Imported Upstream version 60upstream/60

13 files changed, 2142 insertions, 0 deletions

diff --git a/src/pkg/path/Makefile b/src/pkg/path/Makefile
new file mode 100644
index 000000000..fc3e2519c
--- /dev/null
+++ b/src/pkg/path/Makefile
@@ -0,0 +1,14 @@
+# Copyright 2009 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include ../../Make.inc
+
+TARG=path
+GOFILES=\
+	match.go\
+	path.go\
+
+GOFILES+=$(GOFILES_$(GOOS))
+
+include ../../Make.pkg
diff --git a/src/pkg/path/filepath/Makefile b/src/pkg/path/filepath/Makefile
new file mode 100644
index 000000000..af250ab33
--- /dev/null
+++ b/src/pkg/path/filepath/Makefile
@@ -0,0 +1,32 @@
+# Copyright 2009 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include ../../../Make.inc
+
+TARG=path/filepath
+GOFILES=\
+	match.go\
+	path.go\
+
+GOFILES_freebsd=\
+	path_unix.go
+
+GOFILES_darwin=\
+	path_unix.go
+
+GOFILES_linux=\
+	path_unix.go
+
+GOFILES_openbsd=\
+	path_unix.go
+
+GOFILES_plan9=\
+	path_plan9.go
+
+GOFILES_windows=\
+	path_windows.go
+
+GOFILES+=$(GOFILES_$(GOOS))
+
+include ../../../Make.pkg
diff --git a/src/pkg/path/filepath/match.go b/src/pkg/path/filepath/match.go
new file mode 100644
index 000000000..7fcc214c0
--- /dev/null
+++ b/src/pkg/path/filepath/match.go
@@ -0,0 +1,294 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath
+
+import (
+	"os"
+	"sort"
+	"strings"
+	"utf8"
+)
+
+var ErrBadPattern = os.NewError("syntax error in pattern")
+
+// Match returns true if name matches the shell file name pattern.
+// The pattern syntax is:
+//
+//	pattern:
+//		{ term }
+//	term:
+//		'*'         matches any sequence of non-Separator characters
+//		'?'         matches any single non-Separator character
+//		'[' [ '^' ] { character-range } ']'
+//		            character class (must be non-empty)
+//		c           matches character c (c != '*', '?', '\\', '[')
+//		'\\' c      matches character c
+//
+//	character-range:
+//		c           matches character c (c != '\\', '-', ']')
+//		'\\' c      matches character c
+//		lo '-' hi   matches character c for lo <= c <= hi
+//
+// Match requires pattern to match all of name, not just a substring.
+// The only possible error return occurs when the pattern is malformed.
+//
+func Match(pattern, name string) (matched bool, err os.Error) {
+Pattern:
+	for len(pattern) > 0 {
+		var star bool
+		var chunk string
+		star, chunk, pattern = scanChunk(pattern)
+		if star && chunk == "" {
+			// Trailing * matches rest of string unless it has a /.
+			return strings.Index(name, string(Separator)) < 0, nil
+		}
+		// Look for match at current position.
+		t, ok, err := matchChunk(chunk, name)
+		// if we're the last chunk, make sure we've exhausted the name
+		// otherwise we'll give a false result even if we could still match
+		// using the star
+		if ok && (len(t) == 0 || len(pattern) > 0) {
+			name = t
+			continue
+		}
+		if err != nil {
+			return false, err
+		}
+		if star {
+			// Look for match skipping i+1 bytes.
+			// Cannot skip /.
+			for i := 0; i < len(name) && name[i] != Separator; i++ {
+				t, ok, err := matchChunk(chunk, name[i+1:])
+				if ok {
+					// if we're the last chunk, make sure we exhausted the name
+					if len(pattern) == 0 && len(t) > 0 {
+						continue
+					}
+					name = t
+					continue Pattern
+				}
+				if err != nil {
+					return false, err
+				}
+			}
+		}
+		return false, nil
+	}
+	return len(name) == 0, nil
+}
+
+// scanChunk gets the next segment of pattern, which is a non-star string
+// possibly preceded by a star.
+func scanChunk(pattern string) (star bool, chunk, rest string) {
+	for len(pattern) > 0 && pattern[0] == '*' {
+		pattern = pattern[1:]
+		star = true
+	}
+	inrange := false
+	var i int
+Scan:
+	for i = 0; i < len(pattern); i++ {
+		switch pattern[i] {
+		case '\\':
+			// error check handled in matchChunk: bad pattern.
+			if i+1 < len(pattern) {
+				i++
+			}
+		case '[':
+			inrange = true
+		case ']':
+			inrange = false
+		case '*':
+			if !inrange {
+				break Scan
+			}
+		}
+	}
+	return star, pattern[0:i], pattern[i:]
+}
+
+// matchChunk checks whether chunk matches the beginning of s.
+// If so, it returns the remainder of s (after the match).
+// Chunk is all single-character operators: literals, char classes, and ?.
+func matchChunk(chunk, s string) (rest string, ok bool, err os.Error) {
+	for len(chunk) > 0 {
+		if len(s) == 0 {
+			return
+		}
+		switch chunk[0] {
+		case '[':
+			// character class
+			r, n := utf8.DecodeRuneInString(s)
+			s = s[n:]
+			chunk = chunk[1:]
+			// possibly negated
+			negated := chunk[0] == '^'
+			if negated {
+				chunk = chunk[1:]
+			}
+			// parse all ranges
+			match := false
+			nrange := 0
+			for {
+				if len(chunk) > 0 && chunk[0] == ']' && nrange > 0 {
+					chunk = chunk[1:]
+					break
+				}
+				var lo, hi int
+				if lo, chunk, err = getEsc(chunk); err != nil {
+					return
+				}
+				hi = lo
+				if chunk[0] == '-' {
+					if hi, chunk, err = getEsc(chunk[1:]); err != nil {
+						return
+					}
+				}
+				if lo <= r && r <= hi {
+					match = true
+				}
+				nrange++
+			}
+			if match == negated {
+				return
+			}
+
+		case '?':
+			if s[0] == Separator {
+				return
+			}
+			_, n := utf8.DecodeRuneInString(s)
+			s = s[n:]
+			chunk = chunk[1:]
+
+		case '\\':
+			chunk = chunk[1:]
+			if len(chunk) == 0 {
+				err = ErrBadPattern
+				return
+			}
+			fallthrough
+
+		default:
+			if chunk[0] != s[0] {
+				return
+			}
+			s = s[1:]
+			chunk = chunk[1:]
+		}
+	}
+	return s, true, nil
+}
+
+// getEsc gets a possibly-escaped character from chunk, for a character class.
+func getEsc(chunk string) (r int, nchunk string, err os.Error) {
+	if len(chunk) == 0 || chunk[0] == '-' || chunk[0] == ']' {
+		err = ErrBadPattern
+		return
+	}
+	if chunk[0] == '\\' {
+		chunk = chunk[1:]
+		if len(chunk) == 0 {
+			err = ErrBadPattern
+			return
+		}
+	}
+	r, n := utf8.DecodeRuneInString(chunk)
+	if r == utf8.RuneError && n == 1 {
+		err = ErrBadPattern
+	}
+	nchunk = chunk[n:]
+	if len(nchunk) == 0 {
+		err = ErrBadPattern
+	}
+	return
+}
+
+// Glob returns the names of all files matching pattern or nil
+// if there is no matching file. The syntax of patterns is the same
+// as in Match. The pattern may describe hierarchical names such as
+// /usr/*/bin/ed (assuming the Separator is '/').
+// The only possible error return occurs when the pattern is malformed.
+//
+func Glob(pattern string) (matches []string, err os.Error) {
+	if !hasMeta(pattern) {
+		if _, err = os.Stat(pattern); err != nil {
+			return
+		}
+		return []string{pattern}, nil
+	}
+
+	dir, file := Split(pattern)
+	switch dir {
+	case "":
+		dir = "."
