Colony » Colony Scout » Colony Scout OS

/*-

 * Copyright (c) 1990, 1993, 1994

 *        The Regents of the University of California.  All rights reserved.

 *

 * 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.

 * 3. Neither the name of the University nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/param.h>

#include <sys/stat.h>

#include <dirent.h>

#include <errno.h>

#include <fcntl.h>

#include <fts.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

static FTSENT        *fts_alloc(FTS *, char *, int);

static FTSENT        *fts_build(FTS *, int);

static void         fts_lfree(FTSENT *);

static void         fts_load(FTS *, FTSENT *);

static size_t         fts_maxarglen(char * const *);

static void         fts_padjust(FTS *, void *);

static int         fts_palloc(FTS *, size_t);

static FTSENT        *fts_sort(FTS *, FTSENT *, int);

static u_short         fts_stat(FTS *, FTSENT *, int);

#define ALIGNBYTES 7

#define        ISDOT(a)        (a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))

#define        ISSET(opt)        (sp->fts_options & (opt))

#define        SET(opt)        (sp->fts_options |= (opt))

#define        CHDIR(sp, path)        (!ISSET(FTS_NOCHDIR) && chdir(path))

#define        FCHDIR(sp, fd)        (!ISSET(FTS_NOCHDIR) && fchdir(fd))

/* fts_build flags */

#define        BCHILD                1                /* fts_children */

#define        BNAMES                2                /* fts_children, names only */

#define        BREAD                3                /* fts_read */

FTS *

fts_open(char * const *argv, int options,

    int (*compar)(const FTSENT **, const FTSENT **))

{

        FTS *sp;

        FTSENT *p, *root;

        int nitems;

        FTSENT *parent, *tmp = NULL;

        int len;

        /* Options check. */

        if (options & ~FTS_OPTIONMASK) {

                errno = EINVAL;

                return (NULL);

        }

        /* Allocate/initialize the stream */

        if ((sp = malloc((u_int)sizeof(FTS))) == NULL)

                return (NULL);

        memset(sp, 0, sizeof(FTS));

        sp->fts_compar = compar;

        sp->fts_options = options;

        /* Logical walks turn on NOCHDIR; symbolic links are too hard. */

        if (ISSET(FTS_LOGICAL))

                SET(FTS_NOCHDIR);

        /*

         * Start out with 1K of path space, and enough, in any case,

         * to hold the user's paths.

         */

        if (fts_palloc(sp, MAX(fts_maxarglen(argv), MAXPATHLEN)))

                goto mem1;

        /* Allocate/initialize root's parent. */

        if ((parent = fts_alloc(sp, "", 0)) == NULL)

                goto mem2;

        parent->fts_level = FTS_ROOTPARENTLEVEL;

        /* Allocate/initialize root(s). */

        for (root = NULL, nitems = 0; *argv; ++argv, ++nitems) {

                /* Don't allow zero-length paths. */

                if ((len = strlen(*argv)) == 0) {

                        errno = ENOENT;

                        goto mem3;

                }

                p = fts_alloc(sp, *argv, len);

                p->fts_level = FTS_ROOTLEVEL;

                p->fts_parent = parent;

                p->fts_accpath = p->fts_name;

                p->fts_info = fts_stat(sp, p, ISSET(FTS_COMFOLLOW));

                /* Command-line "." and ".." are real directories. */

                if (p->fts_info == FTS_DOT)

                        p->fts_info = FTS_D;

                /*

                 * If comparison routine supplied, traverse in sorted

                 * order; otherwise traverse in the order specified.

                 */

                if (compar) {

                        p->fts_link = root;

                        root = p;

                } else {

                        p->fts_link = NULL;

                        if (root == NULL)

                                tmp = root = p;

                        else {

                                tmp->fts_link = p;

                                tmp = p;

                        }

                }

        }

        if (compar && nitems > 1)

                root = fts_sort(sp, root, nitems);

        /*

         * Allocate a dummy pointer and make fts_read think that we've just

         * finished the node before the root(s); set p->fts_info to FTS_INIT

         * so that everything about the "current" node is ignored.

         */

        if ((sp->fts_cur = fts_alloc(sp, "", 0)) == NULL)

                goto mem3;

        sp->fts_cur->fts_link = root;

        sp->fts_cur->fts_info = FTS_INIT;

        /*

         * If using chdir(2), grab a file descriptor pointing to dot to insure

         * that we can get back here; this could be avoided for some paths,

         * but almost certainly not worth the effort.  Slashes, symbolic links,

         * and ".." are all fairly nasty problems.  Note, if we can't get the

         * descriptor we run anyway, just more slowly.

