dir.c

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/*
 * dir.c
 *
 * Copyright (c) 1999 Al Smith
 */

#include <linux/buffer_head.h>
#include "efs.h"

static int efs_readdir(struct file *, void *, filldir_t);

const struct file_operations efs_dir_operations = {
    .llseek     = generic_file_llseek,
    .read       = generic_read_dir,
    .readdir    = efs_readdir,
};

const struct inode_operations efs_dir_inode_operations = {
    .lookup     = efs_lookup,
};

static int efs_readdir(struct file *filp, void *dirent, filldir_t filldir) {
    struct inode *inode = filp->f_path.dentry->d_inode;
    struct buffer_head *bh;

    struct efs_dir      *dirblock;
    struct efs_dentry   *dirslot;
    efs_ino_t       inodenum;
    efs_block_t     block;
    int         slot, namelen;
    char            *nameptr;

    if (inode->i_size & (EFS_DIRBSIZE-1))
        printk(KERN_WARNING "EFS: WARNING: readdir(): directory size not a multiple of EFS_DIRBSIZE\n");

    /* work out where this entry can be found */
    block = filp->f_pos >> EFS_DIRBSIZE_BITS;

    /* each block contains at most 256 slots */
    slot  = filp->f_pos & 0xff;

    /* look at all blocks */
    while (block < inode->i_blocks) {
        /* read the dir block */
        bh = sb_bread(inode->i_sb, efs_bmap(inode, block));

        if (!bh) {
            printk(KERN_ERR "EFS: readdir(): failed to read dir block %d\n", block);
            break;
        }

        dirblock = (struct efs_dir *) bh->b_data; 

        if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
            printk(KERN_ERR "EFS: readdir(): invalid directory block\n");
            brelse(bh);
            break;
        }

        while (slot < dirblock->slots) {
            if (dirblock->space[slot] == 0) {
                slot++;
                continue;
            }

            dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));

            inodenum = be32_to_cpu(dirslot->inode);
            namelen  = dirslot->namelen;
            nameptr  = dirslot->name;

#ifdef DEBUG
            printk(KERN_DEBUG "EFS: readdir(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", block, slot, dirblock->slots-1, inodenum, nameptr, namelen);
#endif
            if (namelen > 0) {
                /* found the next entry */
                filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;

                /* copy filename and data in dirslot */
                filldir(dirent, nameptr, namelen, filp->f_pos, inodenum, DT_UNKNOWN);

                /* sanity check */
                if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
                    printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
                    slot++;
                    continue;
                }

                /* store position of next slot */
                if (++slot == dirblock->slots) {
                    slot = 0;
                    block++;
                }
                brelse(bh);
                filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
                goto out;
            }
            slot++;
        }
        brelse(bh);

        slot = 0;
        block++;
    }

    filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
out:
    return 0;
}