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fts.c

/*    $NetBSD: __fts13.c,v 1.44 2005/01/19 00:59:48 mycroft Exp $ */

/*-
 * 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.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

/*#include <sys/cdefs.h>*/
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)fts.c   8.6 (Berkeley) 8/14/94";
#else
__RCSID("$NetBSD: __fts13.c,v 1.44 2005/01/19 00:59:48 mycroft Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

/*#include "namespace.h"*/
#ifndef _MSC_VER
#include <sys/param.h>
#endif
#include <sys/stat.h>

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include "ftsfake.h"
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef __sun__
# include "solfakes.h"
# ifndef __XOPEN_OR_POSIX
#  define dirfd(dir) ((dir)->dd_fd)
#else
#  define dirfd(dir) ((dir)->d_fd)
#endif
#endif
#ifdef _MSC_VER
# include "mscfakes.h"
# define dirfd(dir) -1
#endif

#if ! HAVE_NBTOOL_CONFIG_H
#ifndef __sun__
#define HAVE_STRUCT_DIRENT_D_NAMLEN 1
#endif
#endif

#if 0
#ifdef __weak_alias
#ifdef __LIBC12_SOURCE__
__weak_alias(fts_children,_fts_children)
__weak_alias(fts_close,_fts_close)
__weak_alias(fts_open,_fts_open)
__weak_alias(fts_read,_fts_read)
__weak_alias(fts_set,_fts_set)
#endif /* __LIBC12_SOURCE__ */
#endif /* __weak_alias */
#endif

#ifdef __LIBC12_SOURCE__
#define     STAT  stat12
#else
#define     STAT  stat
#endif

#ifdef __LIBC12_SOURCE__
__warn_references(fts_children,
    "warning: reference to compatibility fts_children();"
    " include <fts.h> for correct reference")
__warn_references(fts_close,
    "warning: reference to compatibility fts_close();"
    " include <fts.h> for correct reference")
__warn_references(fts_open,
    "warning: reference to compatibility fts_open();"
    " include <fts.h> for correct reference")
__warn_references(fts_read,
    "warning: reference to compatibility fts_read();"
    " include <fts.h> for correct reference")
__warn_references(fts_set,
    "warning: reference to compatibility fts_set();"
    " include <fts.h> for correct reference")
#endif

static FTSENT     *fts_alloc(FTS *, const char *, size_t);
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 size_t      fts_pow2(size_t);
static int   fts_palloc(FTS *, size_t);
static void  fts_padjust(FTS *, FTSENT *);
static FTSENT     *fts_sort(FTS *, FTSENT *, size_t);
static u_short     fts_stat(FTS *, FTSENT *, int);
static int   fts_safe_changedir(const FTS *, const FTSENT *, int,
    const char *);

#ifdef _MSC_VER
#undef HAVE_STRUCT_DIRENT_D_NAMLEN
#undef HAVE_FCHDIR
#endif

#if defined(__EMX__) || defined(_MSC_VER)
# define NEED_STRRSLASH
# define IS_SLASH(ch)   ( (ch) == '/' || (ch) == '\\' )
#else
# define HAVE_FCHDIR
# define IS_SLASH(ch)   ( (ch) == '/' )
#endif

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

#define     CLR(opt)    (sp->fts_options &= ~(opt))
#define     ISSET(opt)  (sp->fts_options & (opt))
#define     SET(opt)    (sp->fts_options |= (opt))

#define     CHDIR(sp, path)   (!ISSET(FTS_NOCHDIR) && chdir(path))
#ifdef HAVE_FCHDIR
#define     FCHDIR(sp, fd)    (!ISSET(FTS_NOCHDIR) && fchdir(fd))
#else
#define     FCHDIR(sp, rdir) CHDIR(sp, rdir)
#endif


/* fts_build flags */
#define     BCHILD            1           /* fts_children */
#define     BNAMES            2           /* fts_children, names only */
#define     BREAD       3           /* fts_read */

#ifndef DTF_HIDEW
#undef FTS_WHITEOUT
#endif

#ifndef _DIAGASSERT
#define _DIAGASSERT assert
#endif


FTS *
fts_open(argv, options, compar)
      char * const *argv;
      int options;
      int (*compar)(const FTSENT **, const FTSENT **);
{
      FTS *sp;
      FTSENT *p, *root;
      size_t nitems;
      FTSENT *parent, *tmp = NULL;  /* pacify gcc */
      size_t len;

      _DIAGASSERT(argv != NULL);