+	case string(Separator):
+		// nothing
+	default:
+		dir = dir[0 : len(dir)-1] // chop off trailing separator
+	}
+
+	if !hasMeta(dir) {
+		return glob(dir, file, nil)
+	}
+
+	var m []string
+	m, err = Glob(dir)
+	if err != nil {
+		return
+	}
+	for _, d := range m {
+		matches, err = glob(d, file, matches)
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+// glob searches for files matching pattern in the directory dir
+// and appends them to matches. If the directory cannot be
+// opened, it returns the existing matches. New matches are
+// added in lexicographical order.
+// The only possible error return occurs when the pattern is malformed.
+func glob(dir, pattern string, matches []string) (m []string, e os.Error) {
+	m = matches
+	fi, err := os.Stat(dir)
+	if err != nil {
+		return
+	}
+	if !fi.IsDirectory() {
+		return
+	}
+	d, err := os.Open(dir)
+	if err != nil {
+		return
+	}
+	defer d.Close()
+
+	names, err := d.Readdirnames(-1)
+	if err != nil {
+		return
+	}
+	sort.Strings(names)
+
+	for _, n := range names {
+		matched, err := Match(pattern, n)
+		if err != nil {
+			return m, err
+		}
+		if matched {
+			m = append(m, Join(dir, n))
+		}
+	}
+	return
+}
+
+// hasMeta returns true if path contains any of the magic characters
+// recognized by Match.
+func hasMeta(path string) bool {
+	// TODO(niemeyer): Should other magic characters be added here?
+	return strings.IndexAny(path, "*?[") >= 0
+}
diff --git a/src/pkg/path/filepath/match_test.go b/src/pkg/path/filepath/match_test.go
new file mode 100644
index 000000000..a1c8333f3
--- /dev/null
+++ b/src/pkg/path/filepath/match_test.go
@@ -0,0 +1,134 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath_test
+
+import (
+	"os"
+	. "path/filepath"
+	"testing"
+	"runtime"
+)
+
+type MatchTest struct {
+	pattern, s string
+	match      bool
+	err        os.Error
+}
+
+var matchTests = []MatchTest{
+	{"abc", "abc", true, nil},
+	{"*", "abc", true, nil},
+	{"*c", "abc", true, nil},
+	{"a*", "a", true, nil},
+	{"a*", "abc", true, nil},
+	{"a*", "ab/c", false, nil},
+	{"a*/b", "abc/b", true, nil},
+	{"a*/b", "a/c/b", false, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxe/f", true, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxexxx/f", true, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxe/xxx/f", false, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxexxx/fff", false, nil},
+	{"a*b?c*x", "abxbbxdbxebxczzx", true, nil},
+	{"a*b?c*x", "abxbbxdbxebxczzy", false, nil},
+	{"ab[c]", "abc", true, nil},
+	{"ab[b-d]", "abc", true, nil},
+	{"ab[e-g]", "abc", false, nil},
+	{"ab[^c]", "abc", false, nil},
+	{"ab[^b-d]", "abc", false, nil},
+	{"ab[^e-g]", "abc", true, nil},
+	{"a\\*b", "a*b", true, nil},
+	{"a\\*b", "ab", false, nil},
+	{"a?b", "a☺b", true, nil},
+	{"a[^a]b", "a☺b", true, nil},
+	{"a???b", "a☺b", false, nil},
+	{"a[^a][^a][^a]b", "a☺b", false, nil},
+	{"[a-ζ]*", "α", true, nil},
+	{"*[a-ζ]", "A", false, nil},
+	{"a?b", "a/b", false, nil},
+	{"a*b", "a/b", false, nil},
+	{"[\\]a]", "]", true, nil},
+	{"[\\-]", "-", true, nil},
+	{"[x\\-]", "x", true, nil},
+	{"[x\\-]", "-", true, nil},
+	{"[x\\-]", "z", false, nil},
+	{"[\\-x]", "x", true, nil},
+	{"[\\-x]", "-", true, nil},
+	{"[\\-x]", "a", false, nil},
+	{"[]a]", "]", false, ErrBadPattern},
+	{"[-]", "-", false, ErrBadPattern},
+	{"[x-]", "x", false, ErrBadPattern},
+	{"[x-]", "-", false, ErrBadPattern},
+	{"[x-]", "z", false, ErrBadPattern},
+	{"[-x]", "x", false, ErrBadPattern},
+	{"[-x]", "-", false, ErrBadPattern},
+	{"[-x]", "a", false, ErrBadPattern},
+	{"\\", "a", false, ErrBadPattern},
+	{"[a-b-c]", "a", false, ErrBadPattern},
+	{"*x", "xxx", true, nil},
+}
+
+func errp(e os.Error) string {
+	if e == nil {
+		return "<nil>"
+	}
+	return e.String()
+}
+
+func TestMatch(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		// XXX: Don't pass for windows.
+		return
+	}
+	for _, tt := range matchTests {
+		ok, err := Match(tt.pattern, tt.s)
+		if ok != tt.match || err != tt.err {
+			t.Errorf("Match(%#q, %#q) = %v, %q want %v, %q", tt.pattern, tt.s, ok, errp(err), tt.match, errp(tt.err))
+		}
+	}
+}
+
+// contains returns true if vector contains the string s.
+func contains(vector []string, s string) bool {
+	s = ToSlash(s)
+	for _, elem := range vector {
+		if elem == s {
+			return true
+		}
+	}
+	return false
+}
+
+var globTests = []struct {
+	pattern, result string
+}{
+	{"match.go", "match.go"},
+	{"mat?h.go", "match.go"},
+	{"*", "match.go"},
+	{"../*/match.go", "../filepath/match.go"},
+}
+
+func TestGlob(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		// XXX: Don't pass for windows.
+		return
+	}
+	for _, tt := range globTests {
+		matches, err := Glob(tt.pattern)
+		if err != nil {
+			t.Errorf("Glob error for %q: %s", tt.pattern, err)
+			continue
+		}
+		if !contains(matches, tt.result) {
+			t.Errorf("Glob(%#q) = %#v want %v", tt.pattern, matches, tt.result)
+		}
+	}
+}
+
+func TestGlobError(t *testing.T) {
+	_, err := Glob("[7]")
+	if err != nil {
+		t.Error("expected error for bad pattern; got none")
+	}
+}
diff --git a/src/pkg/path/filepath/path.go b/src/pkg/path/filepath/path.go
new file mode 100644
index 000000000..3d5b915c1
--- /dev/null
+++ b/src/pkg/path/filepath/path.go
@@ -0,0 +1,358 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package filepath implements utility routines for manipulating filename paths
+// in a way compatible with the target operating system-defined file paths.
+package filepath
+
+import (
+	"bytes"
+	"os"
+	"runtime"
+	"sort"
+	"strings"
+)
+
+const (
+	Separator     = os.PathSeparator
+	ListSeparator = os.PathListSeparator
+)
+
+// Clean returns the shortest path name equivalent to path
+// by purely lexical processing.  It applies the following rules
+// iteratively until no further processing can be done:
+//
+//	1. Replace multiple Separator elements with a single one.
+//	2. Eliminate each . path name element (the current directory).
+//	3. Eliminate each inner .. path name element (the parent directory)
+//	   along with the non-.. element that precedes it.
+//	4. Eliminate .. elements that begin a rooted path:
+//	   that is, replace "/.." by "/" at the beginning of a path,
+//         assuming Separator is '/'.
+//
+// If the result of this process is an empty string, Clean
+// returns the string ".".
+//
+// See also Rob Pike, ``Lexical File Names in Plan 9 or
+// Getting Dot-Dot right,''
+// http://plan9.bell-labs.com/sys/doc/lexnames.html
+func Clean(path string) string {
+	vol := VolumeName(path)
+	path = path[len(vol):]
+	if path == "" {
+		return vol + "."
+	}
+
+	rooted := os.IsPathSeparator(path[0])
+
+	// Invariants:
+	//	reading from path; r is index of next byte to process.
+	//	writing to buf; w is index of next byte to write.
+	//	dotdot is index in buf where .. must stop, either because
+	//		it is the leading slash or it is a leading ../../.. prefix.
