Merge pull request #121 from cyphar/switch-to-govis

*: switch everything to govis
2017-02-15 13:14:38 -05:00 · 2017-02-15 13:14:38 -05:00 · 7b6f89f33d
commit 7b6f89f33d
parent 5685419c3e c5ec1c9f3a
30 changed files with 1280 additions and 1252 deletions
--- a/4
+++ b/4
@ -4,10 +4,10 @@ BUILDPATH := github.com/vbatts/go-mtree/cmd/gomtree
 CWD := $(shell pwd)
 SOURCE_FILES := $(shell find . -type f -name "*.go")
 CLEAN_FILES := *~
-TAGS := cvis
+TAGS :=
 ARCHES := linux,386 linux,amd64 linux,arm linux,arm64 openbsd,amd64 windows,amd64 darwin,amd64

-default: build validation 
+default: build validation

 .PHONY: validation
 validation: .test .lint .vet .cli.test
--- a/cvis/cvis_test.go
+++ b/cvis/cvis_test.go
@ -1,15 +0,0 @@
-// +build cgo,!govis
-
-package cvis
-
-import "testing"
-
-// The resulting string of Vis output could potentially be four times longer than
-// the original. Vis must handle this possibility.
-func TestVisLength(t *testing.T) {
-	testString := "All work and no play makes Jack a dull boy\n"
-	for i := 0; i < 20; i++ {
-		Vis(testString, DefaultVisFlags)
-		testString = testString + testString
-	}
-}
--- a/cvis/unvis.c
+++ b/cvis/unvis.c
@ -1,293 +0,0 @@
-/*-
- * 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.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)unvis.c     8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
-
-#include <sys/cdefs.h>
-
-#include <sys/types.h>
-#include <ctype.h>
-#include "vis.h"
-
-/*
- * decode driven by state machine
- */
-#define S_GROUND        0       /* haven't seen escape char */
-#define S_START         1       /* start decoding special sequence */
-#define S_META          2       /* metachar started (M) */
-#define S_META1         3       /* metachar more, regular char (-) */
-#define S_CTRL          4       /* control char started (^) */
-#define S_OCTAL2        5       /* octal digit 2 */
-#define S_OCTAL3        6       /* octal digit 3 */
-#define S_HEX2          7       /* hex digit 2 */
-
-#define S_HTTP          0x080   /* %HEXHEX escape */
-
-#define isoctal(c)      (((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
-#define ishex(c)        ((((u_char)(c)) >= '0' && ((u_char)(c)) <= '9') || (((u_char)(c)) >= 'a' && ((u_char)(c)) <= 'f'))
-
-/*
- * unvis - decode characters previously encoded by vis
- */
-int
-unvis(char *cp, int c, int *astate, int flag)
-{
-
-        if (flag & UNVIS_END) {
-                if (*astate == S_OCTAL2 || *astate == S_OCTAL3) {
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                }
-                return (*astate == S_GROUND ? UNVIS_NOCHAR : UNVIS_SYNBAD);
-        }
-
-        switch (*astate & ~S_HTTP) {
-
-        case S_GROUND:
-                *cp = 0;
-                if (c == '\\') {
-                        *astate = S_START;
-                        return (0);
-                }
-                if (flag & VIS_HTTPSTYLE && c == '%') {
-                        *astate = S_START | S_HTTP;
-                        return (0);
-                }
-                *cp = c;
-                return (UNVIS_VALID);
-
-        case S_START:
-                if (*astate & S_HTTP) {
-                    if (ishex(tolower(c))) {
-                        *cp = isdigit(c) ? (c - '0') : (tolower(c) - 'a');
-                        *astate = S_HEX2;
-                        return (0);
-                    }
-                }
-                switch(c) {
-                case '\\':
-                        *cp = c;
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case '0': case '1': case '2': case '3':
-                case '4': case '5': case '6': case '7':
-                        *cp = (c - '0');
-                        *astate = S_OCTAL2;
-                        return (0);
-                case 'M':
-                        *cp = 0200;
-                        *astate = S_META;
-                        return (0);
-                case '^':
-                        *astate = S_CTRL;
-                        return (0);
-                case 'n':
-                        *cp = '\n';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'r':
-                        *cp = '\r';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'b':
-                        *cp = '\b';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'a':
-                        *cp = '\007';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'v':
-                        *cp = '\v';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 't':
-                        *cp = '\t';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'f':
-                        *cp = '\f';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 's':
-                        *cp = ' ';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case 'E':
-                        *cp = '\033';
-                        *astate = S_GROUND;
-                        return (UNVIS_VALID);
-                case '\n':
-                        /*
-                         * hidden newline
-                         */
-                        *astate = S_GROUND;
-                        return (UNVIS_NOCHAR);
-                case '$':
-                        /*
-                         * hidden marker
-                         */
-                        *astate = S_GROUND;
-                        return (UNVIS_NOCHAR);
-                }
-                *astate = S_GROUND;
-                return (UNVIS_SYNBAD);
-
-        case S_META:
-                if (c == '-')
-                        *astate = S_META1;
-                else if (c == '^')
-                        *astate = S_CTRL;
-                else {
-                        *astate = S_GROUND;
-                        return (UNVIS_SYNBAD);
-                }
-                return (0);
-
-        case S_META1:
-                *astate = S_GROUND;
-                *cp |= c;
-                return (UNVIS_VALID);
-
-        case S_CTRL:
-                if (c == '?')
-                        *cp |= 0177;
-                else
-                        *cp |= c & 037;
-                *astate = S_GROUND;
-                return (UNVIS_VALID);
-
-        case S_OCTAL2:  /* second possible octal digit */
-                if (isoctal(c)) {
-                        /*
-                         * yes - and maybe a third
-                         */
-                        *cp = (*cp << 3) + (c - '0');
-                        *astate = S_OCTAL3;
-                        return (0);
-                }
-                /*
-                 * no - done with current sequence, push back passed char
-                 */
-                *astate = S_GROUND;
-                return (UNVIS_VALIDPUSH);
-
-        case S_OCTAL3:  /* third possible octal digit */
-                *astate = S_GROUND;
-                if (isoctal(c)) {
-                        *cp = (*cp << 3) + (c - '0');
-                        return (UNVIS_VALID);
-                }
-                /*
-                 * we were done, push back passed char
-                 */
-                return (UNVIS_VALIDPUSH);
-
-        case S_HEX2:    /* second mandatory hex digit */
-                if (ishex(tolower(c))) {
-                        *cp = (isdigit(c) ? (*cp << 4) + (c - '0') : (*cp << 4) + (tolower(c) - 'a' + 10));
-                }
-                *astate = S_GROUND;
-                return (UNVIS_VALID);
-
-        default:
-                /*
-                 * decoder in unknown state - (probably uninitialized)
-                 */
-                *astate = S_GROUND;
-                return (UNVIS_SYNBAD);
-        }
-}
-
-/*
- * strunvis - decode src into dst
- *
- *      Number of chars decoded into dst is returned, -1 on error.
- *      Dst is null terminated.
- */
-
-int
-strunvis(char *dst, const char *src)
-{
-        char c;
-        char *start = dst;
-        int state = 0;
-
-        while ( (c = *src++) ) {
-        again:
-                switch (unvis(dst, c, &state, 0)) {
-                case UNVIS_VALID:
-                        dst++;
-                        break;
-                case UNVIS_VALIDPUSH:
-                        dst++;
-                        goto again;
-                case 0:
-                case UNVIS_NOCHAR:
-                        break;
-                default:
-                        return (-1);
-                }
-        }
-        if (unvis(dst, c, &state, UNVIS_END) == UNVIS_VALID)
-                dst++;
-        *dst = '\0';
-        return (dst - start);
-}
-
-int
-strunvisx(char *dst, const char *src, int flag)
-{
-        char c;
-        char *start = dst;
-        int state = 0;
-    
-        while ( (c = *src++) ) {
-        again:
-                switch (unvis(dst, c, &state, flag)) {
-                case UNVIS_VALID:
-                        dst++;
-                        break;
-                case UNVIS_VALIDPUSH:
-                        dst++;
-                        goto again;
-                case 0:
-                case UNVIS_NOCHAR:
-                        break;
-                default:
-                        return (-1);
-                }
-        }
-        if (unvis(dst, c, &state, UNVIS_END) == UNVIS_VALID)
-                dst++;
-        *dst = '\0';
-        return (dst - start);
-}
--- a/cvis/unvis.go
+++ b/cvis/unvis.go
@ -1,22 +0,0 @@
-package cvis
-
-// #include "vis.h"
-// #include <stdlib.h>
-import "C"
-import (
-	"fmt"
-	"unsafe"
-)
-
-// Unvis decodes the Vis() string encoding
-func Unvis(src string) (string, error) {
-	cDst, cSrc := C.CString(string(make([]byte, len(src)+1))), C.CString(src)
-	defer C.free(unsafe.Pointer(cDst))
-	defer C.free(unsafe.Pointer(cSrc))
-	ret := C.strunvis(cDst, cSrc)
-	// TODO(vbatts) this needs to be confirmed against UnvisError
-	if ret == -1 {
-		return "", fmt.Errorf("failed to decode: %q", src)
-	}
-	return C.GoString(cDst), nil
-}
--- a/cvis/vis.c
+++ b/cvis/vis.c
@ -1,202 +0,0 @@
-/*-
- * 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.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)vis.c       8.1 (Berkeley) 7/19/93";
-#endif /* LIBC_SCCS and not lint */
-
-
-#include <sys/cdefs.h>
-
-#include <sys/types.h>
-#include <limits.h>
-#include <ctype.h>
-#include <stdio.h>
-#include "vis.h"
-
-#define isoctal(c)      (((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
-
-/*
- * vis - visually encode characters
- */
-char *
-vis(dst, c, flag, nextc)
-        char *dst;
-        int c, nextc;
-        int flag;
-{
-        c = (unsigned char)c;
-
-        if (flag & VIS_HTTPSTYLE) {
-                /* Described in RFC 1808 */
-                if (!(isalnum(c) /* alpha-numeric */
-                    /* safe */
-                    || c == '$' || c == '-' || c == '_' || c == '.' || c == '+'
-                    /* extra */
-                    || c == '!' || c == '*' || c == '\'' || c == '('
-                    || c == ')' || c == ',')) {
-                        *dst++ = '%';
-                        snprintf(dst, 4, (c < 16 ? "0%X" : "%X"), c);
-                        dst += 2;
-                        goto done;
-                }
-        }
-
-        if ((flag & VIS_GLOB) &&
-            (c == '*' || c == '?' || c == '[' || c == '#'))
-                ;
-        else if (isgraph(c) ||
-           ((flag & VIS_SP) == 0 && c == ' ') ||
-           ((flag & VIS_TAB) == 0 && c == '\t') ||
-           ((flag & VIS_NL) == 0 && c == '\n') ||
-           ((flag & VIS_SAFE) && (c == '\b' || c == '\007' || c == '\r'))) {
-                *dst++ = c;
-                if (c == '\\' && (flag & VIS_NOSLASH) == 0)
-                        *dst++ = '\\';
-                *dst = '\0';
-                return (dst);
-        }
-
-        if (flag & VIS_CSTYLE) {
-                switch(c) {
-                case '\n':
-                        *dst++ = '\\';
-                        *dst++ = 'n';
-                        goto done;
-                case '\r':
-                        *dst++ = '\\';
-                        *dst++ = 'r';
-                        goto done;
-                case '\b':
-                        *dst++ = '\\';
-                        *dst++ = 'b';
-                        goto done;
-                case '\a':
-                        *dst++ = '\\';
-                        *dst++ = 'a';
-                        goto done;
-                case '\v':
-                        *dst++ = '\\';
-                        *dst++ = 'v';
-                        goto done;
-                case '\t':
-                        *dst++ = '\\';
-                        *dst++ = 't';
-                        goto done;
-                case '\f':
-                        *dst++ = '\\';
-                        *dst++ = 'f';
-                        goto done;
-                case ' ':
-                        *dst++ = '\\';
-                        *dst++ = 's';
-                        goto done;
-                case '\0':
-                        *dst++ = '\\';
-                        *dst++ = '0';
-                        if (isoctal(nextc)) {
-                                *dst++ = '0';
-                                *dst++ = '0';
-                        }
-                        goto done;
-                }
-        }
-        if (((c & 0177) == ' ') || isgraph(c) || (flag & VIS_OCTAL)) {
-                *dst++ = '\\';
-                *dst++ = ((u_char)c >> 6 & 07) + '0';
-                *dst++ = ((u_char)c >> 3 & 07) + '0';
-                *dst++ = ((u_char)c & 07) + '0';
-                goto done;
-        }
-        if ((flag & VIS_NOSLASH) == 0)
-                *dst++ = '\\';
-        if (c & 0200) {
-                c &= 0177;
-                *dst++ = 'M';
-        }
-        if (iscntrl(c)) {
-                *dst++ = '^';
-                if (c == 0177)
-                        *dst++ = '?';
-                else
-                        *dst++ = c + '@';
-        } else {
-                *dst++ = '-';
-                *dst++ = c;
-        }
-done:
-        *dst = '\0';
-        return (dst);
-}
-
-/*
- * strvis, strvisx - visually encode characters from src into dst
- *
- *      Dst must be 4 times the size of src to account for possible
- *      expansion.  The length of dst, not including the trailing NUL,
- *      is returned.
