Date: Fri, 7 May 2004 11:22:35 +0200 From: Marc Olzheim <marcolz@stack.nl> To: Bruce M Simpson <bms@spc.org> Cc: freebsd-current@lists.freebsd.org Subject: Re: Unified getcwd() implementation Message-ID: <20040507092235.GA61837@stack.nl>
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--K8nIJk4ghYZn606h Content-Type: multipart/mixed; boundary="17pEHd4RhPHOinZp" Content-Disposition: inline --17pEHd4RhPHOinZp Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, (Re: http://lists.freebsd.org/pipermail/freebsd-arch/2003-August/001152.html) > Yes, it's quite an old patch, and much has happened since it was written. Mostly some fine-grained locking was introduced. I hope I got everything covered. Here Bruce's patch reworked, that works for me. (even over NFS ;-)) Anyone care to share their view on it ? Marc --17pEHd4RhPHOinZp Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="getcwd.patch.txt" Content-Transfer-Encoding: quoted-printable --- /usr/src/sys/kern/vfs_cache.c Mon Apr 5 23:03:36 2004 +++ /usr/src/sys/kern/vfs_cache.c Fri May 7 10:39:48 2004 @@ -35,6 +35,8 @@ #include <sys/cdefs.h> __FBSDID("$FreeBSD: src/sys/kern/vfs_cache.c,v 1.87 2004/04/05 21:03:36 im= p Exp $"); =20 +#include "opt_mac.h" + #include <sys/param.h> #include <sys/systm.h> #include <sys/kernel.h> @@ -51,8 +53,11 @@ #include <sys/filedesc.h> #include <sys/fnv_hash.h> =20 -#include <vm/uma.h> - +#include <sys/file.h> +#include <sys/uio.h> +#include <sys/mac.h> +#include <sys/dirent.h> +#include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */ /* * This structure describes the elements in the cache of recent * names looked up by namei. @@ -69,6 +74,8 @@ char nc_name[0]; /* segment name */ }; =20 +#include <vm/uma.h> + /* * Name caching works as follows: * @@ -778,6 +785,13 @@ }; #endif =20 +static int getcwd_impl(struct vnode *lvp, struct vnode *rvp, char **bpp, + char *bufp, struct thread *td); +static int getcwd_scandir(struct vnode **, struct vnode **, char **, char = *, + struct thread *); + +#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4) + /* * XXX All of these sysctls would probably be more productive dead. */ @@ -791,6 +805,7 @@ static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2); static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3); static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4); +static u_long numcwdfail5; STATNODE(CTLFLAG_RD, numcwdfail5, &numcwdfail5); static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound); =20 /* Implementation of the getcwd syscall */ @@ -803,14 +818,20 @@ return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); } =20 +/* + * Find pathname of process's current directory. + * + * Use vfs vnode-to-name reverse cache; if that fails, fall back + * to reading directory contents. + */ int kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int b= uflen) { - char *bp, *tmpbuf; - int error, i, slash_prefixed; + char *bp, *bufp; + int error; struct filedesc *fdp; - struct namecache *ncp; - struct vnode *vp; + struct vnode *rvp; + struct vnode *lvp; =20 numcwdcalls++; if (disablecwd) @@ -819,82 +840,422 @@ return (EINVAL); if (buflen > MAXPATHLEN) buflen =3D MAXPATHLEN; + + buflen *=3D 4; /* XXX */ + error =3D 0; - tmpbuf =3D bp =3D malloc(buflen, M_TEMP, M_WAITOK); + bufp =3D bp =3D malloc(buflen, M_TEMP, M_WAITOK); bp +=3D buflen - 1; *bp =3D '\0'; + fdp =3D td->td_proc->p_fd; - slash_prefixed =3D 0; + FILEDESC_LOCK(fdp); - for (vp =3D fdp->fd_cdir; vp !