      /* 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;
            }

            if ((p = fts_alloc(sp, *argv, len)) == NULL)
                  goto mem3;
            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)) {
#ifdef HAVE_FCHDIR
            if ((sp->fts_rfd = open(".", O_RDONLY, 0)) == -1)
                  SET(FTS_NOCHDIR);
            else if (fcntl(sp->fts_rfd, F_SETFD, FD_CLOEXEC) == -1) {
                  close(sp->fts_rfd);
                  SET(FTS_NOCHDIR);
            }
#else
            if ((sp->fts_rdir = getcwd(NULL, 0)) != NULL)
                  SET(FTS_NOCHDIR);
#endif
      }

      return (sp);

mem3: fts_lfree(root);
      free(parent);
mem2: free(sp->fts_path);
mem1: free(sp);
      return (NULL);
}

#ifdef NEED_STRRSLASH
static char *strrslash(register char *psz)
{
    register char ch;
    char *pszLast = NULL;
    for (; (ch = *psz); psz++)
        switch (ch)
        {
            case '/':
            case '\\':
            case ':':
                pszLast = psz;
                break;
        }
    return pszLast;
}
#endif

static void
fts_load(sp, p)
      FTS *sp;
      FTSENT *p;
{
      size_t len;
      char *cp;

      _DIAGASSERT(sp != NULL);
      _DIAGASSERT(p != NULL);

      /*
       * 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);
#ifdef NEED_STRRSLASH
      if ((cp = strrslash(p->fts_name)) && (cp != p->fts_name || cp[1])) {
#else
      if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
#endif
            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(sp)
      FTS *sp;
{
      FTSENT *freep, *p;
      int saved_errno = 0;

      _DIAGASSERT(sp != NULL);

      /*
       * 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) {
#ifndef _MSC_VER
            if (ISSET(FTS_SYMFOLLOW))
                  (void)close(sp->fts_cur->fts_symfd);
#endif
            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)) {
#ifdef HAVE_FCHDIR
            if (fchdir(sp->fts_rfd))
                  saved_errno = errno;
            (void)close(sp->fts_rfd);
#else
            if (chdir(sp->fts_rdir))
                  saved_errno =  errno;
        free(sp->fts_rdir);
            sp->fts_rdir = NULL;
#endif
      }

      /* Free up the stream pointer. */
      free(sp);
      /* ISSET() is illegal after this, since the macro touches sp */

      /* Set errno and return. */
      if (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 &&    \
          IS_SLASH(p->fts_path[0]) ? 0 : p->fts_pathlen)

FTSENT *
fts_read(sp)
      FTS *sp;
{
      FTSENT *p, *tmp;
      int instr;
      char *t;
      int saved_errno;

      _DIAGASSERT(sp != NULL);

      /* 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)) {
#ifdef HAVE_FCHDIR
                  if ((p->fts_symfd = open(".", O_RDONLY, 0)) == -1) {
                        p->fts_errno = errno;
                        p->fts_info = FTS_ERR;
                  } else if (fcntl(p->fts_symfd, F_SETFD, FD_CLOEXEC) == -1) {
                        p->fts_errno = errno;
                        p->fts_info = FTS_ERR;
                        close(p->fts_symfd);
                  } else
                        p->fts_flags |= FTS_SYMFOLLOW;
#endif
            }
            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)) {
#ifdef HAVE_FCHDIR
                  if (p->fts_flags & FTS_SYMFOLLOW)
                        (void)close(p->fts_symfd);
#endif
                  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 && ISSET(FTS_NAMEONLY)) {
                  CLR(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 (fts_safe_changedir(sp, p, -1, 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) {
#ifdef HAVE_FCHDIR
                  if (FCHDIR(sp, sp->fts_rfd)) {
#else
                  if (CHDIR(sp, sp->fts_rdir)) {
#endif
                        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)) {
#ifdef HAVE_FCHDIR
                        if ((p->fts_symfd =
                            open(".", O_RDONLY, 0)) == -1) {
                              p->fts_errno = errno;
                              p->fts_info = FTS_ERR;
                        } else if (fcntl(p->fts_symfd, F_SETFD, FD_CLOEXEC) == -1) {
                              p->fts_errno = errno;
                              p->fts_info = FTS_ERR;
                              close(p->fts_symfd);
                        } else
                              p->fts_flags |= FTS_SYMFOLLOW;
#endif
                  }
                  p->fts_instr = FTS_NOINSTR;
            }

name:       t = sp->fts_path + NAPPEND(p->fts_parent);
            *t++ = '/';
            memmove(t, p->fts_name, (size_t)(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) {
#ifdef HAVE_FCHDIR
            if (FCHDIR(sp, sp->fts_rfd)) {
#else
            if (CHDIR(sp, sp->fts_rdir)) {
#endif
                  SET(FTS_STOP);
                  return (NULL);
            }
#ifdef HAVE_FCHDIR
      } 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
        (void)saved_errno;
#endif
      } else if (!(p->fts_flags & FTS_DONTCHDIR) &&
          fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
            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(sp, p, instr)
      FTS *sp;
      FTSENT *p;
      int instr;
{

