diff --git a/bin/cp/cp.c b/bin/cp/cp.c
index 5a7834e7c1f3..10072094b3f0 100644
--- a/bin/cp/cp.c
+++ b/bin/cp/cp.c
@@ -92,7 +92,7 @@ static int Rflag, rflag;
 enum op { FILE_TO_FILE, FILE_TO_DIR, DIR_TO_DNE };
 
 static int copy(char *[], enum op, int);
-static int mastercmp(const FTSENT **, const FTSENT **);
+static int mastercmp(const FTSENT * const *, const FTSENT * const *);
 
 int
 main(int argc, char *argv[])
@@ -484,7 +484,7 @@ copy(char *argv[], enum op type, int fts_options)
  *	files first reduces seeking.
  */
 int
-mastercmp(const FTSENT **a, const FTSENT **b)
+mastercmp(const FTSENT * const *a, const FTSENT * const *b)
 {
 	int a_info, b_info;
 
diff --git a/bin/ls/ls.c b/bin/ls/ls.c
index 71158deead22..be19f3634a82 100644
--- a/bin/ls/ls.c
+++ b/bin/ls/ls.c
@@ -82,7 +82,7 @@ __FBSDID("$FreeBSD$");
 
 static void	 display(FTSENT *, FTSENT *);
 static u_quad_t	 makenines(u_long);
-static int	 mastercmp(const FTSENT **, const FTSENT **);
+static int	 mastercmp(const FTSENT * const *, const FTSENT * const *);
 static void	 traverse(int, char **, int);
 
 static void (*printfcn)(DISPLAY *);
@@ -759,7 +759,7 @@ display(FTSENT *p, FTSENT *list)
  * All other levels use the sort function.  Error entries remain unsorted.
  */
 static int
-mastercmp(const FTSENT **a, const FTSENT **b)
+mastercmp(const FTSENT * const *a, const FTSENT * const *b)
 {
 	int a_info, b_info;
 
diff --git a/include/fts.h b/include/fts.h
index 8dd2c4160c10..09c4600a1072 100644
--- a/include/fts.h
+++ b/include/fts.h
@@ -47,7 +47,7 @@ typedef struct {
 	int fts_pathlen;		/* sizeof(path) */
 	int fts_nitems;			/* elements in the sort array */
 	int (*fts_compar)		/* compare function */
-	    (const struct _ftsent **, const struct _ftsent **);
+	    (const struct _ftsent * const *, const struct _ftsent * const *);
 
 #define	FTS_COMFOLLOW	0x001		/* follow command line symlinks */
 #define	FTS_LOGICAL	0x002		/* logical walk */
@@ -62,6 +62,7 @@ typedef struct {
 #define	FTS_NAMEONLY	0x100		/* (private) child names only */
 #define	FTS_STOP	0x200		/* (private) unrecoverable error */
 	int fts_options;		/* fts_open options, global flags */
+	void *fts_clientptr;		/* thunk for sort function */
 } FTS;
 
 typedef struct _ftsent {
@@ -113,7 +114,8 @@ typedef struct _ftsent {
 	u_short fts_instr;		/* fts_set() instructions */
 
 	struct stat *fts_statp;		/* stat(2) information */
-	char fts_name[1];		/* file name */
+	char *fts_name;			/* file name */
+	FTS *fts_fts;			/* back pointer to main FTS */
 } FTSENT;
 
 #include <sys/cdefs.h>
@@ -121,10 +123,15 @@ typedef struct _ftsent {
 __BEGIN_DECLS
 FTSENT	*fts_children(FTS *, int);
 int	 fts_close(FTS *);
+void	*fts_get_clientptr(FTS *);
+#define	 fts_get_clientptr(fts)	((fts)->fts_clientptr)
+FTS	*fts_get_stream(FTSENT *);
+#define	 fts_get_stream(ftsent)	((ftsent)->fts_fts)
 FTS	*fts_open(char * const *, int,
-	    int (*)(const FTSENT **, const FTSENT **));
+	    int (*)(const FTSENT * const *, const FTSENT * const *));
 FTSENT	*fts_read(FTS *);
 int	 fts_set(FTS *, FTSENT *, int);
+void	 fts_set_clientptr(FTS *, void *);
 __END_DECLS
 