=3D fdp->fd_rdir && vp !=3D rootvnode;) { - if (vp->v_vflag & VV_ROOT) { - if (vp->v_mount =3D=3D NULL) { /* forced unmount */ - FILEDESC_UNLOCK(fdp); - free(tmpbuf, M_TEMP); - return (EBADF); - } - vp =3D vp->v_mount->mnt_vnodecovered; - continue; + + rvp =3D fdp->fd_rdir; + if (rvp =3D=3D NULL) + rvp =3D rootvnode; + VREF(rvp); + + lvp =3D fdp->fd_cdir; + + /* We have all the info we need from fdp. */ + FILEDESC_UNLOCK(fdp); + + error =3D getcwd_impl(lvp, rvp, &bp, bufp, td); + if (!error) { + numcwdfound++; + if (bufseg =3D=3D UIO_SYSSPACE) + bcopy(bp, buf, strlen(bp) + 1); + else + error =3D copyout(bp, buf, strlen(bp) + 1); + } else { +#if DIAGNOSTIC + printf("getcwd: error %d\n", error); +#endif + } + + vrele(rvp); + free(bufp, M_TEMP); + return (error); +} + +/* + * Recursively advance up the directory hierarchy from lvp to rvp. + * Look in the namecache first for each path component; if it cannot + * be found, use scandir to find it. Copy the result into the buffer + * pointed to by bufp from *bpp onwards. + */ + +static int +getcwd_impl(lvp, rvp, bpp, bufp, td) + struct vnode *lvp; + struct vnode *rvp; + char **bpp; + char *bufp; + struct thread *td; +{ + int i, error, slash_prefixed; + struct namecache *ncp; + struct vnode *uvp; + struct vnode *tvp; + char *bp; + + error =3D slash_prefixed =3D 0; + uvp =3D NULL; + + VREF(lvp); + error =3D vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); + if (error) { + numcwdfail5++; + vrele(lvp); + lvp =3D NULL; + goto out; + } + if (bufp) + bp =3D *bpp; + + while (lvp !=3D rvp) { +#if 1 + if (lvp->v_type !=3D VDIR) { + numcwdfail1++; + error =3D ENOTDIR; + goto out; } - if (vp->v_dd->v_id !=3D vp->v_ddid) { - FILEDESC_UNLOCK(fdp); +#else + if (lvp->v_dd->v_id !=3D lvp->v_ddid) { numcwdfail1++; - free(tmpbuf, M_TEMP); - return (ENOTDIR); + error =3D ENOTDIR; + goto out; } - CACHE_LOCK(); - ncp =3D TAILQ_FIRST(&vp->v_cache_dst); - if (!ncp) { - numcwdfail2++; - CACHE_UNLOCK(); - FILEDESC_UNLOCK(fdp); - free(tmpbuf, M_TEMP); - return (ENOENT); +#endif + /* + * step up if we're a covered vnode. + */ + while (lvp->v_vflag & VV_ROOT) { + if (lvp =3D=3D rvp) + goto out; + tvp =3D lvp; + lvp =3D lvp->v_mount->mnt_vnodecovered; + vput(tvp); + if (lvp =3D=3D NULL) { + numcwdfail3++; + error =3D ENOENT; + goto out; + } + VREF(lvp); + error =3D vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); + if (error !=3D 0) { + numcwdfail5++; + vrele(lvp); + lvp =3D NULL; + goto out; + } } - if (ncp->nc_dvp !=3D vp->v_dd) { - numcwdfail3++; - CACHE_UNLOCK(); - FILEDESC_UNLOCK(fdp); - free(tmpbuf, M_TEMP); - return (EBADF); - } - for (i =3D ncp->nc_nlen - 1; i >=3D 0; i--) { - if (bp =3D=3D tmpbuf) { - numcwdfail4++; + /* + * look in the cache first + */ + CACHE_LOCK(); + ncp =3D TAILQ_FIRST(&lvp->v_cache_dst); +#if DIAGNOSTIC + /* XXX simulate cache failure every 10 lookups */ + if ((numcwdcalls % 10) =3D=3D 0) + ncp =3D NULL; +#endif + if (ncp) { + if (ncp->nc_dvp !