1 files changed, 270 insertions, 0 deletions
diff --git a/src/pkg/path/filepath/path.go b/src/pkg/path/filepath/path.go
new file mode 100644
index 000000000..414df7d20
--- /dev/null
+++ b/src/pkg/path/filepath/path.go
@@ -0,0 +1,270 @@
+// 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.
+
+// The filepath package implements utility routines for manipulating
+// filename paths in a way compatible with the target operating
+// system-defined file paths.
+package filepath
+
+import (
+	"os"
+	"sort"
+	"strings"
+)
+
+// BUG(niemeyer): Package filepath does not yet work on Windows.
+
+// 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 {
+	if path == "" {
+		return "."
+	}
+
+	rooted := path[0] == Separator
+	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] == Separator:
+			// empty path element
+			r++
+		case path[r] == '.' && (r+1 == n || path[r+1] == Separator):
+			// . element
+			r++
+		case path[r] == '.' && path[r+1] == '.' && (r+2 == n || path[r+2] == Separator):
+			// .. element: remove to last separator
+			r += 2
+			switch {
+			case w > dotdot:
+				// can backtrack
+				w--
+				for w > dotdot && buf[w] != Separator {
+					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 && path[r] != Separator; r++ {
+				buf[w] = path[r]
+				w++
+			}
+		}
+	}
+
+	// Turn empty string into "."
+	if w == 0 {
+		buf[w] = '.'
+		w++
+	}
+
+	return 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), -1)
+}
+
+// Split splits path immediately following the final Separator,
+// partitioning it into a directory and a file name components.
+// If there are no separators in path, Split returns an empty base
+// and file set to path.
+func Split(path string) (dir, file string) {
+	i := strings.LastIndex(path, string(Separator))
+	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 && path[i] != Separator; i-- {
+		if path[i] == '.' {
+			return path[i:]
+		}
+	}
+	return ""
+}
+
+// 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, os.O_RDONLY, 0)
+	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 && path[len(path)-1] == Separator {
+		path = path[0 : len(path)-1]
+	}
+	// Find the last element
+	if i := strings.LastIndex(path, string(Separator)); i >= 0 {
+		path = path[i+1:]
+	}
+	// If empty now, it had only slashes.
+	if path == "" {
+		return string(Separator)
+	}
+	return path
+}
+
+// IsAbs returns true if the path is absolute.
+func IsAbs(path string) bool {
+	return len(path) > 0 && path[0] == Separator
+}