OFFSET, TYPE_DIRENTRY, 3);
        next_pos = cpu_key_k_offset(&pos_key);

        path_to_entry.reada = PATH_READA;
        while (1) {
              research:
                /* search the directory item, containing entry with specified key */
                search_res =
                    search_by_entry_key(inode->i_sb, &pos_key, &path_to_entry,
                                        &de);
                if (search_res == IO_ERROR) {
                        // FIXME: we could just skip part of directory which could
                        // not be read
                        ret = -EIO;
                        goto out;
                }
                entry_num = de.de_entry_num;
                bh = de.de_bh;
                item_num = de.de_item_num;
                ih = de.de_ih;
                store_ih(&tmp_ih, ih);

                /* we must have found item, that is item of this directory, */
                RFALSE(COMP_SHORT_KEYS(&(ih->ih_key), &pos_key),
                       "vs-9000: found item %h does not match to dir we readdir %K",
                       ih, &pos_key);
                RFALSE(item_num > B_NR_ITEMS(bh) - 1,
                       "vs-9005 item_num == %d, item amount == %d",
                       item_num, B_NR_ITEMS(bh));

                /* and entry must be not more than number of entries in the item */
                RFALSE(I_ENTRY_COUNT(ih) < entry_num,
                       "vs-9010: entry number is too big %d (%d)",
                       entry_num, I_ENTRY_COUNT(ih));

                if (search_res == POSITION_FOUND
                    || entry_num < I_ENTRY_COUNT(ih)) {
                        /* go through all entries in the directory item beginning from the entry, that has been found */
                        struct reiserfs_de_head *deh =
                            B_I_DEH(bh, ih) + entry_num;

                        for (; entry_num < I_ENTRY_COUNT(ih);
                             entry_num++, deh++) {
                                int d_reclen;
                                char *d_name;
                                ino_t d_ino;

                                if (!de_visible(deh))
                                        /* it is hidden entry */
                                        continue;
                                d_reclen = entry_length(bh, ih, entry_num);
                                d_name = B_I_DEH_ENTRY_FILE_NAME(bh, ih, deh);

                                if (d_reclen <= 0 ||
                                    d_name + d_reclen > bh->b_data + bh->b_size) {
                                        /* There is corrupted data in entry,
                                         * We'd better stop here */
                                        pathrelse(&path_to_entry);
                                        ret = -EIO;
                                        goto out;
                                }

                                if (!d_name[d_reclen - 1])
                                        d_reclen = strlen(d_name);

                                if (d_reclen >
                                    REISERFS_MAX_NAME(inode->i_sb->
                                                      s_blocksize)) {
                                        /* too big to send back to VFS */
                                        continue;
                                }

                                /* Ignore the .reiserfs_priv entry */
                                if (is_privroot_deh(inode, deh))
                                        continue;

                                ctx->pos = deh_offset(deh);
                                d_ino = deh_objectid(deh);
                                if (d_reclen <= 32) {
                                        local_buf = small_buf;
                                } else {
                                        local_buf = kmalloc(d_reclen,
                                                            GFP_NOFS);
                                        if (!local_buf) {
                                                pathrelse(&path_to_entry);
                                                ret = -ENOMEM;
                                                goto out;
                                        }
                                        if (item_moved(&tmp_ih, &path_to_entry)) {
                                                kfree(local_buf);
                                                goto research;
                                        }
                                }
                                // Note, that we copy name to user space via temporary
                                // buffer (local_buf) because filldir will block if
                                // user space buffer is swapped out. At that time
                                // entry can move to somewhere else
                                memcpy(local_buf, d_name, d_reclen);

                                /*
                                 * Since filldir might sleep, we can release
                                 * the write lock here for other waiters
                                 */
                                reiserfs_write_unlock(inode->i_sb);
                                if (!dir_emit
                                    (ctx, local_buf, d_reclen, d_ino,
                                     DT_UNKNOWN)) {
                                        reiserfs_write_lock(inode->i_sb);
                                        if (local_buf != small_buf) {
                                                kfree(local_buf);
                                        }
                                        goto end;
                                }
                                reiserfs_write_lock(inode->i_sb);
                                if (local_buf != small_buf) {
                                        kfree(local_buf);
                                }
                                // next entry should be looked for with such offset
                                next_pos = deh_offset(deh) + 1;

