root/fs/efs/dir.c

DEFINITIONS

1. efs_readdir

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

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

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

const struct file_operations efs_dir_operations = {
        .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");

        lock_kernel();

        /* 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:
        unlock_kernel();
        return 0;
}