Add an implementation of the fts_*() functions

The fts_*() functions are optional in uClibc, and not compiled in our
default configuration. The best option would be to migrate this
elfutils code to the nftw family of functions, but it requires quite
some work.

So we have several options here:

 *) Enable fts_*() functions in our default uClibc configuration. Not
    nice since only one package needs them (the help text of uClibc
    for fts_*() functions explicitly mention that they have been added
    to be able to build elfutils).

 *) Use gnulib, but it is quite heavy to setup, requires modifications
    to configure.ac, and other things.

 *) Copy the fts function from uClibc into elfutils source code. This
    is the solution used below. uClibc is LGPL, and elfutils is
    LGPL/GPL, so there should not be any licensing issue.

Of course, the fts_*() functions are only built if they are not
already provided by the C library.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/configure.ac
===================================================================
--- a/configure.ac
+++ b/configure.ac
@@ -276,6 +276,10 @@
 fi
 AC_SUBST(ARGP_LIBS)
 
+AC_CHECK_HEADER([fts.h],
+	AC_DEFINE([HAVE_FTS_H], [], [Define if <fts.h> is available in C library]))
+AM_CONDITIONAL(HAVE_FTS, test "$ac_cv_header_fts_h" = yes)
+
 dnl Test for zlib and bzlib, gives ZLIB/BZLIB .am
 dnl conditional and config.h USE_ZLIB/USE_BZLIB #define.
 save_LIBS="$LIBS"
Index: b/libdwfl/Makefile.am
===================================================================
--- a/libdwfl/Makefile.am
+++ b/libdwfl/Makefile.am
@@ -79,6 +79,9 @@
 if LZMA
 libdwfl_a_SOURCES += lzma.c
 endif
+if !HAVE_FTS
+libdwfl_a_SOURCES += fts.c
+endif
 
