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/*

 *  linux/fs/readdir.c

 *

 *  Copyright (C) 1995  Linus Torvalds

 */

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/errno.h>

#include <linux/stat.h>

#include <linux/file.h>

#include <linux/smp_lock.h>

#include <asm/uaccess.h>

int vfs_readdir(struct file *file, filldir_t filler, void *buf)

{

        struct inode *inode = file->f_dentry->d_inode;

        int res = -ENOTDIR;

        if (!file->f_op || !file->f_op->readdir)

                goto out;

        down(&inode->i_sem);

        down(&inode->i_zombie);

        res = -ENOENT;

        if (!IS_DEADDIR(inode)) {

                lock_kernel();

                res = file->f_op->readdir(file, buf, filler);

                unlock_kernel();

        }

        up(&inode->i_zombie);

        up(&inode->i_sem);

out:

        return res;

}

int dcache_dir_open(struct inode *inode, struct file *file)

{

        static struct qstr cursor_name = {len:1, name:"."};

        file->private_data = d_alloc(file->f_dentry, &cursor_name);

        return file->private_data ? 0 : -ENOMEM;

}

int dcache_dir_close(struct inode *inode, struct file *file)

{

        dput(file->private_data);

        return 0;

}

loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)

{

        down(&file->f_dentry->d_inode->i_sem);

        switch (origin) {

                case 1:

                        offset += file->f_pos;

                case 0:

                        if (offset >= 0)

                                break;

                default:

                        up(&file->f_dentry->d_inode->i_sem);

                        return -EINVAL;

        }

        if (offset != file->f_pos) {

                file->f_pos = offset;

                if (file->f_pos >= 2) {

                        struct list_head *p;

                        struct dentry *cursor = file->private_data;

                        loff_t n = file->f_pos - 2;

                        spin_lock(&dcache_lock);

                        list_del(&cursor->d_child);

                        p = file->f_dentry->d_subdirs.next;

                        while (n && p != &file->f_dentry->d_subdirs) {

                                struct dentry *next;

                                next = list_entry(p, struct dentry, d_child);

                                if (!list_empty(&next->d_hash) && next->d_inode)

                                        n--;

                                p = p->next;

                        }

                        list_add_tail(&cursor->d_child, p);

                        spin_unlock(&dcache_lock);

                }

        }

        up(&file->f_dentry->d_inode->i_sem);

        return offset;

}

int dcache_dir_fsync(struct file * file, struct dentry *dentry, int datasync)

{

        return 0;

}

/*

 * Directory is locked and all positive dentries in it are safe, since

 * for ramfs-type trees they can't go away without unlink() or rmdir(),

 * both impossible due to the lock on directory.

 */

int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)

{

        struct dentry *dentry = filp->f_dentry;

        struct dentry *cursor = filp->private_data;

        struct list_head *p, *q = &cursor->d_child;

        ino_t ino;

        int i = filp->f_pos;

        switch (i) {

                case 0:

                        ino = dentry->d_inode->i_ino;

                        if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)

                                break;

                        filp->f_pos++;

                        i++;

                        /* fallthrough */

                case 1:

                        spin_lock(&dcache_lock);

                        ino = dentry->d_parent->d_inode->i_ino;

                        spin_unlock(&dcache_lock);

                        if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)

                                break;

                        filp->f_pos++;

                        i++;

                        /* fallthrough */

                default:

                        spin_lock(&dcache_lock);

                        if (filp->f_pos == 2) {

                                list_del(q);

                                list_add(q, &dentry->d_subdirs);

                        }

                        for (p=q->next; p != &dentry->d_subdirs; p=p->next) {

                                struct dentry *next;

                                next = list_entry(p, struct dentry, d_child);

                                if (list_empty(&next->d_hash) || !next->d_inode)

                                        continue;

                                spin_unlock(&dcache_lock);

                                if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, DT_UNKNOWN) < 0)

                                        return 0;

                                spin_lock(&dcache_lock);

                                /* next is still alive */

                                list_del(q);

                                list_add(q, p);

                                p = q;

                                filp->f_pos++;

                        }

                        spin_unlock(&dcache_lock);

        }

        UPDATE_ATIME(dentry->d_inode);

        return 0;

}

struct file_operations dcache_dir_ops = {

        open:           dcache_dir_open,

        release:        dcache_dir_close,

        llseek:         dcache_dir_lseek,

        read:           generic_read_dir,

        readdir:        dcache_readdir,

        fsync:          dcache_dir_fsync,

};

/*

 * Traditional linux readdir() handling..

 *

 * "count=1" is a special case, meaning that the buffer is one

 * dirent-structure in size and that the code can't handle more

 * anyway. Thus the special "fillonedir()" function for that

 * case (the low-level handlers don't need to care about this).