      _DIAGASSERT(sp != NULL);
      _DIAGASSERT(p != NULL);

      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(sp, instr)
      FTS *sp;
      int instr;
{
      FTSENT *p;
#ifdef HAVE_FCHDIR
      int fd;
#else
      char *pszRoot;
      int rc;
#endif

      _DIAGASSERT(sp != NULL);

      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) {
            SET(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 || IS_SLASH(p->fts_accpath[0]) ||
          ISSET(FTS_NOCHDIR))
            return (sp->fts_child = fts_build(sp, instr));

#ifdef HAVE_FCHDIR
      if ((fd = open(".", O_RDONLY, 0)) == -1)
#else
      if ((pszRoot = getcwd(NULL, 0)) == NULL)
#endif
            return (sp->fts_child = NULL);
      sp->fts_child = fts_build(sp, instr);
#ifdef HAVE_FCHDIR
      if (fchdir(fd)) {
            (void)close(fd);
            return (NULL);
      }
      (void)close(fd);
#else
      rc = chdir(pszRoot);
      free(pszRoot);
      if (rc)
            return (NULL);
#endif

      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(sp, type)
      FTS *sp;
      int type;
{
      struct dirent *dp;
      FTSENT *p, *head;
      size_t nitems;
      FTSENT *cur, *tail;
      DIR *dirp;
      int adjust, cderrno, descend, len, level, nlinks, saved_errno, nostat;
      size_t maxlen;
#ifdef FTS_WHITEOUT
      int oflag;
#endif
      char *cp = NULL;  /* pacify gcc */

      _DIAGASSERT(sp != NULL);

      /* 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;
            nostat = 1;
      } else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
            nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
            nostat = 1;
      } else {
            nlinks = -1;
            nostat = 0;
      }

#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) {
#ifdef HAVE_FCHDIR
            if (fts_safe_changedir(sp, cur, dirfd(dirp), NULL)) {
#else
            if (fts_safe_changedir(sp, cur, dirfd(dirp), cur->fts_accpath)) {
#endif
                  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.
       */
      len = NAPPEND(cur);
      if (ISSET(FTS_NOCHDIR)) {
            cp = sp->fts_path + len;
            *cp++ = '/';
      }
      len++;
      maxlen = sp->fts_pathlen - len;

      level = cur->fts_level + 1;

      /* Read the directory, attaching each entry to the `link' pointer. */
      adjust = 0;
      for (head = tail = NULL, nitems = 0; (dp = readdir(dirp)) != NULL;) {
            size_t dlen;

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

#if HAVE_STRUCT_DIRENT_D_NAMLEN
            dlen = dp->d_namlen;
#else
            dlen = strlen(dp->d_name);
#endif
            if ((p = fts_alloc(sp, dp->d_name, dlen)) == NULL)
                  goto mem1;
            if (dlen >= maxlen) {   /* include space for NUL */
                  if (fts_palloc(sp, len + dlen + 1)) {
                        /*
                         * 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);
                  }
                  adjust = 1;
                  if (ISSET(FTS_NOCHDIR))
                        cp = sp->fts_path + len;
                  maxlen = sp->fts_pathlen - len;
            }

            p->fts_pathlen = len + dlen;
            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
                || (nostat &&
                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,
                                (size_t)(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 (adjust)
            fts_padjust(sp, head);

      /*
       * 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 ?
#ifdef HAVE_FCHDIR
          FCHDIR(sp, sp->fts_rfd) :
#else
          CHDIR(sp, sp->fts_rdir) :
#endif
          fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
            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(sp, p, follow)
      FTS *sp;
      FTSENT *p;
      int follow;
{
      FTSENT *t;
      dev_t dev;
      ino_t ino;
      struct STAT *sbp, sb;
      int saved_errno;

      _DIAGASSERT(sp != NULL);
      _DIAGASSERT(p != NULL);

      /* 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.
             */

#ifdef _MSC_VER
            if (ino && dev) /** @todo ino emulation on windows... */
#endif
            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(sp, head, nitems)
      FTS *sp;
      FTSENT *head;
      size_t nitems;
{
      FTSENT **ap, *p;

      _DIAGASSERT(sp != NULL);
      _DIAGASSERT(head != NULL);

      /*
       * 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) {
            FTSENT **new;

            new = realloc(sp->fts_array, sizeof(FTSENT *) * (nitems + 40));
            if (new == 0)
                  return (head);
            sp->fts_array = new;
            sp->fts_nitems = nitems + 40;
      }
      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(sp, name, namelen)
      FTS *sp;
      const char *name;
      size_t namelen;
{
      FTSENT *p;
      size_t len;