 if MUDFLAP
 libdwfl = libdwfl.a $(libdw) $(libebl) $(libelf) $(libeu)
Index: b/libdwfl/fts.c
===================================================================
--- /dev/null
+++ b/libdwfl/fts.c
@@ -0,0 +1,1095 @@
+/*-
+ * 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.
+ * 4. 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 <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+#include "fts_.h"
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Largest alignment size needed, minus one.
+   Usually long double is the worst case.  */
+#ifndef ALIGNBYTES
+#define ALIGNBYTES	(__alignof__ (long double) - 1)
+#endif
+/* Align P to that size.  */
+#ifndef ALIGN
+#define	ALIGN(p)	(((unsigned long int) (p) + ALIGNBYTES) & ~ALIGNBYTES)
+#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 void	 fts_padjust (FTS *, FTSENT *);
+static int	 fts_palloc (FTS *, size_t);
+static FTSENT	*fts_sort (FTS *, FTSENT *, int);
+static u_short	 fts_stat (FTS *, FTSENT *, int);
+static int      fts_safe_changedir (FTS *, FTSENT *, int, const char *);
+
+#ifndef MAX
+#define MAX(a, b)	({ __typeof__ (a) _a = (a); \
+			   __typeof__ (b) _b = (b); \
+			   _a > _b ? _a : _b; })
+#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	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, register int options,
+		int (*compar) (const FTSENT **, const FTSENT **))
+{
+	register FTS *sp;
+	register FTSENT *p, *root;
+	register int nitems;
+	FTSENT *parent = NULL;
+	FTSENT *tmp = 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 = (int (*) (const void *, const void *)) 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.
+	 */
+#ifndef MAXPATHLEN
+#define MAXPATHLEN 1024
+#endif
+	size_t maxarglen = fts_maxarglen(argv);
+	if (fts_palloc(sp, MAX(maxarglen, MAXPATHLEN)))
+		goto mem1;
+
+	/* Allocate/initialize root's parent. */
+	if (*argv != NULL) {
+		if ((parent = fts_alloc(sp, "", 0)) == NULL)
+			goto mem2;
+		parent->fts_level = FTS_ROOTPARENTLEVEL;
+	  }
+
+	/* Allocate/initialize root(s). */
+	for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
+		/* Don't allow zero-length paths. */
+		size_t len = strlen(*argv);
+		if (len == 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 ensure
+	 * 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, register FTSENT *p)
+{
+	register int len;
+	register 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)
+{
+	register FTSENT *freep, *p;
+	int saved_errno;
+
+	/*
+	 * 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 != NULL ? 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);
+	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);
+
+		/* Set errno and return. */
+		if (saved_errno != 0) {
+			/* Free up the stream pointer. */
+			free(sp);
+			errno = saved_errno;
+			return (-1);
+		}
+	}
+
+	/* Free up the stream pointer. */
+	free(sp);
+	return (0);
+}
+
+/*
+ * Special case of "/" at the end of the path so that slashes aren't
+ * appended which would cause paths to be written as "....//foo".
+ */
+#define	NAPPEND(p)							\
+	(p->fts_path[p->fts_pathlen - 1] == '/'				\
+	    ? p->fts_pathlen - 1 : p->fts_pathlen)
+
+FTSENT *
+fts_read(register FTS *sp)
+{
+	register FTSENT *p, *tmp;
+	register int instr;
+	register 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 != NULL && 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 != NULL) {
+			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 != NULL;
+				     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;
+		sp->fts_cur = p;
+		goto name;
+	}
+
+	/* Move to the next node on this level. */
+next:	tmp = p;
+	if ((p = p->fts_link) != NULL) {
+		sp->fts_cur = p;
+		free(tmp);
+
+		/*
+		 * If reached the top, return to the original directory (or
+		 * the root of the tree), and load the paths for the next root.
+		 */
+		if (p->fts_level == FTS_ROOTLEVEL) {
+			if (FCHDIR(sp, sp->fts_rfd)) {
+				SET(FTS_STOP);
+				return (NULL);
+			}
+			fts_load(sp, p);
+			return 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 p;
+	}
+