         */

        if (!ISSET(FTS_NOCHDIR) && (sp->fts_rfd = open(".", O_RDONLY, 0)) < 0)

                SET(FTS_NOCHDIR);

        return (sp);

mem3:        fts_lfree(root);

        free(parent);

mem2:        free(sp->fts_path);

mem1:        free(sp);

        return (NULL);

}

static void

fts_load(FTS *sp, FTSENT *p)

{

        int len;

        char *cp;

        /*

         * Load the stream structure for the next traversal.  Since we don't

         * actually enter the directory until after the preorder visit, set

         * the fts_accpath field specially so the chdir gets done to the right

         * place and the user can access the first node.  From fts_open it's

         * known that the path will fit.

         */

        len = p->fts_pathlen = p->fts_namelen;

        memmove(sp->fts_path, p->fts_name, len + 1);

        if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {

                len = strlen(++cp);

                memmove(p->fts_name, cp, len + 1);

                p->fts_namelen = len;

        }

        p->fts_accpath = p->fts_path = sp->fts_path;

        sp->fts_dev = p->fts_dev;

}

int

fts_close(FTS *sp)

{

        FTSENT *freep, *p;

        int saved_errno = 0;

        /*

         * This still works if we haven't read anything -- the dummy structure

         * points to the root list, so we step through to the end of the root

         * list which has a valid parent pointer.

         */

        if (sp->fts_cur) {

                for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {

                        freep = p;

                        p = p->fts_link ? p->fts_link : p->fts_parent;

                        free(freep);

                }

                free(p);

        }

        /* Free up child linked list, sort array, path buffer. */

        if (sp->fts_child)

                fts_lfree(sp->fts_child);

        if (sp->fts_array)

                free(sp->fts_array);

        free(sp->fts_path);

        /* Return to original directory, save errno if necessary. */

        if (!ISSET(FTS_NOCHDIR)) {

                saved_errno = fchdir(sp->fts_rfd) ? errno : 0;

                (void)close(sp->fts_rfd);

        }

        /* Free up the stream pointer. */

        free(sp);

        /* Set errno and return. */

        if (!ISSET(FTS_NOCHDIR) && saved_errno) {

                errno = saved_errno;

                return (-1);

        }

        return (0);

}

/*

 * Special case a root of "/" so that slashes aren't appended which would

 * cause paths to be written as "//foo".

 */

#define        NAPPEND(p)                                                        \

        (p->fts_level == FTS_ROOTLEVEL && p->fts_pathlen == 1 &&        \

            p->fts_path[0] == '/' ? 0 : p->fts_pathlen)

FTSENT *

fts_read(FTS *sp)

{

        FTSENT *p, *tmp;

        int instr;

        char *t;

        int saved_errno;

        /* If finished or unrecoverable error, return NULL. */

        if (sp->fts_cur == NULL || ISSET(FTS_STOP))

                return (NULL);

        /* Set current node pointer. */

        p = sp->fts_cur;

        /* Save and zero out user instructions. */

        instr = p->fts_instr;

        p->fts_instr = FTS_NOINSTR;

        /* Any type of file may be re-visited; re-stat and re-turn. */

        if (instr == FTS_AGAIN) {

                p->fts_info = fts_stat(sp, p, 0);

                return (p);

        }

        /*

         * Following a symlink -- SLNONE test allows application to see

         * SLNONE and recover.  If indirecting through a symlink, have

         * keep a pointer to current location.  If unable to get that

         * pointer, follow fails.

         */

        if (instr == FTS_FOLLOW &&

            (p->fts_info == FTS_SL || p->fts_info == FTS_SLNONE)) {

                p->fts_info = fts_stat(sp, p, 1);

                if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {

                        if ((p->fts_symfd = open(".", O_RDONLY, 0)) < 0) {

                                p->fts_errno = errno;

                                p->fts_info = FTS_ERR;

                        } else

                                p->fts_flags |= FTS_SYMFOLLOW;

                }

                return (p);

        }

        /* Directory in pre-order. */

        if (p->fts_info == FTS_D) {

                /* If skipped or crossed mount point, do post-order visit. */

                if (instr == FTS_SKIP ||

                    (ISSET(FTS_XDEV) && p->fts_dev != sp->fts_dev)) {

                        if (p->fts_flags & FTS_SYMFOLLOW)

