1 files changed, 172 insertions, 117 deletions

diff --git a/src/pkg/path/filepath/path.go b/src/pkg/path/filepath/path.go
index 3d5b915c1..1e7487263 100644
--- a/src/pkg/path/filepath/path.go
+++ b/src/pkg/path/filepath/path.go
@@ -7,9 +7,8 @@
 package filepath
 
 import (
-	"bytes"
+	"errors"
 	"os"
-	"runtime"
 	"sort"
 	"strings"
 )
@@ -35,15 +34,18 @@ const (
 // returns the string ".".
 //
 // See also Rob Pike, ``Lexical File Names in Plan 9 or
-// Getting Dot-Dot right,''
+// 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 == "" {
+		if len(vol) > 1 && vol[1] != ':' {
+			// should be UNC
+			return FromSlash(vol)
+		}
 		return vol + "."
 	}
-
 	rooted := os.IsPathSeparator(path[0])
 
 	// Invariants:
@@ -114,7 +116,8 @@ func Clean(path string) string {
 }
 
 // ToSlash returns the result of replacing each separator character
-// in path with a slash ('/') character.
+// in path with a slash ('/') character. Multiple separators are
+// replaced by multiple slashes.
 func ToSlash(path string) string {
 	if Separator == '/' {
 		return path
@@ -123,7 +126,8 @@ func ToSlash(path string) string {
 }
 
 // FromSlash returns the result of replacing each slash ('/') character
-// in path with a separator character.
+// in path with a separator character. Multiple slashes are replaced
+// by multiple separators.
 func FromSlash(path string) string {
 	if Separator == '/' {
 		return path
@@ -131,7 +135,9 @@ func FromSlash(path string) string {
 	return strings.Replace(path, "/", string(Separator), -1)
 }
 
-// SplitList splits a list of paths joined by the OS-specific ListSeparator.
+// SplitList splits a list of paths joined by the OS-specific ListSeparator,
+// usually found in PATH or GOPATH environment variables.
+// Unlike strings.Split, SplitList returns an empty slice when passed an empty string.
 func SplitList(path string) []string {
 	if path == "" {
 		return []string{}
@@ -143,16 +149,19 @@ func SplitList(path string) []string {
 // 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.
+// The returned values have the property that path = dir+file.
 func Split(path string) (dir, file string) {
+	vol := VolumeName(path)
 	i := len(path) - 1
-	for i >= 0 && !os.IsPathSeparator(path[i]) {
+	for i >= len(vol) && !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.
+// a Separator if necessary. The result is Cleaned, in particular
+// all empty strings are ignored.
 func Join(elem ...string) string {
 	for i, e := range elem {
 		if e != "" {
@@ -177,73 +186,17 @@ func Ext(path string) string {
 
 // 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
+// If path is relative the result will be relative to the current directory,
+// unless one of the components is an absolute symbolic link.
+func EvalSymlinks(path string) (string, error) {
+	return evalSymlinks(path)
 }
 
 // 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) {
+func Abs(path string) (string, error) {
 	if IsAbs(path) {
 		return Clean(path), nil
 	}
@@ -254,40 +207,140 @@ func Abs(path string) (string, os.Error) {
 	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)
+// Rel returns a relative path that is lexically equivalent to targpath when
+// joined to basepath with an intervening separator. That is,
+// Join(basepath, Rel(basepath, targpath)) is equivalent to targpath itself.
+// On success, the returned path will always be relative to basepath,
+// even if basepath and targpath share no elements.
+// An error is returned if targpath can't be made relative to basepath or if
+// knowing the current working directory would be necessary to compute it.
+func Rel(basepath, targpath string) (string, error) {
+	baseVol := VolumeName(basepath)
+	targVol := VolumeName(targpath)
+	base := Clean(basepath)
+	targ := Clean(targpath)
+	if targ == base {
+		return ".", nil
+	}
+	base = base[len(baseVol):]
+	targ = targ[len(targVol):]
+	if base == "." {
+		base = ""
+	}
+	// Can't use IsAbs - `\a` and `a` are both relative in Windows.
+	baseSlashed := len(base) > 0 && base[0] == Separator
+	targSlashed := len(targ) > 0 && targ[0] == Separator
+	if baseSlashed != targSlashed || baseVol != targVol {
+		return "", errors.New("Rel: can't make " + targ + " relative to " + base)
+	}
+	// Position base[b0:bi] and targ[t0:ti] at the first differing elements.
+	bl := len(base)
+	tl := len(targ)
+	var b0, bi, t0, ti int
+	for {
+		for bi < bl && base[bi] != Separator {
+			bi++
+		}
+		for ti < tl && targ[ti] != Separator {
+			ti++
+		}
+		if targ[t0:ti] != base[b0:bi] {
+			break
+		}
+		if bi < bl {
+			bi++
+		}
+		if ti < tl {
+			ti++
+		}
+		b0 = bi
+		t0 = ti
+	}
+	if base[b0:bi] == ".." {
+		return "", errors.New("Rel: can't make " + targ + " relative to " + base)
+	}
+	if b0 != bl {
+		// Base elements left. Must go up before going down.
+		seps := strings.Count(base[b0:bl], string(Separator))
+		size := 2 + seps*3
+		if tl != t0 {
+			size += 1 + tl - t0
+		}
+		buf := make([]byte, size)
+		n := copy(buf, "..")
+		for i := 0; i < seps; i++ {
+			buf[n] = Separator
+			copy(buf[n+1:], "..")
+			n += 3
+		}
+		if t0 != tl {
+			buf[n] = Separator
+			copy(buf[n+1:], targ[t0:])
+		}
+		return string(buf), nil
+	}
+	return targ[t0:], nil
 }
 