+	/* Move up to the parent node. */
+	p = tmp->fts_parent;
+	sp->fts_cur = p;
+	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 (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) &&
+		   fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
+		SET(FTS_STOP);
+		return (NULL);
+	}
+	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
+	return 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 != 0 && 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(register FTS *sp, int instr)
+{
+	register FTSENT *p;
+	int fd;
+
+	if (instr != 0 && 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 != NULL)
+		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 || 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(register FTS *sp, int type)
+{
+	register struct dirent *dp;
+	register FTSENT *p, *head;
+	register int nitems;
+	FTSENT *cur, *tail;
+	DIR *dirp;
+	void *oldaddr;
+	int cderrno, descend, len, level, nlinks, saved_errno,
+	    nostat, doadjust;
+	size_t maxlen;
+	char *cp;
+
+	/* 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.
+	 */
+#if defined FTS_WHITEOUT && 0
+	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;
+		/* Be quiet about nostat, GCC. */
+		nostat = 0;
+	} 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) {
+		if (fts_safe_changedir(sp, cur, dirfd(dirp), NULL)) {
+			if (nlinks && type == BREAD)
+				cur->fts_errno = errno;
+			cur->fts_flags |= FTS_DONTCHDIR;
+			descend = 0;
+			cderrno = errno;
+			(void)closedir(dirp);
+			dirp = NULL;
+		} 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++ = '/';
+	} else {
+		/* GCC, you're too verbose. */
+		cp = NULL;
+	}
+	len++;
+	maxlen = sp->fts_pathlen - len;
+
+	level = cur->fts_level + 1;
+
+	/* Read the directory, attaching each entry to the `link' pointer. */
+	doadjust = 0;
+	for (head = tail = NULL, nitems = 0; dirp && (dp = readdir(dirp));) {
+		if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))
+			continue;
+
+		if ((p = fts_alloc(sp, dp->d_name, _D_EXACT_NAMLEN (dp))) == NULL)
+			goto mem1;
+		if (_D_EXACT_NAMLEN (dp) >= maxlen) {/* include space for NUL */
+			oldaddr = sp->fts_path;
+			if (fts_palloc(sp, _D_EXACT_NAMLEN (dp) + len + 1)) {
+				/*
+				 * No more memory for path or structures.  Save
+				 * errno, free up the current structure and the
+				 * structures already allocated.
+				 */
+mem1:				saved_errno = errno;
+				free(p);
+				fts_lfree(head);
+				(void)closedir(dirp);
+				cur->fts_info = FTS_ERR;
+				SET(FTS_STOP);
+				errno = saved_errno;
+				return (NULL);
+			}
+			/* Did realloc() change the pointer? */
+			if (oldaddr != sp->fts_path) {
+				doadjust = 1;
+				if (ISSET(FTS_NOCHDIR))
+					cp = sp->fts_path + len;
+			}
+			maxlen = sp->fts_pathlen - len;
+		}
+
+		if (len + _D_EXACT_NAMLEN (dp) >= USHRT_MAX) {
+			/*
+			 * In an FTSENT, fts_pathlen is a u_short so it is
+			 * possible to wraparound here.  If we do, free up
+			 * the current structure and the structures already
+			 * allocated, then error out with ENAMETOOLONG.
+			 */
+			free(p);
+			fts_lfree(head);
+			(void)closedir(dirp);
+			cur->fts_info = FTS_ERR;
+			SET(FTS_STOP);
+			errno = ENAMETOOLONG;
+			return (NULL);
+		}
+		p->fts_level = level;
+		p->fts_parent = sp->fts_cur;
+		p->fts_pathlen = len + _D_EXACT_NAMLEN (dp);
+
+#if defined FTS_WHITEOUT && 0
+		if (dp->d_type == DT_WHT)
+			p->fts_flags |= FTS_ISW;
+#endif
+
+#if 0
+		/* Unreachable code.  cderrno is only ever set to a nonnull
+		   value if dirp is closed at the same time.  But then we
+		   cannot enter this loop.  */
+		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
+#endif
+		if (nlinks == 0
+#if defined DT_DIR && defined _DIRENT_HAVE_D_TYPE
+			   || (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, 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;
+	}
+	if (dirp)
+		(void)closedir(dirp);
+
+	/*
+	 * If realloc() changed the address of the path, adjust the
+	 * addresses for the rest of the tree and the dir list.
+	 */
+	if (doadjust)
+		fts_padjust(sp, head);