                                (void)close(p->fts_symfd);

                        if (sp->fts_child) {

                                fts_lfree(sp->fts_child);

                                sp->fts_child = NULL;

                        }

                        p->fts_info = FTS_DP;

                        return (p);

                } 

                /* Rebuild if only read the names and now traversing. */

                if (sp->fts_child && sp->fts_options & FTS_NAMEONLY) {

                        sp->fts_options &= ~FTS_NAMEONLY;

                        fts_lfree(sp->fts_child);

                        sp->fts_child = NULL;

                }

                /*

                 * Cd to the subdirectory.

                 *

                 * If have already read and now fail to chdir, whack the list

                 * to make the names come out right, and set the parent errno

                 * so the application will eventually get an error condition.

                 * Set the FTS_DONTCHDIR flag so that when we logically change

                 * directories back to the parent we don't do a chdir.

                 *

                 * If haven't read do so.  If the read fails, fts_build sets

                 * FTS_STOP or the fts_info field of the node.

                 */

                if (sp->fts_child) {

                        if (CHDIR(sp, p->fts_accpath)) {

                                p->fts_errno = errno;

                                p->fts_flags |= FTS_DONTCHDIR;

                                for (p = sp->fts_child; p; p = p->fts_link)

                                        p->fts_accpath =

                                            p->fts_parent->fts_accpath;

                        }

                } else if ((sp->fts_child = fts_build(sp, BREAD)) == NULL) {

                        if (ISSET(FTS_STOP))

                                return (NULL);

                        return (p);

                }

                p = sp->fts_child;

                sp->fts_child = NULL;

                goto name;

        }

        /* Move to the next node on this level. */

next:        tmp = p;

        if ((p = p->fts_link) != NULL) {

                free(tmp);

                /*

                 * If reached the top, return to the original directory, and

                 * load the paths for the next root.

                 */

                if (p->fts_level == FTS_ROOTLEVEL) {

                        if (!ISSET(FTS_NOCHDIR) && FCHDIR(sp, sp->fts_rfd)) {

                                SET(FTS_STOP);

                                return (NULL);

                        }

                        fts_load(sp, p);

                        return (sp->fts_cur = p);

                }

                /*

                 * User may have called fts_set on the node.  If skipped,

                 * ignore.  If followed, get a file descriptor so we can

                 * get back if necessary.

                 */

                if (p->fts_instr == FTS_SKIP)

                        goto next;

                if (p->fts_instr == FTS_FOLLOW) {

                        p->fts_info = fts_stat(sp, p, 1);

                        if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {

                                if ((p->fts_symfd =

                                    open(".", O_RDONLY, 0)) < 0) {

                                        p->fts_errno = errno;

                                        p->fts_info = FTS_ERR;

                                } else

                                        p->fts_flags |= FTS_SYMFOLLOW;

                        }

                        p->fts_instr = FTS_NOINSTR;

                }

name:                t = sp->fts_path + NAPPEND(p->fts_parent);

                *t++ = '/';

                memmove(t, p->fts_name, p->fts_namelen + 1);

                return (sp->fts_cur = p);

        }

        /* Move up to the parent node. */

        p = tmp->fts_parent;

        free(tmp);

        if (p->fts_level == FTS_ROOTPARENTLEVEL) {

                /*

                 * Done; free everything up and set errno to 0 so the user

                 * can distinguish between error and EOF.

                 */

                free(p);

                errno = 0;

                return (sp->fts_cur = NULL);

        }

        /* Nul terminate the pathname. */

        sp->fts_path[p->fts_pathlen] = '\0';

        /*

         * Return to the parent directory.  If at a root node or came through

         * a symlink, go back through the file descriptor.  Otherwise, cd up

         * one directory.

         */

        if (p->fts_level == FTS_ROOTLEVEL) {

                if (!ISSET(FTS_NOCHDIR) && FCHDIR(sp, sp->fts_rfd)) {

                        SET(FTS_STOP);

                        return (NULL);

                }

        } else if (p->fts_flags & FTS_SYMFOLLOW) {

                if (FCHDIR(sp, p->fts_symfd)) {

                        saved_errno = errno;

                        (void)close(p->fts_symfd);

                        errno = saved_errno;

                        SET(FTS_STOP);

                        return (NULL);

                }

                (void)close(p->fts_symfd);

        } else if (!(p->fts_flags & FTS_DONTCHDIR)) {

                if (CHDIR(sp, "..")) {

                        SET(FTS_STOP);

                        return (NULL);

                }

        }

        p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;

        return (sp->fts_cur = p);

}

/*

 * Fts_set takes the stream as an argument although it's not used in this

 * implementation; it would be necessary if anyone wanted to add global

 * semantics to fts using fts_set.  An error return is allowed for similar

 * reasons.