- *
- *      Strvisx encodes exactly len bytes from src into dst.
- *      This is useful for encoding a block of data.
- */
-int
-strvis(dst, src, flag)
-        char *dst;
-        const char *src;
-        int flag;
-{
-        char c;
-        char *start;
-
-        for (start = dst; (c = *src); )
-                dst = vis(dst, c, flag, *++src);
-        *dst = '\0';
-        return (dst - start);
-}
-
-int
-strvisx(dst, src, len, flag)
-        char *dst;
-        const char *src;
-        size_t len;
-        int flag;
-{
-        int c;
-        char *start;
-
-        for (start = dst; len > 1; len--) {
-                c = *src;
-                dst = vis(dst, c, flag, *++src);
-        }
-        if (len)
-                dst = vis(dst, *src, flag, '\0');
-        *dst = '\0';
-
-        return (dst - start);
-}
--- a/cvis/vis.go
+++ b/cvis/vis.go
@ -1,28 +0,0 @@
-package cvis
-
-// #include "vis.h"
-// #include <stdlib.h>
-import "C"
-import (
-	"fmt"
-	"math"
-	"unsafe"
-)
-
-// Vis is a wrapper around the C implementation
-func Vis(src string, flags int) (string, error) {
-	// dst needs to be 4 times the length of str, must check appropriate size
-	if uint32(len(src)*4+1) >= math.MaxUint32/4 {
-		return "", fmt.Errorf("failed to encode: %q", src)
-	}
-	dst := string(make([]byte, 4*len(src)+1))
-	cDst, cSrc := C.CString(dst), C.CString(src)
-	defer C.free(unsafe.Pointer(cDst))
-	defer C.free(unsafe.Pointer(cSrc))
-	C.strvis(cDst, cSrc, C.int(flags))
-
-	return C.GoString(cDst), nil
-}
-
-// DefaultVisFlags are the common flags used in mtree string encoding
-var DefaultVisFlags = C.VIS_WHITE | C.VIS_OCTAL | C.VIS_GLOB
--- a/cvis/vis.h
+++ b/cvis/vis.h
@ -1,90 +0,0 @@
-/*-
- * Copyright (c) 1990, 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.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by the University of
- *      California, Berkeley and its contributors.
- * 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.
- *
- *      @(#)vis.h       8.1 (Berkeley) 6/2/93
- * $FreeBSD$
- */
-
-#ifndef _VIS_H_
-#define _VIS_H_
-
-#include <sys/types.h>
-
-/*
- * to select alternate encoding format
- */
-#define VIS_OCTAL       0x01    /* use octal \ddd format */
-#define VIS_CSTYLE      0x02    /* use \[nrft0..] where appropriate */
-
-/*
- * to alter set of characters encoded (default is to encode all
- * non-graphic except space, tab, and newline).
- */
-#define VIS_SP          0x04    /* also encode space */
-#define VIS_TAB         0x08    /* also encode tab */
-#define VIS_NL          0x10    /* also encode newline */
-#define VIS_WHITE       (VIS_SP | VIS_TAB | VIS_NL)
-#define VIS_SAFE        0x20    /* only encode "unsafe" characters */
-
-/*
- * other
- */
-#define VIS_NOSLASH     0x40    /* inhibit printing '\' */
-#define VIS_HTTPSTYLE   0x80    /* http-style escape % HEX HEX */
-#define VIS_GLOB        0x100   /* encode glob(3) magics */
-
-/*
- * unvis return codes
- */
-#define UNVIS_VALID      1      /* character valid */
-#define UNVIS_VALIDPUSH  2      /* character valid, push back passed char */
-#define UNVIS_NOCHAR     3      /* valid sequence, no character produced */
-#define UNVIS_SYNBAD    -1      /* unrecognized escape sequence */
-#define UNVIS_ERROR     -2      /* decoder in unknown state (unrecoverable) */
-
-/*
- * unvis flags
- */
-#define UNVIS_END       1       /* no more characters */
-
-#include <sys/cdefs.h>
-
-__BEGIN_DECLS
-char    *vis(char *, int, int, int);
-int     strvis(char *, const char *, int);
-int     strvisx(char *, const char *, size_t, int);
-int     strunvis(char *, const char *);
-int     strunvisx(char *, const char *, int);
-int     unvis(char *, int, int *, int);
-__END_DECLS
-
-#endif /* !_VIS_H_ */
--- a/entry.go
+++ b/entry.go
@ -4,6 +4,8 @@ import (
 	"fmt"
 	"path/filepath"
 	"strings"
+
+	"github.com/vbatts/go-mtree/pkg/govis"
 )

 type byPos []Entry
@ -47,7 +49,7 @@ func (e Entry) Descend(filename string) *Entry {
 func (e Entry) Find(filepath string) *Entry {
 	resultnode := &e
 	for _, path := range strings.Split(filepath, "/") {
-		encoded, err := Vis(path, DefaultVisFlags)
+		encoded, err := govis.Vis(path, DefaultVisFlags)
 		if err != nil {
 			return nil
 		}
@ -68,7 +70,7 @@ func (e Entry) Ascend() *Entry {
 // Path provides the full path of the file, despite RelativeType or FullType. It
 // will be in Unvis'd form.
 func (e Entry) Path() (string, error) {
-	decodedName, err := Unvis(e.Name)
+	decodedName, err := govis.Unvis(e.Name, DefaultVisFlags)
 	if err != nil {
 		return "", err
 	}
--- a/keywordfunc.go
+++ b/keywordfunc.go
@ -11,6 +11,7 @@ import (
 	"io"
 	"os"

+	"github.com/vbatts/go-mtree/pkg/govis"
 	"golang.org/x/crypto/ripemd160"
 )

@ -119,7 +120,7 @@ var (
 	linkKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
 		if sys, ok := info.Sys().(*tar.Header); ok {
 			if sys.Linkname != "" {
-				linkname, err := Vis(sys.Linkname, DefaultVisFlags)
+				linkname, err := govis.Vis(sys.Linkname, DefaultVisFlags)
 				if err != nil {
 					return emptyKV, err
 				}
@ -133,7 +134,7 @@ var (
 			if err != nil {
 				return emptyKV, err
 			}
-			linkname, err := Vis(str, DefaultVisFlags)
+			linkname, err := govis.Vis(str, DefaultVisFlags)
 			if err != nil {
 				return emptyKV, err
 			}
--- a/keywords.go
+++ b/keywords.go
@ -3,8 +3,14 @@ package mtree
 import (
 	"fmt"
 	"strings"
+
+	"github.com/vbatts/go-mtree/pkg/govis"
 )

+// DefaultVisFlags is the set of Vis flags used when encoding filenames and
+// other similar entries.
+const DefaultVisFlags govis.VisFlag = govis.VisWhite | govis.VisOctal | govis.VisGlob
+
 // Keyword is the string name of a keyword, with some convenience functions for
 // determining whether it is a default or bsd standard keyword.
 type Keyword string
--- a/keywords_linux.go
+++ b/keywords_linux.go
@ -12,6 +12,7 @@ import (
 	"strings"
 	"syscall"

+	"github.com/vbatts/go-mtree/pkg/govis"
 	"github.com/vbatts/go-mtree/xattr"
 )

@ -62,7 +63,7 @@ var (
 			}
 			klist := []KeyVal{}
 			for k, v := range hdr.Xattrs {
-				encKey, err := Vis(k, DefaultVisFlags)
+				encKey, err := govis.Vis(k, DefaultVisFlags)
 				if err != nil {
 					return emptyKV, err
 				}
@ -84,7 +85,7 @@ var (
 			if err != nil {
 				return emptyKV, err
 			}
-			encKey, err := Vis(xlist[i], DefaultVisFlags)
+			encKey, err := govis.Vis(xlist[i], DefaultVisFlags)
 			if err != nil {
 				return emptyKV, err
 			}
--- a/pkg/govis/.travis.yml
+++ b/pkg/govis/.travis.yml
@ -0,0 +1,28 @@
+# govis: unicode aware vis(3) encoding implementation
+# Copyright (C) 2017 SUSE LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+language: go
+
+notifications:
+  email: false
+
+go:
+  - 1.x
+  - 1.6.x
+  - 1.7.x
+  - master
+
+script:
+  - go test -v ./...