-func walk(path string, f *os.FileInfo, v Visitor, errors chan<- os.Error) {
-	if !f.IsDirectory() {
-		v.VisitFile(path, f)
-		return
+// SkipDir is used as a return value from WalkFuncs to indicate that
+// the directory named in the call is to be skipped. It is not returned
+// as an error by any function.
+var SkipDir = errors.New("skip this directory")
+
+// WalkFunc is the type of the function called for each file or directory
+// visited by Walk.  If there was a problem walking to the file or directory
+// named by path, the incoming error will describe the problem and the
+// function can decide how to handle that error (and Walk will not descend
+// into that directory).  If an error is returned, processing stops.  The
+// sole exception is that if path is a directory and the function returns the
+// special value SkipDir, the contents of the directory are skipped
+// and processing continues as usual on the next file.
+type WalkFunc func(path string, info os.FileInfo, err error) error
+
+// walk recursively descends path, calling w.
+func walk(path string, info os.FileInfo, walkFn WalkFunc) error {
+	err := walkFn(path, info, nil)
+	if err != nil {
+		if info.IsDir() && err == SkipDir {
+			return nil
+		}
+		return err
 	}
 
-	if !v.VisitDir(path, f) {
-		return // skip directory entries
+	if !info.IsDir() {
+		return nil
 	}
 
 	list, err := readDir(path)
 	if err != nil {
-		if errors != nil {
-			errors <- err
+		return walkFn(path, info, err)
+	}
+
+	for _, fileInfo := range list {
+		if err = walk(Join(path, fileInfo.Name()), fileInfo, walkFn); err != nil {
+			return err
 		}
 	}
+	return nil
+}
 
-	for _, e := range list {
-		walk(Join(path, e.Name), e, v, errors)
+// Walk walks the file tree rooted at root, calling walkFn for each file or
+// directory in the tree, including root. All errors that arise visiting files
+// and directories are filtered by walkFn. The files are walked in lexical
+// order, which makes the output deterministic but means that for very
+// large directories Walk can be inefficient.
+func Walk(root string, walkFn WalkFunc) error {
+	info, err := os.Lstat(root)
+	if err != nil {
+		return walkFn(root, nil, err)
 	}
+	return walk(root, info, walkFn)
 }
 
 // readDir reads the directory named by dirname and returns
-// a list of sorted directory entries.
+// a sorted list of directory entries.
 // Copied from io/ioutil to avoid the circular import.
-func readDir(dirname string) ([]*os.FileInfo, os.Error) {
+func readDir(dirname string) ([]os.FileInfo, error) {
 	f, err := os.Open(dirname)
 	if err != nil {
 		return nil, err
@@ -297,38 +350,16 @@ func readDir(dirname string) ([]*os.FileInfo, os.Error) {
 	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
+	sort.Sort(byName(list))
+	return list, nil
 }
 
-// A dirList implements sort.Interface.
-type fileInfoList []*os.FileInfo
+// byName implements sort.Interface.
+type byName []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)
-}
+func (f byName) Len() int           { return len(f) }
+func (f byName) Less(i, j int) bool { return f[i].Name() < f[j].Name() }
+func (f byName) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
 
 // Base returns the last element of path.
 // Trailing path separators are removed before extracting the last element.
@@ -342,6 +373,8 @@ func Base(path string) string {
 	for len(path) > 0 && os.IsPathSeparator(path[len(path)-1]) {
 		path = path[0 : len(path)-1]
 	}
+	// Throw away volume name
+	path = path[len(VolumeName(path)):]
 	// Find the last element
 	i := len(path) - 1
 	for i >= 0 && !os.IsPathSeparator(path[i]) {
@@ -356,3 +389,25 @@ func Base(path string) string {
 	}
 	return path
 }
+
+// Dir returns all but the last element of path, typically the path's directory.
+// Trailing path separators are removed before processing.
+// If the path is empty, Dir returns ".".
+// If the path consists entirely of separators, Dir returns a single separator.
+// The returned path does not end in a separator unless it is the root directory.
+func Dir(path string) string {
+	vol := VolumeName(path)
+	i := len(path) - 1
+	for i >= len(vol) && !os.IsPathSeparator(path[i]) {
+		i--
+	}
+	dir := Clean(path[len(vol) : i+1])
+	last := len(dir) - 1
+	if last > 0 && os.IsPathSeparator(dir[last]) {
+		dir = dir[:last]
+	}
+	if dir == "" {
+		dir = "."
+	}
+	return vol + dir
+}