=3D lvp->v_dd) { CACHE_UNLOCK(); - FILEDESC_UNLOCK(fdp); - free(tmpbuf, M_TEMP); - return (ENOMEM); + numcwdfail3++; + error =3D EBADF; + goto out; + } + for (i =3D ncp->nc_nlen - 1; i >=3D 0; i--) { + if (bp =3D=3D bufp) { + CACHE_UNLOCK(); + numcwdfail4++; + error =3D ENOMEM; + goto out; + } + *--bp =3D ncp->nc_name[i]; } - *--bp =3D ncp->nc_name[i]; - } - if (bp =3D=3D tmpbuf) { - numcwdfail4++; CACHE_UNLOCK(); - FILEDESC_UNLOCK(fdp); - free(tmpbuf, M_TEMP); - return (ENOMEM); + /* + * must ensure lvp is always locked and ref'd + */ + tvp =3D lvp; =09 + lvp =3D lvp->v_dd; + vput(tvp); + if (lvp =3D=3D NULL) { + numcwdfail3++; + error =3D ENOENT; + goto out; + } + VREF(lvp); + error =3D vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); + if (error !=3D 0) { + numcwdfail5++; + vrele(lvp); + lvp =3D NULL; + goto out; + } + } else { + CACHE_UNLOCK(); + numcwdfail2++; +#if DIAGNOSTIC + printf("getcwd: using scandir\n"); +#endif + error =3D getcwd_scandir(&lvp, &uvp, &bp, bufp, td); + if (error) { +#if DIAGNOSTIC + printf("getcwd_scandir returned %d\n", error); +#endif + goto out; + } +#if DIAGNOSTIC + if (lvp !=3D NULL) + panic("getcwd: oops, forgot to null lvp"); +#endif + lvp =3D uvp; + uvp =3D NULL; } +#if DIAGNOSTIC + if (bufp && (bp <=3D bufp)) + panic("getcwd: oops, went back too far"); +#endif *--bp =3D '/'; slash_prefixed =3D 1; - vp =3D vp->v_dd; - CACHE_UNLOCK(); } - FILEDESC_UNLOCK(fdp); + if (!slash_prefixed) { - if (bp =3D=3D tmpbuf) { + if (bp =3D=3D bufp) { numcwdfail4++; - free(tmpbuf, M_TEMP); - return (ENOMEM); + error =3D ENOMEM; + goto out; } *--bp =3D '/'; } - numcwdfound++; - if (bufseg =3D=3D UIO_SYSSPACE) - bcopy(bp, buf, strlen(bp) + 1); - else - error =3D copyout(bp, buf, strlen(bp) + 1); - free(tmpbuf, M_TEMP); +out: + if (bpp) + *bpp =3D bp; + if (uvp) + vput(uvp); + if (lvp) + vput(lvp); + return (error); +} + +/* + * 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 NU= LL'ed + * On exit, *uvpp is either NULL or is a locked vnode reference. + */ + +static int +getcwd_scandir(lvpp, uvpp, bpp, bufp, td) + struct vnode **lvpp; + struct vnode **uvpp; + char **bpp; + char *bufp; + struct thread *td; +{ + int error =3D 0; + int eofflag; + off_t off; + int tries; + struct uio uio; + struct iovec iov; + char *dirbuf =3D NULL; + int dirbuflen; + ino_t fileno; + struct vattr va; + struct vnode *uvp =3D NULL; + struct vnode *lvp =3D *lvpp; + struct componentname cn; + int len, reclen; + tries =3D 0; + + /* + * If we want the filename, get some info we need while the + * current directory is still locked. + */ + if (bufp !