diff --git a/mio/lib/Makefile.am b/mio/lib/Makefile.am
index b315b32..c7f7090 100644
--- a/mio/lib/Makefile.am
+++ b/mio/lib/Makefile.am
@@ -32,6 +32,7 @@ include_HEADERS = \
 	mio-http.h \
 	mio-nwif.h \
 	mio-pac1.h \
+	mio-path.h \
 	mio-pro.h \
 	mio-sck.h \
 	mio-skad.h \
@@ -50,11 +51,13 @@ libmio_la_SOURCES = \
 	fmt.c \
 	fmt-imp.h \
 	htb.c \
+	htrd.c \
 	htre.c \
 	http.c \
 	mio-prv.h \
 	mio.c \
 	nwif.c \
+	path.c \
 	pro.c \
 	sck.c \
 	skad.c \
diff --git a/mio/lib/Makefile.in b/mio/lib/Makefile.in
index a4d79a3..650cff4 100644
--- a/mio/lib/Makefile.in
+++ b/mio/lib/Makefile.in
@@ -140,12 +140,13 @@ libmio_la_DEPENDENCIES = $(am__DEPENDENCIES_2) $(am__DEPENDENCIES_1) \
 	$(am__DEPENDENCIES_1) $(am__DEPENDENCIES_1)
 am_libmio_la_OBJECTS = libmio_la-chr.lo libmio_la-dns.lo \
 	libmio_la-dns-cli.lo libmio_la-ecs.lo libmio_la-err.lo \
-	libmio_la-fmt.lo libmio_la-htb.lo libmio_la-htre.lo \
-	libmio_la-http.lo libmio_la-mio.lo libmio_la-nwif.lo \
-	libmio_la-pro.lo libmio_la-sck.lo libmio_la-skad.lo \
-	libmio_la-sys.lo libmio_la-sys-ass.lo libmio_la-sys-err.lo \
-	libmio_la-sys-log.lo libmio_la-sys-mux.lo libmio_la-sys-tim.lo \
-	libmio_la-tmr.lo libmio_la-utf8.lo libmio_la-utl.lo
+	libmio_la-fmt.lo libmio_la-htb.lo libmio_la-htrd.lo \
+	libmio_la-htre.lo libmio_la-http.lo libmio_la-mio.lo \
+	libmio_la-nwif.lo libmio_la-path.lo libmio_la-pro.lo \
+	libmio_la-sck.lo libmio_la-skad.lo libmio_la-sys.lo \
+	libmio_la-sys-ass.lo libmio_la-sys-err.lo libmio_la-sys-log.lo \
+	libmio_la-sys-mux.lo libmio_la-sys-tim.lo libmio_la-tmr.lo \
+	libmio_la-utf8.lo libmio_la-utl.lo
 libmio_la_OBJECTS = $(am_libmio_la_OBJECTS)
 AM_V_lt = $(am__v_lt_@AM_V@)
 am__v_lt_ = $(am__v_lt_@AM_DEFAULT_V@)
@@ -173,9 +174,10 @@ am__depfiles_remade = ./$(DEPDIR)/libmio_la-chr.Plo \
 	./$(DEPDIR)/libmio_la-dns-cli.Plo \
 	./$(DEPDIR)/libmio_la-dns.Plo ./$(DEPDIR)/libmio_la-ecs.Plo \
 	./$(DEPDIR)/libmio_la-err.Plo ./$(DEPDIR)/libmio_la-fmt.Plo \
-	./$(DEPDIR)/libmio_la-htb.Plo ./$(DEPDIR)/libmio_la-htre.Plo \
-	./$(DEPDIR)/libmio_la-http.Plo ./$(DEPDIR)/libmio_la-mio.Plo \
-	./$(DEPDIR)/libmio_la-nwif.Plo ./$(DEPDIR)/libmio_la-pro.Plo \
+	./$(DEPDIR)/libmio_la-htb.Plo ./$(DEPDIR)/libmio_la-htrd.Plo \
+	./$(DEPDIR)/libmio_la-htre.Plo ./$(DEPDIR)/libmio_la-http.Plo \
+	./$(DEPDIR)/libmio_la-mio.Plo ./$(DEPDIR)/libmio_la-nwif.Plo \
+	./$(DEPDIR)/libmio_la-path.Plo ./$(DEPDIR)/libmio_la-pro.Plo \
 	./$(DEPDIR)/libmio_la-sck.Plo ./$(DEPDIR)/libmio_la-skad.Plo \
 	./$(DEPDIR)/libmio_la-sys-ass.Plo \
 	./$(DEPDIR)/libmio_la-sys-err.Plo \
@@ -412,6 +414,7 @@ include_HEADERS = \
 	mio-http.h \
 	mio-nwif.h \
 	mio-pac1.h \
+	mio-path.h \
 	mio-pro.h \
 	mio-sck.h \
 	mio-skad.h \
@@ -430,11 +433,13 @@ libmio_la_SOURCES = \
 	fmt.c \
 	fmt-imp.h \
 	htb.c \
+	htrd.c \
 	htre.c \
 	http.c \
 	mio-prv.h \
 	mio.c \
 	nwif.c \
+	path.c \
 	pro.c \
 	sck.c \
 	skad.c \
