8322 nl: misleading-indentation

[unleashed/tickless.git] / usr / src / lib / smbsrv / libfksmbsrv / common / fake_lookup.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/file.h>
#include <sys/errno.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/pathname.h>
#include <sys/proc.h>
#include <sys/vtrace.h>
#include <sys/sysmacros.h>
#include <sys/debug.h>
#include <sys/dirent.h>
#include <sys/zone.h>
#include <sys/dnlc.h>
#include <sys/fs/snode.h>

/*
 * Starting at current directory, translate pathname pnp to end.
 * Leave pathname of final component in pnp, return the vnode
 * for the final component in *compvpp, and return the vnode
 * for the parent of the final component in dirvpp.
 *
 * This is the central routine in pathname translation and handles
 * multiple components in pathnames, separating them at /'s.  It also
 * implements mounted file systems and processes symbolic links.
 *
 * vp is the vnode where the directory search should start.
 *
 * Reference counts: vp must be held prior to calling this function.  rootvp
 * should only be held if rootvp != rootdir.
 */
int
lookuppnvp(
        struct pathname *pnp,           /* pathname to lookup */
        struct pathname *rpnp,          /* if non-NULL, return resolved path */
        int flags,                      /* follow symlinks */
        vnode_t **dirvpp,               /* ptr for parent vnode */
        vnode_t **compvpp,              /* ptr for entry vnode */
        vnode_t *rootvp,                /* rootvp */
        vnode_t *vp,                    /* directory to start search at */
        cred_t *cr)                     /* user's credential */
{
        vnode_t *cvp;   /* current component vp */
        vnode_t *tvp;   /* addressable temp ptr */
        char component[MAXNAMELEN];     /* buffer for component (incl null) */
        int error;
        int nlink;
        int lookup_flags;
        struct pathname presrvd; /* case preserved name */
        struct pathname *pp = NULL;
        vnode_t *startvp;
        int must_be_directory = 0;
        boolean_t retry_with_kcred;

        nlink = 0;
        cvp = NULL;
        if (rpnp)
                rpnp->pn_pathlen = 0;

        lookup_flags = dirvpp ? LOOKUP_DIR : 0;
        if (flags & FIGNORECASE) {
                lookup_flags |= FIGNORECASE;
                pn_alloc(&presrvd);
                pp = &presrvd;
        }

        /*
         * Eliminate any trailing slashes in the pathname.
         * If there are any, we must follow all symlinks.
         * Also, we must guarantee that the last component is a directory.
         */
        if (pn_fixslash(pnp)) {
                flags |= FOLLOW;
                must_be_directory = 1;
        }

        startvp = vp;
next:
        retry_with_kcred = B_FALSE;

        /*
         * Make sure we have a directory.
         */
        if (vp->v_type != VDIR) {
                error = ENOTDIR;
                goto bad;
        }

        if (rpnp && VN_CMP(vp, rootvp))
                (void) pn_set(rpnp, "/");

        /*
         * Process the next component of the pathname.
         */
        if (error = pn_getcomponent(pnp, component)) {
                goto bad;
        }

        /*
         * Handle "..": two special cases.
         * 1. If we're at the root directory (e.g. after chroot or
         *    zone_enter) then change ".." to "." so we can't get
         *    out of this subtree.
         * 2. If this vnode is the root of a mounted file system,
         *    then replace it with the vnode that was mounted on
         *    so that we take the ".." in the other file system.
         */
        if (component[0] == '.' && component[1] == '.' && component[2] == 0) {
checkforroot:
                if (VN_CMP(vp, rootvp)) {
                        component[1] = '\0';
                } else if (vp->v_flag & VROOT) {
                        vfs_t *vfsp;
                        cvp = vp;

                        /*
                         * While we deal with the vfs pointer from the vnode
                         * the filesystem could have been forcefully unmounted
                         * and the vnode's v_vfsp could have been invalidated
                         * by VFS_UNMOUNT. Hence, we cache v_vfsp and use it
                         * with vfs_rlock_wait/vfs_unlock.
                         * It is safe to use the v_vfsp even it is freed by
                         * VFS_UNMOUNT because vfs_rlock_wait/vfs_unlock
                         * do not dereference v_vfsp. It is just used as a
                         * magic cookie.
                         * One more corner case here is the memory getting
                         * reused for another vfs structure. In this case
                         * lookuppnvp's vfs_rlock_wait will succeed, domount's
                         * vfs_lock will fail and domount will bail out with an
                         * error (EBUSY).
                         */
                        vfsp = cvp->v_vfsp;

