linux_getcwd.c revision 156874
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 156874 2006-03-19 11:10:33Z ru $"); 41116173Sobrien 42156874Sru#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 62140214Sobrien#ifdef COMPAT_LINUX32 63140214Sobrien#include <machine/../linux32/linux.h> 64140214Sobrien#include <machine/../linux32/linux32_proto.h> 65140214Sobrien#else 6682518Sgallatin#include <machine/../linux/linux.h> 6782518Sgallatin#include <machine/../linux/linux_proto.h> 68133816Stjr#endif 69112430Sphk#include <compat/linux/linux_util.h> 7082518Sgallatin 71112430Sphkstatic int 72112430Sphklinux_getcwd_scandir(struct vnode **, struct vnode **, 73112430Sphk char **, char *, struct thread *); 74112430Sphkstatic int 75112430Sphklinux_getcwd_common(struct vnode *, struct vnode *, 76112430Sphk char **, char *, int, int, struct thread *); 77112430Sphk 78112430Sphk#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4) 79112430Sphk 8082518Sgallatin/* 81112430Sphk * Vnode variable naming conventions in this file: 82112430Sphk * 83112430Sphk * rvp: the current root we're aiming towards. 84112430Sphk * lvp, *lvpp: the "lower" vnode 85112430Sphk * uvp, *uvpp: the "upper" vnode. 86112430Sphk * 87112430Sphk * Since all the vnodes we're dealing with are directories, and the 88112430Sphk * lookups are going *up* in the filesystem rather than *down*, the 89112430Sphk * usual "pvp" (parent) or "dvp" (directory) naming conventions are 90112430Sphk * too confusing. 91112430Sphk */ 92112430Sphk 93112430Sphk/* 94112430Sphk * XXX Will infinite loop in certain cases if a directory read reliably 95112430Sphk * returns EINVAL on last block. 96112430Sphk * XXX is EINVAL the right thing to return if a directory is malformed? 97112430Sphk */ 98112430Sphk 99112430Sphk/* 100112430Sphk * XXX Untested vs. mount -o union; probably does the wrong thing. 101112430Sphk */ 102112430Sphk 103112430Sphk/* 104112430Sphk * Find parent vnode of *lvpp, return in *uvpp 105112430Sphk * 106112430Sphk * If we care about the name, scan it looking for name of directory 107112430Sphk * entry pointing at lvp. 108112430Sphk * 109112430Sphk * Place the name in the buffer which starts at bufp, immediately 110112430Sphk * before *bpp, and move bpp backwards to point at the start of it. 111112430Sphk * 112112430Sphk * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed 113112430Sphk * On exit, *uvpp is either NULL or is a locked vnode reference. 114112430Sphk */ 115112430Sphkstatic int 116112430Sphklinux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td) 117112430Sphk struct vnode **lvpp; 118112430Sphk struct vnode **uvpp; 119112430Sphk char **bpp; 120112430Sphk char *bufp; 121112430Sphk struct thread *td; 122112430Sphk{ 123112430Sphk int error = 0; 124112430Sphk int eofflag; 125112430Sphk off_t off; 126112430Sphk int tries; 127112430Sphk struct uio uio; 128112430Sphk struct iovec iov; 129112430Sphk char *dirbuf = NULL; 130112430Sphk int dirbuflen; 131112430Sphk ino_t fileno; 132112430Sphk struct vattr va; 133112430Sphk struct vnode *uvp = NULL; 134112430Sphk struct vnode *lvp = *lvpp; 135112430Sphk struct componentname cn; 136112430Sphk int len, reclen; 137112430Sphk tries = 0; 138112430Sphk 139112430Sphk /* 140112430Sphk * If we want the filename, get some info we need while the 141112430Sphk * current directory is still locked. 