 */

/* ARGSUSED */

int

fts_set(FTS *sp, FTSENT *p, int instr)

{

        if (instr && instr != FTS_AGAIN && instr != FTS_FOLLOW &&

            instr != FTS_NOINSTR && instr != FTS_SKIP) {

                errno = EINVAL;

                return (1);

        }

        p->fts_instr = instr;

        return (0);

}

FTSENT *

fts_children(FTS *sp, int instr)

{

        FTSENT *p;

        int fd;

        if (instr && instr != FTS_NAMEONLY) {

                errno = EINVAL;

                return (NULL);

        }

        /* Set current node pointer. */

        p = sp->fts_cur;

        /*

         * Errno set to 0 so user can distinguish empty directory from

         * an error.

         */

        errno = 0;

        /* Fatal errors stop here. */

        if (ISSET(FTS_STOP))

                return (NULL);

        /* Return logical hierarchy of user's arguments. */

        if (p->fts_info == FTS_INIT)

                return (p->fts_link);

        /*

         * If not a directory being visited in pre-order, stop here.  Could

         * allow FTS_DNR, assuming the user has fixed the problem, but the

         * same effect is available with FTS_AGAIN.

         */

        if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)

                return (NULL);

        /* Free up any previous child list. */

        if (sp->fts_child)

                fts_lfree(sp->fts_child);

        if (instr == FTS_NAMEONLY) {

                sp->fts_options |= FTS_NAMEONLY;

                instr = BNAMES;

        } else 

                instr = BCHILD;

        /*

         * If using chdir on a relative path and called BEFORE fts_read does

         * its chdir to the root of a traversal, we can lose -- we need to

         * chdir into the subdirectory, and we don't know where the current

         * directory is, so we can't get back so that the upcoming chdir by

         * fts_read will work.

         */

        if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||

            ISSET(FTS_NOCHDIR))

                return (sp->fts_child = fts_build(sp, instr));

        if ((fd = open(".", O_RDONLY, 0)) < 0)

                return (NULL);

        sp->fts_child = fts_build(sp, instr);

        if (fchdir(fd))

                return (NULL);

        (void)close(fd);

        return (sp->fts_child);

}

/*

 * This is the tricky part -- do not casually change *anything* in here.  The

 * idea is to build the linked list of entries that are used by fts_children

 * and fts_read.  There are lots of special cases.

 *

 * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is

 * set and it's a physical walk (so that symbolic links can't be directories),

 * we can do things quickly.  First, if it's a 4.4BSD file system, the type

 * of the file is in the directory entry.  Otherwise, we assume that the number

 * of subdirectories in a node is equal to the number of links to the parent.

 * The former skips all stat calls.  The latter skips stat calls in any leaf

 * directories and for any files after the subdirectories in the directory have

 * been found, cutting the stat calls by about 2/3.

 */

static FTSENT *

fts_build(FTS *sp, int type)

{

        struct dirent *dp;

        FTSENT *p, *head;

        int nitems;

        FTSENT *cur, *tail;

        DIR *dirp;

        void *adjaddr;

        int cderrno, descend, len, level, maxlen, nlinks, saved_errno;

#ifdef FTS_WHITEOUT

        int oflag;

#endif

        char *cp = NULL;        /* pacify gcc */

        /* Set current node pointer. */

        cur = sp->fts_cur;

        /*

         * Open the directory for reading.  If this fails, we're done.

         * If being called from fts_read, set the fts_info field.

         */

#ifdef FTS_WHITEOUT

        if (ISSET(FTS_WHITEOUT))

                oflag = DTF_NODUP|DTF_REWIND;

        else

                oflag = DTF_HIDEW|DTF_NODUP|DTF_REWIND;

#else

#define __opendir2(path, flag) opendir(path)

#endif

        if ((dirp = __opendir2(cur->fts_accpath, oflag)) == NULL) {

                if (type == BREAD) {

                        cur->fts_info = FTS_DNR;

                        cur->fts_errno = errno;

                }

                return (NULL);

        }

        /*

         * Nlinks is the number of possible entries of type directory in the

         * directory if we're cheating on stat calls, 0 if we're not doing

         * any stat calls at all, -1 if we're doing stats on everything.