                        /*
                         * This lock is used to synchronize
                         * mounts/unmounts and lookups.
                         * Threads doing mounts/unmounts hold the
                         * writers version vfs_lock_wait().
                         */

                        vfs_rlock_wait(vfsp);

                        /*
                         * If this vnode is on a file system that
                         * has been forcibly unmounted,
                         * we can't proceed. Cancel this operation
                         * and return EIO.
                         *
                         * vfs_vnodecovered is NULL if unmounted.
                         * Currently, nfs uses VFS_UNMOUNTED to
                         * check if it's a forced-umount. Keep the
                         * same checking here as well even though it
                         * may not be needed.
                         */
                        if (((vp = cvp->v_vfsp->vfs_vnodecovered) == NULL) ||
                            (cvp->v_vfsp->vfs_flag & VFS_UNMOUNTED)) {
                                vfs_unlock(vfsp);
                                VN_RELE(cvp);
                                if (pp)
                                        pn_free(pp);
                                return (EIO);
                        }
                        VN_HOLD(vp);
                        vfs_unlock(vfsp);
                        VN_RELE(cvp);
                        cvp = NULL;
                        /*
                         * Crossing mount points. For eg: We are doing
                         * a lookup of ".." for file systems root vnode
                         * mounted here, and VOP_LOOKUP() (with covered vnode)
                         * will be on underlying file systems mount point
                         * vnode. Set retry_with_kcred flag as we might end
                         * up doing VOP_LOOKUP() with kcred if required.
                         */
                        retry_with_kcred = B_TRUE;
                        goto checkforroot;
                }
        }

        /*
         * Perform a lookup in the current directory.
         */
        error = VOP_LOOKUP(vp, component, &tvp, pnp, lookup_flags,
            rootvp, cr, NULL, NULL, pp);

        /*
         * Retry with kcred - If crossing mount points & error is EACCES.
         *
         * If we are crossing mount points here and doing ".." lookup,
         * VOP_LOOKUP() might fail if the underlying file systems
         * mount point has no execute permission. In cases like these,
         * we retry VOP_LOOKUP() by giving as much privilage as possible
         * by passing kcred credentials.
         *
         * In case of hierarchical file systems, passing kcred still may
         * or may not work.
         * For eg: UFS FS --> Mount NFS FS --> Again mount UFS on some
         *                      directory inside NFS FS.
         */
        if ((error == EACCES) && retry_with_kcred)
                error = VOP_LOOKUP(vp, component, &tvp, pnp, lookup_flags,
                    rootvp, zone_kcred(), NULL, NULL, pp);

        cvp = tvp;
        if (error) {
                cvp = NULL;
                /*
                 * On error, return hard error if
                 * (a) we're not at the end of the pathname yet, or
                 * (b) the caller didn't want the parent directory, or
                 * (c) we failed for some reason other than a missing entry.
                 */
                if (pn_pathleft(pnp) || dirvpp == NULL || error != ENOENT)
                        goto bad;

                pn_setlast(pnp);
                /*
                 * We inform the caller that the desired entry must be
                 * a directory by adding a '/' to the component name.
                 */
                if (must_be_directory && (error = pn_addslash(pnp)) != 0)
                        goto bad;
                *dirvpp = vp;
                if (compvpp != NULL)
                        *compvpp = NULL;
                if (rootvp != rootdir)
                        VN_RELE(rootvp);
                if (pp)
                        pn_free(pp);
                return (0);
        }

        /*
         * Traverse mount points.
         */
        if (vn_mountedvfs(cvp) != NULL) {
                tvp = cvp;
                if ((error = traverse(&tvp)) != 0) {
                        /*
                         * It is required to assign cvp here, because
                         * traverse() will return a held vnode which
                         * may different than the vnode that was passed
                         * in (even in the error case).  If traverse()
                         * changes the vnode it releases the original,
                         * and holds the new one.
                         */
                        cvp = tvp;
                        goto bad;
                }
                cvp = tvp;
        }

