linux_getcwd.c revision 116173
182518Sgallatin/* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */ 282518Sgallatin/* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */ 382518Sgallatin/*- 482518Sgallatin * Copyright (c) 1999 The NetBSD Foundation, Inc. 582518Sgallatin * All rights reserved. 682518Sgallatin * 782518Sgallatin * This code is derived from software contributed to The NetBSD Foundation 882518Sgallatin * by Bill Sommerfeld. 982518Sgallatin * 1082518Sgallatin * Redistribution and use in source and binary forms, with or without 1182518Sgallatin * modification, are permitted provided that the following conditions 1282518Sgallatin * are met: 1382518Sgallatin * 1. Redistributions of source code must retain the above copyright 1482518Sgallatin * notice, this list of conditions and the following disclaimer. 1582518Sgallatin * 2. Redistributions in binary form must reproduce the above copyright 1682518Sgallatin * notice, this list of conditions and the following disclaimer in the 1782518Sgallatin * documentation and/or other materials provided with the distribution. 1882518Sgallatin * 3. All advertising materials mentioning features or use of this software 1982518Sgallatin * must display the following acknowledgement: 2082518Sgallatin * This product includes software developed by the NetBSD 2182518Sgallatin * Foundation, Inc. and its contributors. 2282518Sgallatin * 4. Neither the name of The NetBSD Foundation nor the names of its 2382518Sgallatin * contributors may be used to endorse or promote products derived 2482518Sgallatin * from this software without specific prior written permission. 2582518Sgallatin * 2682518Sgallatin * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 2782518Sgallatin * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 2882518Sgallatin * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 2982518Sgallatin * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 3082518Sgallatin * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 3182518Sgallatin * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 3282518Sgallatin * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 3382518Sgallatin * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 3482518Sgallatin * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 3582518Sgallatin * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 3682518Sgallatin * POSSIBILITY OF SUCH DAMAGE. 3782518Sgallatin */ 38116173Sobrien 39116173Sobrien#include <sys/cdefs.h> 40116173Sobrien__FBSDID("$FreeBSD: head/sys/compat/linux/linux_getcwd.c 116173 2003-06-10 21:29:12Z obrien $"); 41116173Sobrien 42112430Sphk#include "opt_compat.h" 43112430Sphk#include "opt_mac.h" 4482518Sgallatin 4582518Sgallatin#include <sys/param.h> 4682518Sgallatin#include <sys/systm.h> 47112430Sphk#include <sys/namei.h> 48112430Sphk#include <sys/filedesc.h> 49112430Sphk#include <sys/kernel.h> 50112430Sphk#include <sys/file.h> 51112430Sphk#include <sys/stat.h> 52102872Siedowse#include <sys/syscallsubr.h> 53112430Sphk#include <sys/vnode.h> 54112430Sphk#include <sys/mount.h> 5582518Sgallatin#include <sys/proc.h> 56112430Sphk#include <sys/uio.h> 57112430Sphk#include <sys/mac.h> 58112430Sphk#include <sys/malloc.h> 59112430Sphk#include <sys/dirent.h> 60112430Sphk#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */ 6182518Sgallatin 6282518Sgallatin#include <machine/../linux/linux.h> 6382518Sgallatin#include <machine/../linux/linux_proto.h> 64112430Sphk#include <compat/linux/linux_util.h> 6582518Sgallatin 66112430Sphkstatic int 67112430Sphklinux_getcwd_scandir(struct vnode **, struct vnode **, 68112430Sphk char **, char *, struct thread *); 69112430Sphkstatic int 70112430Sphklinux_getcwd_common(struct vnode *, struct vnode *, 71112430Sphk char **, char *, int, int, struct thread *); 72112430Sphk 73112430Sphk#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4) 74112430Sphk 7582518Sgallatin/* 76112430Sphk * Vnode variable naming conventions in this file: 77112430Sphk * 78112430Sphk * rvp: the current root we're aiming towards. 79112430Sphk * lvp, *lvpp: the "lower" vnode 80112430Sphk * uvp, *uvpp: the "upper" vnode. 81112430Sphk * 82112430Sphk * Since all the vnodes we're dealing with are directories, and the 83112430Sphk * lookups are going *up* in the filesystem rather than *down*, the 84112430Sphk * usual "pvp" (parent) or "dvp" (directory) naming conventions are 85112430Sphk * too confusing. 86112430Sphk */ 87112430Sphk 88112430Sphk/* 89112430Sphk * XXX Will infinite loop in certain cases if a directory read reliably 90112430Sphk * returns EINVAL on last block. 91112430Sphk * XXX is EINVAL the right thing to return if a directory is malformed? 92112430Sphk */ 93112430Sphk 94112430Sphk/* 95112430Sphk * XXX Untested vs. mount -o union; probably does the wrong thing. 96112430Sphk */ 97112430Sphk 98112430Sphk/* 99112430Sphk * Find parent vnode of *lvpp, return in *uvpp 100112430Sphk * 101112430Sphk * If we care about the name, scan it looking for name of directory 102112430Sphk * entry pointing at lvp. 103112430Sphk * 104112430Sphk * Place the name in the buffer which starts at bufp, immediately 105112430Sphk * before *bpp, and move bpp backwards to point at the start of it. 106112430Sphk * 107112430Sphk * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed 108112430Sphk * On exit, *uvpp is either NULL or is a locked vnode reference. 109112430Sphk */ 110112430Sphkstatic int 111112430Sphklinux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td) 112112430Sphk struct vnode **lvpp; 113112430Sphk struct vnode **uvpp; 114112430Sphk char **bpp; 115112430Sphk char *bufp; 116112430Sphk struct thread *td; 117112430Sphk{ 118112430Sphk int error = 0; 119112430Sphk int eofflag; 120112430Sphk off_t off; 121112430Sphk int tries; 122112430Sphk struct uio uio; 123112430Sphk struct iovec iov; 124112430Sphk char *dirbuf = NULL; 125112430Sphk int dirbuflen; 126112430Sphk ino_t fileno; 127112430Sphk struct vattr va; 128112430Sphk struct vnode *uvp = NULL; 129112430Sphk struct vnode *lvp = *lvpp; 130112430Sphk struct componentname cn; 131112430Sphk int len, reclen; 132112430Sphk tries = 0; 133112430Sphk 134112430Sphk /* 135112430Sphk * If we want the filename, get some info we need while the 136112430Sphk * current directory is still locked. 137112430Sphk */ 138112430Sphk if (bufp != NULL) { 139112430Sphk error = VOP_GETATTR(lvp, &va, td->td_ucred, td); 140112430Sphk if (error) { 141112430Sphk vput(lvp); 142112430Sphk *lvpp = NULL; 143112430Sphk *uvpp = NULL; 144112430Sphk return error; 145112430Sphk } 146112430Sphk } 147112430Sphk 148112430Sphk /* 149112430Sphk * Ok, we have to do it the hard way.. 150112430Sphk * Next, get parent vnode using lookup of .. 