 #endif /* !_FTS_H_ */
diff --git a/lib/libc/gen/fts-compat.c b/lib/libc/gen/fts-compat.c
index 6220dc6f130c..7a0b068f6b57 100644
--- a/lib/libc/gen/fts-compat.c
+++ b/lib/libc/gen/fts-compat.c
@@ -81,7 +81,7 @@ FTS *
 fts_open(argv, options, compar)
 	char * const *argv;
 	int options;
-	int (*compar)(const FTSENT **, const FTSENT **);
+	int (*compar)(const FTSENT * const *, const FTSENT * const *);
 {
 	FTS *sp;
 	FTSENT *p, *root;
@@ -96,7 +96,7 @@ fts_open(argv, options, compar)
 	}
 
 	/* Allocate/initialize the stream */
-	if ((sp = malloc((u_int)sizeof(FTS))) == NULL)
+	if ((sp = malloc(sizeof(FTS))) == NULL)
 		return (NULL);
 	memset(sp, 0, sizeof(FTS));
 	sp->fts_compar = compar;
@@ -547,6 +547,34 @@ fts_children(sp, instr)
 	return (sp->fts_child);
 }
 
+#ifndef fts_get_clientptr
+#error "fts_get_clientptr not defined"
+#endif
+
+void *
+(fts_get_clientptr)(FTS *sp)
+{
+
+	return (fts_get_clientptr(sp));
+}
+
+#ifndef fts_get_stream
+#error "fts_get_stream not defined"
+#endif
+
+FTS *
+(fts_get_stream)(FTSENT *p)
+{
+	return (fts_get_stream(p));
+}
+
+void
+fts_set_clientptr(FTS *sp, void *clientptr)
+{
+
+	sp->fts_clientptr = clientptr;
+}
+
 /*
  * 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
@@ -907,6 +935,21 @@ err:		memset(sbp, 0, sizeof(struct stat));
 	return (FTS_DEFAULT);
 }
 
+/*
+ * The comparison function takes pointers to pointers to FTSENT structures.
+ * Qsort wants a comparison function that takes pointers to void.
+ * (Both with appropriate levels of const-poisoning, of course!)
+ * Use a trampoline function to deal with the difference.
+ */
+static int
+fts_compar(const void *a, const void *b)
+{
+	FTS *parent;
+
+	parent = (*(const FTSENT * const *)a)->fts_fts;
+	return (*parent->fts_compar)(a, b);
+}
+
 static FTSENT *
 fts_sort(sp, head, nitems)
 	FTS *sp;
@@ -932,7 +975,7 @@ fts_sort(sp, head, nitems)
 	}
 	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);
+	qsort(sp->fts_array, nitems, sizeof(FTSENT *), fts_compar);
 	for (head = *(ap = sp->fts_array); --nitems; ++ap)
 		ap[0]->fts_link = ap[1];
 	ap[0]->fts_link = NULL;
@@ -948,26 +991,36 @@ fts_alloc(sp, name, namelen)
 	FTSENT *p;
 	size_t len;
 
+	struct ftsent_withstat {
+		FTSENT	ent;
+		struct	stat statbuf;
+	};
+
 	/*
 	 * 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.
+	 * be careful that the stat structure is reasonably aligned.
 	 */
-	len = sizeof(FTSENT) + namelen;
-	if (!ISSET(FTS_NOSTAT))
-		len += sizeof(struct stat) + ALIGNBYTES;
+	if (ISSET(FTS_NOSTAT))
+		len = sizeof(FTSENT) + namelen + 1;
+	else
+		len = sizeof(struct ftsent_withstat) + namelen + 1;
+
 	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_name = (char *)(p + 1);
+		p->fts_statp = NULL;
+	} else {
+		p->fts_name = (char *)((struct ftsent_withstat *)p + 1);
+		p->fts_statp = &((struct ftsent_withstat *)p)->statbuf;
+	}
 
-	if (!ISSET(FTS_NOSTAT))
-		p->fts_statp = (struct stat *)ALIGN(p->fts_name + namelen + 2);
+	/* Copy the name and guarantee NUL termination. */
+	memcpy(p->fts_name, name, namelen);
+	p->fts_name[namelen] = '\0';
 	p->fts_namelen = namelen;
 	p->fts_path = sp->fts_path;
 	p->fts_errno = 0;
@@ -975,6 +1028,7 @@ fts_alloc(sp, name, namelen)
 	p->fts_instr = FTS_NOINSTR;
 	p->fts_number = 0;
 	p->fts_pointer = NULL;
+	p->fts_fts = sp;
 	return (p);
 }
 
diff --git a/lib/libc/gen/fts-compat.h b/lib/libc/gen/fts-compat.h
index 8dd2c4160c10..09c4600a1072 100644
--- a/lib/libc/gen/fts-compat.h
+++ b/lib/libc/gen/fts-compat.h
@@ -47,7 +47,7 @@ typedef struct {
 	int fts_pathlen;		/* sizeof(path) */
 	int fts_nitems;			/* elements in the sort array */
 	int (*fts_compar)		/* compare function */
-	    (const struct _ftsent **, const struct _ftsent **);
+	    (const struct _ftsent * const *, const struct _ftsent * const *);
 