      _DIAGASSERT(sp != NULL);
      _DIAGASSERT(name != NULL);

#if defined(ALIGNBYTES) && defined(ALIGN)
      /*
       * 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);

      if (!ISSET(FTS_NOSTAT))
            p->fts_statp =
                (struct STAT *)ALIGN((u_long)(p->fts_name + namelen + 2));
#else
      (void)len;
      if ((p = malloc(sizeof(FTSENT) + namelen)) == NULL)
            return (NULL);

      if (!ISSET(FTS_NOSTAT))
            if ((p->fts_statp = malloc(sizeof(struct STAT))) == NULL) {
                  free(p);
                  return (NULL);
            }
#endif

      /* Copy the name plus the trailing NULL. */
      memmove(p->fts_name, name, namelen + 1);

      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(head)
      FTSENT *head;
{
      FTSENT *p;

      /* XXX: head may be NULL ? */

      /* Free a linked list of structures. */
      while ((p = head) != NULL) {
            head = head->fts_link;

#if !defined(ALIGNBYTES) || !defined(ALIGN)
            if (p->fts_statp)
                  free(p->fts_statp);
#endif
            free(p);
      }
}

static size_t
fts_pow2(x)
      size_t x;
{

      x--;
      x |= x>>1;
      x |= x>>2;
      x |= x>>4;
      x |= x>>8;
      x |= x>>16;
#if LONG_BIT > 32
      x |= x>>32;
#endif
#if LONG_BIT > 64
      x |= x>>64;
#endif
      x++;
      return (x);
}

/*
 * 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.  Round up the new size to a power of 2,
 * so we don't realloc the path 2 bytes at a time.
 */
static int
fts_palloc(sp, size)
      FTS *sp;
      size_t size;
{
      char *new;

      _DIAGASSERT(sp != NULL);

#if 1
      /* Protect against fts_pathlen overflow. */
      if (size > USHRT_MAX + 1) {
            errno = ENOMEM;
            return (1);
      }
#endif
      size = fts_pow2(size);
      new = realloc(sp->fts_path, size);
      if (new == 0)
            return (1);
      sp->fts_path = new;
      sp->fts_pathlen = size;
      return (0);
}

/*
 * When the path is realloc'd, have to fix all of the pointers in structures
 * already returned.
 */
static void
fts_padjust(sp, head)
      FTS *sp;
      FTSENT *head;
{
      FTSENT *p;
      char *addr;

      _DIAGASSERT(sp != NULL);

#define     ADJUST(p) do {                                        \
      if ((p)->fts_accpath != (p)->fts_name)                      \
            (p)->fts_accpath =                              \
                addr + ((p)->fts_accpath - (p)->fts_path);        \
      (p)->fts_path = addr;                                 \
} while (/*CONSTCOND*/0)

      addr = sp->fts_path;

      /* Adjust the current set of children. */
      for (p = sp->fts_child; p; p = p->fts_link)
            ADJUST(p);

      /* Adjust the rest of the tree, including the current level. */
      for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
            ADJUST(p);
            p = p->fts_link ? p->fts_link : p->fts_parent;
      }
}

static size_t
fts_maxarglen(argv)
      char * const *argv;
{
      size_t len, max;

      _DIAGASSERT(argv != NULL);

      for (max = 0; *argv; ++argv)
            if ((len = strlen(*argv)) > max)
                  max = len;
      return (max + 1);
}

/*
 * Change to dir specified by fd or p->fts_accpath without getting
 * tricked by someone changing the world out from underneath us.
 * Assumes p->fts_dev and p->fts_ino are filled in.
 */
static int
fts_safe_changedir(sp, p, fd, path)
      const FTS *sp;
      const FTSENT *p;
      int fd;
      const char *path;
{
      int oldfd = fd, ret = -1;
      struct STAT sb;

      if (ISSET(FTS_NOCHDIR))
            return 0;

#ifdef HAVE_FCHDIR
      if (oldfd < 0 && (fd = open(path, O_RDONLY)) == -1)
            return -1;

      if (fstat(fd, &sb) == -1)
            goto bail;
#else
      if (stat(path, &sb))
            goto bail;
#endif

      if (sb.st_ino != p->fts_ino || sb.st_dev != p->fts_dev) {
            errno = ENOENT;
            goto bail;
      }

#ifdef HAVE_FCHDIR
      ret = fchdir(fd);
#else
      ret = chdir(path);
#endif

bail:
#ifdef HAVE_FCHDIR
      if (oldfd < 0) {
            int save_errno = errno;
            (void)close(fd);
            errno = save_errno;
      }
#endif
      return ret;
}

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