         */

        if (type == BNAMES)

                nlinks = 0;

        else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL))

                nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);

        else

                nlinks = -1;

#ifdef notdef

        (void)printf("nlinks == %d (cur: %d)\n", nlinks, cur->fts_nlink);

        (void)printf("NOSTAT %d PHYSICAL %d SEEDOT %d\n",

            ISSET(FTS_NOSTAT), ISSET(FTS_PHYSICAL), ISSET(FTS_SEEDOT));

#endif

        /*

         * If we're going to need to stat anything or we want to descend

         * and stay in the directory, chdir.  If this fails we keep going,

         * but set a flag so we don't chdir after the post-order visit.

         * We won't be able to stat anything, but we can still return the

         * names themselves.  Note, that since fts_read won't be able to

         * chdir into the directory, it will have to return different path

         * names than before, i.e. "a/b" instead of "b".  Since the node

         * has already been visited in pre-order, have to wait until the

         * post-order visit to return the error.  There is a special case

         * here, if there was nothing to stat then it's not an error to

         * not be able to stat.  This is all fairly nasty.  If a program

         * needed sorted entries or stat information, they had better be

         * checking FTS_NS on the returned nodes.

         */

        cderrno = 0;

        if (nlinks || type == BREAD)

                if (FCHDIR(sp, dirfd(dirp))) {

                        if (nlinks && type == BREAD)

                                cur->fts_errno = errno;

                        cur->fts_flags |= FTS_DONTCHDIR;

                        descend = 0;

                        cderrno = errno;

                } else

                        descend = 1;

        else

                descend = 0;

        /*

         * Figure out the max file name length that can be stored in the

         * current path -- the inner loop allocates more path as necessary.

         * We really wouldn't have to do the maxlen calculations here, we

         * could do them in fts_read before returning the path, but it's a

         * lot easier here since the length is part of the dirent structure.

         *

         * If not changing directories set a pointer so that can just append

         * each new name into the path.

         */

        maxlen = sp->fts_pathlen - cur->fts_pathlen - 1;

        len = NAPPEND(cur);

        if (ISSET(FTS_NOCHDIR)) {

                cp = sp->fts_path + len;

                *cp++ = '/';

        }

        level = cur->fts_level + 1;

        /* Read the directory, attaching each entry to the `link' pointer. */

        adjaddr = NULL;

        for (head = tail = NULL, nitems = 0; (dp = readdir(dirp)) != NULL;) {

                if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))

                        continue;

                if ((p = fts_alloc(sp, dp->d_name, (int)dp->d_namlen)) == NULL)

                        goto mem1;

                if (dp->d_namlen > maxlen) {

                        if (fts_palloc(sp, (size_t)dp->d_namlen)) {

                                /*

                                 * No more memory for path or structures.  Save

                                 * errno, free up the current structure and the

                                 * structures already allocated.

                                 */

mem1:                                saved_errno = errno;

                                if (p)

                                        free(p);

                                fts_lfree(head);

                                (void)closedir(dirp);

                                errno = saved_errno;

                                cur->fts_info = FTS_ERR;

                                SET(FTS_STOP);

                                return (NULL);

                        }

                        adjaddr = sp->fts_path;

                        maxlen = sp->fts_pathlen - sp->fts_cur->fts_pathlen - 1;

                }

                p->fts_pathlen = len + dp->d_namlen + 1;

                p->fts_parent = sp->fts_cur;

                p->fts_level = level;

#ifdef FTS_WHITEOUT

                if (dp->d_type == DT_WHT)

                        p->fts_flags |= FTS_ISW;

#endif

                if (cderrno) {

                        if (nlinks) {

                                p->fts_info = FTS_NS;

                                p->fts_errno = cderrno;

                        } else

                                p->fts_info = FTS_NSOK;

                        p->fts_accpath = cur->fts_accpath;

                } else if (nlinks == 0

#ifdef DT_DIR

                    || (nlinks > 0 && 

                        dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)

#endif

                    ) {

                        p->fts_accpath =

                            ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;

                        p->fts_info = FTS_NSOK;

