FreeBSD-5.3/sys/compat/linux/linux_getcwd.c
/* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */
/* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Bill Sommerfeld.
*
* 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 the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__FBSDID("$FreeBSD: src/sys/compat/linux/linux_getcwd.c,v 1.15 2004/08/16 07:28:16 tjr Exp $");
#include "opt_compat.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/syscallsubr.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/dirent.h>
#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */
#include "opt_compat.h"
#if !COMPAT_LINUX32
#include <machine/../linux/linux.h>
#include <machine/../linux/linux_proto.h>
#else
#include <machine/../linux32/linux.h>
#include <machine/../linux32/linux32_proto.h>
#endif
#include <compat/linux/linux_util.h>
static int
linux_getcwd_scandir(struct vnode **, struct vnode **,
char **, char *, struct thread *);
static int
linux_getcwd_common(struct vnode *, struct vnode *,
char **, char *, int, int, struct thread *);
#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
/*
* Vnode variable naming conventions in this file:
*
* rvp: the current root we're aiming towards.
* lvp, *lvpp: the "lower" vnode
* uvp, *uvpp: the "upper" vnode.
*
* Since all the vnodes we're dealing with are directories, and the
* lookups are going *up* in the filesystem rather than *down*, the
* usual "pvp" (parent) or "dvp" (directory) naming conventions are
* too confusing.
*/
/*
* XXX Will infinite loop in certain cases if a directory read reliably
* returns EINVAL on last block.
* XXX is EINVAL the right thing to return if a directory is malformed?
*/
/*
* XXX Untested vs. mount -o union; probably does the wrong thing.
*/
/*
* Find parent vnode of *lvpp, return in *uvpp
*
* If we care about the name, scan it looking for name of directory
* entry pointing at lvp.
*
* Place the name in the buffer which starts at bufp, immediately
* before *bpp, and move bpp backwards to point at the start of it.
*
* On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed
* On exit, *uvpp is either NULL or is a locked vnode reference.
*/
static int
linux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td)
struct vnode **lvpp;
struct vnode **uvpp;
char **bpp;
char *bufp;
struct thread *td;
{
int error = 0;
int eofflag;
off_t off;
int tries;
struct uio uio;
struct iovec iov;
char *dirbuf = NULL;
int dirbuflen;
ino_t fileno;
struct vattr va;
struct vnode *uvp = NULL;
struct vnode *lvp = *lvpp;
struct componentname cn;
int len, reclen;
tries = 0;
/*
* If we want the filename, get some info we need while the
* current directory is still locked.
*/
if (bufp != NULL) {
error = VOP_GETATTR(lvp, &va, td->td_ucred, td);
if (error) {
vput(lvp);
*lvpp = NULL;
*uvpp = NULL;
return error;
}
}
/*
* Ok, we have to do it the hard way..
* Next, get parent vnode using lookup of ..
*/
cn.cn_nameiop = LOOKUP;
cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY;
cn.cn_thread = td;
cn.cn_cred = td->td_ucred;
cn.cn_pnbuf = NULL;
cn.cn_nameptr = "..";
cn.cn_namelen = 2;
cn.cn_consume = 0;
/*
* At this point, lvp is locked and will be unlocked by the lookup.
* On successful return, *uvpp will be locked
*/
#ifdef MAC
error = mac_check_vnode_lookup(td->td_ucred, lvp, &cn);
if (error == 0)
#endif
error = VOP_LOOKUP(lvp, uvpp, &cn);
if (error) {
vput(lvp);
*lvpp = NULL;
*uvpp = NULL;
return error;
}
uvp = *uvpp;
/* If we don't care about the pathname, we're done */
if (bufp == NULL) {
vrele(lvp);
*lvpp = NULL;
return 0;
}
fileno = va.va_fileid;
dirbuflen = DIRBLKSIZ;
if (dirbuflen < va.va_blocksize)
dirbuflen = va.va_blocksize;
dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
#if 0
unionread:
#endif
off = 0;
do {
/* call VOP_READDIR of parent */
iov.iov_base = dirbuf;
iov.iov_len = dirbuflen;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = off;
uio.uio_resid = dirbuflen;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_rw = UIO_READ;
uio.uio_td = td;
eofflag = 0;
#ifdef MAC
error = mac_check_vnode_readdir(td->td_ucred, uvp);
if (error == 0)
#endif /* MAC */
error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag,
0, 0);
off = uio.uio_offset;
/*
* Try again if NFS tosses its cookies.
* XXX this can still loop forever if the directory is busted
* such that the second or subsequent page of it always
* returns EINVAL
*/
if ((error == EINVAL) && (tries < 3)) {
off = 0;
tries++;
continue; /* once more, with feeling */
}
if (!error) {
char *cpos;
struct dirent *dp;
cpos = dirbuf;
tries = 0;
/* scan directory page looking for matching vnode */
for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) {
dp = (struct dirent *) cpos;
reclen = dp->d_reclen;
/* check for malformed directory.. */
if (reclen < DIRENT_MINSIZE) {
error = EINVAL;
goto out;
}
/*
* XXX should perhaps do VOP_LOOKUP to
* check that we got back to the right place,
* but getting the locking games for that
* right would be heinous.
