| // 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 |
| } |