151112430Sphk */ 152112430Sphk cn.cn_nameiop = LOOKUP; 153112430Sphk cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY; 154112430Sphk cn.cn_thread = td; 155112430Sphk cn.cn_cred = td->td_ucred; 156112430Sphk cn.cn_pnbuf = NULL; 157112430Sphk cn.cn_nameptr = ".."; 158112430Sphk cn.cn_namelen = 2; 159112430Sphk cn.cn_consume = 0; 160112430Sphk 161112430Sphk /* 162112430Sphk * At this point, lvp is locked and will be unlocked by the lookup. 163112430Sphk * On successful return, *uvpp will be locked 164112430Sphk */ 165112430Sphk error = VOP_LOOKUP(lvp, uvpp, &cn); 166112430Sphk if (error) { 167112430Sphk vput(lvp); 168112430Sphk *lvpp = NULL; 169112430Sphk *uvpp = NULL; 170112430Sphk return error; 171112430Sphk } 172112430Sphk uvp = *uvpp; 173112430Sphk 174112430Sphk /* If we don't care about the pathname, we're done */ 175112430Sphk if (bufp == NULL) { 176112430Sphk vrele(lvp); 177112430Sphk *lvpp = NULL; 178112430Sphk return 0; 179112430Sphk } 180112430Sphk 181112430Sphk fileno = va.va_fileid; 182112430Sphk 183112430Sphk dirbuflen = DIRBLKSIZ; 184112430Sphk if (dirbuflen < va.va_blocksize) 185112430Sphk dirbuflen = va.va_blocksize; 186112430Sphk dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK); 187112430Sphk 188112430Sphk#if 0 189112430Sphkunionread: 190112430Sphk#endif 191112430Sphk off = 0; 192112430Sphk do { 193112430Sphk /* call VOP_READDIR of parent */ 194112430Sphk iov.iov_base = dirbuf; 195112430Sphk iov.iov_len = dirbuflen; 196112430Sphk 197112430Sphk uio.uio_iov = &iov; 198112430Sphk uio.uio_iovcnt = 1; 199112430Sphk uio.uio_offset = off; 200112430Sphk uio.uio_resid = dirbuflen; 201112430Sphk uio.uio_segflg = UIO_SYSSPACE; 202112430Sphk uio.uio_rw = UIO_READ; 203112430Sphk uio.uio_td = td; 204112430Sphk 205112430Sphk eofflag = 0; 206112430Sphk 207112430Sphk#ifdef MAC 208112430Sphk error = mac_check_vnode_readdir(td->td_ucred, uvp); 209112430Sphk if (error == 0) 210112430Sphk#endif /* MAC */ 211112430Sphk error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, 212112430Sphk 0, 0); 213112430Sphk 214112430Sphk off = uio.uio_offset; 215112430Sphk 216112430Sphk /* 217112430Sphk * Try again if NFS tosses its cookies. 218112430Sphk * XXX this can still loop forever if the directory is busted 219112430Sphk * such that the second or subsequent page of it always 220112430Sphk * returns EINVAL 221112430Sphk */ 222112430Sphk if ((error == EINVAL) && (tries < 3)) { 223112430Sphk off = 0; 224112430Sphk tries++; 225112430Sphk continue; /* once more, with feeling */ 226112430Sphk } 227112430Sphk 228112430Sphk if (!error) { 229112430Sphk char *cpos; 230112430Sphk struct dirent *dp; 231112430Sphk 232112430Sphk cpos = dirbuf; 233112430Sphk tries = 0; 234112430Sphk 235112430Sphk /* scan directory page looking for matching vnode */ 236112430Sphk for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) { 237112430Sphk dp = (struct dirent *) cpos; 238112430Sphk reclen = dp->d_reclen; 239112430Sphk 240112430Sphk /* check for malformed directory.. */ 241112430Sphk if (reclen < DIRENT_MINSIZE) { 242112430Sphk error = EINVAL; 243112430Sphk goto out; 244112430Sphk } 245112430Sphk /* 246112430Sphk * XXX should perhaps do VOP_LOOKUP to 247112430Sphk * check that we got back to the right place, 248112430Sphk * but getting the locking games for that 249112430Sphk * right would be heinous. 