+
+	/*
+	 * If not changing directories, reset the path back to original
+	 * state.
+	 */
+	if (ISSET(FTS_NOCHDIR)) {
+		if (len == sp->fts_pathlen || nitems == 0)
+			--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) :
+	     fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
+		cur->fts_info = FTS_ERR;
+		SET(FTS_STOP);
+		fts_lfree(head);
+		return (NULL);
+	}
+
+	/* If didn't find anything, return NULL. */
+	if (!nitems) {
+		if (type == BREAD)
+			cur->fts_info = FTS_DP;
+		fts_lfree(head);
+		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, register FTSENT *p, int follow)
+{
+	register FTSENT *t;
+	register dev_t dev;
+	register 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;
+
+#if defined FTS_WHITEOUT && 0
+	/* 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, register int nitems)
+{
+	register 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) {
+		struct _ftsent **a;
+
+		sp->fts_nitems = nitems + 40;
+		if ((a = realloc(sp->fts_array,
+ 		    (size_t)(sp->fts_nitems * sizeof(FTSENT *)))) == NULL) {
+			free(sp->fts_array);
+			sp->fts_array = NULL;
+			sp->fts_nitems = 0;
+			return (head);
+		}
+		sp->fts_array = a;
+	}
+	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
+		*ap++ = p;
+	qsort((void *)sp->fts_array, nitems, sizeof(FTSENT *), 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, const char *name, size_t namelen)
+{
+	register 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 and guarantee NUL termination. */
+	memmove(p->fts_name, name, namelen);
+	p->fts_name[namelen] = '\0';
+
+	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(register FTSENT *head)
+{
+	register FTSENT *p;
+
+	/* Free a linked list of structures. */
+	while ((p = head)) {
+		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)
+{
+	char *p;
+
+	sp->fts_pathlen += more + 256;
+	/*
+	 * Check for possible wraparound.  In an FTS, fts_pathlen is
+	 * a signed int but in an FTSENT it is an unsigned short.
+	 * We limit fts_pathlen to USHRT_MAX to be safe in both cases.
+	 */
+	if (sp->fts_pathlen < 0 || sp->fts_pathlen >= USHRT_MAX) {
+		free(sp->fts_path);
+		sp->fts_path = NULL;
+		errno = ENAMETOOLONG;
+		return (1);
+	}
+	p = realloc(sp->fts_path, sp->fts_pathlen);
+	if (p == NULL) {
+		free(sp->fts_path);
+		sp->fts_path = NULL;
+		return 1;
+	}
+	sp->fts_path = p;
+	return 0;
+}
+
+/*
+ * When the path is realloc'd, have to fix all of the pointers in structures
+ * already returned.
+ */
+static void
+fts_padjust(FTS *sp, FTSENT *head)
+{
+	FTSENT *p;
+	char *addr = sp->fts_path;
+
+#define	ADJUST(p) do {							\
+	if ((p)->fts_accpath != (p)->fts_name) {			\
+		(p)->fts_accpath =					\
+		    (char *)addr + ((p)->fts_accpath - (p)->fts_path);	\
+	}								\
+	(p)->fts_path = addr;						\
+} while (0)
+	/* 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(char * const *argv)
+{
+	size_t len, max;
+
+	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(FTS *sp, FTSENT *p, int fd, const char *path)
+{
+	int ret, oerrno, newfd;
+	struct stat64 sb;
+
+	newfd = fd;
+	if (ISSET(FTS_NOCHDIR))
+		return (0);
+	if (fd < 0 && (newfd = open(path, O_RDONLY, 0)) < 0)
+		return (-1);
+	if (fstat64(newfd, &sb)) {
+		ret = -1;
+		goto bail;
+	}
+	if (p->fts_dev != sb.st_dev || p->fts_ino != sb.st_ino) {
+		errno = ENOENT;		/* disinformation */
+		ret = -1;
+		goto bail;
+	}
+	ret = fchdir(newfd);
+bail:
+	oerrno = errno;
+	if (fd < 0)
+		(void)close(newfd);
+	errno = oerrno;
+	return (ret);
+}
Index: b/libdwfl/fts_.h
===================================================================
--- /dev/null
+++ b/libdwfl/fts_.h
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 1989, 1993
+ *	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.
+ * 4. 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.
+ *
+ *	@(#)fts.h	8.3 (Berkeley) 8/14/94
+ */
+
+#ifndef	_FTS_H
+#define	_FTS_H 1
+
+#include <features.h>
+#include <sys/types.h>
+
+/* The fts interface is incompatible with the LFS interface which