        /*
         * If we hit a symbolic link and there is more path to be
         * translated or this operation does not wish to apply
         * to a link, then place the contents of the link at the
         * front of the remaining pathname.
         */
        if (cvp->v_type == VLNK && ((flags & FOLLOW) || pn_pathleft(pnp))) {
                struct pathname linkpath;

                if (++nlink > MAXSYMLINKS) {
                        error = ELOOP;
                        goto bad;
                }
                pn_alloc(&linkpath);
                if (error = pn_getsymlink(cvp, &linkpath, cr)) {
                        pn_free(&linkpath);
                        goto bad;
                }

                if (pn_pathleft(&linkpath) == 0)
                        (void) pn_set(&linkpath, ".");
                error = pn_insert(pnp, &linkpath, strlen(component));
                pn_free(&linkpath);
                if (error)
                        goto bad;
                VN_RELE(cvp);
                cvp = NULL;
                if (pnp->pn_pathlen == 0) {
                        error = ENOENT;
                        goto bad;
                }
                if (pnp->pn_path[0] == '/') {
                        do {
                                pnp->pn_path++;
                                pnp->pn_pathlen--;
                        } while (pnp->pn_path[0] == '/');
                        VN_RELE(vp);
                        vp = rootvp;
                        VN_HOLD(vp);
                }
                if (pn_fixslash(pnp)) {
                        flags |= FOLLOW;
                        must_be_directory = 1;
                }
                goto next;
        }

        /*
         * If rpnp is non-NULL, remember the resolved path name therein.
         * Do not include "." components.  Collapse occurrences of
         * "previous/..", so long as "previous" is not itself "..".
         * Exhausting rpnp results in error ENAMETOOLONG.
         */
        if (rpnp && strcmp(component, ".") != 0) {
                size_t len;

                if (strcmp(component, "..") == 0 &&
                    rpnp->pn_pathlen != 0 &&
                    !((rpnp->pn_pathlen > 2 &&
                    strncmp(rpnp->pn_path+rpnp->pn_pathlen-3, "/..", 3) == 0) ||
                    (rpnp->pn_pathlen == 2 &&
                    strncmp(rpnp->pn_path, "..", 2) == 0))) {
                        while (rpnp->pn_pathlen &&
                            rpnp->pn_path[rpnp->pn_pathlen-1] != '/')
                                rpnp->pn_pathlen--;
                        if (rpnp->pn_pathlen > 1)
                                rpnp->pn_pathlen--;
                        rpnp->pn_path[rpnp->pn_pathlen] = '\0';
                } else {
                        if (rpnp->pn_pathlen != 0 &&
                            rpnp->pn_path[rpnp->pn_pathlen-1] != '/')
                                rpnp->pn_path[rpnp->pn_pathlen++] = '/';
                        if (flags & FIGNORECASE) {
                                /*
                                 * Return the case-preserved name
                                 * within the resolved path.
                                 */
                                error = copystr(pp->pn_buf,
                                    rpnp->pn_path + rpnp->pn_pathlen,
                                    rpnp->pn_bufsize - rpnp->pn_pathlen, &len);
                        } else {
                                error = copystr(component,
                                    rpnp->pn_path + rpnp->pn_pathlen,
                                    rpnp->pn_bufsize - rpnp->pn_pathlen, &len);
                        }
                        if (error)      /* copystr() returns ENAMETOOLONG */
                                goto bad;
                        rpnp->pn_pathlen += (len - 1);
                        ASSERT(rpnp->pn_bufsize > rpnp->pn_pathlen);
                }
        }