250112430Sphk */ 251112430Sphk if ((dp->d_type != DT_WHT) && 252112430Sphk (dp->d_fileno == fileno)) { 253112430Sphk char *bp = *bpp; 254112430Sphk bp -= dp->d_namlen; 255112430Sphk 256112430Sphk if (bp <= bufp) { 257112430Sphk error = ERANGE; 258112430Sphk goto out; 259112430Sphk } 260112430Sphk bcopy(dp->d_name, bp, dp->d_namlen); 261112430Sphk error = 0; 262112430Sphk *bpp = bp; 263112430Sphk goto out; 264112430Sphk } 265112430Sphk cpos += reclen; 266112430Sphk } 267112430Sphk } 268112430Sphk } while (!eofflag); 269112430Sphk error = ENOENT; 270112430Sphk 271112430Sphkout: 272112430Sphk vrele(lvp); 273112430Sphk *lvpp = NULL; 274112430Sphk free(dirbuf, M_TEMP); 275112430Sphk return error; 276112430Sphk} 277112430Sphk 278112430Sphk 279112430Sphk/* 280112430Sphk * common routine shared by sys___getcwd() and linux_vn_isunder() 281112430Sphk */ 282112430Sphk 283112430Sphk#define GETCWD_CHECK_ACCESS 0x0001 284112430Sphk 285112430Sphkstatic int 286112430Sphklinux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td) 287112430Sphk struct vnode *lvp; 288112430Sphk struct vnode *rvp; 289112430Sphk char **bpp; 290112430Sphk char *bufp; 291112430Sphk int limit; 292112430Sphk int flags; 293112430Sphk struct thread *td; 294112430Sphk{ 295112430Sphk struct filedesc *fdp = td->td_proc->p_fd; 296112430Sphk struct vnode *uvp = NULL; 297112430Sphk char *bp = NULL; 298112430Sphk int error; 299112430Sphk int perms = VEXEC; 300112430Sphk 301112430Sphk if (rvp == NULL) { 302112430Sphk rvp = fdp->fd_rdir; 303112430Sphk if (rvp == NULL) 304112430Sphk rvp = rootvnode; 305112430Sphk } 306112430Sphk 307112430Sphk VREF(rvp); 308112430Sphk VREF(lvp); 309112430Sphk 310112430Sphk /* 311112430Sphk * Error handling invariant: 312112430Sphk * Before a `goto out': 313112430Sphk * lvp is either NULL, or locked and held. 314112430Sphk * uvp is either NULL, or locked and held. 315112430Sphk */ 316112430Sphk 317112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 318112430Sphk if (error) { 319112430Sphk vrele(lvp); 320112430Sphk lvp = NULL; 321112430Sphk goto out; 322112430Sphk } 323112430Sphk if (bufp) 324112430Sphk bp = *bpp; 325112430Sphk /* 326112430Sphk * this loop will terminate when one of the following happens: 327112430Sphk * - we hit the root 328112430Sphk * - getdirentries or lookup fails 329112430Sphk * - we run out of space in the buffer. 330112430Sphk */ 331112430Sphk if (lvp == rvp) { 332112430Sphk if (bp) 333112430Sphk *(--bp) = '/'; 334112430Sphk goto out; 335112430Sphk } 336112430Sphk do { 337112430Sphk if (lvp->v_type != VDIR) { 338112430Sphk error = ENOTDIR; 339112430Sphk goto out; 340112430Sphk } 341112430Sphk 342112430Sphk /* 343112430Sphk * access check here is optional, depending on 344112430Sphk * whether or not caller cares. 345112430Sphk */ 346112430Sphk if (flags & GETCWD_CHECK_ACCESS) { 347112430Sphk error = VOP_ACCESS(lvp, perms, td->td_ucred, td); 348112430Sphk if (error) 349112430Sphk goto out; 350112430Sphk perms = VEXEC|VREAD; 351112430Sphk } 352112430Sphk 353112430Sphk /* 354112430Sphk * step up if we're a covered vnode.. 