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// 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
}
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