 */

#define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))

#define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))

#ifndef __ia64__

struct old_linux_dirent {

        unsigned long   d_ino;

        unsigned long   d_offset;

        unsigned short  d_namlen;

        char            d_name[1];

};

struct readdir_callback {

        struct old_linux_dirent * dirent;

        int count;

};

static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,

                      ino_t ino, unsigned int d_type)

{

        struct readdir_callback * buf = (struct readdir_callback *) __buf;

        struct old_linux_dirent * dirent;

        if (buf->count)

                return -EINVAL;

        buf->count++;

        dirent = buf->dirent;

        put_user(ino, &dirent->d_ino);

        put_user(offset, &dirent->d_offset);

        put_user(namlen, &dirent->d_namlen);

        copy_to_user(dirent->d_name, name, namlen);

        put_user(0, dirent->d_name + namlen);

        return 0;

}

asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count)

{

        int error;

        struct file * file;

        struct readdir_callback buf;

        error = -EBADF;

        file = fget(fd);

        if (!file)

                goto out;

        buf.count = 0;

        buf.dirent = dirent;

        error = vfs_readdir(file, fillonedir, &buf);

        if (error >= 0)

                error = buf.count;

        fput(file);

out:

        return error;

}

#endif /* !__ia64__ */

/*

 * New, all-improved, singing, dancing, iBCS2-compliant getdents()

 * interface.

 */

struct linux_dirent {

        unsigned long   d_ino;

        unsigned long   d_off;

        unsigned short  d_reclen;

        char            d_name[1];

};

struct getdents_callback {

        struct linux_dirent * current_dir;

        struct linux_dirent * previous;

        int count;

        int error;

};

static int filldir(void * __buf, const char * name, int namlen, loff_t offset,

                   ino_t ino, unsigned int d_type)

{

        struct linux_dirent * dirent;

        struct getdents_callback * buf = (struct getdents_callback *) __buf;

        int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);

        buf->error = -EINVAL;   /* only used if we fail.. */

        if (reclen > buf->count)

                return -EINVAL;

        dirent = buf->previous;

        if (dirent)

                put_user(offset, &dirent->d_off);

        dirent = buf->current_dir;

        buf->previous = dirent;

        put_user(ino, &dirent->d_ino);

        put_user(reclen, &dirent->d_reclen);

        copy_to_user(dirent->d_name, name, namlen);

        put_user(0, dirent->d_name + namlen);

        ((char *) dirent) += reclen;

        buf->current_dir = dirent;

        buf->count -= reclen;

        return 0;

}

asmlinkage long sys_getdents(unsigned int fd, void * dirent, unsigned int count)

{

        struct file * file;

        struct linux_dirent * lastdirent;

        struct getdents_callback buf;

        int error;

        error = -EBADF;

        file = fget(fd);

        if (!file)

                goto out;

        buf.current_dir = (struct linux_dirent *) dirent;

        buf.previous = NULL;

        buf.count = count;

        buf.error = 0;

        error = vfs_readdir(file, filldir, &buf);

        if (error < 0)

                goto out_putf;

        error = buf.error;

        lastdirent = buf.previous;

        if (lastdirent) {

                put_user(file->f_pos, &lastdirent->d_off);

                error = count - buf.count;

        }

out_putf:

        fput(file);

out:

        return error;

}

/*

 * And even better one including d_type field and 64bit d_ino and d_off.

 */

struct linux_dirent64 {

        u64             d_ino;

        s64             d_off;

        unsigned short  d_reclen;

        unsigned char   d_type;

        char            d_name[0];

};

#define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))

struct getdents_callback64 {

        struct linux_dirent64 * current_dir;

        struct linux_dirent64 * previous;

        int count;

        int error;

};

static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,

                     ino_t ino, unsigned int d_type)

{

        struct linux_dirent64 * dirent, d;

        struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;

        int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);

        buf->error = -EINVAL;   /* only used if we fail.. */

        if (reclen > buf->count)

                return -EINVAL;

        dirent = buf->previous;

        if (dirent) {

                d.d_off = offset;

                copy_to_user(&dirent->d_off, &d.d_off, sizeof(d.d_off));

        }

        dirent = buf->current_dir;

        buf->previous = dirent;

        memset(&d, 0, NAME_OFFSET(&d));

        d.d_ino = ino;

        d.d_reclen = reclen;

        d.d_type = d_type;

        copy_to_user(dirent, &d, NAME_OFFSET(&d));

        copy_to_user(dirent->d_name, name, namlen);

        put_user(0, dirent->d_name + namlen);

        ((char *) dirent) += reclen;

        buf->current_dir = dirent;

        buf->count -= reclen;

        return 0;

}

asmlinkage long sys_getdents64(unsigned int fd, void * dirent, unsigned int count)

{

        struct file * file;

        struct linux_dirent64 * lastdirent;

        struct getdents_callback64 buf;

        int error;

        error = -EBADF;

        file = fget(fd);

        if (!file)

                goto out;

        buf.current_dir = (struct linux_dirent64 *) dirent;

        buf.previous = NULL;

        buf.count = count;

        buf.error = 0;

        error = vfs_readdir(file, filldir64, &buf);

        if (error < 0)

                goto out_putf;

        error = buf.error;

        lastdirent = buf.previous;

        if (lastdirent) {

                struct linux_dirent64 d;

                d.d_off = file->f_pos;

                copy_to_user(&lastdirent->d_off, &d.d_off, sizeof(d.d_off));

                error = count - buf.count;

        }

out_putf:

        fput(file);

out:

        return error;

}