/* $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. * * 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 __FBSDID("$FreeBSD$"); #include "opt_compat.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* XXX only for DIRBLKSIZ */ #ifdef COMPAT_LINUX32 #include #include #else #include #include #endif #include #include 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); 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; cn.cn_lkflags = LK_SHARED; /* * At this point, lvp is locked and will be unlocked by the lookup. * On successful return, *uvpp will be locked */ #ifdef MAC error = mac_vnode_check_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) { vput(lvp); *lvpp = NULL; return 0; } fileno = va.va_fileid; dirbuflen = DIRBLKSIZ; if (dirbuflen < va.va_blocksize) dirbuflen = va.va_blocksize; dirbuf = 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_vnode_check_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: vput(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; accmode_t accmode = 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); if (error != 0) panic("vn_lock LK_RETRY returned error %d", error); 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, accmode, td->td_ucred, td); if (error) goto out; accmode = 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); if (error != 0) panic("vn_lock LK_RETRY returned %d", error); } error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); if (error) goto out; #ifdef 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) { char *bp, *bend, *path; int error, len, lenused; #ifdef DEBUG if (ldebug(getcwd)) printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize); #endif len = args->bufsize; if (len > MAXPATHLEN*4) len = MAXPATHLEN*4; else if (len < 2) return ERANGE; path = 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); }