root/fs/adfs/dir.c

DEFINITIONS

1. adfs_readdir
2. adfs_dir_update
3. adfs_match
4. adfs_dir_lookup_byname
5. adfs_hash
6. adfs_compare
7. adfs_lookup

/*
 *  linux/fs/adfs/dir.c
 *
 *  Copyright (C) 1999-2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Common directory handling for ADFS
 */
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/adfs_fs.h>
#include <linux/time.h>
#include <linux/stat.h>
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>          /* for file_fsync() */

#include "adfs.h"

/*
 * For future.  This should probably be per-directory.
 */
static DEFINE_RWLOCK(adfs_dir_lock);

static int
adfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        struct super_block *sb = inode->i_sb;
        struct adfs_dir_ops *ops = ADFS_SB(sb)->s_dir;
        struct object_info obj;
        struct adfs_dir dir;
        int ret = 0;

        lock_kernel();  

        if (filp->f_pos >> 32)
                goto out;

        ret = ops->read(sb, inode->i_ino, inode->i_size, &dir);
        if (ret)
                goto out;

        switch ((unsigned long)filp->f_pos) {
        case 0:
                if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
                        goto free_out;
                filp->f_pos += 1;

        case 1:
                if (filldir(dirent, "..", 2, 1, dir.parent_id, DT_DIR) < 0)
                        goto free_out;
                filp->f_pos += 1;

        default:
                break;
        }

        read_lock(&adfs_dir_lock);

        ret = ops->setpos(&dir, filp->f_pos - 2);
        if (ret)
                goto unlock_out;
        while (ops->getnext(&dir, &obj) == 0) {
                if (filldir(dirent, obj.name, obj.name_len,
                            filp->f_pos, obj.file_id, DT_UNKNOWN) < 0)
                        goto unlock_out;
                filp->f_pos += 1;
        }

unlock_out:
        read_unlock(&adfs_dir_lock);

free_out:
        ops->free(&dir);

out:
        unlock_kernel();
        return ret;
}

int
adfs_dir_update(struct super_block *sb, struct object_info *obj)
{
        int ret = -EINVAL;
#ifdef CONFIG_ADFS_FS_RW
        struct adfs_dir_ops *ops = ADFS_SB(sb)->s_dir;
        struct adfs_dir dir;

        printk(KERN_INFO "adfs_dir_update: object %06X in dir %06X\n",
                 obj->file_id, obj->parent_id);

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

        ret = ops->read(sb, obj->parent_id, 0, &dir);
        if (ret)
                goto out;

        write_lock(&adfs_dir_lock);
        ret = ops->update(&dir, obj);
        write_unlock(&adfs_dir_lock);

        ops->free(&dir);
out:
#endif
        return ret;
}

static int
adfs_match(struct qstr *name, struct object_info *obj)
{
        int i;

        if (name->len != obj->name_len)
                return 0;

        for (i = 0; i < name->len; i++) {
                char c1, c2;

                c1 = name->name[i];
                c2 = obj->name[i];

                if (c1 >= 'A' && c1 <= 'Z')
                        c1 += 'a' - 'A';
                if (c2 >= 'A' && c2 <= 'Z')
                        c2 += 'a' - 'A';

                if (c1 != c2)
                        return 0;
        }
        return 1;
}

static int
adfs_dir_lookup_byname(struct inode *inode, struct qstr *name, struct object_info *obj)
{
        struct super_block *sb = inode->i_sb;
        struct adfs_dir_ops *ops = ADFS_SB(sb)->s_dir;
        struct adfs_dir dir;
        int ret;

        ret = ops->read(sb, inode->i_ino, inode->i_size, &dir);
        if (ret)
                goto out;

        if (ADFS_I(inode)->parent_id != dir.parent_id) {
                adfs_error(sb, "parent directory changed under me! (%lx but got %lx)\n",
                           ADFS_I(inode)->parent_id, dir.parent_id);
                ret = -EIO;
                goto free_out;
        }

        obj->parent_id = inode->i_ino;

        /*
         * '.' is handled by reserved_lookup() in fs/namei.c
         */
        if (name->len == 2 && name->name[0] == '.' && name->name[1] == '.') {
                /*
                 * Currently unable to fill in the rest of 'obj',
                 * but this is better than nothing.  We need to
                 * ascend one level to find it's parent.
                 */
                obj->name_len = 0;
                obj->file_id  = obj->parent_id;
                goto free_out;
        }

        read_lock(&adfs_dir_lock);

        ret = ops->setpos(&dir, 0);
        if (ret)
                goto unlock_out;

        ret = -ENOENT;
        while (ops->getnext(&dir, obj) == 0) {
                if (adfs_match(name, obj)) {
                        ret = 0;
                        break;
                }
        }

unlock_out:
        read_unlock(&adfs_dir_lock);

free_out:
        ops->free(&dir);
out:
        return ret;
}

const struct file_operations adfs_dir_operations = {
        .read           = generic_read_dir,
        .llseek         = generic_file_llseek,
        .readdir        = adfs_readdir,
        .fsync          = file_fsync,
};

static int
adfs_hash(struct dentry *parent, struct qstr *qstr)
{
        const unsigned int name_len = ADFS_SB(parent->d_sb)->s_namelen;
        const unsigned char *name;
        unsigned long hash;
        int i;

        if (qstr->len < name_len)
                return 0;

        /*
         * Truncate the name in place, avoids
         * having to define a compare function.
         */
        qstr->len = i = name_len;
        name = qstr->name;
        hash = init_name_hash();
        while (i--) {
                char c;

                c = *name++;
                if (c >= 'A' && c <= 'Z')
                        c += 'a' - 'A';

                hash = partial_name_hash(c, hash);
        }
        qstr->hash = end_name_hash(hash);

        return 0;
}

/*
 * Compare two names, taking note of the name length
 * requirements of the underlying filesystem.
 */
static int
adfs_compare(struct dentry *parent, struct qstr *entry, struct qstr *name)
{
        int i;

        if (entry->len != name->len)
                return 1;

        for (i = 0; i < name->len; i++) {
                char a, b;

                a = entry->name[i];
                b = name->name[i];

                if (a >= 'A' && a <= 'Z')
                        a += 'a' - 'A';
                if (b >= 'A' && b <= 'Z')
                        b += 'a' - 'A';

                if (a != b)
                        return 1;
        }
        return 0;
}

struct dentry_operations adfs_dentry_operations = {
        .d_hash         = adfs_hash,
        .d_compare      = adfs_compare,
};

static struct dentry *
adfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
        struct inode *inode = NULL;
        struct object_info obj;
        int error;

        dentry->d_op = &adfs_dentry_operations; 
        lock_kernel();
        error = adfs_dir_lookup_byname(dir, &dentry->d_name, &obj);
        if (error == 0) {
                error = -EACCES;
                /*
                 * This only returns NULL if get_empty_inode
                 * fails.
                 */
                inode = adfs_iget(dir->i_sb, &obj);
                if (inode)
                        error = 0;
        }
        unlock_kernel();
        d_add(dentry, inode);
        return ERR_PTR(error);
}

/*
 * directories can handle most operations...
 */
const struct inode_operations adfs_dir_inode_operations = {
        .lookup         = adfs_lookup,
        .setattr        = adfs_notify_change,
};