 #define	FTS_COMFOLLOW	0x001		/* follow command line symlinks */
 #define	FTS_LOGICAL	0x002		/* logical walk */
@@ -62,6 +62,7 @@ typedef struct {
 #define	FTS_NAMEONLY	0x100		/* (private) child names only */
 #define	FTS_STOP	0x200		/* (private) unrecoverable error */
 	int fts_options;		/* fts_open options, global flags */
+	void *fts_clientptr;		/* thunk for sort function */
 } FTS;
 
 typedef struct _ftsent {
@@ -113,7 +114,8 @@ typedef struct _ftsent {
 	u_short fts_instr;		/* fts_set() instructions */
 
 	struct stat *fts_statp;		/* stat(2) information */
-	char fts_name[1];		/* file name */
+	char *fts_name;			/* file name */
+	FTS *fts_fts;			/* back pointer to main FTS */
 } FTSENT;
 
 #include <sys/cdefs.h>
@@ -121,10 +123,15 @@ typedef struct _ftsent {
 __BEGIN_DECLS
 FTSENT	*fts_children(FTS *, int);
 int	 fts_close(FTS *);
+void	*fts_get_clientptr(FTS *);
+#define	 fts_get_clientptr(fts)	((fts)->fts_clientptr)
+FTS	*fts_get_stream(FTSENT *);
+#define	 fts_get_stream(ftsent)	((ftsent)->fts_fts)
 FTS	*fts_open(char * const *, int,
-	    int (*)(const FTSENT **, const FTSENT **));
+	    int (*)(const FTSENT * const *, const FTSENT * const *));
 FTSENT	*fts_read(FTS *);
 int	 fts_set(FTS *, FTSENT *, int);
+void	 fts_set_clientptr(FTS *, void *);
 __END_DECLS
 
 #endif /* !_FTS_H_ */
diff --git a/lib/libc/gen/fts.3 b/lib/libc/gen/fts.3
index 1e40a81f924a..452626654db3 100644
--- a/lib/libc/gen/fts.3
+++ b/lib/libc/gen/fts.3
@@ -32,7 +32,7 @@
 .\"     @(#)fts.3	8.5 (Berkeley) 4/16/94
 .\" $FreeBSD$
 .\"
-.Dd April 16, 1994
+.Dd September 15, 2002
 .Dt FTS 3
 .Os
 .Sh NAME
@@ -52,6 +52,12 @@
 .Fn fts_children "FTS *ftsp" "int options"
 .Ft int
 .Fn fts_set "FTS *ftsp" "FTSENT *f" "int options"
+.Ft void
+.Fn fts_set_clientptr "FTS *ftsp" "void *clientdata"
+.Ft void *
+.Fn fts_get_clientptr "FTS *ftsp"
+.Ft FTS *
+.Fn fts_get_stream "FTSENT *f"
 .Ft int
 .Fn fts_close "FTS *ftsp"
 .Sh DESCRIPTION
@@ -105,6 +111,26 @@ and
 .Dq Fa FTSENT No structure
 are generally
 interchangeable.
+.Pp
+The
+.Fa FTS
+structure contains space for a single pointer, which may be used to
+store application data or per-hierarchy state.
+The
+.Fn fts_set_clientptr
+and
+.Fn fts_get_clientptr
+functions may be used to set and retrieve this pointer.
+This is likely to be useful only when accessed from the sort
+comparison function, which can determine the original
+.Fa FTS
+stream of its arguments using the
+.Fn fts_get_stream
+function.
+The two
+.Li get
+functions are also available as macros of the same name.
+.Pp
 The
 .Fa FTSENT
 structure contains at least the following fields, which are
@@ -753,9 +779,18 @@ The options were invalid.
 .Xr chdir 2 ,
 .Xr stat 2 ,
 .Xr qsort 3
-.Sh STANDARDS
+.Sh HISTORY
 The
 .Nm
-utility is expected to be included in a future
-.St -p1003.1-88
-revision.
+interface was first introduced in
+.Bx 4.4 .
+The
+.Fn fts_get_clientptr ,
+.Fn fts_get_stream ,
+and
+.Fn fts_set_clientptr
+functions were introduced in
+.Fx 5.0 ,
+principally to provide for alternative interfaces to the
+.Nm
+functionality using different data structures.
diff --git a/lib/libc/gen/fts.c b/lib/libc/gen/fts.c
index 6220dc6f130c..7a0b068f6b57 100644
--- a/lib/libc/gen/fts.c
+++ b/lib/libc/gen/fts.c
@@ -81,7 +81,7 @@ FTS *
 fts_open(argv, options, compar)
 	char * const *argv;
 	int options;
-	int (*compar)(const FTSENT **, const FTSENT **);
+	int (*compar)(const FTSENT * const *, const FTSENT * const *);
 {
 	FTS *sp;
 	FTSENT *p, *root;
@@ -96,7 +96,7 @@ fts_open(argv, options, compar)
 	}
 