142112430Sphk */ 143112430Sphk if (bufp != NULL) { 144112430Sphk error = VOP_GETATTR(lvp, &va, td->td_ucred, td); 145112430Sphk if (error) { 146112430Sphk vput(lvp); 147112430Sphk *lvpp = NULL; 148112430Sphk *uvpp = NULL; 149112430Sphk return error; 150112430Sphk } 151112430Sphk } 152112430Sphk 153112430Sphk /* 154112430Sphk * Ok, we have to do it the hard way.. 155112430Sphk * Next, get parent vnode using lookup of .. 156112430Sphk */ 157112430Sphk cn.cn_nameiop = LOOKUP; 158112430Sphk cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY; 159112430Sphk cn.cn_thread = td; 160112430Sphk cn.cn_cred = td->td_ucred; 161112430Sphk cn.cn_pnbuf = NULL; 162112430Sphk cn.cn_nameptr = ".."; 163112430Sphk cn.cn_namelen = 2; 164112430Sphk cn.cn_consume = 0; 165144290Sjeff cn.cn_lkflags = LK_EXCLUSIVE; 166112430Sphk 167112430Sphk /* 168112430Sphk * At this point, lvp is locked and will be unlocked by the lookup. 169112430Sphk * On successful return, *uvpp will be locked 170112430Sphk */ 171122861Srwatson#ifdef MAC 172122861Srwatson error = mac_check_vnode_lookup(td->td_ucred, lvp, &cn); 173122861Srwatson if (error == 0) 174122861Srwatson#endif 175122861Srwatson error = VOP_LOOKUP(lvp, uvpp, &cn); 176112430Sphk if (error) { 177112430Sphk vput(lvp); 178112430Sphk *lvpp = NULL; 179112430Sphk *uvpp = NULL; 180112430Sphk return error; 181112430Sphk } 182112430Sphk uvp = *uvpp; 183112430Sphk 184112430Sphk /* If we don't care about the pathname, we're done */ 185112430Sphk if (bufp == NULL) { 186145006Sjeff vput(lvp); 187112430Sphk *lvpp = NULL; 188112430Sphk return 0; 189112430Sphk } 190112430Sphk 191112430Sphk fileno = va.va_fileid; 192112430Sphk 193112430Sphk dirbuflen = DIRBLKSIZ; 194112430Sphk if (dirbuflen < va.va_blocksize) 195112430Sphk dirbuflen = va.va_blocksize; 196112430Sphk dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK); 197112430Sphk 198112430Sphk#if 0 199112430Sphkunionread: 200112430Sphk#endif 201112430Sphk off = 0; 202112430Sphk do { 203112430Sphk /* call VOP_READDIR of parent */ 204112430Sphk iov.iov_base = dirbuf; 205112430Sphk iov.iov_len = dirbuflen; 206112430Sphk 207112430Sphk uio.uio_iov = &iov; 208112430Sphk uio.uio_iovcnt = 1; 209112430Sphk uio.uio_offset = off; 210112430Sphk uio.uio_resid = dirbuflen; 211112430Sphk uio.uio_segflg = UIO_SYSSPACE; 212112430Sphk uio.uio_rw = UIO_READ; 213112430Sphk uio.uio_td = td; 214112430Sphk 215112430Sphk eofflag = 0; 216112430Sphk 217112430Sphk#ifdef MAC 218112430Sphk error = mac_check_vnode_readdir(td->td_ucred, uvp); 219112430Sphk if (error == 0) 220112430Sphk#endif /* MAC */ 221112430Sphk error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, 222112430Sphk 0, 0); 223112430Sphk 224112430Sphk off = uio.uio_offset; 225112430Sphk 226112430Sphk /* 227112430Sphk * Try again if NFS tosses its cookies. 228112430Sphk * XXX this can still loop forever if the directory is busted 229112430Sphk * such that the second or subsequent page of it always 230112430Sphk * returns EINVAL 231112430Sphk */ 232112430Sphk if ((error == EINVAL) && (tries < 3)) { 233112430Sphk off = 0; 234112430Sphk tries++; 235112430Sphk continue; /* once more, with feeling */ 236112430Sphk } 237112430Sphk 238112430Sphk if (!error) { 239112430Sphk char *cpos; 240112430Sphk struct dirent *dp; 241112430Sphk 242112430Sphk cpos = dirbuf; 243112430Sphk tries = 0; 244112430Sphk 245112430Sphk /* scan directory page looking for matching vnode */ 246112430Sphk for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) { 247112430Sphk dp = (struct dirent *) cpos; 248112430Sphk reclen = dp->d_reclen; 249112430Sphk 250112430Sphk /* check for malformed directory.. */ 251112430Sphk if (reclen < DIRENT_MINSIZE) { 252112430Sphk error = EINVAL; 253112430Sphk goto out; 254112430Sphk } 255112430Sphk /* 256112430Sphk * XXX should perhaps do VOP_LOOKUP to 257112430Sphk * check that we got back to the right place, 258112430Sphk * but getting the locking games for that 259112430Sphk * right would be heinous. 