+	n := len(path)
+	buf := []byte(path)
+	r, w, dotdot := 0, 0, 0
+	if rooted {
+		buf[0] = Separator
+		r, w, dotdot = 1, 1, 1
+	}
+
+	for r < n {
+		switch {
+		case os.IsPathSeparator(path[r]):
+			// empty path element
+			r++
+		case path[r] == '.' && (r+1 == n || os.IsPathSeparator(path[r+1])):
+			// . element
+			r++
+		case path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
+			// .. element: remove to last separator
+			r += 2
+			switch {
+			case w > dotdot:
+				// can backtrack
+				w--
+				for w > dotdot && !os.IsPathSeparator(buf[w]) {
+					w--
+				}
+			case !rooted:
+				// cannot backtrack, but not rooted, so append .. element.
+				if w > 0 {
+					buf[w] = Separator
+					w++
+				}
+				buf[w] = '.'
+				w++
+				buf[w] = '.'
+				w++
+				dotdot = w
+			}
+		default:
+			// real path element.
+			// add slash if needed
+			if rooted && w != 1 || !rooted && w != 0 {
+				buf[w] = Separator
+				w++
+			}
+			// copy element
+			for ; r < n && !os.IsPathSeparator(path[r]); r++ {
+				buf[w] = path[r]
+				w++
+			}
+		}
+	}
+
+	// Turn empty string into "."
+	if w == 0 {
+		buf[w] = '.'
+		w++
+	}
+
+	return FromSlash(vol + string(buf[0:w]))
+}
+
+// ToSlash returns the result of replacing each separator character
+// in path with a slash ('/') character.
+func ToSlash(path string) string {
+	if Separator == '/' {
+		return path
+	}
+	return strings.Replace(path, string(Separator), "/", -1)
+}
+
+// FromSlash returns the result of replacing each slash ('/') character
+// in path with a separator character.
+func FromSlash(path string) string {
+	if Separator == '/' {
+		return path
+	}
+	return strings.Replace(path, "/", string(Separator), -1)
+}
+
+// SplitList splits a list of paths joined by the OS-specific ListSeparator.
+func SplitList(path string) []string {
+	if path == "" {
+		return []string{}
+	}
+	return strings.Split(path, string(ListSeparator))
+}
+
+// Split splits path immediately following the final Separator,
+// separating it into a directory and file name component.
+// If there is no Separator in path, Split returns an empty dir
+// and file set to path.
+func Split(path string) (dir, file string) {
+	i := len(path) - 1
+	for i >= 0 && !os.IsPathSeparator(path[i]) {
+		i--
+	}
+	return path[:i+1], path[i+1:]
+}
+
+// Join joins any number of path elements into a single path, adding
+// a Separator if necessary.  All empty strings are ignored.
+func Join(elem ...string) string {
+	for i, e := range elem {
+		if e != "" {
+			return Clean(strings.Join(elem[i:], string(Separator)))
+		}
+	}
+	return ""
+}
+
+// Ext returns the file name extension used by path.
+// The extension is the suffix beginning at the final dot
+// in the final element of path; it is empty if there is
+// no dot.
+func Ext(path string) string {
+	for i := len(path) - 1; i >= 0 && !os.IsPathSeparator(path[i]); i-- {
+		if path[i] == '.' {
+			return path[i:]
+		}
+	}
+	return ""
+}
+
+// EvalSymlinks returns the path name after the evaluation of any symbolic
+// links.
+// If path is relative it will be evaluated relative to the current directory.
+func EvalSymlinks(path string) (string, os.Error) {
+	if runtime.GOOS == "windows" {
+		// Symlinks are not supported under windows.
+		_, err := os.Lstat(path)
+		if err != nil {
+			return "", err
+		}
+		return Clean(path), nil
+	}
+	const maxIter = 255
+	originalPath := path
+	// consume path by taking each frontmost path element,
+	// expanding it if it's a symlink, and appending it to b
+	var b bytes.Buffer
+	for n := 0; path != ""; n++ {
+		if n > maxIter {
+			return "", os.NewError("EvalSymlinks: too many links in " + originalPath)
+		}
+
+		// find next path component, p
+		i := strings.IndexRune(path, Separator)
+		var p string
+		if i == -1 {
+			p, path = path, ""
+		} else {
+			p, path = path[:i], path[i+1:]
+		}
+
+		if p == "" {
+			if b.Len() == 0 {
+				// must be absolute path
+				b.WriteRune(Separator)
+			}
+			continue
+		}
+
+		fi, err := os.Lstat(b.String() + p)
+		if err != nil {
+			return "", err
+		}
+		if !fi.IsSymlink() {
+			b.WriteString(p)
+			if path != "" {
+				b.WriteRune(Separator)
+			}
+			continue
+		}
+
+		// it's a symlink, put it at the front of path
+		dest, err := os.Readlink(b.String() + p)
+		if err != nil {
+			return "", err
+		}
+		if IsAbs(dest) {
+			b.Reset()
+		}
+		path = dest + string(Separator) + path
+	}
+	return Clean(b.String()), nil
+}
+
+// Abs returns an absolute representation of path.
+// If the path is not absolute it will be joined with the current
+// working directory to turn it into an absolute path.  The absolute
+// path name for a given file is not guaranteed to be unique.
+func Abs(path string) (string, os.Error) {
+	if IsAbs(path) {
+		return Clean(path), nil
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	return Join(wd, path), nil
+}
+
+// Visitor methods are invoked for corresponding file tree entries
+// visited by Walk. The parameter path is the full path of f relative
+// to root.
+type Visitor interface {
+	VisitDir(path string, f *os.FileInfo) bool
+	VisitFile(path string, f *os.FileInfo)
+}
+
+func walk(path string, f *os.FileInfo, v Visitor, errors chan<- os.Error) {
+	if !f.IsDirectory() {
+		v.VisitFile(path, f)
+		return
+	}
+
+	if !v.VisitDir(path, f) {
+		return // skip directory entries
+	}
+
+	list, err := readDir(path)
+	if err != nil {
+		if errors != nil {
+			errors <- err
+		}
+	}
+
+	for _, e := range list {
+		walk(Join(path, e.Name), e, v, errors)
+	}
+}
+
+// readDir reads the directory named by dirname and returns
+// a list of sorted directory entries.
+// Copied from io/ioutil to avoid the circular import.
+func readDir(dirname string) ([]*os.FileInfo, os.Error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	list, err := f.Readdir(-1)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	fi := make(fileInfoList, len(list))
+	for i := range list {
+		fi[i] = &list[i]
+	}
+	sort.Sort(fi)
+	return fi, nil
+}
+
+// A dirList implements sort.Interface.
+type fileInfoList []*os.FileInfo
+
+func (f fileInfoList) Len() int           { return len(f) }
+func (f fileInfoList) Less(i, j int) bool { return f[i].Name < f[j].Name }
+func (f fileInfoList) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
+
+// Walk walks the file tree rooted at root, calling v.VisitDir or
+// v.VisitFile for each directory or file in the tree, including root.
+// If v.VisitDir returns false, Walk skips the directory's entries;
+// otherwise it invokes itself for each directory entry in sorted order.
+// An error reading a directory does not abort the Walk.
+// If errors != nil, Walk sends each directory read error
+// to the channel.  Otherwise Walk discards the error.
+func Walk(root string, v Visitor, errors chan<- os.Error) {
+	f, err := os.Lstat(root)
+	if err != nil {
+		if errors != nil {
+			errors <- err
+		}
+		return // can't progress
+	}
+	walk(root, f, v, errors)
+}
+
+// Base returns the last element of path.
+// Trailing path separators are removed before extracting the last element.
+// If the path is empty, Base returns ".".
+// If the path consists entirely of separators, Base returns a single separator.
+func Base(path string) string {
+	if path == "" {
+		return "."
+	}
+	// Strip trailing slashes.
+	for len(path) > 0 && os.IsPathSeparator(path[len(path)-1]) {
+		path = path[0 : len(path)-1]
+	}
+	// Find the last element
+	i := len(path) - 1
+	for i >= 0 && !os.IsPathSeparator(path[i]) {
+		i--
+	}
+	if i >= 0 {
+		path = path[i+1:]
+	}
+	// If empty now, it had only slashes.