355112430Sphk */ 356112430Sphk while (lvp->v_vflag & VV_ROOT) { 357112430Sphk struct vnode *tvp; 358112430Sphk 359112430Sphk if (lvp == rvp) 360112430Sphk goto out; 361112430Sphk 362112430Sphk tvp = lvp; 363112430Sphk lvp = lvp->v_mount->mnt_vnodecovered; 364112430Sphk vput(tvp); 365112430Sphk /* 366112430Sphk * hodie natus est radici frater 367112430Sphk */ 368112430Sphk if (lvp == NULL) { 369112430Sphk error = ENOENT; 370112430Sphk goto out; 371112430Sphk } 372112430Sphk VREF(lvp); 373112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 374112430Sphk if (error != 0) { 375112430Sphk vrele(lvp); 376112430Sphk lvp = NULL; 377112430Sphk goto out; 378112430Sphk } 379112430Sphk } 380112430Sphk error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); 381112430Sphk if (error) 382112430Sphk goto out; 383112430Sphk#if DIAGNOSTIC 384112430Sphk if (lvp != NULL) 385112430Sphk panic("getcwd: oops, forgot to null lvp"); 386112430Sphk if (bufp && (bp <= bufp)) { 387112430Sphk panic("getcwd: oops, went back too far"); 388112430Sphk } 389112430Sphk#endif 390112430Sphk if (bp) 391112430Sphk *(--bp) = '/'; 392112430Sphk lvp = uvp; 393112430Sphk uvp = NULL; 394112430Sphk limit--; 395112430Sphk } while ((lvp != rvp) && (limit > 0)); 396112430Sphk 397112430Sphkout: 398112430Sphk if (bpp) 399112430Sphk *bpp = bp; 400112430Sphk if (uvp) 401112430Sphk vput(uvp); 402112430Sphk if (lvp) 403112430Sphk vput(lvp); 404112430Sphk vrele(rvp); 405112430Sphk return error; 406112430Sphk} 407112430Sphk 408112430Sphk 409112430Sphk/* 41082518Sgallatin * Find pathname of process's current directory. 41182518Sgallatin * 41282518Sgallatin * Use vfs vnode-to-name reverse cache; if that fails, fall back 413112430Sphk * to reading directory contents. 41482518Sgallatin */ 41582518Sgallatin 41682518Sgallatinint 41783366Sjulianlinux_getcwd(struct thread *td, struct linux_getcwd_args *args) 41882518Sgallatin{ 419112430Sphk caddr_t bp, bend, path; 420112430Sphk int error, len, lenused; 421112430Sphk 422112430Sphk#ifdef DEBUG 423112430Sphk printf("Linux-emul(%ld): getcwd(%p, %ld)\n", (long)td->td_proc->p_pid, 424112430Sphk args->buf, (long)args->bufsize); 425112430Sphk#endif 426112430Sphk 427112430Sphk len = args->bufsize; 428112430Sphk 429112430Sphk if (len > MAXPATHLEN*4) 430112430Sphk len = MAXPATHLEN*4; 431112430Sphk else if (len < 2) 432112430Sphk return ERANGE; 433112430Sphk 434112430Sphk path = (char *)malloc(len, M_TEMP, M_WAITOK); 435112430Sphk 436112430Sphk error = kern___getcwd(td, path, UIO_SYSSPACE, len); 437112430Sphk if (!error) { 438112430Sphk lenused = strlen(path) + 1; 439112430Sphk if (lenused <= args->bufsize) { 440112430Sphk td->td_retval[0] = lenused; 441112430Sphk error = copyout(path, args->buf, lenused); 442112430Sphk } 443112430Sphk else 444112430Sphk error = ERANGE; 445112430Sphk } else { 446112430Sphk bp = &path[len]; 447112430Sphk bend = bp; 448112430Sphk *(--bp) = '\0'; 449112430Sphk 450112430Sphk /* 451112430Sphk * 5th argument here is "max number of vnodes to traverse". 452112430Sphk * Since each entry takes up at least 2 bytes in the output buffer, 453112430Sphk * limit it to N/2 vnodes for an N byte buffer. 454112430Sphk */ 455112430Sphk 456112430Sphk error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL, 457112430Sphk &bp, path, len/2, GETCWD_CHECK_ACCESS, td); 458112430Sphk 459112430Sphk if (error) 460112430Sphk goto out; 461112430Sphk lenused = bend - bp; 462112430Sphk td->td_retval[0] = lenused; 463112430Sphk /* put the result into user buffer */ 464112430Sphk error = copyout(bp, args->buf, lenused); 465112430Sphk } 466112430Sphkout: 467112430Sphk free(path, M_TEMP); 468112430Sphk return (error); 46982518Sgallatin} 47082518Sgallatin 471