260112430Sphk */ 261112430Sphk if ((dp->d_type != DT_WHT) && 262112430Sphk (dp->d_fileno == fileno)) { 263112430Sphk char *bp = *bpp; 264112430Sphk bp -= dp->d_namlen; 265112430Sphk 266112430Sphk if (bp <= bufp) { 267112430Sphk error = ERANGE; 268112430Sphk goto out; 269112430Sphk } 270112430Sphk bcopy(dp->d_name, bp, dp->d_namlen); 271112430Sphk error = 0; 272112430Sphk *bpp = bp; 273112430Sphk goto out; 274112430Sphk } 275112430Sphk cpos += reclen; 276112430Sphk } 277112430Sphk } 278112430Sphk } while (!eofflag); 279112430Sphk error = ENOENT; 280112430Sphk 281112430Sphkout: 282145006Sjeff vput(lvp); 283112430Sphk *lvpp = NULL; 284112430Sphk free(dirbuf, M_TEMP); 285112430Sphk return error; 286112430Sphk} 287112430Sphk 288112430Sphk 289112430Sphk/* 290112430Sphk * common routine shared by sys___getcwd() and linux_vn_isunder() 291112430Sphk */ 292112430Sphk 293112430Sphk#define GETCWD_CHECK_ACCESS 0x0001 294112430Sphk 295112430Sphkstatic int 296112430Sphklinux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td) 297112430Sphk struct vnode *lvp; 298112430Sphk struct vnode *rvp; 299112430Sphk char **bpp; 300112430Sphk char *bufp; 301112430Sphk int limit; 302112430Sphk int flags; 303112430Sphk struct thread *td; 304112430Sphk{ 305112430Sphk struct filedesc *fdp = td->td_proc->p_fd; 306112430Sphk struct vnode *uvp = NULL; 307112430Sphk char *bp = NULL; 308112430Sphk int error; 309112430Sphk int perms = VEXEC; 310112430Sphk 311112430Sphk if (rvp == NULL) { 312112430Sphk rvp = fdp->fd_rdir; 313112430Sphk if (rvp == NULL) 314112430Sphk rvp = rootvnode; 315112430Sphk } 316112430Sphk 317112430Sphk VREF(rvp); 318112430Sphk VREF(lvp); 319112430Sphk 320112430Sphk /* 321112430Sphk * Error handling invariant: 322112430Sphk * Before a `goto out': 323112430Sphk * lvp is either NULL, or locked and held. 324112430Sphk * uvp is either NULL, or locked and held. 325112430Sphk */ 326112430Sphk 327112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 328155033Sjeff if (error != 0) 329155033Sjeff panic("vn_lock LK_RETRY returned error %d", error); 330112430Sphk if (bufp) 331112430Sphk bp = *bpp; 332112430Sphk /* 333112430Sphk * this loop will terminate when one of the following happens: 334112430Sphk * - we hit the root 335112430Sphk * - getdirentries or lookup fails 336112430Sphk * - we run out of space in the buffer. 337112430Sphk */ 338112430Sphk if (lvp == rvp) { 339112430Sphk if (bp) 340112430Sphk *(--bp) = '/'; 341112430Sphk goto out; 342112430Sphk } 343112430Sphk do { 344112430Sphk if (lvp->v_type != VDIR) { 345112430Sphk error = ENOTDIR; 346112430Sphk goto out; 347112430Sphk } 348112430Sphk 349112430Sphk /* 350112430Sphk * access check here is optional, depending on 351112430Sphk * whether or not caller cares. 352112430Sphk */ 353112430Sphk if (flags & GETCWD_CHECK_ACCESS) { 354112430Sphk error = VOP_ACCESS(lvp, perms, td->td_ucred, td); 355112430Sphk if (error) 356112430Sphk goto out; 357112430Sphk perms = VEXEC|VREAD; 358112430Sphk } 359112430Sphk 360112430Sphk /* 361112430Sphk * step up if we're a covered vnode.. 