--- a/pkg/govis/COPYING
+++ b/pkg/govis/COPYING
@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+
+   3. Grant of Patent License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
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+   4. Redistribution. You may reproduce and distribute copies of the
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+
+      (a) You must give any other recipients of the Work or
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+
+      (b) You must cause any modified files to carry prominent notices
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+
+      (c) You must retain, in the Source form of any Derivative Works
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+
+      (d) If the Work includes a "NOTICE" text file as part of its
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+          of the following places: within a NOTICE text file distributed
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+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
--- a/pkg/govis/README.md
+++ b/pkg/govis/README.md
@ -0,0 +1,28 @@
+## `govis` ##
+[![Travis CI](https://travis-ci.org/cyphar/govis.svg?branch=master)](https://travis-ci.org/cyphar/govis)
+
+`govis` is a BSD-compatible `vis(3)` and `unvis(3)` encoding implementation
+that is unicode aware and written in Go. None of this code comes from the
+original BSD code, nor does it come from `go-mtree`'s port of said code.
+Because 80s BSD code is not very nice to read.
+
+### License ###
+
+`govis` is licensed under the Apache 2.0 license.
+
+```
+govis: unicode aware vis(3) encoding implementation
+Copyright (C) 2017 SUSE LLC.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+```
--- a/pkg/govis/govis.go
+++ b/pkg/govis/govis.go
@ -0,0 +1,38 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+type VisFlag uint
+
+// vis() has a variety of flags when deciding what encodings to use. While
+// mtree only uses one set of flags, implementing them all is necessary in
+// order to have compatibility with BSD's vis() and unvis() commands.
+const (
+	VisOctal     VisFlag = (1 << iota)     // VIS_OCTAL: Use octal \ddd format.
+	VisCStyle                              // VIS_CSTYLE: Use \[nrft0..] where appropriate.
+	VisSpace                               // VIS_SP: Also encode space.
+	VisTab                                 // VIS_TAB: Also encode tab.
+	VisNewline                             // VIS_NL: Also encode newline.
+	VisSafe                                // VIS_SAFE: Encode unsafe characters.
+	VisNoSlash                             // VIS_NOSLASH: Inhibit printing '\'.
+	VisHTTPStyle                           // VIS_HTTPSTYLE: HTTP-style escape %xx.
+	VisGlob                                // VIS_GLOB: Encode glob(3) magics.
+	visMask      VisFlag = (1 << iota) - 1 // Mask of all flags.
+
+	VisWhite VisFlag = (VisSpace | VisTab | VisNewline)
+)
--- a/pkg/govis/govis_test.go
+++ b/pkg/govis/govis_test.go
@ -0,0 +1,194 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+import (
+	"bytes"
+	"crypto/rand"
+	"testing"
+)
+
+const DefaultVisFlags = VisWhite | VisOctal | VisGlob
+
+func TestRandomVisUnvis(t *testing.T) {
+	// Randomly generate N strings.
+	const N = 100
+
+	for i := 0; i < N; i++ {
+		testBytes := make([]byte, 256)
+		if n, err := rand.Read(testBytes); n != cap(testBytes) || err != nil {
+			t.Fatalf("could not read enough bytes: err=%v n=%d", err, n)
+		}
+		test := string(testBytes)
+
+		for flag := VisFlag(0); flag <= visMask; flag++ {
+			// VisNoSlash is frankly just a dumb flag, and it is impossible for us
+			// to actually preserve things in a round-trip.
+			if flag&VisNoSlash == VisNoSlash {
+				continue
+			}
+
+			enc, err := Vis(test, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing vis(%q, %b): %s", test, flag, err)
+				continue
+			}
+			dec, err := Unvis(enc, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing unvis(%q, %b): %s", enc, flag, err)
+				continue
+			}
+			if dec != test {
+				t.Errorf("roundtrip failed: unvis(vis(%q, %b) = %q, %b) = %q", test, flag, enc, flag, dec)
+			}
+		}
+	}
+}
+
+func TestRandomVisVisUnvisUnvis(t *testing.T) {
+	// Randomly generate N strings.
+	const N = 100
+
+	for i := 0; i < N; i++ {
+		testBytes := make([]byte, 256)
+		if n, err := rand.Read(testBytes); n != cap(testBytes) || err != nil {
+			t.Fatalf("could not read enough bytes: err=%v n=%d", err, n)
+		}
+		test := string(testBytes)
+
+		for flag := VisFlag(0); flag <= visMask; flag++ {
+			// VisNoSlash is frankly just a dumb flag, and it is impossible for us
+			// to actually preserve things in a round-trip.
+			if flag&VisNoSlash == VisNoSlash {
+				continue
+			}
+
+			enc, err := Vis(test, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing vis(%q, %b): %s", test, flag, err)
+				continue
+			}
+			enc2, err := Vis(enc, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing vis(%q, %b): %s", enc, flag, err)
+				continue
+			}
+			dec, err := Unvis(enc2, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing unvis(%q, %b): %s", enc2, flag, err)
+				continue
+			}
+			dec2, err := Unvis(dec, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing unvis(%q, %b): %s", dec, flag, err)
+				continue
+			}
+			if dec2 != test {
+				t.Errorf("roundtrip failed: unvis(unvis(vis(vis(%q) = %q) = %q) = %q, %b) = %q", test, enc, enc2, dec, flag, dec2)
+			}
+		}
+	}
+}
+
+func TestVisUnvis(t *testing.T) {
+	for flag := VisFlag(0); flag <= visMask; flag++ {
+		// VisNoSlash is frankly just a dumb flag, and it is impossible for us
+		// to actually preserve things in a round-trip.
+		if flag&VisNoSlash == VisNoSlash {
+			continue
+		}
+
+		// Round-trip testing.
+		for _, test := range []string{
+			"",
+			"hello world",
+			"THIS\\IS_A_TEST1234",
+			"this.is.a.normal_string",
+			"AC_Ra\u00edz_Certic\u00e1mara_S.A..pem",
+			"NetLock_Arany_=Class_Gold=_F\u0151tan\u00fas\u00edtv\u00e1ny.pem",
+			"T\u00dcB\u0130TAK_UEKAE_K\u00f6k_Sertifika_Hizmet_Sa\u011flay\u0131c\u0131s\u0131_-_S\u00fcr\u00fcm_3.pem",
+			"hello world [ this string needs=enco ding! ]",
+			"even \n more encoding necessary\a\a ",
+			"\024 <-- some more weird characters --> \u4f60\u597d\uff0c\u4e16\u754c",
+			"\\xff\\n double encoding is also great fun \\x",
+			"AC_Ra\\M-C\\M--z_Certic\\M-C\\M-!mara_S.A..pem",
+			"z^i3i$\u00d3\u008anqgh5/t\u00e5<86>\u00b2kzla\\e^lv\u00df\u0093nv\u00df\u00aea|3}\u00d8\u0088\u00d6\u0084",
+			`z^i3i$\M-C\M^S\M-B\M^Jnqgh5/t\M-C\M-%<86>\M-B\M-2kzla\\e^lv\M-C\M^_\M-B\M^Snv\M-C\M^_\M-B\M-.a|3}\M-C\M^X\M-B\M^H\M-C\M^V\M-B\M^D`,
+			"@?e1xs+.R_Kjo]7s8pgRP:*nXCE4{!c",
+			"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb",
+			`62_\M-C\M^F\M-C\M^F2\M-B\M-.\M-B\M-7m\M-C\M^[\M-C\M^Cr^\M-B\M-?p\M-C\M^Fu'q\M-C\M-;c2\M-C\M-0u\M-B\M-8\M-C\M^]\M-C\M-(v\M-C\M-?\M-B\M-0\M-C\M^\\M-C\M^B\M-C\M-53\M-C\M^[-k\M-C\M-2sd4\\p\M-C\M^Z\M-B\M-&\M-C\M^S\M-C\M-.a<\M-C\M-&s{\M-B\240p\M-C\M-0\M-C\M-?j\M-C\240\M-C\M-(\M-B\M-8\M-B\M-8\M-B\M-<\M-C\M-<b`,
+			"\u9003\"9v1)T798|o;fly jnKX\u0489Be=",
+			`\M-i\M^@\M^C"9v1)T798|o;fly jnKX\M-R\M^IBe=`,
+			"'3Ze\u050e|\u02del\u069du-Rpct4+Z5b={@_{b",
+			`'3Ze\M-T\M^N|\M-K\M^^l\M-Z\M^]u-Rpct4+Z5b={@_{b`,
+			"1\u00c6\u00abTcz+Vda?)k1%\\\"P;`po`h",
+			`1%C3%86%C2%ABTcz+Vda%3F)k1%25%5C%22P%3B%60po%60h`,
+		} {
+			enc, err := Vis(test, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing vis(%q, %b): %s", test, flag, err)
+				continue
+			}
+			dec, err := Unvis(enc, flag)
+			if err != nil {
+				t.Errorf("unexpected error doing unvis(%q, %b): %s", enc, flag, err)
+				continue
+			}
+			if dec != test {
+				t.Errorf("roundtrip failed: unvis(vis(%q, %b) = %q, %b) = %q", test, flag, enc, flag, dec)
+			}
+		}
+	}
+}
+
+func TestByteStrings(t *testing.T) {
+	// It's important to make sure that we don't mess around with the layout of
+	// bytes when doing a round-trip. Otherwise we risk outputting visually
+	// identical but bit-stream non-identical strings (causing much confusion
+	// when trying to access such files).
+
+	for _, test := range [][]byte{
+		[]byte("This is a man in business suit levitating: \U0001f574"),
+		{0x7f, 0x17, 0x01, 0x33},
+		// TODO: Test arbitrary byte streams like the one below. Currently this
+		//       fails because Vis() is messing around with it (converting it
+		//       to a rune and spacing it out).