+	if path == "" {
+		return string(Separator)
+	}
+	return path
+}
diff --git a/src/pkg/path/filepath/path_plan9.go b/src/pkg/path/filepath/path_plan9.go
new file mode 100644
index 000000000..17b873f1a
--- /dev/null
+++ b/src/pkg/path/filepath/path_plan9.go
@@ -0,0 +1,23 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath
+
+import "strings"
+
+// IsAbs returns true if the path is absolute.
+func IsAbs(path string) bool {
+	return strings.HasPrefix(path, "/") || strings.HasPrefix(path, "#")
+}
+
+// VolumeName returns the leading volume name on Windows.
+// It returns "" elsewhere
+func VolumeName(path string) string {
+	return ""
+}
+
+// HasPrefix tests whether the path p begins with prefix.
+func HasPrefix(p, prefix string) bool {
+	return strings.HasPrefix(p, prefix)
+}
diff --git a/src/pkg/path/filepath/path_test.go b/src/pkg/path/filepath/path_test.go
new file mode 100644
index 000000000..d2a10698e
--- /dev/null
+++ b/src/pkg/path/filepath/path_test.go
@@ -0,0 +1,576 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath_test
+
+import (
+	"os"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+type PathTest struct {
+	path, result string
+}
+
+var cleantests = []PathTest{
+	// Already clean
+	{"", "."},
+	{"abc", "abc"},
+	{"abc/def", "abc/def"},
+	{"a/b/c", "a/b/c"},
+	{".", "."},
+	{"..", ".."},
+	{"../..", "../.."},
+	{"../../abc", "../../abc"},
+	{"/abc", "/abc"},
+	{"/", "/"},
+
+	// Remove trailing slash
+	{"abc/", "abc"},
+	{"abc/def/", "abc/def"},
+	{"a/b/c/", "a/b/c"},
+	{"./", "."},
+	{"../", ".."},
+	{"../../", "../.."},
+	{"/abc/", "/abc"},
+
+	// Remove doubled slash
+	{"abc//def//ghi", "abc/def/ghi"},
+	{"//abc", "/abc"},
+	{"///abc", "/abc"},
+	{"//abc//", "/abc"},
+	{"abc//", "abc"},
+
+	// Remove . elements
+	{"abc/./def", "abc/def"},
+	{"/./abc/def", "/abc/def"},
+	{"abc/.", "abc"},
+
+	// Remove .. elements
+	{"abc/def/ghi/../jkl", "abc/def/jkl"},
+	{"abc/def/../ghi/../jkl", "abc/jkl"},
+	{"abc/def/..", "abc"},
+	{"abc/def/../..", "."},
+	{"/abc/def/../..", "/"},
+	{"abc/def/../../..", ".."},
+	{"/abc/def/../../..", "/"},
+	{"abc/def/../../../ghi/jkl/../../../mno", "../../mno"},
+
+	// Combinations
+	{"abc/./../def", "def"},
+	{"abc//./../def", "def"},
+	{"abc/../../././../def", "../../def"},
+}
+
+var wincleantests = []PathTest{
+	{`c:`, `c:.`},
+	{`c:\`, `c:\`},
+	{`c:\abc`, `c:\abc`},
+	{`c:abc\..\..\.\.\..\def`, `c:..\..\def`},
+	{`c:\abc\def\..\..`, `c:\`},
+	{`c:..\abc`, `c:..\abc`},
+	{`\`, `\`},
+	{`/`, `\`},
+}
+
+func TestClean(t *testing.T) {
+	tests := cleantests
+	if runtime.GOOS == "windows" {
+		for i, _ := range tests {
+			tests[i].result = filepath.FromSlash(tests[i].result)
+		}
+		tests = append(tests, wincleantests...)
+	}
+	for _, test := range tests {
+		if s := filepath.Clean(test.path); s != test.result {
+			t.Errorf("Clean(%q) = %q, want %q", test.path, s, test.result)
+		}
+	}
+}
+
+const sep = filepath.Separator
+
+var slashtests = []PathTest{
+	{"", ""},
+	{"/", string(sep)},
+	{"/a/b", string([]byte{sep, 'a', sep, 'b'})},
+	{"a//b", string([]byte{'a', sep, sep, 'b'})},
+}
+
+func TestFromAndToSlash(t *testing.T) {
+	for _, test := range slashtests {
+		if s := filepath.FromSlash(test.path); s != test.result {
+			t.Errorf("FromSlash(%q) = %q, want %q", test.path, s, test.result)
+		}
+		if s := filepath.ToSlash(test.result); s != test.path {
+			t.Errorf("ToSlash(%q) = %q, want %q", test.result, s, test.path)
+		}
+	}
+}
+
+type SplitListTest struct {
+	list   string
+	result []string
+}
+
+const lsep = filepath.ListSeparator
+
+var splitlisttests = []SplitListTest{
+	{"", []string{}},
+	{string([]byte{'a', lsep, 'b'}), []string{"a", "b"}},
+	{string([]byte{lsep, 'a', lsep, 'b'}), []string{"", "a", "b"}},
+}
+
+func TestSplitList(t *testing.T) {
+	for _, test := range splitlisttests {
+		if l := filepath.SplitList(test.list); !reflect.DeepEqual(l, test.result) {
+			t.Errorf("SplitList(%q) = %s, want %s", test.list, l, test.result)
+		}
+	}
+}
+
+type SplitTest struct {
+	path, dir, file string
+}
+
+var unixsplittests = []SplitTest{
+	{"a/b", "a/", "b"},
+	{"a/b/", "a/b/", ""},
+	{"a/", "a/", ""},
+	{"a", "", "a"},
+	{"/", "/", ""},
+}
+
+func TestSplit(t *testing.T) {
+	var splittests []SplitTest
+	splittests = unixsplittests
+	for _, test := range splittests {
+		if d, f := filepath.Split(test.path); d != test.dir || f != test.file {
+			t.Errorf("Split(%q) = %q, %q, want %q, %q", test.path, d, f, test.dir, test.file)
+		}
+	}
+}
+
+type JoinTest struct {
+	elem []string
+	path string
+}
+
+var jointests = []JoinTest{
+	// zero parameters
+	{[]string{}, ""},
+
+	// one parameter
+	{[]string{""}, ""},
+	{[]string{"a"}, "a"},
+
+	// two parameters
+	{[]string{"a", "b"}, "a/b"},
+	{[]string{"a", ""}, "a"},
+	{[]string{"", "b"}, "b"},
+	{[]string{"/", "a"}, "/a"},
+	{[]string{"/", ""}, "/"},
+	{[]string{"a/", "b"}, "a/b"},
+	{[]string{"a/", ""}, "a"},
+	{[]string{"", ""}, ""},
+}
+
+var winjointests = []JoinTest{
+	{[]string{`directory`, `file`}, `directory\file`},
+	{[]string{`C:\Windows\`, `System32`}, `C:\Windows\System32`},
+	{[]string{`C:\Windows\`, ``}, `C:\Windows`},
+	{[]string{`C:\`, `Windows`}, `C:\Windows`},
+	{[]string{`C:`, `Windows`}, `C:\Windows`},
+}
+
+// join takes a []string and passes it to Join.
+func join(elem []string, args ...string) string {
+	args = elem
+	return filepath.Join(args...)
+}
+
+func TestJoin(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		jointests = append(jointests, winjointests...)