@@ -553,10 +558,12 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-err.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-fmt.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-htb.Plo@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-htrd.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-htre.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-http.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-mio.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-nwif.Plo@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-path.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-pro.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-sck.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-skad.Plo@am__quote@ # am--include-marker
@@ -649,6 +656,13 @@ libmio_la-htb.lo: htb.c
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libmio_la-htb.lo `test -f 'htb.c' || echo '$(srcdir)/'`htb.c
 
+libmio_la-htrd.lo: htrd.c
+@am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libmio_la-htrd.lo -MD -MP -MF $(DEPDIR)/libmio_la-htrd.Tpo -c -o libmio_la-htrd.lo `test -f 'htrd.c' || echo '$(srcdir)/'`htrd.c
+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-htrd.Tpo $(DEPDIR)/libmio_la-htrd.Plo
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='htrd.c' object='libmio_la-htrd.lo' libtool=yes @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libmio_la-htrd.lo `test -f 'htrd.c' || echo '$(srcdir)/'`htrd.c
+
 libmio_la-htre.lo: htre.c
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libmio_la-htre.lo -MD -MP -MF $(DEPDIR)/libmio_la-htre.Tpo -c -o libmio_la-htre.lo `test -f 'htre.c' || echo '$(srcdir)/'`htre.c
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-htre.Tpo $(DEPDIR)/libmio_la-htre.Plo
@@ -677,6 +691,13 @@ libmio_la-nwif.lo: nwif.c
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libmio_la-nwif.lo `test -f 'nwif.c' || echo '$(srcdir)/'`nwif.c
 
+libmio_la-path.lo: path.c
+@am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libmio_la-path.lo -MD -MP -MF $(DEPDIR)/libmio_la-path.Tpo -c -o libmio_la-path.lo `test -f 'path.c' || echo '$(srcdir)/'`path.c
+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-path.Tpo $(DEPDIR)/libmio_la-path.Plo
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='path.c' object='libmio_la-path.lo' libtool=yes @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libmio_la-path.lo `test -f 'path.c' || echo '$(srcdir)/'`path.c
+
 libmio_la-pro.lo: pro.c
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libmio_la-pro.lo -MD -MP -MF $(DEPDIR)/libmio_la-pro.Tpo -c -o libmio_la-pro.lo `test -f 'pro.c' || echo '$(srcdir)/'`pro.c
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-pro.Tpo $(DEPDIR)/libmio_la-pro.Plo
@@ -923,10 +944,12 @@ distclean: distclean-am
 	-rm -f ./$(DEPDIR)/libmio_la-err.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-fmt.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-htb.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-htrd.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-htre.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-http.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-mio.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-nwif.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-path.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pro.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-sck.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-skad.Plo