+		//{'\xef', '\xae', 'h', '\077', 'k'},
+	} {
+		testString := string(test)
+		enc, err := Vis(testString, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing vis(%q): %s", test, err)
+			continue
+		}
+		dec, err := Unvis(enc, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %s", enc, err)
+			continue
+		}
+		decBytes := []byte(dec)
+
+		if dec != testString {
+			t.Errorf("roundtrip failed [string comparison]: unvis(vis(%q) = %q) = %q", test, enc, dec)
+		}
+		if !bytes.Equal(decBytes, test) {
+			t.Errorf("roundtrip failed [byte comparison]: unvis(vis(%q) = %q) = %q", test, enc, dec)
+		}
+	}
+
+}
--- a/pkg/govis/unvis.go
+++ b/pkg/govis/unvis.go
@ -0,0 +1,294 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+import (
+	"fmt"
+	"strconv"
+	"unicode"
+)
+
+// unvisParser stores the current state of the token parser.
+type unvisParser struct {
+	tokens []rune
+	idx    int
+	flag   VisFlag
+}
+
+// Next moves the index to the next character.
+func (p *unvisParser) Next() {
+	p.idx++
+}
+
+// Peek gets the current token.
+func (p *unvisParser) Peek() (rune, error) {
+	if p.idx >= len(p.tokens) {
+		return unicode.ReplacementChar, fmt.Errorf("tried to read past end of token list")
+	}
+	return p.tokens[p.idx], nil
+}
+
+// End returns whether all of the tokens have been consumed.
+func (p *unvisParser) End() bool {
+	return p.idx >= len(p.tokens)
+}
+
+func newParser(input string, flag VisFlag) *unvisParser {
+	return &unvisParser{
+		tokens: []rune(input),
+		idx:    0,
+		flag:   flag,
+	}
+}
+
+// While a recursive descent parser is overkill for parsing simple escape
+// codes, this is IMO much easier to read than the ugly 80s coroutine code used
+// by the original unvis(3) parser. Here's the EBNF for an unvis sequence:
+//
+// <input>           ::= (<rune>)*
+// <rune>            ::= ("\" <escape-sequence>) | ("%" <escape-hex>) | <plain-rune>
+// <plain-rune>      ::= any rune
+// <escape-sequence> ::= ("x" <escape-hex>) | ("M" <escape-meta>) | ("^" <escape-ctrl) | <escape-cstyle> | <escape-octal>
+// <escape-meta>     ::= ("-" <escape-meta1>) | ("^" <escape-ctrl>)
+// <escape-meta1>    ::= any rune
+// <escape-ctrl>     ::= "?" | any rune
+// <escape-cstyle>   ::= "\" | "n" | "r" | "b" | "a" | "v" | "t" | "f"
+// <escape-hex>      ::= [0-9a-f] [0-9a-f]
+// <escape-octal>    ::= [0-7] ([0-7] ([0-7])?)?
+
+func unvisPlainRune(p *unvisParser) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("plain rune: %c", ch)
+	}
+	p.Next()
+
+	// XXX: Maybe we should not be converting to runes and then back to strings
+	//      here. Are we sure that the byte-for-byte representation is the
+	//      same? If the bytes change, then using these strings for paths will
+	//      break...
+
+	str := string(ch)
+	return []byte(str), nil
+}
+
+func unvisEscapeCStyle(p *unvisParser) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("escape hex: %s", err)
+	}
+
+	output := ""
+	switch ch {
+	case 'n':
+		output = "\n"
+	case 'r':
+		output = "\r"
+	case 'b':
+		output = "\b"
+	case 'a':
+		output = "\x07"
+	case 'v':
+		output = "\v"
+	case 't':
+		output = "\t"
+	case 'f':
+		output = "\f"
+	case 's':
+		output = " "
+	case 'E':
+		output = "\x1b"
+	case '\n':
+		// Hidden newline.
+	case '$':
+		// Hidden marker.
+	default:
+		// XXX: We should probably allow falling through and return "\" here...
+		return nil, fmt.Errorf("escape cstyle: unknown escape character: %q", ch)
+	}
+
+	p.Next()
+	return []byte(output), nil
+}
+
+func unvisEscapeDigits(p *unvisParser, base int, force bool) ([]byte, error) {
+	var code int
+
+	for i := int(0xFF); i > 0; i /= base {
+		ch, err := p.Peek()
+		if err != nil {
+			if !force && i != 0xFF {
+				break
+			}
+			return nil, fmt.Errorf("escape base %d: %s", base, err)
+		}
+
+		digit, err := strconv.ParseInt(string(ch), base, 8)
+		if err != nil {
+			if !force && i != 0xFF {
+				break
+			}
+			return nil, fmt.Errorf("escape base %d: could not parse digit: %s", base, err)
+		}
+
+		code = (code * base) + int(digit)
+		p.Next()
+	}
+
+	if code > unicode.MaxLatin1 {
+		return nil, fmt.Errorf("escape base %d: code %q outside latin-1 encoding", base, code)
+	}
+
+	char := byte(code & 0xFF)
+	return []byte{char}, nil
+}
+
+func unvisEscapeCtrl(p *unvisParser, mask byte) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("escape ctrl: %s", err)
+	}
+	if ch > unicode.MaxLatin1 {
+		return nil, fmt.Errorf("escape ctrl: code %q outside latin-1 encoding", ch)
+	}
+
+	char := byte(ch) & 0x1f
+	if ch == '?' {
+		char = 0x7f
+	}
+
+	p.Next()
+	return []byte{mask | char}, nil
+}
+
+func unvisEscapeMeta(p *unvisParser) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("escape meta: %s", err)
+	}
+
+	mask := byte(0x80)
+
+	switch ch {
+	case '^':
+		// The same as "\^..." except we apply a mask.
+		p.Next()
+		return unvisEscapeCtrl(p, mask)
+
+	case '-':
+		p.Next()
+
+		ch, err := p.Peek()
+		if err != nil {
+			return nil, fmt.Errorf("escape meta1: %s", err)
+		}
+		if ch > unicode.MaxLatin1 {
+			return nil, fmt.Errorf("escape meta1: code %q outside latin-1 encoding", ch)
+		}
+
+		// Add mask to character.
+		p.Next()
+		return []byte{mask | byte(ch)}, nil
+	}
+
+	return nil, fmt.Errorf("escape meta: unknown escape char: %s", err)
+}
+
+func unvisEscapeSequence(p *unvisParser) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("escape sequence: %s", err)
+	}
+
+	switch ch {
+	case '\\':
+		p.Next()
+		return []byte("\\"), nil
+
+	case '0', '1', '2', '3', '4', '5', '6', '7':
+		return unvisEscapeDigits(p, 8, false)
+
+	case 'x':
+		p.Next()
+		return unvisEscapeDigits(p, 16, true)
+
+	case '^':
+		p.Next()
+		return unvisEscapeCtrl(p, 0x00)
+
+	case 'M':
+		p.Next()
+		return unvisEscapeMeta(p)
+
+	default:
+		return unvisEscapeCStyle(p)
+	}
+}
+
+func unvisRune(p *unvisParser) ([]byte, error) {
+	ch, err := p.Peek()
+	if err != nil {
+		return nil, fmt.Errorf("rune: %s", err)
+	}
+
+	switch ch {
+	case '\\':
+		p.Next()
+		return unvisEscapeSequence(p)
+
+	case '%':
+		// % HEX HEX only applies to HTTPStyle encodings.
+		if p.flag&VisHTTPStyle == VisHTTPStyle {
+			p.Next()
+			return unvisEscapeDigits(p, 16, true)
+		}
+		fallthrough
+
+	default:
+		return unvisPlainRune(p)
+	}
+}
+
+func unvis(p *unvisParser) (string, error) {
+	var output []byte
+	for !p.End() {
+		ch, err := unvisRune(p)
+		if err != nil {
+			return "", fmt.Errorf("input: %s", err)
+		}
+		output = append(output, ch...)
+	}
+	return string(output), nil
+}
+
+// Unvis takes a string formatted with the given Vis flags (though only the
+// VisHTTPStyle flag is checked) and output the un-encoded version of the
+// encoded string. An error is returned if any escape sequences in the input
+// string were invalid.
+func Unvis(input string, flag VisFlag) (string, error) {
+	// TODO: Check all of the VisFlag bits.
+	p := newParser(input, flag)
+	output, err := unvis(p)
+	if err != nil {
+		return "", fmt.Errorf("unvis: %s", err)
+	}
+	if !p.End() {
+		return "", fmt.Errorf("unvis: trailing characters at end of input")
+	}
+	return output, nil
+}
--- a/pkg/govis/unvis_test.go
+++ b/pkg/govis/unvis_test.go
@ -0,0 +1,166 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+import (
+	"testing"
+)
+
+func TestUnvisError(t *testing.T) {
+	for _, test := range []string{
+		// Octal escape codes allow you to specify invalid byte values.
+		"\\777",
+		"\\420\\322\\455",
+		"\\652\\233",
+	} {
+		got, err := Unvis(test, DefaultVisFlags)
+		if err == nil {
+			t.Errorf("expected unvis(%q) to give an error, got %q", test, got)
+		}
+	}
+}
+
+func TestUnvisCStyleEscape(t *testing.T) {
+	for _, test := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"\\n\\v\\t\\s", "\n\v\t "},
+		{"\\\\n\\tt", "\\n\tt"},
+		{"\\b", "\b"},
+		{"\\r\\b\\n", "\r\b\n"},
+		{"\\a\\a\\b", "\x07\x07\b"},
+		{"\\f\\s\\E", "\f \x1b"},
+		// Hidden markers. They actually aren't generated by vis(3) but for
+		// some reason, they're supported...
+		{"test\\\ning", "testing"},
+		{"test\\$\\$ing", "testing"},
+	} {
+		got, err := Unvis(test.input, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %q", test.input, err)
+			continue
+		}
+		if got != test.expected {
+			t.Errorf("expected unvis(%q) = %q, got %q", test.input, test.expected, got)
+		}
+	}
+}
+
+func TestUnvisMetaEscape(t *testing.T) {
+	for _, test := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"\\M^ ?\\^ ", "\x80?\x00"},
+		{"\\M- ?\\^?", "\xa0?\x7f"},
+		{"\\M-x butterfly\\M^?", "\xf8 butterfly\xff"},
+		{"\\M^X steady-hand \\^& needle", "\x98 steady-hand \x06 needle"},
+		// TODO: Add some more of these tests, but I need to have some
+		//       secondary source to verify these outputs properly.
