Imported Upstream version 1.4upstream/1.4

1 files changed, 72 insertions, 0 deletions

diff --git a/src/path/filepath/symlink.go b/src/path/filepath/symlink.go
new file mode 100644
index 000000000..df0a9e0c2
--- /dev/null
+++ b/src/path/filepath/symlink.go
@@ -0,0 +1,72 @@
+// Copyright 2012 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 (
+	"bytes"
+	"errors"
+	"os"
+)
+
+const utf8RuneSelf = 0x80
+
+func walkSymlinks(path string) (string, error) {
+	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 "", errors.New("EvalSymlinks: too many links in " + originalPath)
+		}
+
+		// find next path component, p
+		var i = -1
+		for j, c := range path {
+			if c < utf8RuneSelf && os.IsPathSeparator(uint8(c)) {
+				i = j
+				break
+			}
+		}
+		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.Mode()&os.ModeSymlink == 0 {
+			b.WriteString(p)
+			if path != "" || (b.Len() == 2 && len(p) == 2 && p[1] == ':') {
+				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) || os.IsPathSeparator(dest[0]) {
+			b.Reset()
+		}
+		path = dest + string(Separator) + path
+	}
+	return Clean(b.String()), nil
+}