+   transparently uses the 64-bit file access functions.  */
+#ifdef __USE_FILE_OFFSET64
+# error "<fts.h> cannot be used with -D_FILE_OFFSET_BITS==64"
+#endif
+
+
+typedef struct {
+	struct _ftsent *fts_cur;	/* current node */
+	struct _ftsent *fts_child;	/* linked list of children */
+	struct _ftsent **fts_array;	/* sort array */
+	dev_t fts_dev;			/* starting device # */
+	char *fts_path;			/* path for this descent */
+	int fts_rfd;			/* fd for root */
+	int fts_pathlen;		/* sizeof(path) */
+	int fts_nitems;			/* elements in the sort array */
+	int (*fts_compar) (const void *, const void *); /* compare fn */
+
+#define	FTS_COMFOLLOW	0x0001		/* follow command line symlinks */
+#define	FTS_LOGICAL	0x0002		/* logical walk */
+#define	FTS_NOCHDIR	0x0004		/* don't change directories */
+#define	FTS_NOSTAT	0x0008		/* don't get stat info */
+#define	FTS_PHYSICAL	0x0010		/* physical walk */
+#define	FTS_SEEDOT	0x0020		/* return dot and dot-dot */
+#define	FTS_XDEV	0x0040		/* don't cross devices */
+#define FTS_WHITEOUT	0x0080		/* return whiteout information */
+#define	FTS_OPTIONMASK	0x00ff		/* valid user option mask */
+
+#define	FTS_NAMEONLY	0x0100		/* (private) child names only */
+#define	FTS_STOP	0x0200		/* (private) unrecoverable error */
+	int fts_options;		/* fts_open options, global flags */
+} FTS;
+
+typedef struct _ftsent {
+	struct _ftsent *fts_cycle;	/* cycle node */
+	struct _ftsent *fts_parent;	/* parent directory */
+	struct _ftsent *fts_link;	/* next file in directory */
+	long fts_number;	        /* local numeric value */
+	void *fts_pointer;	        /* local address value */
+	char *fts_accpath;		/* access path */
+	char *fts_path;			/* root path */
+	int fts_errno;			/* errno for this node */
+	int fts_symfd;			/* fd for symlink */
+	u_short fts_pathlen;		/* strlen(fts_path) */
+	u_short fts_namelen;		/* strlen(fts_name) */
+
+	ino_t fts_ino;			/* inode */
+	dev_t fts_dev;			/* device */
+	nlink_t fts_nlink;		/* link count */
+
+#define	FTS_ROOTPARENTLEVEL	-1
+#define	FTS_ROOTLEVEL		 0
+	short fts_level;		/* depth (-1 to N) */
+
+#define	FTS_D		 1		/* preorder directory */
+#define	FTS_DC		 2		/* directory that causes cycles */
+#define	FTS_DEFAULT	 3		/* none of the above */
+#define	FTS_DNR		 4		/* unreadable directory */
+#define	FTS_DOT		 5		/* dot or dot-dot */
+#define	FTS_DP		 6		/* postorder directory */
+#define	FTS_ERR		 7		/* error; errno is set */
+#define	FTS_F		 8		/* regular file */
+#define	FTS_INIT	 9		/* initialized only */
+#define	FTS_NS		10		/* stat(2) failed */
+#define	FTS_NSOK	11		/* no stat(2) requested */
+#define	FTS_SL		12		/* symbolic link */
+#define	FTS_SLNONE	13		/* symbolic link without target */
+#define FTS_W		14		/* whiteout object */
+	u_short fts_info;		/* user flags for FTSENT structure */
+
+#define	FTS_DONTCHDIR	 0x01		/* don't chdir .. to the parent */
+#define	FTS_SYMFOLLOW	 0x02		/* followed a symlink to get here */
+	u_short fts_flags;		/* private flags for FTSENT structure */
+
+#define	FTS_AGAIN	 1		/* read node again */
+#define	FTS_FOLLOW	 2		/* follow symbolic link */
+#define	FTS_NOINSTR	 3		/* no instructions */
+#define	FTS_SKIP	 4		/* discard node */
+	u_short fts_instr;		/* fts_set() instructions */
+
+	struct stat *fts_statp;		/* stat(2) information */
+	char fts_name[1];		/* file name */
+} FTSENT;
+
+__BEGIN_DECLS
+FTSENT	*fts_children (FTS *, int);
+int	 fts_close (FTS *);
+FTS	*fts_open (char * const *, int,
+		   int (*)(const FTSENT **, const FTSENT **));
+FTSENT	*fts_read (FTS *);
+int	 fts_set (FTS *, FTSENT *, int) __THROW;
+__END_DECLS
+
+#endif /* fts.h */
Index: b/libdwfl/linux-kernel-modules.c
===================================================================
--- a/libdwfl/linux-kernel-modules.c
+++ b/libdwfl/linux-kernel-modules.c
@@ -29,7 +29,11 @@
 /* We include this before config.h because it can't handle _FILE_OFFSET_BITS.
    Everything we need here is fine if its declarations just come first.  */
 
+#ifdef HAVE_FTS_H
 #include <fts.h>
+#else
+#include "fts_.h"
+#endif
 
 #include <config.h>
 