+	}
+	for _, test := range jointests {
+		if p := join(test.elem); p != filepath.FromSlash(test.path) {
+			t.Errorf("join(%q) = %q, want %q", test.elem, p, test.path)
+		}
+	}
+}
+
+type ExtTest struct {
+	path, ext string
+}
+
+var exttests = []ExtTest{
+	{"path.go", ".go"},
+	{"path.pb.go", ".go"},
+	{"a.dir/b", ""},
+	{"a.dir/b.go", ".go"},
+	{"a.dir/", ""},
+}
+
+func TestExt(t *testing.T) {
+	for _, test := range exttests {
+		if x := filepath.Ext(test.path); x != test.ext {
+			t.Errorf("Ext(%q) = %q, want %q", test.path, x, test.ext)
+		}
+	}
+}
+
+type Node struct {
+	name    string
+	entries []*Node // nil if the entry is a file
+	mark    int
+}
+
+var tree = &Node{
+	"testdata",
+	[]*Node{
+		&Node{"a", nil, 0},
+		&Node{"b", []*Node{}, 0},
+		&Node{"c", nil, 0},
+		&Node{
+			"d",
+			[]*Node{
+				&Node{"x", nil, 0},
+				&Node{"y", []*Node{}, 0},
+				&Node{
+					"z",
+					[]*Node{
+						&Node{"u", nil, 0},
+						&Node{"v", nil, 0},
+					},
+					0,
+				},
+			},
+			0,
+		},
+	},
+	0,
+}
+
+func walkTree(n *Node, path string, f func(path string, n *Node)) {
+	f(path, n)
+	for _, e := range n.entries {
+		walkTree(e, filepath.Join(path, e.name), f)
+	}
+}
+
+func makeTree(t *testing.T) {
+	walkTree(tree, tree.name, func(path string, n *Node) {
+		if n.entries == nil {
+			fd, err := os.Create(path)
+			if err != nil {
+				t.Errorf("makeTree: %v", err)
+			}
+			fd.Close()
+		} else {
+			os.Mkdir(path, 0770)
+		}
+	})
+}
+
+func markTree(n *Node) { walkTree(n, "", func(path string, n *Node) { n.mark++ }) }
+
+func checkMarks(t *testing.T) {
+	walkTree(tree, tree.name, func(path string, n *Node) {
+		if n.mark != 1 {
+			t.Errorf("node %s mark = %d; expected 1", path, n.mark)
+		}
+		n.mark = 0
+	})
+}
+
+// Assumes that each node name is unique. Good enough for a test.
+func mark(name string) {
+	name = filepath.ToSlash(name)
+	walkTree(tree, tree.name, func(path string, n *Node) {
+		if n.name == name {
+			n.mark++
+		}
+	})
+}
+
+type TestVisitor struct{}
+
+func (v *TestVisitor) VisitDir(path string, f *os.FileInfo) bool {
+	mark(f.Name)
+	return true
+}
+
+func (v *TestVisitor) VisitFile(path string, f *os.FileInfo) {
+	mark(f.Name)
+}
+
+func TestWalk(t *testing.T) {
+	makeTree(t)
+
+	// 1) ignore error handling, expect none
+	v := &TestVisitor{}
+	filepath.Walk(tree.name, v, nil)
+	checkMarks(t)
+
+	// 2) handle errors, expect none
+	errors := make(chan os.Error, 64)
+	filepath.Walk(tree.name, v, errors)
+	select {
+	case err := <-errors:
+		t.Errorf("no error expected, found: %s", err)
+	default:
+		// ok
+	}
+	checkMarks(t)
+
+	// Test permission errors.  Only possible if we're not root
+	// and only on some file systems (AFS, FAT).  To avoid errors during
+	// all.bash on those file systems, skip during gotest -short.
+	if os.Getuid() > 0 && !testing.Short() {
+		// introduce 2 errors: chmod top-level directories to 0
+		os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0)
+		os.Chmod(filepath.Join(tree.name, tree.entries[3].name), 0)
+		// mark respective subtrees manually
+		markTree(tree.entries[1])
+		markTree(tree.entries[3])
+		// correct double-marking of directory itself
+		tree.entries[1].mark--
+		tree.entries[3].mark--
+
+		// 3) handle errors, expect two
+		errors = make(chan os.Error, 64)
+		os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0)
+		filepath.Walk(tree.name, v, errors)
+	Loop:
+		for i := 1; i <= 2; i++ {
+			select {
+			case <-errors:
+				// ok
+			default:
+				t.Errorf("%d. error expected, none found", i)
+				break Loop
+			}
+		}
+		select {
+		case err := <-errors:
+			t.Errorf("only two errors expected, found 3rd: %v", err)
+		default:
+			// ok
+		}
+		// the inaccessible subtrees were marked manually
+		checkMarks(t)
+	}
+
+	// cleanup
+	os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0770)
+	os.Chmod(filepath.Join(tree.name, tree.entries[3].name), 0770)
+	if err := os.RemoveAll(tree.name); err != nil {
+		t.Errorf("removeTree: %v", err)
+	}
+}
+
+var basetests = []PathTest{
+	{"", "."},
+	{".", "."},
+	{"/.", "."},
+	{"/", "/"},
+	{"////", "/"},
+	{"x/", "x"},
+	{"abc", "abc"},
+	{"abc/def", "def"},
+	{"a/b/.x", ".x"},
+	{"a/b/c.", "c."},
+	{"a/b/c.x", "c.x"},
+}
+
+func TestBase(t *testing.T) {
+	for _, test := range basetests {
+		if s := filepath.ToSlash(filepath.Base(test.path)); s != test.result {
+			t.Errorf("Base(%q) = %q, want %q", test.path, s, test.result)
+		}
+	}
+}
+
+type IsAbsTest struct {
+	path  string
+	isAbs bool
+}
+
+var isabstests = []IsAbsTest{
+	{"", false},
+	{"/", true},
+	{"/usr/bin/gcc", true},
+	{"..", false},
+	{"/a/../bb", true},
+	{".", false},
+	{"./", false},
+	{"lala", false},
+}
+
+var winisabstests = []IsAbsTest{
+	{`C:\`, true},
+	{`c\`, false},
+	{`c::`, false},
+	{`c:`, false},
+	{`/`, false},
+	{`\`, false},
+	{`\Windows`, false},
+	{`c:a\b`, false},
+}
+
+func TestIsAbs(t *testing.T) {
+	var tests []IsAbsTest
+	if runtime.GOOS == "windows" {
+		tests = append(tests, winisabstests...)
+		// All non-windows tests should fail, because they have no volume letter.
+		for _, test := range isabstests {
+			tests = append(tests, IsAbsTest{test.path, false})
+		}
+		// All non-windows test should work as intended if prefixed with volume letter.
