xref: /src/sys/compat/linux32/common/linux32_dirent.c

/*	$NetBSD: linux32_dirent.c,v 1.20 2019/08/23 07:53:36 maxv Exp $ */

/*-
 * Copyright (c) 2006 Emmanuel Dreyfus, all rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Emmanuel Dreyfus
 * 4. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>

__KERNEL_RCSID(0, "$NetBSD: linux32_dirent.c,v 1.20 2019/08/23 07:53:36 maxv Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/fstypes.h>
#include <sys/signal.h>
#include <sys/dirent.h>
#include <sys/kernel.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/malloc.h>
#include <sys/select.h>
#include <sys/proc.h>
#include <sys/ucred.h>
#include <sys/vnode.h>
#include <sys/swap.h>

#include <machine/types.h>

#include <sys/syscallargs.h>

#include <compat/netbsd32/netbsd32.h>
#include <compat/netbsd32/netbsd32_conv.h>
#include <compat/netbsd32/netbsd32_syscallargs.h>

#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_signal.h>
#include <compat/linux/common/linux_machdep.h>
#include <compat/linux/common/linux_misc.h>
#include <compat/linux/common/linux_oldolduname.h>
#include <compat/linux/common/linux_dirent.h>
#include <compat/linux/common/linux_ipc.h>
#include <compat/linux/common/linux_sem.h>
#include <compat/linux/linux_syscallargs.h>

#include <compat/linux32/common/linux32_types.h>
#include <compat/linux32/common/linux32_signal.h>
#include <compat/linux32/common/linux32_machdep.h>
#include <compat/linux32/common/linux32_sysctl.h>
#include <compat/linux32/common/linux32_socketcall.h>
#include <compat/linux32/linux32_syscallargs.h>

/*
 * Linux 'readdir' call. This code is mostly taken from the
 * SunOS getdents call (see compat/sunos/sunos_misc.c), though
 * an attempt has been made to keep it a little cleaner (failing
 * miserably, because of the cruft needed if count 1 is passed).
 *
 * The d_off field should contain the offset of the next valid entry,
 * but in Linux it has the offset of the entry itself. We emulate
 * that bug here.
 *
 * Read in BSD-style entries, convert them, and copy them out.
 *
 * Note that this doesn't handle union-mounted filesystems.
 */

int
linux32_sys_getdents(struct lwp *l, const struct linux32_sys_getdents_args *uap, register_t *retval)
{
	/* {
		syscallarg(int) fd;
		syscallarg(linux32_direntp_t) dent;
		syscallarg(unsigned int) count;
	} */
	struct dirent *bdp;
	struct vnode *vp;
	char *inp, *tbuf;		/* BSD-format */
	int len, reclen;		/* BSD-format */
	char *outp;			/* Linux-format */
	int resid, linux32_reclen = 0;	/* Linux-format */
	struct file *fp;
	struct uio auio;
	struct iovec aiov;
	struct linux32_dirent idb;
	off_t off;		/* true file offset */
	int buflen, error, eofflag, nbytes, oldcall;
	struct vattr va;
	off_t *cookiebuf = NULL, *cookie;
	int ncookies;

	/* fd_getvnode() will use the descriptor for us */
	if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
		return (error);

	if ((fp->f_flag & FREAD) == 0) {
		error = EBADF;
		goto out1;
	}

	vp = (struct vnode *)fp->f_data;
	if (vp->v_type != VDIR) {
		error = ENOTDIR;
		goto out1;
	}

	vn_lock(vp, LK_SHARED | LK_RETRY);
	error = VOP_GETATTR(vp, &va, l->l_cred);
	VOP_UNLOCK(vp);
	if (error)
		goto out1;

	nbytes = SCARG(uap, count);
	if (nbytes == 1) {	/* emulating old, broken behaviour */
		nbytes = sizeof (idb);
		buflen = uimax(va.va_blocksize, nbytes);
		oldcall = 1;
	} else {
		buflen = uimin(MAXBSIZE, nbytes);
		if (buflen < va.va_blocksize)
			buflen = va.va_blocksize;
		oldcall = 0;
	}
	tbuf = malloc(buflen, M_TEMP, M_WAITOK);

