root/fs/readdir.c

/*
 *  linux/fs/readdir.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

#include <linux/module.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/file.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/dirent.h>
#include <linux/security.h>
#include <linux/unistd.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;

        res = security_file_permission(file, MAY_READ);
        if (res)
                goto out;

        down(&inode->i_sem);
        res = -ENOENT;
        if (!IS_DEADDIR(inode)) {
                res = file->f_op->readdir(file, buf, filler);
                file_accessed(file);
        }
        up(&inode->i_sem);
out:
        return res;
}

EXPORT_SYMBOL(vfs_readdir);

/*
 * 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 __user *) (de)))
#define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))

#ifdef __ARCH_WANT_OLD_READDIR

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 __user * dirent;
        int result;
};

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 __user * dirent;

        if (buf->result)
                return -EINVAL;
        buf->result++;
        dirent = buf->dirent;
        if (!access_ok(VERIFY_WRITE, dirent,
                        (unsigned long)(dirent->d_name + namlen + 1) -
                                (unsigned long)dirent))
                goto efault;
        if (    __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))
                goto efault;
        return 0;
efault:
        buf->result = -EFAULT;
        return -EFAULT;
}

asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
{
        int error;
        struct file * file;
        struct readdir_callback buf;

        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;

        buf.result = 0;
        buf.dirent = dirent;

        error = vfs_readdir(file, fillonedir, &buf);
        if (error >= 0)
                error = buf.result;

        fput(file);
out:
        return error;
}

#endif /* __ARCH_WANT_OLD_READDIR */

/*
 * 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 __user * current_dir;
        struct linux_dirent __user * 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 __user * dirent;
        struct getdents_callback * buf = (struct getdents_callback *) __buf;
        int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);

        buf->error = -EINVAL;   /* only used if we fail.. */
        if (reclen > buf->count)
                return -EINVAL;
        dirent = buf->previous;
        if (dirent) {
                if (__put_user(offset, &dirent->d_off))
                        goto efault;
        }
        dirent = buf->current_dir;
        if (__put_user(ino, &dirent->d_ino))
                goto efault;
        if (__put_user(reclen, &dirent->d_reclen))
                goto efault;
        if (copy_to_user(dirent->d_name, name, namlen))
                goto efault;
        if (__put_user(0, dirent->d_name + namlen))
                goto efault;
        if (__put_user(d_type, (char __user *) dirent + reclen - 1))
                goto efault;
        buf->previous = dirent;
        dirent = (void __user *)dirent + reclen;
        buf->current_dir = dirent;
        buf->count -= reclen;
        return 0;
efault:
        buf->error = -EFAULT;
        return -EFAULT;
}

asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
{
        struct file * file;
        struct linux_dirent __user * lastdirent;
        struct getdents_callback buf;
        int error;

        error = -EFAULT;
        if (!access_ok(VERIFY_WRITE, dirent, count))
                goto out;

        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;

        buf.current_dir = 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) {
                if (put_user(file->f_pos, &lastdirent->d_off))
                        error = -EFAULT;
                else
                        error = count - buf.count;
        }

out_putf:
        fput(file);
out:
        return error;
}

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

struct getdents_callback64 {
        struct linux_dirent64 __user * current_dir;
        struct linux_dirent64 __user * 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 __user *dirent;
        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) {
                if (__put_user(offset, &dirent->d_off))
                        goto efault;
        }
        dirent = buf->current_dir;
        if (__put_user(ino, &dirent->d_ino))
                goto efault;
        if (__put_user(0, &dirent->d_off))
                goto efault;
        if (__put_user(reclen, &dirent->d_reclen))
                goto efault;
        if (__put_user(d_type, &dirent->d_type))
                goto efault;
        if (copy_to_user(dirent->d_name, name, namlen))
                goto efault;
        if (__put_user(0, dirent->d_name + namlen))
                goto efault;
        buf->previous = dirent;
        dirent = (void __user *)dirent + reclen;
        buf->current_dir = dirent;
        buf->count -= reclen;
        return 0;
efault:
        buf->error = -EFAULT;
        return -EFAULT;
}

asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
{
        struct file * file;
        struct linux_dirent64 __user * lastdirent;
        struct getdents_callback64 buf;
        int error;

        error = -EFAULT;
        if (!access_ok(VERIFY_WRITE, dirent, count))
                goto out;

        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;

        buf.current_dir = 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) {
                typeof(lastdirent->d_off) d_off = file->f_pos;
                __put_user(d_off, &lastdirent->d_off);
                error = count - buf.count;
        }

out_putf:
        fput(file);
out:
        return error;
}