362112430Sphk */ 363112430Sphk while (lvp->v_vflag & VV_ROOT) { 364112430Sphk struct vnode *tvp; 365112430Sphk 366112430Sphk if (lvp == rvp) 367112430Sphk goto out; 368112430Sphk 369112430Sphk tvp = lvp; 370112430Sphk lvp = lvp->v_mount->mnt_vnodecovered; 371112430Sphk vput(tvp); 372112430Sphk /* 373112430Sphk * hodie natus est radici frater 374112430Sphk */ 375112430Sphk if (lvp == NULL) { 376112430Sphk error = ENOENT; 377112430Sphk goto out; 378112430Sphk } 379112430Sphk VREF(lvp); 380112430Sphk error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); 381155033Sjeff if (error != 0) 382155033Sjeff panic("vn_lock LK_RETRY returned %d", error); 383112430Sphk } 384112430Sphk error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); 385112430Sphk if (error) 386112430Sphk goto out; 387153072Sru#ifdef DIAGNOSTIC 388112430Sphk if (lvp != NULL) 389112430Sphk panic("getcwd: oops, forgot to null lvp"); 390112430Sphk if (bufp && (bp <= bufp)) { 391112430Sphk panic("getcwd: oops, went back too far"); 392112430Sphk } 393112430Sphk#endif 394112430Sphk if (bp) 395112430Sphk *(--bp) = '/'; 396112430Sphk lvp = uvp; 397112430Sphk uvp = NULL; 398112430Sphk limit--; 399112430Sphk } while ((lvp != rvp) && (limit > 0)); 400112430Sphk 401112430Sphkout: 402112430Sphk if (bpp) 403112430Sphk *bpp = bp; 404112430Sphk if (uvp) 405112430Sphk vput(uvp); 406112430Sphk if (lvp) 407112430Sphk vput(lvp); 408112430Sphk vrele(rvp); 409112430Sphk return error; 410112430Sphk} 411112430Sphk 412112430Sphk 413112430Sphk/* 41482518Sgallatin * Find pathname of process's current directory. 41582518Sgallatin * 41682518Sgallatin * Use vfs vnode-to-name reverse cache; if that fails, fall back 417112430Sphk * to reading directory contents. 41882518Sgallatin */ 41982518Sgallatin 42082518Sgallatinint 42183366Sjulianlinux_getcwd(struct thread *td, struct linux_getcwd_args *args) 42282518Sgallatin{ 423112430Sphk caddr_t bp, bend, path; 424112430Sphk int error, len, lenused; 425112430Sphk 426112430Sphk#ifdef DEBUG 427112430Sphk printf("Linux-emul(%ld): getcwd(%p, %ld)\n", (long)td->td_proc->p_pid, 428112430Sphk args->buf, (long)args->bufsize); 429112430Sphk#endif 430112430Sphk 431112430Sphk len = args->bufsize; 432112430Sphk 433112430Sphk if (len > MAXPATHLEN*4) 434112430Sphk len = MAXPATHLEN*4; 435112430Sphk else if (len < 2) 436112430Sphk return ERANGE; 437112430Sphk 438112430Sphk path = (char *)malloc(len, M_TEMP, M_WAITOK); 439112430Sphk 440112430Sphk error = kern___getcwd(td, path, UIO_SYSSPACE, len); 441112430Sphk if (!error) { 442112430Sphk lenused = strlen(path) + 1; 443112430Sphk if (lenused <= args->bufsize) { 444112430Sphk td->td_retval[0] = lenused; 445112430Sphk error = copyout(path, args->buf, lenused); 446112430Sphk } 447112430Sphk else 448112430Sphk error = ERANGE; 449112430Sphk } else { 450112430Sphk bp = &path[len]; 451112430Sphk bend = bp; 452112430Sphk *(--bp) = '\0'; 453112430Sphk 454112430Sphk /* 455112430Sphk * 5th argument here is "max number of vnodes to traverse". 456112430Sphk * Since each entry takes up at least 2 bytes in the output buffer, 457112430Sphk * limit it to N/2 vnodes for an N byte buffer. 458112430Sphk */ 459112430Sphk 460147854Sjhb mtx_lock(&Giant); 461112430Sphk error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL, 462112430Sphk &bp, path, len/2, GETCWD_CHECK_ACCESS, td); 463147854Sjhb mtx_unlock(&Giant); 464112430Sphk 465112430Sphk if (error) 466112430Sphk goto out; 467112430Sphk lenused = bend - bp; 468112430Sphk td->td_retval[0] = lenused; 469112430Sphk /* put the result into user buffer */ 470112430Sphk error = copyout(bp, args->buf, lenused); 471112430Sphk } 472112430Sphkout: 473112430Sphk free(path, M_TEMP); 474112430Sphk return (error); 47582518Sgallatin} 47682518Sgallatin 477