@@ -992,10 +1015,12 @@ maintainer-clean: maintainer-clean-am
 	-rm -f ./$(DEPDIR)/libmio_la-err.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-fmt.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-htb.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-htrd.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-htre.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-http.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-mio.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-nwif.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-path.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pro.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-sck.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-skad.Plo
diff --git a/mio/lib/chr.c b/mio/lib/chr.c
index 18c2db1..8007615 100644
--- a/mio/lib/chr.c
+++ b/mio/lib/chr.c
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/ecs-imp.h b/mio/lib/ecs-imp.h
index 4844bdf..3f557ac 100644
--- a/mio/lib/ecs-imp.h
+++ b/mio/lib/ecs-imp.h
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/ecs.c b/mio/lib/ecs.c
index 38edf17..e841176 100644
--- a/mio/lib/ecs.c
+++ b/mio/lib/ecs.c
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/htb.c b/mio/lib/htb.c
index 0515679..c929692 100644
--- a/mio/lib/htb.c
+++ b/mio/lib/htb.c
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/htrd.c b/mio/lib/htrd.c
index 63295f6..b1f5675 100644
--- a/mio/lib/htrd.c
+++ b/mio/lib/htrd.c
@@ -24,6 +24,7 @@
 
 #include "mio-htrd.h"
 #include "mio-chr.h"
+#include "mio-path.h"
 #include "mio-prv.h"
 
 static const mio_bch_t NUL = '\0';
diff --git a/mio/lib/mio-chr.h b/mio/lib/mio-chr.h
index 43cce22..dc2cf13 100644
--- a/mio/lib/mio-chr.h
+++ b/mio/lib/mio-chr.h
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/mio-ecs.h b/mio/lib/mio-ecs.h
index 3c8b570..121cc50 100644
--- a/mio/lib/mio-ecs.h
+++ b/mio/lib/mio-ecs.h
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/mio-htb.h b/mio/lib/mio-htb.h
index 78f84e1..57a4ede 100644
--- a/mio/lib/mio-htb.h
+++ b/mio/lib/mio-htb.h
@@ -1,7 +1,7 @@
 /*
  * $Id$
  *
-    Copyright (c) 2006-2020 Chung, Hyung-Hwan. All rights reserved.
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
diff --git a/mio/lib/mio-path.h b/mio/lib/mio-path.h
new file mode 100644
index 0000000..8df186f
--- /dev/null
+++ b/mio/lib/mio-path.h
@@ -0,0 +1,96 @@
+/*
+ * $Id$
+ *
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. 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.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "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 AUTHOR 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.
+ */
+
+#ifndef _MIO_PATH_H_
+#define _MIO_PATH_H_
+
+#include <mio.h>
+#include <mio-utl.h>
+
+enum mio_canon_path_flag_t
+{
+	/** if the final output is . logically, return an empty path */
+	MIO_CANON_PATH_EMPTY_SINGLE_DOT    = (1 << 0),
+
+	/** keep the .. segment in the path name */
+	MIO_CANON_PATH_KEEP_DOUBLE_DOTS    = (1 << 1),
+
+	/** drop a trailing separator even if the source contains one */
+	MIO_CANON_PATH_DROP_TRAILING_SEP   = (1 << 2)
+};
+
+typedef enum mio_canon_path_flag_t mio_canon_path_flag_t;
+