                                if (item_moved(&tmp_ih, &path_to_entry)) {
                                        set_cpu_key_k_offset(&pos_key,
                                                             next_pos);
                                        goto research;
                                }
                        }       /* for */
                }

                if (item_num != B_NR_ITEMS(bh) - 1)
                        // end of directory has been reached
                        goto end;

                /* item we went through is last item of node. Using right
                   delimiting key check is it directory end */
                rkey = get_rkey(&path_to_entry, inode->i_sb);
                if (!comp_le_keys(rkey, &MIN_KEY)) {
                        /* set pos_key to key, that is the smallest and greater
                           that key of the last entry in the item */
                        set_cpu_key_k_offset(&pos_key, next_pos);
                        continue;
                }

                if (COMP_SHORT_KEYS(rkey, &pos_key)) {
                        // end of directory has been reached
                        goto end;
                }

                /* directory continues in the right neighboring block */
                set_cpu_key_k_offset(&pos_key,
                                     le_key_k_offset(KEY_FORMAT_3_5, rkey));

        }                       /* while */

end:
        ctx->pos = next_pos;
        pathrelse(&path_to_entry);
        reiserfs_check_path(&path_to_entry);
out:
        reiserfs_write_unlock(inode->i_sb);
        return ret;
}

static int reiserfs_readdir(struct file *file, struct dir_context *ctx)
{
        return reiserfs_readdir_inode(file_inode(file), ctx);
}

/* compose directory item containing "." and ".." entries (entries are
   not aligned to 4 byte boundary) */
/* the last four params are LE */
void make_empty_dir_item_v1(char *body, __le32 dirid, __le32 objid,
                            __le32 par_dirid, __le32 par_objid)
{
        struct reiserfs_de_head *deh;

        memset(body, 0, EMPTY_DIR_SIZE_V1);
        deh = (struct reiserfs_de_head *)body;

        /* direntry header of "." */
        put_deh_offset(&(deh[0]), DOT_OFFSET);
        /* these two are from make_le_item_head, and are are LE */
        deh[0].deh_dir_id = dirid;
        deh[0].deh_objectid = objid;
        deh[0].deh_state = 0;   /* Endian safe if 0 */
        put_deh_location(&(deh[0]), EMPTY_DIR_SIZE_V1 - strlen("."));
        mark_de_visible(&(deh[0]));

        /* direntry header of ".." */
        put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
        /* key of ".." for the root directory */
        /* these two are from the inode, and are are LE */
        deh[1].deh_dir_id = par_dirid;
        deh[1].deh_objectid = par_objid;
        deh[1].deh_state = 0;   /* Endian safe if 0 */
        put_deh_location(&(deh[1]), deh_location(&(deh[0])) - strlen(".."));
        mark_de_visible(&(deh[1]));

        /* copy ".." and "." */
        memcpy(body + deh_location(&(deh[0])), ".", 1);
        memcpy(body + deh_location(&(deh[1])), "..", 2);
}

/* compose directory item containing "." and ".." entries */
void make_empty_dir_item(char *body, __le32 dirid, __le32 objid,
                         __le32 par_dirid, __le32 par_objid)
{
        struct reiserfs_de_head *deh;

        memset(body, 0, EMPTY_DIR_SIZE);
        deh = (struct reiserfs_de_head *)body;

        /* direntry header of "." */
        put_deh_offset(&(deh[0]), DOT_OFFSET);
        /* these two are from make_le_item_head, and are are LE */
        deh[0].deh_dir_id = dirid;
        deh[0].deh_objectid = objid;
        deh[0].deh_state = 0;   /* Endian safe if 0 */
        put_deh_location(&(deh[0]), EMPTY_DIR_SIZE - ROUND_UP(strlen(".")));
        mark_de_visible(&(deh[0]));

        /* direntry header of ".." */
        put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
        /* key of ".." for the root directory */
        /* these two are from the inode, and are are LE */
        deh[1].deh_dir_id = par_dirid;
        deh[1].deh_objectid = par_objid;
        deh[1].deh_state = 0;   /* Endian safe if 0 */
        put_deh_location(&(deh[1]),
                         deh_location(&(deh[0])) - ROUND_UP(strlen("..")));
        mark_de_visible(&(deh[1]));

        /* copy ".." and "." */
        memcpy(body + deh_location(&(deh[0])), ".", 1);
        memcpy(body + deh_location(&(deh[1])), "..", 2);
}