=3D NULL) { + error =3D VOP_GETATTR(lvp, &va, td->td_ucred, td); + if (error) { + vput(lvp); + *lvpp =3D NULL; + *uvpp =3D NULL; +#if DIAGNOSTICS + printf("VOP_GETATTR returned %d", error); +#endif + return error; + } + } + + /* + * Ok, we have to do it the hard way.. + * Next, get parent vnode using lookup of .. + */ + cn.cn_nameiop =3D LOOKUP; + cn.cn_flags =3D ISLASTCN | ISDOTDOT | RDONLY; + cn.cn_thread =3D td; + cn.cn_cred =3D td->td_ucred; + cn.cn_pnbuf =3D NULL; + cn.cn_nameptr =3D ".."; + cn.cn_namelen =3D 2; + cn.cn_consume =3D 0; + + /* + * At this point, lvp is locked and will be unlocked by the lookup. + * On successful return, *uvpp will be locked + */ + error =3D VOP_LOOKUP(lvp, uvpp, &cn); + if (error) { + vput(lvp); + *lvpp =3D NULL; + *uvpp =3D NULL; + return error; + } + uvp =3D *uvpp; + + /* If we don't care about the pathname, we're done */ + if (bufp =3D=3D NULL) { + vrele(lvp); + *lvpp =3D NULL; + return 0; + } + + fileno =3D va.va_fileid; + + dirbuflen =3D DIRBLKSIZ; + if (dirbuflen < va.va_blocksize) + dirbuflen =3D va.va_blocksize; + dirbuf =3D (char *)malloc(dirbuflen, M_TEMP, M_WAITOK); + +#if 0 +unionread: +#endif + off =3D 0; + do { + /* call VOP_READDIR of parent */ + iov.iov_base =3D dirbuf; + iov.iov_len =3D dirbuflen; + + uio.uio_iov =3D &iov; + uio.uio_iovcnt =3D 1; + uio.uio_offset =3D off; + uio.uio_resid =3D dirbuflen; + uio.uio_segflg =3D UIO_SYSSPACE; + uio.uio_rw =3D UIO_READ; + uio.uio_td =3D td; + + eofflag =3D 0; + +#ifdef MAC + error =3D mac_check_vnode_readdir(td->td_ucred, uvp); + if (error =3D=3D 0) +#endif /* MAC */ + error =3D VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, + 0, 0); + + off =3D 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 =3D=3D EINVAL) && (tries < 3)) { + off =3D 0; + tries++; + continue; /* once more, with feeling */ + } + + if (!error) { + char *cpos; + struct dirent *dp; + =09 + cpos =3D dirbuf; + tries =3D 0; + =09 + /* scan directory page looking for matching vnode */=20 + for (len =3D (dirbuflen - uio.uio_resid); + len > 0; + len -=3D reclen) + { + dp =3D (struct dirent *) cpos; + reclen =3D dp->d_reclen; + + /* check for malformed directory.. */ + if (reclen < DIRENT_MINSIZE) { + error =3D 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 !=3D DT_WHT) && + (dp->d_fileno =3D=3D fileno)) { + char *bp =3D *bpp; + bp -=3D dp->d_namlen; +#if DIAGNOSTIC + printf("bp: %p bufp: %p dp->d_name: %s" + " (%d)\n", + bp, bufp, + dp->d_name, dp->d_namlen); +#endif + if (bp <=3D bufp) { + error =3D ERANGE; + goto out; + } + bcopy(dp->d_name, bp, dp->d_namlen); + error =3D 0; + *bpp =3D bp; + goto out; + } + cpos +=3D reclen; + } + } + } while (!eofflag); + error =3D ENOENT; + +out: + vrele(lvp); + *lvpp =3D NULL; + free(dirbuf, M_TEMP); return (error); } =20 --- /usr/src/sys/compat/linux/linux_getcwd.c Mon Nov 17 19:57:20 2003 +++ /usr/src/sys/compat/linux/linux_getcwd.c Fri May 7 11:12:28 2004 @@ -40,435 +40,27 @@ __FBSDID("$FreeBSD: src/sys/compat/linux/linux_getcwd.c,v 1.14 2003/11/17 = 18:57:20 rwatson Exp $"); =20 #include "opt_compat.h" -#include "opt_mac.h" =20 #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 <sys/syscallsubr.h> =20 #include <machine/../linux/linux.h> #include <machine/../linux/linux_proto.h> #include <compat/linux/linux_util.h> =20 -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 NU= LL'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 =3D 0; - int eofflag; - off_t off; - int tries; - struct uio uio; - struct iovec iov; - char *dirbuf =3D NULL; - int dirbuflen; - ino_t fileno; - struct vattr va; - struct vnode *uvp =3D NULL; - struct vnode *lvp =3D *lvpp;=09 - struct componentname cn; - int len, reclen; - tries =3D 0; - - /* - * If we want the filename, get some info we need while the - * current directory is still locked. - */ - if (bufp !