+#define MIO_CANON_OOCSTR_PATH_EMPTY_SINGLE_DOT MIO_CANON_PATH_EMPTY_SINGLE_DOT
+#define MIO_CANON_OOCSTR_PATH_KEEP_DOUBLE_DOTS MIO_CANON_PATH_KEEP_DOUBLE_DOTS
+#define MIO_CANON_OOCSTR_PATH_DROP_TRAILING_SEP MIO_CANON_PATH_DROP_TRAILING_SEP
+
+#define MIO_CANON_UCSTR_PATH_EMPTY_SINGLE_DOT MIO_CANON_PATH_EMPTY_SINGLE_DOT
+#define MIO_CANON_UCSTR_PATH_KEEP_DOUBLE_DOTS MIO_CANON_PATH_KEEP_DOUBLE_DOTS
+#define MIO_CANON_UCSTR_PATH_DROP_TRAILING_SEP MIO_CANON_PATH_DROP_TRAILING_SEP
+
+#define MIO_CANON_BCSTR_PATH_EMPTY_SINGLE_DOT MIO_CANON_PATH_EMPTY_SINGLE_DOT
+#define MIO_CANON_BCSTR_PATH_KEEP_DOUBLE_DOTS MIO_CANON_PATH_KEEP_DOUBLE_DOTS
+#define MIO_CANON_BCSTR_PATH_DROP_TRAILING_SEP MIO_CANON_PATH_DROP_TRAILING_SEP
+
+
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+
+#	define MIO_IS_PATH_SEP(c) ((c) == '/' || (c) == '\\')
+
+#else
+#	define MIO_IS_PATH_SEP(c) ((c) == '/')
+#endif
+
+#define MIO_IS_PATH_DRIVE(s) \
+	(((s[0] >= 'A' && s[0] <= 'Z') || \
+	  (s[0] >= 'a' && s[0] <= 'z')) && \
+	 s[1] == ':')
+
+#define MIO_IS_PATH_SEP_OR_NIL(c) (MIO_IS_PATH_SEP(c) || (c) == '\0')
+
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+MIO_EXPORT mio_oow_t mio_canon_ucstr_path (
+	const mio_uch_t* path,
+	mio_uch_t*       canon,
+	int              flags
+);
+
+MIO_EXPORT mio_oow_t mio_canon_bcstr_path (
+	const mio_bch_t* path,
+	mio_bch_t*       canon,
+	int              flags
+);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
diff --git a/mio/lib/path.c b/mio/lib/path.c
new file mode 100644
index 0000000..6796185
--- /dev/null
+++ b/mio/lib/path.c
@@ -0,0 +1,641 @@
+/*
+ * $Id
+ *
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. 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.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "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 AUTHOR 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 "mio-path.h"
+#include "mio-prv.h"
+
+/* TODO: support the \\?\ prefix and the \\.\ prefix on windows 
+ *       support \\?\UNC\server\path which is equivalent to \\server\path. 
+ * */
+/* ------------------------------------------------------------------ */
+/*  WCS IMPLEMENTATION                                                */
+/* ------------------------------------------------------------------ */
+
+#if 0
+int mio_is_ucstr_path_absolute (const mio_uch_t* path)
+{
+	if (MIO_IS_PATH_SEP(path[0])) return 1;
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	/* a drive like c:tmp is absolute in positioning the drive.
+	 * but the path within the drive is kind of relative */
+	if (MIO_IS_PATH_DRIVE(path)) return 1;
+#endif
+     return 0;
+}
+
+int mio_is_ucstr_path_drive (const mio_uch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path)) return 1;
+#endif
+	return 0;
+}
+
+int mio_is_ucstr_path_drive_absolute (const mio_uch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path) && MIO_IS_PATH_SEP(path[2])) return 1;
+#endif
+	return 0;
+}
+
+int mio_is_ucstr_path_drive_current (const mio_uch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path) && path[2] == '\0') return 1;
+#endif
+	return 0;
+}
+#endif
+
+mio_oow_t mio_canon_ucstr_path (const mio_uch_t* path, mio_uch_t* canon, int flags)