                } else {

                        /* Build a file name for fts_stat to stat. */

                        if (ISSET(FTS_NOCHDIR)) {

                                p->fts_accpath = p->fts_path;

                                memmove(cp, p->fts_name, p->fts_namelen + 1);

                        } else

                                p->fts_accpath = p->fts_name;

                        /* Stat it. */

                        p->fts_info = fts_stat(sp, p, 0);

                        /* Decrement link count if applicable. */

                        if (nlinks > 0 && (p->fts_info == FTS_D ||

                            p->fts_info == FTS_DC || p->fts_info == FTS_DOT))

                                --nlinks;

                }

                /* We walk in directory order so "ls -f" doesn't get upset. */

                p->fts_link = NULL;

                if (head == NULL)

                        head = tail = p;

                else {

                        tail->fts_link = p;

                        tail = p;

                }

                ++nitems;

        }

        (void)closedir(dirp);

        /*

         * If had to realloc the path, adjust the addresses for the rest

         * of the tree.

         */

        if (adjaddr)

                fts_padjust(sp, adjaddr);

        /*

         * If not changing directories, reset the path back to original

         * state.

         */

        if (ISSET(FTS_NOCHDIR)) {

                if (cp - 1 > sp->fts_path)

                        --cp;

                *cp = '\0';

        }

        /*

         * If descended after called from fts_children or after called from

         * fts_read and nothing found, get back.  At the root level we use

         * the saved fd; if one of fts_open()'s arguments is a relative path

         * to an empty directory, we wind up here with no other way back.  If

         * can't get back, we're done.

         */

        if (descend && (type == BCHILD || !nitems) &&

            (cur->fts_level == FTS_ROOTLEVEL ?

            FCHDIR(sp, sp->fts_rfd) : CHDIR(sp, ".."))) {

                cur->fts_info = FTS_ERR;

                SET(FTS_STOP);

                return (NULL);

        }

        /* If didn't find anything, return NULL. */

        if (!nitems) {

                if (type == BREAD)

                        cur->fts_info = FTS_DP;

                return (NULL);

        }

        /* Sort the entries. */

        if (sp->fts_compar && nitems > 1)

                head = fts_sort(sp, head, nitems);

        return (head);

}

static u_short

fts_stat(FTS *sp, FTSENT *p, int follow)

{

        FTSENT *t;

        dev_t dev;

        ino_t ino;

        struct stat *sbp, sb;

        int saved_errno;

        /* If user needs stat info, stat buffer already allocated. */

        sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;

#ifdef FTS_WHITEOUT

        /* check for whiteout */

        if (p->fts_flags & FTS_ISW) {

                if (sbp != &sb) {

                        memset(sbp, '\0', sizeof (*sbp));

                        sbp->st_mode = S_IFWHT;

                }

                return (FTS_W);

        }

#endif

        /*

         * If doing a logical walk, or application requested FTS_FOLLOW, do

         * a stat(2).  If that fails, check for a non-existent symlink.  If

         * fail, set the errno from the stat call.

         */

        if (ISSET(FTS_LOGICAL) || follow) {

                if (stat(p->fts_accpath, sbp)) {

                        saved_errno = errno;

                        if (!lstat(p->fts_accpath, sbp)) {

                                errno = 0;

                                return (FTS_SLNONE);

                        } 

                        p->fts_errno = saved_errno;

                        goto err;

                }

        } else if (lstat(p->fts_accpath, sbp)) {

                p->fts_errno = errno;

err:                memset(sbp, 0, sizeof(struct stat));

                return (FTS_NS);

        }

        if (S_ISDIR(sbp->st_mode)) {

                /*

                 * Set the device/inode.  Used to find cycles and check for

                 * crossing mount points.  Also remember the link count, used

                 * in fts_build to limit the number of stat calls.  It is

                 * understood that these fields are only referenced if fts_info

                 * is set to FTS_D.

                 */

                dev = p->fts_dev = sbp->st_dev;

                ino = p->fts_ino = sbp->st_ino;

                p->fts_nlink = sbp->st_nlink;

                if (ISDOT(p->fts_name))

                        return (FTS_DOT);

                /*

                 * Cycle detection is done by brute force when the directory

                 * is first encountered.  If the tree gets deep enough or the

                 * number of symbolic links to directories is high enough,

                 * something faster might be worthwhile.