+	} {
+		got, err := Unvis(test.input, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %q", test.input, err)
+			continue
+		}
+		if got != test.expected {
+			t.Errorf("expected unvis(%q) = %q, got %q", test.input, test.expected, got)
+		}
+	}
+}
+
+func TestUnvisOctalEscape(t *testing.T) {
+	for _, test := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"\\1", "\001"},
+		{"\\01\\02\\3", "\001\002\003"},
+		{"\\001\\023\\32", "\001\023\032"},
+		{"this is a test\\0k1\\133", "this is a test\000k1\133"},
+		{"\\170YET\\01another test\\1\\\\82", "\170YET\001another test\001\\82"},
+		{"\\177MORE tests\\09a", "\177MORE tests\x009a"},
+		{"\\\\710more\\1215testing", "\\710more\1215testing"},
+		// Make sure that decoding unicode works properly, when it's been encoded as single bytes.
+		{"\\360\\237\\225\\264", "\U0001f574"},
+		{"T\\303\\234B\\304\\260TAK_UEKAE_K\\303\\266k_Sertifika_Hizmet_Sa\\304\\237lay\\304\\261c\\304\\261s\\304\\261_-_S\\303\\274r\\303\\274m_3.pem", "TÜBİTAK_UEKAE_Kök_Sertifika_Hizmet_Sağlayıcısı_-_Sürüm_3.pem"},
+		// Some invalid characters...
+		{"\\377\\2\\225\\264", "\xff\x02\x95\xb4"},
+	} {
+		got, err := Unvis(test.input, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %q", test.input, err)
+			continue
+		}
+		if got != test.expected {
+			t.Errorf("expected unvis(%q) = %q, got %q", test.input, test.expected, got)
+		}
+	}
+}
+
+func TestUnvisHexEscape(t *testing.T) {
+	for _, test := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"\\x01", "\x01"},
+		{"\\x01\\x02\\x7a", "\x01\x02\x7a"},
+		{"this is a test\\x13\\x52\\x6f", "this is a test\x13\x52\x6f"},
+		{"\\x170YET\\x01a\\x22nother test\\x11", "\x170YET\x01a\x22nother test\x11"},
+		{"\\\\x007more\\\\x215testing", "\\x007more\\x215testing"},
+		// Make sure that decoding unicode works properly, when it's been encoded as single bytes.
+		{"\\xf0\\x9f\\x95\\xb4", "\U0001f574"},
+		{"T\\xc3\\x9cB\\xc4\\xb0TAK_UEKAE_K\\xc3\\xb6k_Sertifika_Hizmet_Sa\\xc4\\x9flay\\xc4\\xb1c\\xc4\\xb1s\\xc4\\xb1_-_S\\xc3\\xbcr\\xc3\\xbcm_3.pem", "TÜBİTAK_UEKAE_Kök_Sertifika_Hizmet_Sağlayıcısı_-_Sürüm_3.pem"},
+		// Some invalid characters...
+		{"\\xff\\x02\\x95\\xb4", "\xff\x02\x95\xb4"},
+	} {
+		got, err := Unvis(test.input, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %q", test.input, err)
+			continue
+		}
+		if got != test.expected {
+			t.Errorf("expected unvis(%q) = %q, got %q", test.input, test.expected, got)
+		}
+	}
+}
+
+func TestUnvisUnicode(t *testing.T) {
+	// Ensure that unicode strings are not messed up by Unvis.
+	for _, test := range []string{
+		"",
+		"this.is.a.normal_string",
+		"AC_Raíz_Certicámara_S.A..pem",
+		"NetLock_Arany_=Class_Gold=_Főtanúsítvány.pem",
+		"TÜBİTAK_UEKAE_Kök_Sertifika_Hizmet_Sağlayıcısı_-_Sürüm_3.pem",
+	} {
+		got, err := Unvis(test, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error doing unvis(%q): %s", test, err)
+			continue
+		}
+		if got != test {
+			t.Errorf("expected %q to be unchanged, got %q", test, got)
+		}
+	}
+}
--- a/pkg/govis/vis.go
+++ b/pkg/govis/vis.go
@ -0,0 +1,177 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+import (
+	"fmt"
+	"unicode"
+)
+
+func isunsafe(ch rune) bool {
+	return ch == '\b' || ch == '\007' || ch == '\r'
+}
+
+func isglob(ch rune) bool {
+	return ch == '*' || ch == '?' || ch == '[' || ch == '#'
+}
+
+// ishttp is defined by RFC 1808.
+func ishttp(ch rune) bool {
+	// RFC1808 does not really consider characters outside of ASCII, so just to
+	// be safe always treat characters outside the ASCII character set as "not
+	// HTTP".
+	if ch > unicode.MaxASCII {
+		return false
+	}
+
+	return unicode.IsDigit(ch) || unicode.IsLetter(ch) ||
+		// Safe characters.
+		ch == '$' || ch == '-' || ch == '_' || ch == '.' || ch == '+' ||
+		// Extra characters.
+		ch == '!' || ch == '*' || ch == '\'' || ch == '(' ||
+		ch == ')' || ch == ','
+}
+
+func isgraph(ch rune) bool {
+	return unicode.IsGraphic(ch) && !unicode.IsSpace(ch) && ch <= unicode.MaxASCII
+}
+
+// vis converts a single *byte* into its encoding. While Go supports the
+// concept of runes (and thus native utf-8 parsing), in order to make sure that
+// the bit-stream will be completely maintained through an Unvis(Vis(...))
+// round-trip. The downside is that Vis() will never output unicode -- but on
+// the plus side this is actually a benefit on the encoding side (it will
+// always work with the simple unvis(3) implementation). It also means that we
+// don't have to worry about different multi-byte encodings.
+func vis(b byte, flag VisFlag) (string, error) {
+	// Treat the single-byte character as a rune.
+	ch := rune(b)
+
+	// XXX: This is quite a horrible thing to support.
+	if flag&VisHTTPStyle == VisHTTPStyle {
+		if !ishttp(ch) {
+			return "%" + fmt.Sprintf("%.2X", ch), nil
+		}
+	}
+
+	// Figure out if the character doesn't need to be encoded. Effectively, we
+	// encode most "normal" (graphical) characters as themselves unless we have
+	// been specifically asked not to. Note though that we *ALWAYS* encode
+	// everything outside ASCII.
+	// TODO: Switch this to much more logical code.
+
+	if ch > unicode.MaxASCII {
+		/* ... */
+	} else if flag&VisGlob == VisGlob && isglob(ch) {
+		/* ... */
+	} else if isgraph(ch) ||
+		(flag&VisSpace != VisSpace && ch == ' ') ||
+		(flag&VisTab != VisTab && ch == '\t') ||
+		(flag&VisNewline != VisNewline && ch == '\n') ||
+		(flag&VisSafe != 0 && isunsafe(ch)) {
+
+		encoded := string(ch)
+		if ch == '\\' && flag&VisNoSlash == 0 {
+			encoded += "\\"
+		}
+		return encoded, nil
+	}
+
+	// Try to use C-style escapes first.
+	if flag&VisCStyle == VisCStyle {
+		switch ch {
+		case ' ':
+			return "\\s", nil
+		case '\n':
+			return "\\n", nil
+		case '\r':
+			return "\\r", nil
+		case '\b':
+			return "\\b", nil
+		case '\a':
+			return "\\a", nil
+		case '\v':
+			return "\\v", nil
+		case '\t':
+			return "\\t", nil
+		case '\f':
+			return "\\f", nil
+		case '\x00':
+			// Output octal just to be safe.
+			return "\\000", nil
+		}
+	}
+
+	// For graphical characters we generate octal output (and also if it's
+	// being forced by the caller's flags). Also spaces should always be
+	// encoded as octal.
+	if flag&VisOctal == VisOctal || isgraph(ch) || ch&0x7f == ' ' {
+		// Always output three-character octal just to be safe.
+		return fmt.Sprintf("\\%.3o", ch), nil
+	}
+
+	// Now we have to output meta or ctrl escapes. As far as I can tell, this
+	// is not actually defined by any standard -- so this logic is basically
+	// copied from the original vis(3) implementation. Hopefully nobody
+	// actually relies on this (octal and hex are better).
+
+	encoded := ""
+	if flag&VisNoSlash == 0 {
+		encoded += "\\"
+	}
+
+	// Meta characters have 0x80 set, but are otherwise identical to control
+	// characters.
+	if b&0x80 != 0 {
+		b &= 0x7f
+		encoded += "M"
+	}
+
+	if unicode.IsControl(rune(b)) {
+		encoded += "^"
+		if b == 0x7f {
+			encoded += "?"
+		} else {
+			encoded += fmt.Sprintf("%c", b+'@')
+		}
+	} else {
+		encoded += fmt.Sprintf("-%c", b)
+	}
+
+	return encoded, nil
+}
+
+// Vis encodes the provided string to a BSD-compatible encoding using BSD's
+// vis() flags. However, it will correctly handle multi-byte encoding (which is
+// not done properly by BSD's vis implementation).