	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
	off = fp->f_offset;
again:
	aiov.iov_base = tbuf;
	aiov.iov_len = buflen;
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_rw = UIO_READ;
	auio.uio_resid = buflen;
	auio.uio_offset = off;
	UIO_SETUP_SYSSPACE(&auio);
	/*
         * First we read into the malloc'ed buffer, then
         * we massage it into user space, one record at a time.
         */
	error = VOP_READDIR(vp, &auio, fp->f_cred, &eofflag, &cookiebuf,
	    &ncookies);
	if (error)
		goto out;

	inp = tbuf;
	outp = (void *)SCARG_P32(uap, dent);
	resid = nbytes;
	if ((len = buflen - auio.uio_resid) == 0)
		goto eof;

	for (cookie = cookiebuf; len > 0; len -= reclen) {
		bdp = (struct dirent *)inp;
		reclen = bdp->d_reclen;
		if (reclen & 3) {
			error = EIO;
			goto out;
		}
		if (bdp->d_fileno == 0) {
			inp += reclen;	/* it is a hole; squish it out */
			if (cookie)
				off = *cookie++;
			else
				off += reclen;
			continue;
		}
		linux32_reclen = LINUX_RECLEN(&idb, bdp->d_namlen);
		if (reclen > len || resid < linux32_reclen) {
			/* entry too big for buffer, so just stop */
			outp++;
			break;
		}
		/*
		 * Massage in place to make a Linux-shaped dirent (otherwise
		 * we have to worry about touching user memory outside of
		 * the copyout() call).
		 */
		memset(&idb, 0, sizeof(idb));
		idb.d_ino = bdp->d_fileno;
		/*
		 * The old readdir() call misuses the offset and reclen fields.
		 */
		if (oldcall) {
			idb.d_off = (linux32_off_t)linux32_reclen;
			idb.d_reclen = (u_short)bdp->d_namlen;
		} else {
			if (sizeof (idb.d_off) <= 4 && (off >> 32) != 0) {
				compat_offseterr(vp, "linux32_getdents");
				error = EINVAL;
				goto out;
			}
			idb.d_off = (linux32_off_t)off;
			idb.d_reclen = (u_short)linux32_reclen;
		}
		size_t dirl = MIN(sizeof(idb.d_name) - 1, bdp->d_namlen + 1);
		memcpy(idb.d_name, bdp->d_name, dirl);
		idb.d_name[dirl + 1] = bdp->d_type;
		if ((error = copyout((void *)&idb, outp, linux32_reclen)))
			goto out;
		/* advance past this real entry */
		inp += reclen;
		if (cookie)
			off = *cookie++; /* each entry points to itself */
		else
			off += reclen;
		/* advance output past Linux-shaped entry */
		outp += linux32_reclen;
		resid -= linux32_reclen;
		if (oldcall)
			break;
	}

	/* if we squished out the whole block, try again */
	if (outp == (void *)SCARG_P32(uap, dent)) {
		if (cookiebuf)
			free(cookiebuf, M_TEMP);
		cookiebuf = NULL;
		goto again;
	}
	fp->f_offset = off;	/* update the vnode offset */

	if (oldcall)
		nbytes = resid + linux32_reclen;

eof:
	*retval = nbytes - resid;
out:
	VOP_UNLOCK(vp);
	if (cookiebuf)
		free(cookiebuf, M_TEMP);
	free(tbuf, M_TEMP);
out1:
	fd_putfile(SCARG(uap, fd));
	return error;
}

int
linux32_sys_getdents64(struct lwp *l, const struct linux32_sys_getdents64_args *uap, register_t *retval)
{
	/* {
		syscallarg(int) fd;
		syscallarg(linux32_dirent64p_t) dent;
		syscallarg(unsigned int) count;
	} */
	struct linux_sys_getdents64_args ua;

	NETBSD32TO64_UAP(fd);
	NETBSD32TOP_UAP(dent, struct linux_dirent64);
	NETBSD32TO64_UAP(count);

	return linux_sys_getdents64(l, &ua, retval);
}

int
linux32_sys_readdir(struct lwp *l, const struct linux32_sys_readdir_args *uap, register_t *retval)
{
	/* {
		syscallarg(int) fd;
		syscallarg(struct linux32_direntp_t) dent;
		syscallarg(unsigned int) count;
	} */
	int error;
	struct linux32_sys_getdents_args da;

	SCARG(&da, fd) = SCARG(uap, fd);
	SCARG(&da, dent) = SCARG(uap, dent);
	SCARG(&da, count) = 1;

	error = linux32_sys_getdents(l, &da, retval);
	if (error == 0 && *retval > 1)
		*retval = 1;

	return error;
}