+		for _, test := range isabstests {
+			tests = append(tests, IsAbsTest{"c:" + test.path, test.isAbs})
+		}
+	} else {
+		tests = isabstests
+	}
+
+	for _, test := range tests {
+		if r := filepath.IsAbs(test.path); r != test.isAbs {
+			t.Errorf("IsAbs(%q) = %v, want %v", test.path, r, test.isAbs)
+		}
+	}
+}
+
+type EvalSymlinksTest struct {
+	path, dest string
+}
+
+var EvalSymlinksTestDirs = []EvalSymlinksTest{
+	{"test", ""},
+	{"test/dir", ""},
+	{"test/dir/link3", "../../"},
+	{"test/link1", "../test"},
+	{"test/link2", "dir"},
+}
+
+var EvalSymlinksTests = []EvalSymlinksTest{
+	{"test", "test"},
+	{"test/dir", "test/dir"},
+	{"test/dir/../..", "."},
+	{"test/link1", "test"},
+	{"test/link2", "test/dir"},
+	{"test/link1/dir", "test/dir"},
+	{"test/link2/..", "test"},
+	{"test/dir/link3", "."},
+	{"test/link2/link3/test", "test"},
+}
+
+var EvalSymlinksAbsWindowsTests = []EvalSymlinksTest{
+	{`c:\`, `c:\`},
+}
+
+func testEvalSymlinks(t *testing.T, tests []EvalSymlinksTest) {
+	for _, d := range tests {
+		if p, err := filepath.EvalSymlinks(d.path); err != nil {
+			t.Errorf("EvalSymlinks(%q) error: %v", d.path, err)
+		} else if filepath.Clean(p) != filepath.Clean(d.dest) {
+			t.Errorf("EvalSymlinks(%q)=%q, want %q", d.path, p, d.dest)
+		}
+	}
+}
+
+func TestEvalSymlinks(t *testing.T) {
+	defer os.RemoveAll("test")
+	for _, d := range EvalSymlinksTestDirs {
+		var err os.Error
+		if d.dest == "" {
+			err = os.Mkdir(d.path, 0755)
+		} else {
+			if runtime.GOOS != "windows" {
+				err = os.Symlink(d.dest, d.path)
+			}
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+	var tests []EvalSymlinksTest
+	if runtime.GOOS == "windows" {
+		for _, d := range EvalSymlinksTests {
+			if d.path == d.dest {
+				// will test only real files and directories
+				tests = append(tests, d)
+			}
+		}
+	} else {
+		tests = EvalSymlinksTests
+	}
+	// relative
+	testEvalSymlinks(t, tests)
+	// absolute
+	goroot, err := filepath.EvalSymlinks(os.Getenv("GOROOT"))
+	if err != nil {
+		t.Fatalf("EvalSymlinks(%q) error: %v", os.Getenv("GOROOT"), err)
+	}
+	testroot := filepath.Join(goroot, "src", "pkg", "path", "filepath")
+	for i, d := range tests {
+		tests[i].path = filepath.Join(testroot, d.path)
+		tests[i].dest = filepath.Join(testroot, d.dest)
+	}
+	if runtime.GOOS == "windows" {
+		for _, d := range EvalSymlinksAbsWindowsTests {
+			tests = append(tests, d)
+		}
+	}
+	testEvalSymlinks(t, tests)
+}
+
+// Test paths relative to $GOROOT/src
+var abstests = []string{
+	"../AUTHORS",
+	"pkg/../../AUTHORS",
+	"Make.pkg",
+	"pkg/Makefile",
+
+	// Already absolute
+	"$GOROOT/src/Make.pkg",
+	"$GOROOT/src/../src/Make.pkg",
+}
+
+func TestAbs(t *testing.T) {
+	oldwd, err := os.Getwd()
+	if err != nil {
+		t.Fatal("Getwd failed: " + err.String())
+	}
+	defer os.Chdir(oldwd)
+	goroot := os.Getenv("GOROOT")
+	cwd := filepath.Join(goroot, "src")
+	os.Chdir(cwd)
+	for _, path := range abstests {
+		path = strings.Replace(path, "$GOROOT", goroot, -1)
+		abspath, err := filepath.Abs(path)
+		if err != nil {
+			t.Errorf("Abs(%q) error: %v", path, err)
+		}
+		info, err := os.Stat(path)
+		if err != nil {
+			t.Errorf("%s: %s", path, err)
+		}
+		absinfo, err := os.Stat(abspath)
+		if err != nil || absinfo.Ino != info.Ino {
+			t.Errorf("Abs(%q)=%q, not the same file", path, abspath)
+		}
+		if !filepath.IsAbs(abspath) {
+			t.Errorf("Abs(%q)=%q, not an absolute path", path, abspath)
+		}
+		if filepath.IsAbs(path) && abspath != filepath.Clean(path) {
+			t.Errorf("Abs(%q)=%q, isn't clean", path, abspath)
+		}
+	}
+}
diff --git a/src/pkg/path/filepath/path_unix.go b/src/pkg/path/filepath/path_unix.go
new file mode 100644
index 000000000..b2a4151c1
--- /dev/null
+++ b/src/pkg/path/filepath/path_unix.go
@@ -0,0 +1,23 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath
+
+import "strings"
+
+// IsAbs returns true if the path is absolute.
+func IsAbs(path string) bool {
+	return strings.HasPrefix(path, "/")
+}
+
+// VolumeName returns the leading volume name on Windows.
+// It returns "" elsewhere.
+func VolumeName(path string) string {
+	return ""
+}
+
+// HasPrefix tests whether the path p begins with prefix.
+func HasPrefix(p, prefix string) bool {
+	return strings.HasPrefix(p, prefix)
+}
diff --git a/src/pkg/path/filepath/path_windows.go b/src/pkg/path/filepath/path_windows.go
new file mode 100644
index 000000000..2535697fd
--- /dev/null
+++ b/src/pkg/path/filepath/path_windows.go
@@ -0,0 +1,46 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath
+
+import "strings"
+
+// IsAbs returns true if the path is absolute.
+func IsAbs(path string) (b bool) {
+	v := VolumeName(path)
+	if v == "" {
+		return false
+	}
+	path = path[len(v):]
+	if path == "" {
+		return false
+	}
+	return path[0] == '/' || path[0] == '\\'
+}
+
+// VolumeName returns leading volume name.  
+// Given "C:\foo\bar" it returns "C:" under windows.
+// On other platforms it returns "".
+func VolumeName(path string) (v string) {
+	if len(path) < 2 {
+		return ""
+	}
+	// with drive letter
+	c := path[0]
+	if path[1] == ':' &&
+		('0' <= c && c <= '9' || 'a' <= c && c <= 'z' ||
+			'A' <= c && c <= 'Z') {
+		return path[:2]
+	}
+	return ""
+}
+
+// HasPrefix tests whether the path p begins with prefix.
+// It ignores case while comparing.
+func HasPrefix(p, prefix string) bool {
+	if strings.HasPrefix(p, prefix) {
+		return true
+	}
+	return strings.HasPrefix(strings.ToLower(p), strings.ToLower(prefix))
+}
diff --git a/src/pkg/path/match.go b/src/pkg/path/match.go
new file mode 100644
index 000000000..efb8c5ce7
--- /dev/null
+++ b/src/pkg/path/match.go
@@ -0,0 +1,207 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package path
+
+import (
+	"os"
+	"strings"
+	"utf8"
+)
+
+var ErrBadPattern = os.NewError("syntax error in pattern")
+
+// Match returns true if name matches the shell file name pattern.
+// The pattern syntax is:
+//
+//	pattern:
+//		{ term }
+//	term:
+//		'*'         matches any sequence of non-/ characters
+//		'?'         matches any single non-/ character
+//		'[' [ '^' ] { character-range } ']'
+//		            character class (must be non-empty)
+//		c           matches character c (c != '*', '?', '\\', '[')
+//		'\\' c      matches character c
+//
+//	character-range:
+//		c           matches character c (c != '\\', '-', ']')
+//		'\\' c      matches character c
+//		lo '-' hi   matches character c for lo <= c <= hi
+//
+// Match requires pattern to match all of name, not just a substring.
+// The only possible error return is when pattern is malformed.
+//
+func Match(pattern, name string) (matched bool, err os.Error) {
+Pattern:
+	for len(pattern) > 0 {
+		var star bool
+		var chunk string
+		star, chunk, pattern = scanChunk(pattern)
+		if star && chunk == "" {
+			// Trailing * matches rest of string unless it has a /.
+			return strings.Index(name, "/") < 0, nil
+		}
+		// Look for match at current position.
+		t, ok, err := matchChunk(chunk, name)
+		// if we're the last chunk, make sure we've exhausted the name
+		// otherwise we'll give a false result even if we could still match
+		// using the star
+		if ok && (len(t) == 0 || len(pattern) > 0) {
+			name = t
+			continue
+		}
+		if err != nil {
+			return false, err
+		}
+		if star {
+			// Look for match skipping i+1 bytes.
+			// Cannot skip /.
+			for i := 0; i < len(name) && name[i] != '/'; i++ {
+				t, ok, err := matchChunk(chunk, name[i+1:])
+				if ok {
+					// if we're the last chunk, make sure we exhausted the name
+					if len(pattern) == 0 && len(t) > 0 {
+						continue
+					}
+					name = t
+					continue Pattern
+				}
+				if err != nil {
+					return false, err
+				}
+			}
+		}
+		return false, nil
+	}
+	return len(name) == 0, nil
+}
+
+// scanChunk gets the next segment of pattern, which is a non-star string
+// possibly preceded by a star.
+func scanChunk(pattern string) (star bool, chunk, rest string) {
+	for len(pattern) > 0 && pattern[0] == '*' {
+		pattern = pattern[1:]
+		star = true
+	}
+	inrange := false
+	var i int
+Scan:
+	for i = 0; i < len(pattern); i++ {
+		switch pattern[i] {
+		case '\\':
+			// error check handled in matchChunk: bad pattern.
+			if i+1 < len(pattern) {
+				i++
+			}
+		case '[':
+			inrange = true
+		case ']':
+			inrange = false
+		case '*':
+			if !inrange {
+				break Scan
+			}
+		}
+	}
+	return star, pattern[0:i], pattern[i:]
+}
+
+// matchChunk checks whether chunk matches the beginning of s.
+// If so, it returns the remainder of s (after the match).
+// Chunk is all single-character operators: literals, char classes, and ?.