+func Vis(src string, flag VisFlag) (string, error) {
+	if flag&visMask != flag {
+		return "", fmt.Errorf("vis: flag %q contains unknown or unsupported flags", flag)
+	}
+
+	output := ""
+	for _, ch := range []byte(src) {
+		encodedCh, err := vis(ch, flag)
+		if err != nil {
+			return "", err
+		}
+		output += encodedCh
+	}
+
+	return output, nil
+}
--- a/pkg/govis/vis_test.go
+++ b/pkg/govis/vis_test.go
@ -0,0 +1,127 @@
+/*
+ * govis: unicode aware vis(3) encoding implementation
+ * Copyright (C) 2017 SUSE LLC.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package govis
+
+import (
+	"testing"
+)
+
+func TestVisUnchanged(t *testing.T) {
+	for _, test := range []struct {
+		input string
+		flag  VisFlag
+	}{
+		{"", DefaultVisFlags},
+		{"helloworld", DefaultVisFlags},
+		{"THIS_IS_A_TEST1234", DefaultVisFlags},
+		{"SomeEncodingsAreCool", DefaultVisFlags},
+		{"spaces are totally safe", DefaultVisFlags &^ VisSpace},
+		{"tabs\tare\talso\tsafe!!", DefaultVisFlags &^ VisTab},
+		{"just\a\atrustme\r\b\b!!", DefaultVisFlags | VisSafe},
+	} {
+		enc, err := Vis(test.input, test.flag)
+		if err != nil {
+			t.Errorf("unexpected error with %q: %s", test, err)
+		}
+		if enc != test.input {
+			t.Errorf("expected encoding of %q (flag=%q) to be unchanged, got %q", test.input, test.flag, enc)
+		}
+	}
+}
+
+func TestVisFlags(t *testing.T) {
+	for _, test := range []struct {
+		input  string
+		output string
+		flag   VisFlag
+	}{
+		// Default
+		{"AC_Ra\u00edz_Certic\u00e1mara_S.A..pem", "AC_Ra\\M-C\\M--z_Certic\\M-C\\M-!mara_S.A..pem", 0},
+		{"z^i3i$\u00d3\u008anqgh5/t\u00e5<86>\u00b2kzla\\e^lv\u00df\u0093nv\u00df\u00aea|3}\u00d8\u0088\u00d6\u0084", `z^i3i$\M-C\M^S\M-B\M^Jnqgh5/t\M-C\M-%<86>\M-B\M-2kzla\\e^lv\M-C\M^_\M-B\M^Snv\M-C\M^_\M-B\M-.a|3}\M-C\M^X\M-B\M^H\M-C\M^V\M-B\M^D`, 0},
+		{"@?e1xs+.R_Kjo]7s8pgRP:*nXCE4{!c", "@?e1xs+.R_Kjo]7s8pgRP:*nXCE4{!c", 0},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_\M-C\M^F\M-C\M^F2\M-B\M-.\M-B\M-7m\M-C\M^[\M-C\M^Cr^\M-B\M-?p\M-C\M^Fu'q\M-C\M-;c2\M-C\M-0u\M-B\M-8\M-C\M^]\M-C\M-(v\M-C\M-?\M-B\M-0\M-C\M^\\M-C\M^B\M-C\M-53\M-C\M^[-k\M-C\M-2sd4\\p\M-C\M^Z\M-B\M-&\M-C\M^S\M-C\M-.a<\M-C\M-&s{\M-B\240p\M-C\M-0\M-C\M-?j\M-C\240\M-C\M-(\M-B\M-8\M-B\M-8\M-B\M-<\M-C\M-<b`, 0},
+		{"\u9003\"9v1)T798|o;fly jnKX\u0489Be=", `\M-i\M^@\M^C"9v1)T798|o;fly jnKX\M-R\M^IBe=`, 0},
+		// VisOctal
+		{"", "", VisOctal},
+		{"\022", "\\022", VisOctal},
+		{"\n \t", "\\012\\040\t", VisNewline | VisSpace | VisOctal},
+		{"\x12\f\a\n\v\b  \U00012312", "\\022\\014\\007\n\\013\\010  \\360\\222\\214\\222", VisOctal},
+		{"AC_Ra\u00edz_Certic\u00e1mara_S.A..pem", "AC_Ra\\303\\255z_Certic\\303\\241mara_S.A..pem", VisOctal},
+		{"z^i3i$\u00d3\u008anqgh5/t\u00e5<86>\u00b2kzla\\e^lv\u00df\u0093nv\u00df\u00aea|3}\u00d8\u0088\u00d6\u0084", `z^i3i$\303\223\302\212nqgh5/t\303\245<86>\302\262kzla\\e^lv\303\237\302\223nv\303\237\302\256a|3}\303\230\302\210\303\226\302\204`, VisOctal},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_\303\206\303\2062\302\256\302\267m\303\233\303\203r^\302\277p\303\206u'q\303\273c2\303\260u\302\270\303\235\303\250v\303\277\302\260\303\234\303\202\303\2653\303\233-k\303\262sd4\\p\303\232\302\246\303\223\303\256a<\303\246s{\302\240p\303\260\303\277j\303\240\303\250\302\270\302\270\302\274\303\274b`, VisOctal},
+		{"\u9003\"9v1)T798|o;fly jnKX\u0489Be=", `\351\200\203"9v1)T798|o;fly jnKX\322\211Be=`, VisOctal},
+		// VisCStyle
+		{"\x00 \f \a \n\v\b \r \t\r", "\\000 \\f \\a \n\\v\\b \\r \t\\r", VisCStyle},
+		{"\t \n\v\b", "\\t \n\\v\\b", VisTab | VisCStyle},
+		{"\n\v\t   ", "\n\\v\t\\s\\s\\s", VisSpace | VisCStyle},
+		{"\n \n   ", "\\n \\n   ", VisNewline | VisCStyle},
+		{"z^i3i$\u00d3\u008anqgh5/t\u00e5<86>\u00b2kzla\\e^lv\u00df\u0093nv\u00df\u00aea|3}\u00d8\u0088\u00d6\u0084", `z^i3i$\M-C\M^S\M-B\M^Jnqgh5/t\M-C\M-%<86>\M-B\M-2kzla\\e^lv\M-C\M^_\M-B\M^Snv\M-C\M^_\M-B\M-.a|3}\M-C\M^X\M-B\M^H\M-C\M^V\M-B\M^D`, VisCStyle},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_\M-C\M^F\M-C\M^F2\M-B\M-.\M-B\M-7m\M-C\M^[\M-C\M^Cr^\M-B\M-?p\M-C\M^Fu'q\M-C\M-;c2\M-C\M-0u\M-B\M-8\M-C\M^]\M-C\M-(v\M-C\M-?\M-B\M-0\M-C\M^\\M-C\M^B\M-C\M-53\M-C\M^[-k\M-C\M-2sd4\\p\M-C\M^Z\M-B\M-&\M-C\M^S\M-C\M-.a<\M-C\M-&s{\M-B\240p\M-C\M-0\M-C\M-?j\M-C\240\M-C\M-(\M-B\M-8\M-B\M-8\M-B\M-<\M-C\M-<b`, VisCStyle},
+		{"\u9003\"9v1)T798|o;fly jnKX\u0489Be=", `\M-i\M^@\M^C"9v1)T798|o;fly\sjnKX\M-R\M^IBe=`, VisCStyle | VisSpace},
+		// VisSpace
+		{"  ", `\040\040`, VisSpace},
+		{"\t \t", "\t\\040\t", VisSpace},
+		{"\\040   plenty of characters here   ", `\\040\040\040\040plenty\040of\040characters\040here\040\040\040`, VisSpace},
+		{"Js9L\u00cd\u00b2o?4824y'$|P}FIr%mW /KL9$]~", `Js9L\M-C\M^M\M-B\M-2o?4824y'$|P}FIr%mW\040/KL9$]~`, VisWhite},
+		{"1\u00c6\u00abTcz+Vda?)k1%\\\"P;`po`h", `1\M-C\M^F\M-B\M-+Tcz+Vda?)k1%\\"P;` + "`po`" + `h`, VisWhite},
+		{"\u9003\"9v1)T798|o;fly jnKX\u0489Be=", `\M-i\M^@\M^C"9v1)T798|o;fly\040jnKX\M-R\M^IBe=`, VisSpace},
+		// VisTab
+		{"\t  \v", "\\^I  \\^K", VisTab},
+		{"\t  \v", "\\011  \\013", VisTab | VisOctal},
+		// VisNewline
+		{"\t\n  \v\r\n", "\t\\^J  \\^K\\^M\\^J", VisNewline},
+		{"\t\n  \v\r\n", "\t\\012  \\013\\015\\012", VisNewline | VisOctal},
+		// VisSafe
+		// VisHTTPStyle
+		{"\x12\f\a\n\v\b  \U00012312", `%12%0C%07%0A%0B%08%20%20%F0%92%8C%92`, VisHTTPStyle},
+		{"1\u00c6\u00abTcz+Vda?)k1%\\\"P;`po`h", `1%C3%86%C2%ABTcz+Vda%3F)k1%25%5C%22P%3B%60po%60h`, VisHTTPStyle},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_%C3%86%C3%862%C2%AE%C2%B7m%C3%9B%C3%83r%5E%C2%BFp%C3%86u'q%C3%BBc2%C3%B0u%C2%B8%C3%9D%C3%A8v%C3%BF%C2%B0%C3%9C%C3%82%C3%B53%C3%9B-k%C3%B2sd4%5Cp%C3%9A%C2%A6%C3%93%C3%AEa%3C%C3%A6s%7B%C2%A0p%C3%B0%C3%BFj%C3%A0%C3%A8%C2%B8%C2%B8%C2%BC%C3%BCb`, VisHTTPStyle},
+		{"'3Ze\u050e|\u02del\u069du-Rpct4+Z5b={@_{b", `'3Ze%D4%8E%7C%CB%9El%DA%9Du-Rpct4+Z5b%3D%7B%40_%7Bb`, VisHTTPStyle},
+		// VisGlob
+		{"cat /proc/**/status | grep '[pid]' ;; # cool code here", `cat /proc/\052\052/status | grep '\133pid]' ;; \043 cool code here`, VisGlob},
+		{"@?e1xs+.R_Kjo]7s8pgRP:*nXCE4{!c", `@\077e1xs+.R_Kjo]7s8pgRP:\052nXCE4{!c`, VisGlob},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_\M-C\M^F\M-C\M^F2\M-B\M-.\M-B\M-7m\M-C\M^[\M-C\M^Cr^\M-B\M-?p\M-C\M^Fu'q\M-C\M-;c2\M-C\M-0u\M-B\M-8\M-C\M^]\M-C\M-(v\M-C\M-?\M-B\M-0\M-C\M^\\M-C\M^B\M-C\M-53\M-C\M^[-k\M-C\M-2sd4\\p\M-C\M^Z\M-B\M-&\M-C\M^S\M-C\M-.a<\M-C\M-&s{\M-B\240p\M-C\M-0\M-C\M-?j\M-C\240\M-C\M-(\M-B\M-8\M-B\M-8\M-B\M-<\M-C\M-<b`, VisGlob},
+		{"62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb", `62_\303\206\303\2062\302\256\302\267m\303\233\303\203r^\302\277p\303\206u'q\303\273c2\303\260u\302\270\303\235\303\250v\303\277\302\260\303\234\303\202\303\2653\303\233-k\303\262sd4\\p\303\232\302\246\303\223\303\256a<\303\246s{\302\240p\303\260\303\277j\303\240\303\250\302\270\302\270\302\274\303\274b`, VisGlob | VisOctal},
+		{"'3Ze\u050e|\u02del\u069du-Rpct4+Z5b={@_{b", `'3Ze\M-T\M^N|\M-K\M^^l\M-Z\M^]u-Rpct4+Z5b={@_{b`, VisGlob},
+		{"'3Ze\u050e|\u02del\u069du-Rpct4+Z5b={@_{b", `'3Ze\324\216|\313\236l\332\235u-Rpct4+Z5b={@_{b`, VisGlob | VisOctal},
+	} {
+		enc, err := Vis(test.input, test.flag)
+		if err != nil {
+			t.Errorf("unexpected error with %q: %s", test, err)
+		}
+		if enc != test.output {
+			t.Errorf("expected vis(%q, flag=%b) = %q, got %q", test.input, test.flag, test.output, enc)
+		}
+	}
+}
+
+func TestVisChanged(t *testing.T) {
+	for _, test := range []string{
+		"hello world",
+		"THIS\\IS_A_TEST1234",
+		"AC_Ra\u00edz_Certic\u00e1mara_S.A..pem",
+	} {
+		enc, err := Vis(test, DefaultVisFlags)
+		if err != nil {