+{
+	const mio_uch_t* ptr;
+	mio_uch_t* dst;
+	mio_uch_t* non_root_start;
+	int has_root = 0;
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	int is_drive = 0;
+#endif
+	mio_oow_t canon_len;
+
+	if (path[0] == '\0') 
+	{
+		/* if the source is empty, no translation is needed */
+		canon[0] = '\0';
+		return 0;
+	}
+
+	ptr = path;
+	dst = canon;
+
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(ptr))
+	{
+		/* handle drive letter */
+		*dst++ = *ptr++; /* drive letter */
+		*dst++ = *ptr++; /* colon */
+
+		is_drive = 1;
+		if (MIO_IS_PATH_SEP(*ptr)) 
+		{
+			*dst++ = *ptr++; /* root directory */
+			has_root = 1;
+		}
+	}
+	else if (MIO_IS_PATH_SEP(*ptr)) 
+	{
+		*dst++ = *ptr++; /* root directory */
+		has_root = 1;
+
+	#if defined(_WIN32)
+		/* handle UNC path for Windows */
+		if (MIO_IS_PATH_SEP(*ptr)) 
+		{
+			*dst++ = *ptr++;
+
+			if (MIO_IS_PATH_SEP_OR_NIL(*ptr))
+			{
+				/* if there is another separator after \\,
+				 * it's not an UNC path. */
+				dst--;
+			}
+			else
+			{
+				/* if it starts with \\, process host name */
+				do { *dst++ = *ptr++; } while (!MIO_IS_PATH_SEP_OR_NIL(*ptr));
+				if (MIO_IS_PATH_SEP(*ptr)) *dst++ = *ptr++;
+			}
+		}
+	#endif
+	}
+#else
+	if (MIO_IS_PATH_SEP(*ptr)) 
+	{
+		*dst++ = *ptr++; /* root directory */
+		has_root = 1;
+	}
+#endif
+
+	/* non_root_start points to the beginning of the canonicalized 
+	 * path excluding the root directory part. */
+	non_root_start = dst;
+
+	do
+	{
+		const mio_uch_t* seg;
+		mio_oow_t seglen;
+
+		/* skip duplicate separators */
+		while (MIO_IS_PATH_SEP(*ptr)) ptr++;
+
+		/* end of path reached */
+		if (*ptr == '\0') break;
+
+		/* find the next segment */
+		seg = ptr;
+		while (!MIO_IS_PATH_SEP_OR_NIL(*ptr)) ptr++;
+		seglen = ptr - seg;
+
+		/* handle the segment */
+		if (seglen == 1 && seg[0] == '.')
+		{
+			/* eat up . */
+		}
+		else if (!(flags & MIO_CANON_UCSTR_PATH_KEEP_DOUBLE_DOTS) &&
+		         seglen == 2 && seg[0] == '.' && seg[1] == '.')
+		{
+			/* eat up the previous segment */
+			mio_uch_t* tmp;
+
+			tmp = dst;
+			if (tmp > non_root_start) 
+			{
+				/* there is a previous segment. */
+
+				tmp--; /* skip the separator just before .. */
+
+				/* find the beginning of the previous segment */
+				while (tmp > non_root_start)
+				{
+					tmp--;
+					if (MIO_IS_PATH_SEP(*tmp)) 
+					{
+						tmp++; /* position it next to the separator */
+						break; 
+					}
+				}
+			}
+
+			if (has_root)
+			{
+				/*
+				 * Eat up the previous segment if it exists.
+				 *
+				 * If it doesn't exist, tmp == dst so dst = tmp
+				 * keeps dst unchanged. If it exists, 
+				 * tmp != dst. so dst = tmp changes dst.
+				 *
+				 * path  /abc/def/..
+				 *                ^ ^
+				 *              seg ptr
+				 *
+				 * canon /abc/def/
+				 *            ^   ^   
+				 *           tmp dst
+				 */
+				dst = tmp;
+			}
+			else
+			{
+				mio_oow_t prevlen;
+
+				prevlen = dst - tmp;
+
+				if (/*tmp == non_root_start &&*/ prevlen == 0)
+				{
+					/* there is no previous segment */
+					goto normal;
+				}
+
+				if (prevlen == 3 && tmp[0] == '.' && tmp[1] == '.') 