+func matchChunk(chunk, s string) (rest string, ok bool, err os.Error) {
+	for len(chunk) > 0 {
+		if len(s) == 0 {
+			return
+		}
+		switch chunk[0] {
+		case '[':
+			// character class
+			r, n := utf8.DecodeRuneInString(s)
+			s = s[n:]
+			chunk = chunk[1:]
+			// possibly negated
+			notNegated := true
+			if len(chunk) > 0 && chunk[0] == '^' {
+				notNegated = false
+				chunk = chunk[1:]
+			}
+			// parse all ranges
+			match := false
+			nrange := 0
+			for {
+				if len(chunk) > 0 && chunk[0] == ']' && nrange > 0 {
+					chunk = chunk[1:]
+					break
+				}
+				var lo, hi int
+				if lo, chunk, err = getEsc(chunk); err != nil {
+					return
+				}
+				hi = lo
+				if chunk[0] == '-' {
+					if hi, chunk, err = getEsc(chunk[1:]); err != nil {
+						return
+					}
+				}
+				if lo <= r && r <= hi {
+					match = true
+				}
+				nrange++
+			}
+			if match != notNegated {
+				return
+			}
+
+		case '?':
+			if s[0] == '/' {
+				return
+			}
+			_, n := utf8.DecodeRuneInString(s)
+			s = s[n:]
+			chunk = chunk[1:]
+
+		case '\\':
+			chunk = chunk[1:]
+			if len(chunk) == 0 {
+				err = ErrBadPattern
+				return
+			}
+			fallthrough
+
+		default:
+			if chunk[0] != s[0] {
+				return
+			}
+			s = s[1:]
+			chunk = chunk[1:]
+		}
+	}
+	return s, true, nil
+}
+
+// getEsc gets a possibly-escaped character from chunk, for a character class.
+func getEsc(chunk string) (r int, nchunk string, err os.Error) {
+	if len(chunk) == 0 || chunk[0] == '-' || chunk[0] == ']' {
+		err = ErrBadPattern
+		return
+	}
+	if chunk[0] == '\\' {
+		chunk = chunk[1:]
+		if len(chunk) == 0 {
+			err = ErrBadPattern
+			return
+		}
+	}
+	r, n := utf8.DecodeRuneInString(chunk)
+	if r == utf8.RuneError && n == 1 {
+		err = ErrBadPattern
+	}
+	nchunk = chunk[n:]
+	if len(nchunk) == 0 {
+		err = ErrBadPattern
+	}
+	return
+}
diff --git a/src/pkg/path/match_test.go b/src/pkg/path/match_test.go
new file mode 100644
index 000000000..f377f1083
--- /dev/null
+++ b/src/pkg/path/match_test.go
@@ -0,0 +1,77 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package path
+
+import (
+	"os"
+	"testing"
+)
+
+type MatchTest struct {
+	pattern, s string
+	match      bool
+	err        os.Error
+}
+
+var matchTests = []MatchTest{
+	{"abc", "abc", true, nil},
+	{"*", "abc", true, nil},
+	{"*c", "abc", true, nil},
+	{"a*", "a", true, nil},
+	{"a*", "abc", true, nil},
+	{"a*", "ab/c", false, nil},
+	{"a*/b", "abc/b", true, nil},
+	{"a*/b", "a/c/b", false, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxe/f", true, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxexxx/f", true, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxe/xxx/f", false, nil},
+	{"a*b*c*d*e*/f", "axbxcxdxexxx/fff", false, nil},
+	{"a*b?c*x", "abxbbxdbxebxczzx", true, nil},
+	{"a*b?c*x", "abxbbxdbxebxczzy", false, nil},
+	{"ab[c]", "abc", true, nil},
+	{"ab[b-d]", "abc", true, nil},
+	{"ab[e-g]", "abc", false, nil},
+	{"ab[^c]", "abc", false, nil},
+	{"ab[^b-d]", "abc", false, nil},
+	{"ab[^e-g]", "abc", true, nil},
+	{"a\\*b", "a*b", true, nil},
+	{"a\\*b", "ab", false, nil},
+	{"a?b", "a☺b", true, nil},
+	{"a[^a]b", "a☺b", true, nil},
+	{"a???b", "a☺b", false, nil},
+	{"a[^a][^a][^a]b", "a☺b", false, nil},
+	{"[a-ζ]*", "α", true, nil},
+	{"*[a-ζ]", "A", false, nil},
+	{"a?b", "a/b", false, nil},
+	{"a*b", "a/b", false, nil},
+	{"[\\]a]", "]", true, nil},
+	{"[\\-]", "-", true, nil},
+	{"[x\\-]", "x", true, nil},
+	{"[x\\-]", "-", true, nil},
+	{"[x\\-]", "z", false, nil},
+	{"[\\-x]", "x", true, nil},
+	{"[\\-x]", "-", true, nil},
+	{"[\\-x]", "a", false, nil},
+	{"[]a]", "]", false, ErrBadPattern},
+	{"[-]", "-", false, ErrBadPattern},
+	{"[x-]", "x", false, ErrBadPattern},
+	{"[x-]", "-", false, ErrBadPattern},
+	{"[x-]", "z", false, ErrBadPattern},
+	{"[-x]", "x", false, ErrBadPattern},
+	{"[-x]", "-", false, ErrBadPattern},
+	{"[-x]", "a", false, ErrBadPattern},
+	{"\\", "a", false, ErrBadPattern},
+	{"[a-b-c]", "a", false, ErrBadPattern},
+	{"*x", "xxx", true, nil},
+}
+
+func TestMatch(t *testing.T) {
+	for _, tt := range matchTests {
+		ok, err := Match(tt.pattern, tt.s)
+		if ok != tt.match || err != tt.err {
+			t.Errorf("Match(%#q, %#q) = %v, %v want %v, nil", tt.pattern, tt.s, ok, err, tt.match)
+		}
+	}
+}
diff --git a/src/pkg/path/path.go b/src/pkg/path/path.go
new file mode 100644
index 000000000..235384667
--- /dev/null
+++ b/src/pkg/path/path.go
@@ -0,0 +1,162 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package path implements utility routines for manipulating slash-separated
+// filename paths.
+package path
+
+import (
+	"strings"
+)
+
+// Clean returns the shortest path name equivalent to path
+// by purely lexical processing.  It applies the following rules
+// iteratively until no further processing can be done:
+//
+//	1. Replace multiple slashes with a single slash.
+//	2. Eliminate each . path name element (the current directory).
+//	3. Eliminate each inner .. path name element (the parent directory)
+//	   along with the non-.. element that precedes it.
+//	4. Eliminate .. elements that begin a rooted path:
+//	   that is, replace "/.." by "/" at the beginning of a path.
+//
+// If the result of this process is an empty string, Clean
+// returns the string ".".
+//
+// See also Rob Pike, ``Lexical File Names in Plan 9 or
+// Getting Dot-Dot right,''
+// http://plan9.bell-labs.com/sys/doc/lexnames.html
+func Clean(path string) string {
+	if path == "" {
+		return "."
+	}
+
+	rooted := path[0] == '/'
+	n := len(path)
+
+	// Invariants:
+	//	reading from path; r is index of next byte to process.
+	//	writing to buf; w is index of next byte to write.
+	//	dotdot is index in buf where .. must stop, either because
+	//		it is the leading slash or it is a leading ../../.. prefix.
+	buf := []byte(path)
+	r, w, dotdot := 0, 0, 0
+	if rooted {
+		r, w, dotdot = 1, 1, 1
+	}
+
+	for r < n {
+		switch {
+		case path[r] == '/':
+			// empty path element
+			r++
+		case path[r] == '.' && (r+1 == n || path[r+1] == '/'):
+			// . element
+			r++
+		case path[r] == '.' && path[r+1] == '.' && (r+2 == n || path[r+2] == '/'):
+			// .. element: remove to last /
+			r += 2
+			switch {
+			case w > dotdot:
+				// can backtrack
+				w--
+				for w > dotdot && buf[w] != '/' {
+					w--
+				}
+			case !rooted:
+				// cannot backtrack, but not rooted, so append .. element.
+				if w > 0 {
+					buf[w] = '/'
+					w++
+				}
+				buf[w] = '.'
+				w++
+				buf[w] = '.'