 	/* Allocate/initialize the stream */
-	if ((sp = malloc((u_int)sizeof(FTS))) == NULL)
+	if ((sp = malloc(sizeof(FTS))) == NULL)
 		return (NULL);
 	memset(sp, 0, sizeof(FTS));
 	sp->fts_compar = compar;
@@ -547,6 +547,34 @@ fts_children(sp, instr)
 	return (sp->fts_child);
 }
 
+#ifndef fts_get_clientptr
+#error "fts_get_clientptr not defined"
+#endif
+
+void *
+(fts_get_clientptr)(FTS *sp)
+{
+
+	return (fts_get_clientptr(sp));
+}
+
+#ifndef fts_get_stream
+#error "fts_get_stream not defined"
+#endif
+
+FTS *
+(fts_get_stream)(FTSENT *p)
+{
+	return (fts_get_stream(p));
+}
+
+void
+fts_set_clientptr(FTS *sp, void *clientptr)
+{
+
+	sp->fts_clientptr = clientptr;
+}
+
 /*
  * 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
@@ -907,6 +935,21 @@ err:		memset(sbp, 0, sizeof(struct stat));
 	return (FTS_DEFAULT);
 }
 
+/*
+ * The comparison function takes pointers to pointers to FTSENT structures.
+ * Qsort wants a comparison function that takes pointers to void.
+ * (Both with appropriate levels of const-poisoning, of course!)
+ * Use a trampoline function to deal with the difference.
+ */
+static int
+fts_compar(const void *a, const void *b)
+{
+	FTS *parent;
+
+	parent = (*(const FTSENT * const *)a)->fts_fts;
+	return (*parent->fts_compar)(a, b);
+}
+
 static FTSENT *
 fts_sort(sp, head, nitems)
 	FTS *sp;
@@ -932,7 +975,7 @@ fts_sort(sp, head, nitems)
 	}
 	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);
+	qsort(sp->fts_array, nitems, sizeof(FTSENT *), fts_compar);
 	for (head = *(ap = sp->fts_array); --nitems; ++ap)
 		ap[0]->fts_link = ap[1];
 	ap[0]->fts_link = NULL;
@@ -948,26 +991,36 @@ fts_alloc(sp, name, namelen)
 	FTSENT *p;
 	size_t len;
 
+	struct ftsent_withstat {
+		FTSENT	ent;
+		struct	stat statbuf;
+	};
+
 	/*
 	 * 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.
+	 * be careful that the stat structure is reasonably aligned.
 	 */
-	len = sizeof(FTSENT) + namelen;
-	if (!ISSET(FTS_NOSTAT))
-		len += sizeof(struct stat) + ALIGNBYTES;
+	if (ISSET(FTS_NOSTAT))
+		len = sizeof(FTSENT) + namelen + 1;
+	else
+		len = sizeof(struct ftsent_withstat) + namelen + 1;
+
 	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_name = (char *)(p + 1);
+		p->fts_statp = NULL;
+	} else {
+		p->fts_name = (char *)((struct ftsent_withstat *)p + 1);
+		p->fts_statp = &((struct ftsent_withstat *)p)->statbuf;
+	}
 