                 */

                for (t = p->fts_parent;

                    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)

                        if (ino == t->fts_ino && dev == t->fts_dev) {

                                p->fts_cycle = t;

                                return (FTS_DC);

                        }

                return (FTS_D);

        }

        if (S_ISLNK(sbp->st_mode))

                return (FTS_SL);

        if (S_ISREG(sbp->st_mode))

                return (FTS_F);

        return (FTS_DEFAULT);

}

static FTSENT *

fts_sort(FTS *sp, FTSENT *head, int nitems)

{

        FTSENT **ap, *p;

        /*

         * Construct an array of pointers to the structures and call qsort(3).

         * Reassemble the array in the order returned by qsort.  If unable to

         * sort for memory reasons, return the directory entries in their

         * current order.  Allocate enough space for the current needs plus

         * 40 so don't realloc one entry at a time.

         */

        if (nitems > sp->fts_nitems) {

                sp->fts_nitems = nitems + 40;

                if ((sp->fts_array = realloc(sp->fts_array,

                    (size_t)(sp->fts_nitems * sizeof(FTSENT *)))) == NULL) {

                        sp->fts_nitems = 0;

                        return (head);

                }

        }

        for (ap = sp->fts_array, p = head; p; p = p->fts_link)

                *ap++ = p;

        qsort((void *)sp->fts_array, nitems, sizeof(FTSENT *),

                (int (*)(const void *, const void *))sp->fts_compar);

        for (head = *(ap = sp->fts_array); --nitems; ++ap)

                ap[0]->fts_link = ap[1];

        ap[0]->fts_link = NULL;

        return (head);

}

static FTSENT *

fts_alloc(FTS *sp, char *name, int namelen)

{

        FTSENT *p;

        size_t len;

        /*

         * The file name is a variable length array and no stat structure is

         * necessary if the user has set the nostat bit.  Allocate the FTSENT

         * structure, the file name and the stat structure in one chunk, but

         * be careful that the stat structure is reasonably aligned.  Since the

         * fts_name field is declared to be of size 1, the fts_name pointer is

         * namelen + 2 before the first possible address of the stat structure.

         */

        len = sizeof(FTSENT) + namelen;

        if (!ISSET(FTS_NOSTAT))

                len += sizeof(struct stat) + ALIGNBYTES;

        if ((p = malloc(len)) == NULL)

                return (NULL);

        /* Copy the name plus the trailing NULL. */

        memmove(p->fts_name, name, namelen + 1);

        if (!ISSET(FTS_NOSTAT))

                p->fts_statp = (struct stat *)ALIGN(p->fts_name + namelen + 2);

        p->fts_namelen = namelen;

        p->fts_path = sp->fts_path;

        p->fts_errno = 0;

        p->fts_flags = 0;

        p->fts_instr = FTS_NOINSTR;

        p->fts_number = 0;

        p->fts_pointer = NULL;

        return (p);

}

static void

fts_lfree(FTSENT *head)

{

        FTSENT *p;

        /* Free a linked list of structures. */

        while ((p = head) != NULL) {

                head = head->fts_link;

                free(p);

        }

}

/*

 * Allow essentially unlimited paths; find, rm, ls should all work on any tree.

 * Most systems will allow creation of paths much longer than MAXPATHLEN, even

 * though the kernel won't resolve them.  Add the size (not just what's needed)

 * plus 256 bytes so don't realloc the path 2 bytes at a time. 

 */

static int

fts_palloc(FTS *sp, size_t more)

{

        sp->fts_pathlen += more + 256;

        sp->fts_path = realloc(sp->fts_path, (size_t)sp->fts_pathlen);

        return (sp->fts_path == NULL);

}

/*

 * When the path is realloc'd, have to fix all of the pointers in structures

 * already returned.

 */

static void

fts_padjust(FTS *sp, void *addr)

{

        FTSENT *p;

#define        ADJUST(p) {                                                        \

        (p)->fts_accpath =                                                \

            (char *)addr + ((p)->fts_accpath - (p)->fts_path);                \

        (p)->fts_path = addr;                                                \

}

        /* Adjust the current set of children. */

        for (p = sp->fts_child; p; p = p->fts_link)

                ADJUST(p);

        /* Adjust the rest of the tree. */

        for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {

                ADJUST(p);

                p = p->fts_link ? p->fts_link : p->fts_parent;

        }

}

static size_t

fts_maxarglen(char * const *argv)

{

        size_t len, max;

        for (max = 0; *argv; ++argv)

                if ((len = strlen(*argv)) > max)

                        max = len;

        return (max);

}