+				{
+					/* nothing to eat away because the previous segment is ../
+					 *
+					 * path  ../../
+					 *          ^ ^
+					 *        seg ptr
+					 *
+					 * canon ../
+					 *       ^  ^
+					 *      tmp dst
+					 */
+					goto normal;
+				}
+
+				dst = tmp;
+			}
+		}
+		else
+		{
+		normal:
+			while (seg < ptr) *dst++ = *seg++;
+			if (MIO_IS_PATH_SEP(*ptr)) 
+			{
+				/* this segment ended with a separator */
+				*dst++ = *seg++; /* copy the separator */
+				ptr++; /* move forward the pointer */
+			}
+		}
+	}
+	while (1);
+
+	if (dst > non_root_start && MIO_IS_PATH_SEP(dst[-1]) && 
+	    ((flags & MIO_CANON_BCSTR_PATH_DROP_TRAILING_SEP) || !MIO_IS_PATH_SEP(ptr[-1]))) 
+	{
+		/* if the canoncal path composed so far ends with a separator
+		 * and the original path didn't end with the separator, delete
+		 * the ending separator. 
+		 * also delete it if MIO_CANON_BCSTR_PATH_DROP_TRAILING_SEP is set.
+		 *
+		 *   dst > non_root_start:
+		 *     there is at least 1 character after the root directory 
+		 *     part.
+		 *   MIO_IS_PATH_SEP(dst[-1]):
+		 *     the canonical path ends with a separator.
+		 *   MIO_IS_PATH_SEP(ptr[-1]):
+		 *     the origial path ends with a separator.
+		 */
+		dst[-1] = '\0';
+		canon_len = dst - canon - 1;
+	}
+	else 
+	{
+		/* just null-terminate the canonical path normally */
+		dst[0] = '\0';	
+		canon_len = dst - canon;
+	}
+
+	if (canon_len <= 0) 
+	{
+		if (!(flags & MIO_CANON_UCSTR_PATH_EMPTY_SINGLE_DOT))
+		{
+			/* when resolving to a single dot, a trailing separator is not
+			 * retained though the orignal path name contains it. */
+			canon[0] = '.';
+			canon[1] = '\0';
+			canon_len = 1;
+		}
+	}
+	else 
+	{
+		/* drop a traling separator if the last segment is 
+		 * double slashes */
+
+		int adj_base_len = 3;
+
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+		if (is_drive && !has_root) 
+		{
+			/* A path like A:..\\\ need some adjustment for
+			 * finalization below. */
+			adj_base_len += 2;
+		}
+#endif
+
+		if (canon_len == adj_base_len)
+		{
+			/* i don't have to retain a trailing separator
+			 * if the last segment is double slashes because 
+			 * the double slahses indicate a directory obviously */
+			if (canon[canon_len-3] == '.' &&
+			    canon[canon_len-2] == '.' &&
+			    MIO_IS_PATH_SEP(canon[canon_len-1]))
+			{
+				canon[--canon_len] = '\0';
+			}
+		}
+		else if (canon_len > adj_base_len)
+		{
+			if (MIO_IS_PATH_SEP(canon[canon_len-4]) &&
+			    canon[canon_len-3] == '.' &&
+			    canon[canon_len-2] == '.' &&
+			    MIO_IS_PATH_SEP(canon[canon_len-1]))
+			{
+				canon[--canon_len] = '\0';
+			}
+		}
+	}
+
+	return canon_len;
+}
+
+
+/* ------------------------------------------------------------------ */
+/*  MBS IMPLEMENTATION                                                */
+/* ------------------------------------------------------------------ */
+
+#if 0
+int mio_is_bcstr_path_absolute (const mio_bch_t* path)
+{
+	if (MIO_IS_PATH_SEP(path[0])) return 1;
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	/* a drive like c:tmp is absolute in positioning the drive.