*/
if ((dp->d_type != DT_WHT) &&
(dp->d_fileno == fileno)) {
char *bp = *bpp;
bp -= dp->d_namlen;
if (bp <= bufp) {
error = ERANGE;
goto out;
}
bcopy(dp->d_name, bp, dp->d_namlen);
error = 0;
*bpp = bp;
goto out;
}
cpos += reclen;
}
}
} while (!eofflag);
error = ENOENT;
out:
vrele(lvp);
*lvpp = NULL;
free(dirbuf, M_TEMP);
return error;
}
/*
* common routine shared by sys___getcwd() and linux_vn_isunder()
*/
#define GETCWD_CHECK_ACCESS 0x0001
static int
linux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td)
struct vnode *lvp;
struct vnode *rvp;
char **bpp;
char *bufp;
int limit;
int flags;
struct thread *td;
{
struct filedesc *fdp = td->td_proc->p_fd;
struct vnode *uvp = NULL;
char *bp = NULL;
int error;
int perms = VEXEC;
if (rvp == NULL) {
rvp = fdp->fd_rdir;
if (rvp == NULL)
rvp = rootvnode;
}
VREF(rvp);
VREF(lvp);
/*
* Error handling invariant:
* Before a `goto out':
* lvp is either NULL, or locked and held.
* uvp is either NULL, or locked and held.
*/
error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td);
if (error) {
vrele(lvp);
lvp = NULL;
goto out;
}
if (bufp)
bp = *bpp;
/*
* this loop will terminate when one of the following happens:
* - we hit the root
* - getdirentries or lookup fails
* - we run out of space in the buffer.
*/
if (lvp == rvp) {
if (bp)
*(--bp) = '/';
goto out;
}
do {
if (lvp->v_type != VDIR) {
error = ENOTDIR;
goto out;
}
/*
* access check here is optional, depending on
* whether or not caller cares.
*/
if (flags & GETCWD_CHECK_ACCESS) {
error = VOP_ACCESS(lvp, perms, td->td_ucred, td);
if (error)
goto out;
perms = VEXEC|VREAD;
}
/*
* step up if we're a covered vnode..
*/
while (lvp->v_vflag & VV_ROOT) {
struct vnode *tvp;
if (lvp == rvp)
goto out;
tvp = lvp;
lvp = lvp->v_mount->mnt_vnodecovered;
vput(tvp);
/*
* hodie natus est radici frater
*/
if (lvp == NULL) {
error = ENOENT;
goto out;
}
VREF(lvp);
error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td);
if (error != 0) {
vrele(lvp);
lvp = NULL;
goto out;
}
}
error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td);
if (error)
goto out;
#if DIAGNOSTIC
if (lvp != NULL)
panic("getcwd: oops, forgot to null lvp");
if (bufp && (bp <= bufp)) {
panic("getcwd: oops, went back too far");
}
#endif
if (bp)
*(--bp) = '/';
lvp = uvp;
uvp = NULL;
limit--;
} while ((lvp != rvp) && (limit > 0));
out:
if (bpp)
*bpp = bp;
if (uvp)
vput(uvp);
if (lvp)
vput(lvp);
vrele(rvp);
return error;
}
/*
* Find pathname of process's current directory.
*
* Use vfs vnode-to-name reverse cache; if that fails, fall back
* to reading directory contents.
*/
int
linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
{
caddr_t bp, bend, path;
int error, len, lenused;
#ifdef DEBUG
printf("Linux-emul(%ld): getcwd(%p, %ld)\n", (long)td->td_proc->p_pid,
args->buf, (long)args->bufsize);
#endif
len = args->bufsize;
if (len > MAXPATHLEN*4)
len = MAXPATHLEN*4;
else if (len < 2)
return ERANGE;
path = (char *)malloc(len, M_TEMP, M_WAITOK);
error = kern___getcwd(td, path, UIO_SYSSPACE, len);
if (!error) {
lenused = strlen(path) + 1;
if (lenused <= args->bufsize) {
td->td_retval[0] = lenused;
error = copyout(path, args->buf, lenused);
}
else
error = ERANGE;
} else {
bp = &path[len];
bend = bp;
*(--bp) = '\0';
/*
* 5th argument here is "max number of vnodes to traverse".
* Since each entry takes up at least 2 bytes in the output buffer,
* limit it to N/2 vnodes for an N byte buffer.
*/
error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL,
&bp, path, len/2, GETCWD_CHECK_ACCESS, td);
if (error)
goto out;
lenused = bend - bp;
td->td_retval[0] = lenused;
/* put the result into user buffer */
error = copyout(bp, args->buf, lenused);
}
out:
free(path, M_TEMP);
return (error);
}