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/*

 *  linux/fs/readdir.c

 *

 *  Copyright (C) 1995  Linus Torvalds

 */

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/stat.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <asm/segment.h>

/*

 * 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))

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, off_t offset, ino_t ino)

{

        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);

        memcpy_tofs(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;

        if (fd >= NR_OPEN || !(file = current->files->fd[fd]))

                return -EBADF;

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

                return -ENOTDIR;

        error = verify_area(VERIFY_WRITE, dirent, sizeof(struct old_linux_dirent));

        if (error)

                return error;

        buf.count = 0;

        buf.dirent = dirent;

        error = file->f_op->readdir(file->f_inode, file, &buf, fillonedir);

        if (error < 0)

                return error;

        return buf.count;

}

/*

 * 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, off_t offset, ino_t ino)

{

        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);

        memcpy_tofs(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 int sys_getdents(unsigned int fd, void * dirent, unsigned int count)

{

        struct file * file;

        struct linux_dirent * lastdirent;

        struct getdents_callback buf;

        int error;

        if (fd >= NR_OPEN || !(file = current->files->fd[fd]))

                return -EBADF;

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

                return -ENOTDIR;

        error = verify_area(VERIFY_WRITE, dirent, count);

        if (error)

                return error;

        buf.current_dir = (struct linux_dirent *) dirent;

        buf.previous = NULL;

        buf.count = count;

        buf.error = 0;

        error = file->f_op->readdir(file->f_inode, file, &buf, filldir);

        if (error < 0)

                return error;

        lastdirent = buf.previous;

        if (!lastdirent)

                return buf.error;

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

        return count - buf.count;

}