+	 * but the path within the drive is kind of relative */
+	if (MIO_IS_PATH_DRIVE(path)) return 1;
+#endif
+	return 0;
+}
+
+int mio_is_bcstr_path_drive (const mio_bch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path)) return 1;
+#endif
+	return 0;
+}
+
+int mio_is_bcstr_path_drive_absolute (const mio_bch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path) && MIO_IS_PATH_SEP(path[2])) return 1;
+#endif
+	return 0;
+}
+
+int mio_is_bcstr_path_drive_current (const mio_bch_t* path)
+{
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(path) && path[2] == '\0') return 1;
+#endif
+	return 0;
+}
+
+#endif
+
+mio_oow_t mio_canon_bcstr_path (const mio_bch_t* path, mio_bch_t* canon, int flags)
+{
+	const mio_bch_t* ptr;
+	mio_bch_t* dst;
+	mio_bch_t* non_root_start;
+	int has_root = 0;
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	int is_drive = 0;
+#endif
+	mio_oow_t canon_len;
+
+	if (path[0] == '\0') 
+	{
+		/* if the source is empty, no translation is needed */
+		canon[0] = '\0';
+		return 0;
+	}
+
+	ptr = path;
+	dst = canon;
+
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+	if (MIO_IS_PATH_DRIVE(ptr))
+	{
+		/* handle drive letter */
+		*dst++ = *ptr++; /* drive letter */
+		*dst++ = *ptr++; /* colon */
+
+		is_drive = 1;
+		if (MIO_IS_PATH_SEP(*ptr)) 
+		{
+			*dst++ = *ptr++; /* root directory */
+			has_root = 1;
+		}
+	}
+	else if (MIO_IS_PATH_SEP(*ptr)) 
+	{
+		*dst++ = *ptr++; /* root directory */
+		has_root = 1;
+
+	#if defined(_WIN32)
+		/* handle UNC path for Windows */
+		if (MIO_IS_PATH_SEP(*ptr)) 
+		{
+			*dst++ = *ptr++;
+
+			if (MIO_IS_PATH_SEP_OR_NIL(*ptr))
+			{
+				/* if there is another separator after \\,
+				 * it's not an UNC path. */
+				dst--;
+			}
+			else
+			{
+				/* if it starts with \\, process host name */
+				do { *dst++ = *ptr++; } while (!MIO_IS_PATH_SEP_OR_NIL(*ptr));
+				if (MIO_IS_PATH_SEP(*ptr)) *dst++ = *ptr++;
+			}
+		}
+	#endif
+	}
+#else
+	if (MIO_IS_PATH_SEP(*ptr)) 
+	{
+		*dst++ = *ptr++; /* root directory */
+		has_root = 1;
+	}
+#endif
+
+	/* non_root_start points to the beginning of the canonicalized 
+	 * path excluding the root directory part. */
+	non_root_start = dst;
+
+	do
+	{
+		const mio_bch_t* seg;
+		mio_oow_t seglen;
+
+		/* skip duplicate separators */
+		while (MIO_IS_PATH_SEP(*ptr)) ptr++;
+
+		/* end of path reached */
+		if (*ptr == '\0') break;
+
+		/* find the next segment */
+		seg = ptr;
+		while (!MIO_IS_PATH_SEP_OR_NIL(*ptr)) ptr++;
+		seglen = ptr - seg;
+
+		/* handle the segment */
+		if (seglen == 1 && seg[0] == '.')
+		{
+			/* eat up . */
+		}
+		else if (!(flags & MIO_CANON_BCSTR_PATH_KEEP_DOUBLE_DOTS) &&
+		         seglen == 2 && seg[0] == '.' && seg[1] == '.')
+		{
+			/* eat up the previous segment */
+			mio_bch_t* tmp;
+
+			tmp = dst;
+			if (tmp > non_root_start) 
+			{
+				/* there is a previous segment. */
+
+				tmp--; /* skip the separator just before .. */
+
+				/* find the beginning of the previous segment */
+				while (tmp > non_root_start)
+				{
+					tmp--;
+					if (MIO_IS_PATH_SEP(*tmp)) 
+					{
+						tmp++; /* position it next to the separator */
+						break; 
+					}
+				}
+			}
+
+			if (has_root)
+			{
+				/*
+				 * Eat up the previous segment if it exists.
+				 *
+				 * If it doesn't exist, tmp == dst so dst = tmp
+				 * keeps dst unchanged. If it exists, 
+				 * tmp != dst. so dst = tmp changes dst.
+				 *
+				 * path  /abc/def/..