+			t.Errorf("unexpected error with %q: %s", test, err)
+		}
+		if enc == test {
+			t.Errorf("expected encoding of %q to be changed", test)
+		}
+	}
+}
--- a/tar.go
+++ b/tar.go
@ -9,6 +9,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/vbatts/go-mtree/pkg/govis"
 )

 // Streamer creates a file hierarchy out of a tar stream
@ -128,7 +130,7 @@ hdrloop:
 			return
 		}
 		// Alright, it's either file or directory
-		encodedName, err := Vis(filepath.Base(hdr.Name), DefaultVisFlags)
+		encodedName, err := govis.Vis(filepath.Base(hdr.Name), DefaultVisFlags)
 		if err != nil {
 			tmpFile.Close()
 			os.Remove(tmpFile.Name())
@ -148,7 +150,7 @@ hdrloop:
 				log.Println(err)
 				break
 			}
-			linkname, err := Unvis(KeyVal(kv).Value())
+			linkname, err := govis.Unvis(KeyVal(kv).Value(), DefaultVisFlags)
 			if err != nil {
 				log.Println(err)
 				break
@ -248,7 +250,7 @@ func populateTree(root, e *Entry, hdr *tar.Header) error {
 	dirNames := strings.Split(wd, "/")
 	parent := root
 	for _, name := range dirNames[:] {
-		encoded, err := Vis(name, DefaultVisFlags)
+		encoded, err := govis.Vis(name, DefaultVisFlags)
 		if err != nil {
 			return err
 		}
--- a/unvis.go
+++ b/unvis.go
@ -1,7 +0,0 @@
-package mtree
-
-// Unvis is a wrapper for the C implementation of unvis, which decodes a string
-// that potentially has characters that are encoded with Vis
-func Unvis(src string) (string, error) {
-	return unvis(src)
-}
--- a/unvis_c.go
+++ b/unvis_c.go
@ -1,11 +0,0 @@
-// +build cgo,cvis
-
-package mtree
-
-import (
-	"github.com/vbatts/go-mtree/cvis"
-)
-
-func unvis(src string) (string, error) {
-	return cvis.Unvis(src)
-}
--- a/unvis_go.go
+++ b/unvis_go.go
@ -1,233 +0,0 @@
-// +build !cvis
-
-package mtree
-
-import "unicode"
-
-func unvis(src string) (string, error) {
-	dst := []rune{}
-	var s state
-	for i, r := range src {
-	again:
-		err := unvisRune(&dst, r, &s, 0)
-		switch err {
-		case unvisValid:
-			break
-		case unvisValidPush:
-			goto again
-		case unvisNone:
-			fallthrough
-		case unvisNochar:
-			break
-		default:
-			return "", err
-		}
-		if i == len(src)-1 {
-			unvisRune(&dst, r, &s, unvisEnd)
-		}
-	}
-
-	str := ""
-	for _, ch := range dst {
-		str += string(ch)
-	}
-	return str, nil
-}
-
-func unvisRune(dst *[]rune, r rune, s *state, flags VisFlag) error {
-	if (flags & unvisEnd) != 0 {
-		if *s == stateOctal2 || *s == stateOctal3 {
-			*s = stateGround
-			return unvisValid
-		}
-		if *s == stateGround {
-			return unvisNochar
-		}
-		return unvisErrSynbad
-	}
-
-	switch *s & ^stateHTTP {
-	case stateGround:
-		if r == '\\' {
-			*s = stateStart
-			return unvisNone
-		}
-		if flags&VisHttpstyle != 0 && r == '%' {
-			*s = stateStart | stateHTTP
-			return unvisNone
-		}
-		*dst = append(*dst, r)
-		return unvisValid
-	case stateStart:
-		if *s&stateHTTP != 0 && ishex(unicode.ToLower(r)) {
-			if unicode.IsNumber(r) {
-				*dst = append(*dst, r-'0')
-			} else {
-				*dst = append(*dst, unicode.ToLower(r)-'a')
-			}
-			*s = stateHex2
-			return unvisNone
-		}
-		switch r {
-		case '\\':
-			*s = stateGround
-			*dst = append(*dst, r)
-			return unvisValid
-		case '0':
-			fallthrough
-		case '1':
-			fallthrough
-		case '2':
-			fallthrough
-		case '3':
-			fallthrough
-		case '4':
-			fallthrough
-		case '5':
-			fallthrough
-		case '6':
-			fallthrough
-		case '7':
-			*s = stateOctal2
-			*dst = append(*dst, r-'0')
-			return unvisNone
-		case 'M':
-			*s = stateMeta
-			*dst = append(*dst, rune(0200))
-			return unvisNone
-		case '^':
-			*s = stateCtrl
-			return unvisNone
-		case 'n':
-			*s = stateGround
-			*dst = append(*dst, '\n')
-			return unvisValid
-		case 'r':
-			*s = stateGround
-			*dst = append(*dst, '\r')
-			return unvisValid
-		case 'b':
-			*s = stateGround
-			*dst = append(*dst, '\b')
-			return unvisValid
-		case 'a':
-			*s = stateGround
-			*dst = append(*dst, '\007')
-			return unvisValid
-		case 'v':
-			*s = stateGround
-			*dst = append(*dst, '\v')
-			return unvisValid
-		case 't':
-			*s = stateGround
-			*dst = append(*dst, '\t')
-			return unvisValid
-		case 'f':
-			*s = stateGround
-			*dst = append(*dst, '\f')
-			return unvisValid
-		case 's':
-			*s = stateGround
-			*dst = append(*dst, ' ')
-			return unvisValid
-		case 'E':
-			*s = stateGround
-			*dst = append(*dst, '\033')
-			return unvisValid
-		case '\n':
-			// hidden newline
-			*s = stateGround
-			return unvisNochar
-		case '$':
-			// hidden marker
-			*s = stateGround
-			return unvisNochar
-		}
-		*s = stateGround
-		return unvisErrSynbad
-	case stateMeta:
-		if r == '-' {
-			*s = stateMeta1
-		} else if r == '^' {
-			*s = stateCtrl
-		} else {
-			*s = stateGround
-			return unvisErrSynbad
-		}
-		return unvisNone
-	case stateMeta1:
-		*s = stateGround
-		dp := *dst
-		dp[len(dp)-1] |= r
-		return unvisValid
-	case stateCtrl:
-		dp := *dst
-		if r == '?' {
-			dp[len(dp)-1] |= rune(0177)
-		} else {
-			dp[len(dp)-1] |= r & 037
-		}
-		*s = stateGround
-		return unvisValid
-	case stateOctal2:
-		if isoctal(r) {
-			dp := *dst
-			if len(dp) > 0 {
-				last := dp[len(dp)-1]
-				dp[len(dp)-1] = (last << 3) + (r - '0')
-			} else {
-				dp = append(dp, (0<<3)+(r-'0'))
-			}
-			*s = stateOctal3
-			return unvisNone
-		}
-		*s = stateGround
-		return unvisValidPush
-	case stateOctal3:
-		*s = stateGround
-		if isoctal(r) {
-			dp := *dst
-			if len(dp) > 0 {
-				last := dp[len(dp)-1]
-				dp[len(dp)-1] = (last << 3) + (r - '0')
-			} else {
-				dp = append(dp, (0<<3)+(r-'0'))
-			}
-			return unvisValid
-		}
-		return unvisValidPush
-	case stateHex2:
-		if ishex(unicode.ToLower(r)) {
-			last := rune(0)
-			dp := *dst
-			if len(dp) > 0 {
-				last = dp[len(dp)-1]
-			}
-			if unicode.IsNumber(r) {
-				dp = append(dp, (last<<4)+(r-'0'))
-			} else {
-				dp = append(dp, (last<<4)+(unicode.ToLower(r)-'a'+10))
-			}
-		}
-		*s = stateGround
-		return unvisValid
-	}
-
-	*s = stateGround
-	return unvisErrSynbad
-}
-
-type state int
-
-const (
-	stateGround state = iota /* haven't seen escape char */
-	stateStart               /* start decoding special sequence */
-	stateMeta                /* metachar started (M) */
-	stateMeta1               /* metachar more, regular char (-) */
-	stateCtrl                /* control char started (^) */
-	stateOctal2              /* octal digit 2 */
-	stateOctal3              /* octal digit 3 */
-	stateHex2                /* hex digit 2 */
-
-	stateHTTP state = 0x080 /* %HEXHEX escape */
-)
--- a/unvis_go_test.go
+++ b/unvis_go_test.go
@ -1,93 +0,0 @@
-package mtree
-
-import "testing"
-
-type runeCheck func(rune) bool
-
-func TestUnvisHelpers(t *testing.T) {
-	testset := []struct {
-		R      rune
-		Check  runeCheck
-		Expect bool
-	}{
-		{'a', ishex, true},
-		{'A', ishex, true},
-		{'z', ishex, false},
-		{'Z', ishex, false},
-		{'G', ishex, false},
-		{'1', ishex, true},
-		{'0', ishex, true},
-		{'9', ishex, true},
-		{'0', isoctal, true},
-		{'3', isoctal, true},
-		{'7', isoctal, true},
-		{'9', isoctal, false},
-		{'a', isoctal, false},
-		{'z', isoctal, false},
-		{'3', isalnum, true},
-		{'a', isalnum, true},
-		{';', isalnum, false},
-		{'!', isalnum, false},
-		{' ', isalnum, false},
-		{'3', isgraph, true},
-		{'a', isgraph, true},
-		{';', isgraph, true},
-		{'!', isgraph, true},
-		{' ', isgraph, false},
-	}
-
-	for i, ts := range testset {
-		got := ts.Check(ts.R)
-		if got != ts.Expect {
-			t.Errorf("%d: %q expected: %t; got %t", i, string(ts.R), ts.Expect, got)
-		}
-	}
-}
-
-func TestUnvisUnicode(t *testing.T) {
-	// Ensure that unicode strings are not messed up by Unvis.