+				w++
+				dotdot = w
+			}
+		default:
+			// real path element.
+			// add slash if needed
+			if rooted && w != 1 || !rooted && w != 0 {
+				buf[w] = '/'
+				w++
+			}
+			// copy element
+			for ; r < n && path[r] != '/'; r++ {
+				buf[w] = path[r]
+				w++
+			}
+		}
+	}
+
+	// Turn empty string into "."
+	if w == 0 {
+		buf[w] = '.'
+		w++
+	}
+
+	return string(buf[0:w])
+}
+
+// Split splits path immediately following the final path separator,
+// separating it into a directory and file name component.
+// If there is no separator in path, Split returns an empty dir and
+// file set to path.
+func Split(path string) (dir, file string) {
+	i := strings.LastIndex(path, "/")
+	return path[:i+1], path[i+1:]
+}
+
+// Join joins any number of path elements into a single path, adding a
+// separating slash if necessary.  All empty strings are ignored.
+func Join(elem ...string) string {
+	for i, e := range elem {
+		if e != "" {
+			return Clean(strings.Join(elem[i:], "/"))
+		}
+	}
+	return ""
+}
+
+// Ext returns the file name extension used by path.
+// The extension is the suffix beginning at the final dot
+// in the final slash-separated element of path;
+// it is empty if there is no dot.
+func Ext(path string) string {
+	for i := len(path) - 1; i >= 0 && path[i] != '/'; i-- {
+		if path[i] == '.' {
+			return path[i:]
+		}
+	}
+	return ""
+}
+
+// Base returns the last element of path.
+// Trailing slashes are removed before extracting the last element.
+// If the path is empty, Base returns ".".
+// If the path consists entirely of slashes, Base returns "/".
+func Base(path string) string {
+	if path == "" {
+		return "."
+	}
+	// Strip trailing slashes.
+	for len(path) > 0 && path[len(path)-1] == '/' {
+		path = path[0 : len(path)-1]
+	}
+	// Find the last element
+	if i := strings.LastIndex(path, "/"); i >= 0 {
+		path = path[i+1:]
+	}
+	// If empty now, it had only slashes.
+	if path == "" {
+		return "/"
+	}
+	return path
+}
+
+// IsAbs returns true if the path is absolute.
+func IsAbs(path string) bool {
+	return len(path) > 0 && path[0] == '/'
+}
diff --git a/src/pkg/path/path_test.go b/src/pkg/path/path_test.go
new file mode 100644
index 000000000..1fd57cc80
--- /dev/null
+++ b/src/pkg/path/path_test.go
@@ -0,0 +1,196 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package path
+
+import (
+	"testing"
+)
+
+type CleanTest struct {
+	path, clean string
+}
+
+var cleantests = []CleanTest{
+	// Already clean
+	{"", "."},
+	{"abc", "abc"},
+	{"abc/def", "abc/def"},
+	{"a/b/c", "a/b/c"},
+	{".", "."},
+	{"..", ".."},
+	{"../..", "../.."},
+	{"../../abc", "../../abc"},
+	{"/abc", "/abc"},
+	{"/", "/"},
+
+	// Remove trailing slash
+	{"abc/", "abc"},
+	{"abc/def/", "abc/def"},
+	{"a/b/c/", "a/b/c"},
+	{"./", "."},
+	{"../", ".."},
+	{"../../", "../.."},
+	{"/abc/", "/abc"},
+
+	// Remove doubled slash
+	{"abc//def//ghi", "abc/def/ghi"},
+	{"//abc", "/abc"},
+	{"///abc", "/abc"},
+	{"//abc//", "/abc"},
+	{"abc//", "abc"},
+
+	// Remove . elements
+	{"abc/./def", "abc/def"},
+	{"/./abc/def", "/abc/def"},
+	{"abc/.", "abc"},
+
+	// Remove .. elements
+	{"abc/def/ghi/../jkl", "abc/def/jkl"},
+	{"abc/def/../ghi/../jkl", "abc/jkl"},
+	{"abc/def/..", "abc"},
+	{"abc/def/../..", "."},
+	{"/abc/def/../..", "/"},
+	{"abc/def/../../..", ".."},
+	{"/abc/def/../../..", "/"},
+	{"abc/def/../../../ghi/jkl/../../../mno", "../../mno"},
+
+	// Combinations
+	{"abc/./../def", "def"},
+	{"abc//./../def", "def"},
+	{"abc/../../././../def", "../../def"},
+}
+
+func TestClean(t *testing.T) {
+	for _, test := range cleantests {
+		if s := Clean(test.path); s != test.clean {
+			t.Errorf("Clean(%q) = %q, want %q", test.path, s, test.clean)
+		}
+	}
+}
+
+type SplitTest struct {
+	path, dir, file string
+}
+
+var splittests = []SplitTest{
+	{"a/b", "a/", "b"},
+	{"a/b/", "a/b/", ""},
+	{"a/", "a/", ""},
+	{"a", "", "a"},
+	{"/", "/", ""},
+}
+
+func TestSplit(t *testing.T) {
+	for _, test := range splittests {
+		if d, f := Split(test.path); d != test.dir || f != test.file {
+			t.Errorf("Split(%q) = %q, %q, want %q, %q", test.path, d, f, test.dir, test.file)
+		}
+	}
+}
+
+type JoinTest struct {
+	elem []string
+	path string
+}
+
+var jointests = []JoinTest{
+	// zero parameters
+	{[]string{}, ""},
+
+	// one parameter
+	{[]string{""}, ""},
+	{[]string{"a"}, "a"},
+
+	// two parameters
+	{[]string{"a", "b"}, "a/b"},
+	{[]string{"a", ""}, "a"},
+	{[]string{"", "b"}, "b"},
+	{[]string{"/", "a"}, "/a"},
+	{[]string{"/", ""}, "/"},
+	{[]string{"a/", "b"}, "a/b"},
+	{[]string{"a/", ""}, "a"},
+	{[]string{"", ""}, ""},
+}
+
+// join takes a []string and passes it to Join.
+func join(elem []string, args ...string) string {
+	args = elem
+	return Join(args...)
+}
+
+func TestJoin(t *testing.T) {
+	for _, test := range jointests {
+		if p := join(test.elem); p != test.path {
+			t.Errorf("join(%q) = %q, want %q", test.elem, p, test.path)
+		}
+	}
+}
+
+type ExtTest struct {
+	path, ext string
+}
+
+var exttests = []ExtTest{
+	{"path.go", ".go"},
+	{"path.pb.go", ".go"},
+	{"a.dir/b", ""},
+	{"a.dir/b.go", ".go"},
+	{"a.dir/", ""},
+}
+
+func TestExt(t *testing.T) {
+	for _, test := range exttests {
+		if x := Ext(test.path); x != test.ext {
+			t.Errorf("Ext(%q) = %q, want %q", test.path, x, test.ext)
+		}
+	}
+}
+
+var basetests = []CleanTest{
+	// Already clean
+	{"", "."},
+	{".", "."},
+	{"/.", "."},
+	{"/", "/"},
+	{"////", "/"},
+	{"x/", "x"},
+	{"abc", "abc"},
+	{"abc/def", "def"},
+	{"a/b/.x", ".x"},
+	{"a/b/c.", "c."},
+	{"a/b/c.x", "c.x"},
+}
+
+func TestBase(t *testing.T) {
+	for _, test := range basetests {
+		if s := Base(test.path); s != test.clean {
+			t.Errorf("Base(%q) = %q, want %q", test.path, s, test.clean)
+		}
+	}
+}
+
+type IsAbsTest struct {
+	path  string
+	isAbs bool
+}
+
+var isAbsTests = []IsAbsTest{
+	{"", false},
+	{"/", true},
+	{"/usr/bin/gcc", true},
+	{"..", false},
+	{"/a/../bb", true},
+	{".", false},
+	{"./", false},
+	{"lala", false},
+}
+
+func TestIsAbs(t *testing.T) {
+	for _, test := range isAbsTests {
+		if r := IsAbs(test.path); r != test.isAbs {
+			t.Errorf("IsAbs(%q) = %v, want %v", test.path, r, test.isAbs)
+		}
+	}
+}