        /*
         * If no more components, return last directory (if wanted) and
         * last component (if wanted).
         */
        if (pn_pathleft(pnp) == 0) {
                /*
                 * If there was a trailing slash in the pathname,
                 * make sure the last component is a directory.
                 */
                if (must_be_directory && cvp->v_type != VDIR) {
                        error = ENOTDIR;
                        goto bad;
                }
                if (dirvpp != NULL) {
                        /*
                         * Check that we have the real parent and not
                         * an alias of the last component.
                         */
                        if (vn_compare(vp, cvp)) {
                                pn_setlast(pnp);
                                VN_RELE(vp);
                                VN_RELE(cvp);
                                if (rootvp != rootdir)
                                        VN_RELE(rootvp);
                                if (pp)
                                        pn_free(pp);
                                return (EINVAL);
                        }
                        *dirvpp = vp;
                } else
                        VN_RELE(vp);
                if (pnp->pn_path == pnp->pn_buf)
                        (void) pn_set(pnp, ".");
                else
                        pn_setlast(pnp);
                if (rpnp) {
                        if (VN_CMP(cvp, rootvp))
                                (void) pn_set(rpnp, "/");
                        else if (rpnp->pn_pathlen == 0)
                                (void) pn_set(rpnp, ".");
                }

                if (compvpp != NULL)
                        *compvpp = cvp;
                else
                        VN_RELE(cvp);
                if (rootvp != rootdir)
                        VN_RELE(rootvp);
                if (pp)
                        pn_free(pp);
                return (0);
        }

        /*
         * Skip over slashes from end of last component.
         */
        while (pnp->pn_path[0] == '/') {
                pnp->pn_path++;
                pnp->pn_pathlen--;
        }

        /*
         * Searched through another level of directory:
         * release previous directory handle and save new (result
         * of lookup) as current directory.
         */
        VN_RELE(vp);
        vp = cvp;
        cvp = NULL;
        goto next;

bad:
        /*
         * Error.  Release vnodes and return.
         */
        if (cvp)
                VN_RELE(cvp);
        /*
         * If the error was ESTALE and the current directory to look in
         * was the root for this lookup, the root for a mounted file
         * system, or the starting directory for lookups, then
         * return ENOENT instead of ESTALE.  In this case, no recovery
         * is possible by the higher level.  If ESTALE was returned for
         * some intermediate directory along the path, then recovery
         * is potentially possible and retrying from the higher level
         * will either correct the situation by purging stale cache
         * entries or eventually get back to the point where no recovery
         * is possible.
         */
        if (error == ESTALE &&
            (VN_CMP(vp, rootvp) || (vp->v_flag & VROOT) || vp == startvp))
                error = ENOENT;
        VN_RELE(vp);
        if (rootvp != rootdir)
                VN_RELE(rootvp);
        if (pp)
                pn_free(pp);
        return (error);
}

/*
 * Traverse a mount point.  Routine accepts a vnode pointer as a reference
 * parameter and performs the indirection, releasing the original vnode.
 */
int
traverse(vnode_t **cvpp)
{
        int error = 0;
        vnode_t *cvp;
        vnode_t *tvp;
        vfs_t *vfsp;

        cvp = *cvpp;

        /*
         * If this vnode is mounted on, then we transparently indirect
         * to the vnode which is the root of the mounted file system.
         * Before we do this we must check that an unmount is not in
         * progress on this vnode.
         */

        for (;;) {
                /*
                 * Used to try to read lock the vnode here.
                 */

                /*
                 * Reached the end of the mount chain?
                 */
                vfsp = vn_mountedvfs(cvp);
                if (vfsp == NULL) {
                        break;
                }

                /*
                 * The read lock must be held across the call to VFS_ROOT() to
                 * prevent a concurrent unmount from destroying the vfs.
                 */
                error = VFS_ROOT(vfsp, &tvp);
                if (error)
                        break;

                VN_RELE(cvp);

                cvp = tvp;
        }

        *cvpp = cvp;
        return (error);
}

/*
 * Get the vnode path, relative to the passed rootvp.
 * Our vncache always fills in v_path, so this is easy.
 */
/* ARGSUSED */
int
vnodetopath(vnode_t *vrootp, vnode_t *vp, char *buf, size_t buflen, cred_t *cr)
{
        int len, rvp_len = 0;
        const char *p = vp->v_path;

        if (vrootp)
                rvp_len = strlen(vrootp->v_path);
        len = strlen(p);
        if (rvp_len < len)
                p += rvp_len;
        else
                p = "/";

        (void) strlcpy(buf, p, buflen);
        return (0);
}