-	for _, test := range []string{
-		"",
-		"this.is.a.normal_string",
-		"AC_Raíz_Certicámara_S.A..pem",
-		"NetLock_Arany_=Class_Gold=_Főtanúsítvány.pem",
-		"TÜBİTAK_UEKAE_Kök_Sertifika_Hizmet_Sağlayıcısı_-_Sürüm_3.pem",
-	} {
-		got, err := Unvis(test)
-		if err != nil {
-			t.Errorf("unexpected error doing unvis(%q): %s", test, err)
-			continue
-		}
-		if got != test {
-			t.Errorf("expected %q to be unchanged, got %q", test, got)
-		}
-	}
-}
-
-func TestVisUnvis(t *testing.T) {
-	// Round-trip testing.
-	for _, test := range []string{
-		"",
-		"this.is.a.normal_string",
-		"AC_Raíz_Certicámara_S.A..pem",
-		"NetLock_Arany_=Class_Gold=_Főtanúsítvány.pem",
-		"TÜBİTAK_UEKAE_Kök_Sertifika_Hizmet_Sağlayıcısı_-_Sürüm_3.pem",
-		"hello world [ this string needs=enco ding! ]",
-		"even \n more encoding necessary\a\a ",
-		"\024 <-- some more weird characters --> 你好，世界",
-	} {
-		enc, err := Vis(test, DefaultVisFlags)
-		if err != nil {
-			t.Errorf("unexpected error doing vis(%q): %s", test, err)
-			continue
-		}
-		dec, err := Unvis(enc)
-		if err != nil {
-			t.Errorf("unexpected error doing unvis(%q): %s", enc, err)
-			continue
-		}
-		if dec != test {
-			t.Errorf("roundtrip failed: unvis(vis(%q) = %q) = %q", test, enc, dec)
-		}
-	}
-}
--- a/vis.go
+++ b/vis.go
@ -1,89 +0,0 @@
-package mtree
-
-import "unicode"
-
-// Vis is a wrapper of the C implementation of the function vis, which encodes
-// a character with a particular format/style.
-// For most use-cases use DefaultVisFlags.
-func Vis(src string, flags VisFlag) (string, error) {
-	return vis(src, flags)
-}
-
-// DefaultVisFlags are the typical flags used for encoding strings in mtree
-// manifests.
-var DefaultVisFlags = VisWhite | VisOctal | VisGlob
-
-// VisFlag sets the extent of charactures to be encoded
-type VisFlag int
-
-// flags for encoding
-const (
-	// to select alternate encoding format
-	VisOctal  VisFlag = 0x01 // use octal \ddd format
-	VisCstyle VisFlag = 0x02 // use \[nrft0..] where appropriate
-
-	// to alter set of characters encoded (default is to encode all non-graphic
-	// except space, tab, and newline).
-	VisSp    VisFlag = 0x04 // also encode space
-	VisTab   VisFlag = 0x08 // also encode tab
-	VisNl    VisFlag = 0x10 // also encode newline
-	VisWhite VisFlag = (VisSp | VisTab | VisNl)
-	VisSafe  VisFlag = 0x20 // only encode "unsafe" characters
-
-	// other
-	VisNoSlash   VisFlag = 0x40  // inhibit printing '\'
-	VisHttpstyle VisFlag = 0x80  // http-style escape % HEX HEX
-	VisGlob      VisFlag = 0x100 // encode glob(3) magics
-
-)
-
-// errors used in the tokenized decoding strings
-const (
-	// unvis return codes
-	unvisValid            unvisErr = 1  // character valid
-	unvisValidPush        unvisErr = 2  // character valid, push back passed char
-	unvisNochar           unvisErr = 3  // valid sequence, no character produced
-	unvisErrSynbad        unvisErr = -1 // unrecognized escape sequence
-	unvisErrUnrecoverable unvisErr = -2 // decoder in unknown state (unrecoverable)
-	unvisNone             unvisErr = 0
-
-	// unvisEnd means there are no more characters
-	unvisEnd VisFlag = 1 // no more characters
-)
-
-// unvisErr are the return conditions for Unvis
-type unvisErr int
-
-func (ue unvisErr) Error() string {
-	switch ue {
-	case unvisValid:
-		return "character valid"
-	case unvisValidPush:
-		return "character valid, push back passed char"
-	case unvisNochar:
-		return "valid sequence, no character produced"
-	case unvisErrSynbad:
-		return "unrecognized escape sequence"
-	case unvisErrUnrecoverable:
-		return "decoder in unknown state (unrecoverable)"
-	}
-	return "Unknown Error"
-}
-
-func ishex(r rune) bool {
-	lr := unicode.ToLower(r)
-	return (lr >= '0' && lr <= '9') || (lr >= 'a' && lr <= 'f')
-}
-
-func isoctal(r rune) bool {
-	return r <= '7' && r >= '0'
-}
-
-// the ctype isgraph is "any printable character except space"
-func isgraph(r rune) bool {
-	return unicode.IsPrint(r) && !unicode.IsSpace(r)
-}
-
-func isalnum(r rune) bool {
-	return unicode.IsNumber(r) || unicode.IsLetter(r)
-}
--- a/vis_c.go
+++ b/vis_c.go
@ -1,11 +0,0 @@
-// +build cgo,cvis
-
-package mtree
-
-import (
-	"github.com/vbatts/go-mtree/cvis"
-)
-
-func vis(src string, flags VisFlag) (string, error) {
-	return cvis.Vis(src, int(flags))
-}
--- a/vis_go.go
+++ b/vis_go.go
@ -1,107 +0,0 @@
-// +build !cvis
-
-package mtree
-
-import (
-	"fmt"
-	"unicode"
-)
-
-func vis(src string, flags VisFlag) (string, error) {
-	var ret string
-	for _, r := range src {
-		vStr, err := visRune(r, flags)
-		if err != nil {
-			return "", err
-		}
-		ret = ret + vStr
-	}
-	return ret, nil
-}
-
-func visRune(r rune, flags VisFlag) (string, error) {
-	if flags&VisHttpstyle != 0 {
-		// Described in RFC 1808
-		if !isalnum(r) ||
-			/* safe */
-			r == '$' || r == '-' || r == '_' || r == '.' || r == '+' ||
-			/* extra */
-			r == '!' || r == '*' || r == '\'' || r == '(' ||
-			r == ')' || r == ',' {
-			if r < 16 {
-				return fmt.Sprintf("%%0%X", r), nil
-			}
-			return fmt.Sprintf("%%%X", r), nil
-		}
-	}
-
-	if (flags&VisGlob) != 0 && (r == '*' || r == '?' || r == '[' || r == '#') {
-		// ... ?
-	} else if isgraph(r) ||
-		((flags&VisSp) == 0 && r == ' ') ||
-		((flags&VisTab) == 0 && r == '\t') ||
-		((flags&VisNl) == 0 && r == '\n') ||
-		((flags&VisSafe) != 0 && (r == '\b' || r == '\007' || r == '\r')) {
-		if r == '\\' && (flags&VisNoSlash) == 0 {
-			return fmt.Sprintf("%s\\", string(r)), nil
-		}
-		return string(r), nil
-	}
-
-	if (flags & VisCstyle) != 0 {
-		switch r {
-		case '\n':
-			return "\\n", nil
-		case '\r':
-			return "\\r", nil
-		case '\b':
-			return "\\b", nil
-		case '\a':
-			return "\\a", nil
-		case '\v':
-			return "\\v", nil
-		case '\t':
-			return "\\t", nil
-		case '\f':
-			return "\\f", nil
-		case ' ':
-			return "\\s", nil
-		case rune(0x0):
-			return "\\0", nil
-			/*
-				if isoctal(nextr) {
-					dst = append(dst, '0')
-					dst = append(dst, '0')
-				}
-			*/
-		}
-	}
-	if ((r & 0177) == ' ') || isgraph(r) || (flags&VisOctal) != 0 {
-		dst := make([]rune, 4)
-		dst[0] = '\\'
-		dst[1] = (r >> 6 & 07) + '0'
-		dst[2] = (r >> 3 & 07) + '0'
-		dst[3] = (r & 07) + '0'
-		return string(dst), nil
-	}
-	var dst []rune
-	if (flags & VisNoSlash) == 0 {
-		dst = append(dst, '\\')
-	}
-	if (r & 0200) != 0 {
-		r &= 0177
-		dst = append(dst, 'M')
-	}
-	if unicode.IsControl(r) {
-		dst = append(dst, '^')
-		if r == 0177 {
-			dst = append(dst, '?')
-		} else {
-			dst = append(dst, r+'@')
-		}
-	} else {
-		dst = append(dst, '-')
-		dst = append(dst, r)
-	}
-	return string(dst), nil
-}
--- a/vis_test.go
+++ b/vis_test.go
@ -1,39 +0,0 @@
-package mtree
-
-import "testing"
-
-func TestVisBasic(t *testing.T) {
-	testset := []struct {
-		Src, Dest string
-	}{
-		{"[", "\\133"},
-		{" ", "\\040"},
-		{"	", "\\011"},
-		{"dir with space", "dir\\040with\\040space"},
-		{"consec   spaces", "consec\\040\\040\\040spaces"},
-		{"trailingsymbol[", "trailingsymbol\\133"},
-		{" [ leadingsymbols", "\\040\\133\\040leadingsymbols"},
-		{"no_need_for_encoding", "no_need_for_encoding"},
-	}
-
-	for i := range testset {
-		got, err := Vis(testset[i].Src, DefaultVisFlags)
-		if err != nil {
-			t.Errorf("working with %q: %s", testset[i].Src, err)
-		}
-		if got != testset[i].Dest {
-			t.Errorf("%q: expected %#v; got %#v", testset[i].Src, testset[i].Dest, got)
-			continue
-		}
-
-		got, err = Unvis(got)
-		if err != nil {
-			t.Errorf("working with %q: %s: %q", testset[i].Src, err, got)
-			continue
-		}
-		if got != testset[i].Src {
-			t.Errorf("%q: expected %#v; got %#v", testset[i].Dest, testset[i].Src, got)
-			continue
-		}
-	}
-}
--- a/walk.go
+++ b/walk.go
@ -9,6 +9,8 @@ import (
 	"sort"
 	"strings"
 	"time"
+
+	"github.com/vbatts/go-mtree/pkg/govis"
 )

 // ExcludeFunc is the type of function called on each path walked to determine
@ -165,7 +167,7 @@ func Walk(root string, excludes []ExcludeFunc, keywords []Keyword, fsEval FsEval
 				}
 			}
 		}
-		encodedEntryName, err := Vis(entryPathName, DefaultVisFlags)
+		encodedEntryName, err := govis.Vis(entryPathName, DefaultVisFlags)
 		if err != nil {
 			return err
 		}