-	if (!ISSET(FTS_NOSTAT))
-		p->fts_statp = (struct stat *)ALIGN(p->fts_name + namelen + 2);
+	/* Copy the name and guarantee NUL termination. */
+	memcpy(p->fts_name, name, namelen);
+	p->fts_name[namelen] = '\0';
 	p->fts_namelen = namelen;
 	p->fts_path = sp->fts_path;
 	p->fts_errno = 0;
@@ -975,6 +1028,7 @@ fts_alloc(sp, name, namelen)
 	p->fts_instr = FTS_NOINSTR;
 	p->fts_number = 0;
 	p->fts_pointer = NULL;
+	p->fts_fts = sp;
 	return (p);
 }
 
diff --git a/usr.bin/find/find.c b/usr.bin/find/find.c
index 5006e9ec7e32..4ef37e880807 100644
--- a/usr.bin/find/find.c
+++ b/usr.bin/find/find.c
@@ -56,7 +56,7 @@ __FBSDID("$FreeBSD$");
 
 #include "find.h"
 
-static int	find_compare(const FTSENT **s1, const FTSENT **s2);
+static int find_compare(const FTSENT * const *s1, const FTSENT * const *s2);
 
 /*
  * find_compare --
@@ -66,7 +66,7 @@ static int	find_compare(const FTSENT **s1, const FTSENT **s2);
  */
 static int
 find_compare(s1, s2)
-	const FTSENT **s1, **s2;
+	const FTSENT * const *s1, * const *s2;
 {
 
 	return (strcoll((*s1)->fts_name, (*s2)->fts_name));
diff --git a/usr.sbin/ctm/ctm_dequeue/ctm_dequeue.c b/usr.sbin/ctm/ctm_dequeue/ctm_dequeue.c
index b5a1411adeb4..783fd3f4a1a6 100644
--- a/usr.sbin/ctm/ctm_dequeue/ctm_dequeue.c
+++ b/usr.sbin/ctm/ctm_dequeue/ctm_dequeue.c
@@ -53,7 +53,7 @@
 
 #define DEFAULT_NUM	1	/* Default number of pieces mailed per run. */
 
-int fts_sort(const FTSENT **, const FTSENT **);
+int fts_sort(const FTSENT * const *, const FTSENT * const *);
 int run_sendmail(int ifd);
 
 int
@@ -156,7 +156,7 @@ main(int argc, char **argv)
 }
 
 int
-fts_sort(const FTSENT ** a, const FTSENT ** b)
+fts_sort(const FTSENT * const * a, const FTSENT * const * b)
 {
     if ((*a)->fts_info != FTS_F)
 	return(0);
diff --git a/usr.sbin/mtree/create.c b/usr.sbin/mtree/create.c
index 3ab160299624..ae82966fe10e 100644
--- a/usr.sbin/mtree/create.c
+++ b/usr.sbin/mtree/create.c
@@ -80,7 +80,7 @@ static uid_t uid;
 static mode_t mode;
 static u_long flags = 0xffffffff;
 
-static int	dsort(const FTSENT **, const FTSENT **);
+static int	dsort(const FTSENT * const *, const FTSENT * const *);
 static void	output(int, int *, const char *, ...) __printflike(3, 4);
 static int	statd(FTS *, FTSENT *, uid_t *, gid_t *, mode_t *, u_long *);
 static void	statf(int, FTSENT *);
@@ -398,7 +398,7 @@ statd(t, parent, puid, pgid, pmode, pflags)
 
 static int
 dsort(a, b)
-	const FTSENT **a, **b;
+	const FTSENT * const *a, * const *b;
 {
 	if (S_ISDIR((*a)->fts_statp->st_mode)) {
 		if (!S_ISDIR((*b)->fts_statp->st_mode))
diff --git a/usr.sbin/pkg_install/lib/match.c b/usr.sbin/pkg_install/lib/match.c
index cf745c32105c..5312c27c2041 100644
--- a/usr.sbin/pkg_install/lib/match.c
+++ b/usr.sbin/pkg_install/lib/match.c
@@ -40,7 +40,7 @@ struct store {
 static int rex_match(const char *, const char *);
 struct store *storecreate(struct store *);
 static int storeappend(struct store *, const char *);
-static int fname_cmp(const FTSENT **, const FTSENT **);
+static int fname_cmp(const FTSENT * const *, const FTSENT * const *);
 
 /*
  * Function to query names of installed packages.
@@ -337,7 +337,7 @@ storeappend(struct store *store, const char *item)
 }
 
 static int
-fname_cmp(const FTSENT **a, const FTSENT **b)
+fname_cmp(const FTSENT * const *a, const FTSENT * const *b)
 {
     return strcmp((*a)->fts_name, (*b)->fts_name);
 }