=3D NULL) { - error =3D VOP_GETATTR(lvp, &va, td->td_ucred, td); - if (error) { - vput(lvp); - *lvpp =3D NULL; - *uvpp =3D NULL; - return error; - } - } - - /* - * Ok, we have to do it the hard way.. - * Next, get parent vnode using lookup of .. - */ - cn.cn_nameiop =3D LOOKUP; - cn.cn_flags =3D ISLASTCN | ISDOTDOT | RDONLY; - cn.cn_thread =3D td; - cn.cn_cred =3D td->td_ucred; - cn.cn_pnbuf =3D NULL; - cn.cn_nameptr =3D ".."; - cn.cn_namelen =3D 2; - cn.cn_consume =3D 0; -=09 - /* - * At this point, lvp is locked and will be unlocked by the lookup. - * On successful return, *uvpp will be locked - */ -#ifdef MAC - error =3D mac_check_vnode_lookup(td->td_ucred, lvp, &cn); - if (error =3D=3D 0) -#endif - error =3D VOP_LOOKUP(lvp, uvpp, &cn); - if (error) { - vput(lvp); - *lvpp =3D NULL; - *uvpp =3D NULL; - return error; - } - uvp =3D *uvpp; - - /* If we don't care about the pathname, we're done */ - if (bufp =3D=3D NULL) { - vrele(lvp); - *lvpp =3D NULL; - return 0; - } -=09 - fileno =3D va.va_fileid; - - dirbuflen =3D DIRBLKSIZ; - if (dirbuflen < va.va_blocksize) - dirbuflen =3D va.va_blocksize; - dirbuf =3D (char *)malloc(dirbuflen, M_TEMP, M_WAITOK); - -#if 0 -unionread: -#endif - off =3D 0; - do { - /* call VOP_READDIR of parent */ - iov.iov_base =3D dirbuf; - iov.iov_len =3D dirbuflen; - - uio.uio_iov =3D &iov; - uio.uio_iovcnt =3D 1; - uio.uio_offset =3D off; - uio.uio_resid =3D dirbuflen; - uio.uio_segflg =3D UIO_SYSSPACE; - uio.uio_rw =3D UIO_READ; - uio.uio_td =3D td; - - eofflag =3D 0; - -#ifdef MAC - error =3D mac_check_vnode_readdir(td->td_ucred, uvp); - if (error =3D=3D 0) -#endif /* MAC */ - error =3D VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag, - 0, 0); - - off =3D 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 =3D=3D EINVAL) && (tries < 3)) { - off =3D 0; - tries++; - continue; /* once more, with feeling */ - } - - if (!error) { - char *cpos; - struct dirent *dp; - =09 - cpos =3D dirbuf; - tries =3D 0; - =09 - /* scan directory page looking for matching vnode */=20 - for (len =3D (dirbuflen - uio.uio_resid); len > 0; len -=3D reclen) { - dp =3D (struct dirent *) cpos; - reclen =3D dp->d_reclen; - - /* check for malformed directory.. */ - if (reclen < DIRENT_MINSIZE) { - error =3D 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 !