+				 *                ^ ^
+				 *              seg ptr
+				 *
+				 * canon /abc/def/
+				 *            ^   ^   
+				 *           tmp dst
+				 */
+				dst = tmp;
+			}
+			else
+			{
+				mio_oow_t prevlen;
+
+				prevlen = dst - tmp;
+
+				if (/*tmp == non_root_start &&*/ prevlen == 0)
+				{
+					/* there is no previous segment */
+					goto normal;
+				}
+
+				if (prevlen == 3 && tmp[0] == '.' && tmp[1] == '.') 
+				{
+					/* nothing to eat away because the previous segment is ../
+					 *
+					 * path  ../../
+					 *          ^ ^
+					 *        seg ptr
+					 *
+					 * canon ../
+					 *       ^  ^
+					 *      tmp dst
+					 */
+					goto normal;
+				}
+
+				dst = tmp;
+			}
+		}
+		else
+		{
+		normal:
+			while (seg < ptr) *dst++ = *seg++;
+			if (MIO_IS_PATH_SEP(*ptr)) 
+			{
+				/* this segment ended with a separator */
+				*dst++ = *seg++; /* copy the separator */
+				ptr++; /* move forward the pointer */
+			}
+		}
+	}
+	while (1);
+
+	if (dst > non_root_start && MIO_IS_PATH_SEP(dst[-1]) && 
+	    ((flags & MIO_CANON_BCSTR_PATH_DROP_TRAILING_SEP) || !MIO_IS_PATH_SEP(ptr[-1]))) 
+	{
+		/* if the canoncal path composed so far ends with a separator
+		 * and the original path didn't end with the separator, delete
+		 * the ending separator. 
+		 * also delete it if MIO_CANON_BCSTR_PATH_DROP_TRAILING_SEP is set.
+		 *
+		 *   dst > non_root_start:
+		 *     there is at least 1 character after the root directory 
+		 *     part.
+		 *   MIO_IS_PATH_SEP(dst[-1]):
+		 *     the canonical path ends with a separator.
+		 *   MIO_IS_PATH_SEP(ptr[-1]):
+		 *     the origial path ends with a separator.
+		 */
+		dst[-1] = '\0';
+		canon_len = dst - canon - 1;
+	}
+	else 
+	{
+		/* just null-terminate the canonical path normally */
+		dst[0] = '\0';
+		canon_len = dst - canon;
+	}
+
+	if (canon_len <= 0) 
+	{
+		if (!(flags & MIO_CANON_BCSTR_PATH_EMPTY_SINGLE_DOT))
+		{
+			/* when resolving to a single dot, a trailing separator is not
+			 * retained though the orignal path name contains it. */
+			canon[0] = '.';
+			canon[1] = '\0';
+			canon_len = 1;
+		}
+	}
+	else 
+	{
+		/* drop a traling separator if the last segment is 
+		 * double slashes */
+
+		int adj_base_len = 3;
+
+#if defined(_WIN32) || defined(__OS2__) || defined(__DOS__)
+		if (is_drive && !has_root) 
+		{
+			/* A path like A:..\\\ need some adjustment for
+			 * finalization below. */
+			adj_base_len += 2;
+		}
+#endif
+
+		if (canon_len == adj_base_len)
+		{
+			/* i don't have to retain a trailing separator
+			 * if the last segment is double slashes because 
+			 * the double slahses indicate a directory obviously */
+			if (canon[canon_len-3] == '.' &&
+			    canon[canon_len-2] == '.' &&
+			    MIO_IS_PATH_SEP(canon[canon_len-1]))
+			{
+				canon[--canon_len] = '\0';
+			}
+		}
+		else if (canon_len > adj_base_len)
+		{
+			if (MIO_IS_PATH_SEP(canon[canon_len-4]) &&
+			    canon[canon_len-3] == '.' &&
+			    canon[canon_len-2] == '.' &&
+			    MIO_IS_PATH_SEP(canon[canon_len-1]))
+			{
+				canon[--canon_len] = '\0';
+			}
+		}
+	}
+
+	return canon_len;
+}
+
+