=3D DT_WHT) && - (dp->d_fileno =3D=3D fileno)) { - char *bp =3D *bpp; - bp -=3D dp->d_namlen; - =09 - if (bp <=3D bufp) { - error =3D ERANGE; - goto out; - } - bcopy(dp->d_name, bp, dp->d_namlen); - error =3D 0; - *bpp =3D bp; - goto out; - } - cpos +=3D reclen; - } - } - } while (!eofflag); - error =3D ENOENT; - =09 -out: - vrele(lvp); - *lvpp =3D 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 =3D td->td_proc->p_fd; - struct vnode *uvp =3D NULL; - char *bp =3D NULL; - int error; - int perms =3D VEXEC; - - if (rvp =3D=3D NULL) { - rvp =3D fdp->fd_rdir; - if (rvp =3D=3D NULL) - rvp =3D rootvnode; - } -=09 - 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 =3D vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); - if (error) { - vrele(lvp); - lvp =3D NULL; - goto out; - } - if (bufp) - bp =3D *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 =3D=3D rvp) { - if (bp) - *(--bp) =3D '/'; - goto out; - } - do { - if (lvp->v_type !=3D VDIR) { - error =3D ENOTDIR; - goto out; - } - =09 - /* - * access check here is optional, depending on - * whether or not caller cares. - */ - if (flags & GETCWD_CHECK_ACCESS) { - error =3D VOP_ACCESS(lvp, perms, td->td_ucred, td); - if (error) - goto out; - perms =3D VEXEC|VREAD; - } - =09 - /* - * step up if we're a covered vnode.. - */ - while (lvp->v_vflag & VV_ROOT) { - struct vnode *tvp; - - if (lvp =3D=3D rvp) - goto out; - =09 - tvp =3D lvp; - lvp =3D lvp->v_mount->mnt_vnodecovered; - vput(tvp); - /* - * hodie natus est radici frater - */ - if (lvp =3D=3D NULL) { - error =3D ENOENT; - goto out; - } - VREF(lvp); - error =3D vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td); - if (error !=3D 0) { - vrele(lvp); - lvp =3D NULL; - goto out; - } - } - error =3D linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td); - if (error) - goto out; -#if DIAGNOSTIC =09 - if (lvp !=3D NULL) - panic("getcwd: oops, forgot to null lvp"); - if (bufp && (bp <=3D bufp)) { - panic("getcwd: oops, went back too far"); - } -#endif =09 - if (bp)=20 - *(--bp) =3D '/'; - lvp =3D uvp; - uvp =3D NULL; - limit--; - } while ((lvp !=3D rvp) && (limit > 0));=20 - -out: - if (bpp) - *bpp =3D 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. + * Simply use the new, complete getcwd() implementation. */ =20 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 =3D args->bufsize; - - if (len > MAXPATHLEN*4) - len =3D MAXPATHLEN*4; - else if (len < 2) - return ERANGE; - - path =3D (char *)malloc(len, M_TEMP, M_WAITOK); - - error =3D kern___getcwd(td, path, UIO_SYSSPACE, len); - if (!error) { - lenused =3D strlen(path) + 1; - if (lenused <=3D args->bufsize) { - td->td_retval[0] =3D lenused; - error =3D copyout(path, args->buf, lenused); - } - else - error =3D ERANGE; - } else { - bp =3D &path[len]; - bend =3D bp; - *(--bp) =3D '\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 =3D linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL, - &bp, path, len/2, GETCWD_CHECK_ACCESS, td); - - if (error) - goto out; - lenused =3D bend - bp; - td->td_retval[0] =3D lenused; - /* put the result into user buffer */ - error =3D copyout(bp, args->buf, lenused); - } -out: - free(path, M_TEMP); - return (error); + return (kern___getcwd(td, args->buf, UIO_USERSPACE, args->bufsize)); } - --17pEHd4RhPHOinZp-- --K8nIJk4ghYZn606h Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAm1VbezjnobFOgrERAg1aAJwIyNFytGIsdVEV/pqDVbepuH4vEACeNrkP nWe9bieUeUTGqejixBBtPgY= =ZVqL -----END PGP SIGNATURE----- --K8nIJk4ghYZn606h--
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