155 lines
3.6 KiB
Go
155 lines
3.6 KiB
Go
package symlink
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"os"
|
|
"path/filepath"
|
|
"strings"
|
|
"syscall"
|
|
|
|
"github.com/docker/docker/pkg/longpath"
|
|
)
|
|
|
|
func toShort(path string) (string, error) {
|
|
p, err := syscall.UTF16FromString(path)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
b := p // GetShortPathName says we can reuse buffer
|
|
n, err := syscall.GetShortPathName(&p[0], &b[0], uint32(len(b)))
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
if n > uint32(len(b)) {
|
|
b = make([]uint16, n)
|
|
if _, err = syscall.GetShortPathName(&p[0], &b[0], uint32(len(b))); err != nil {
|
|
return "", err
|
|
}
|
|
}
|
|
return syscall.UTF16ToString(b), nil
|
|
}
|
|
|
|
func toLong(path string) (string, error) {
|
|
p, err := syscall.UTF16FromString(path)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
b := p // GetLongPathName says we can reuse buffer
|
|
n, err := syscall.GetLongPathName(&p[0], &b[0], uint32(len(b)))
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
if n > uint32(len(b)) {
|
|
b = make([]uint16, n)
|
|
n, err = syscall.GetLongPathName(&p[0], &b[0], uint32(len(b)))
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
}
|
|
b = b[:n]
|
|
return syscall.UTF16ToString(b), nil
|
|
}
|
|
|
|
func evalSymlinks(path string) (string, error) {
|
|
path, err := walkSymlinks(path)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
p, err := toShort(path)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
p, err = toLong(p)
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
// syscall.GetLongPathName does not change the case of the drive letter,
|
|
// but the result of EvalSymlinks must be unique, so we have
|
|
// EvalSymlinks(`c:\a`) == EvalSymlinks(`C:\a`).
|
|
// Make drive letter upper case.
|
|
if len(p) >= 2 && p[1] == ':' && 'a' <= p[0] && p[0] <= 'z' {
|
|
p = string(p[0]+'A'-'a') + p[1:]
|
|
} else if len(p) >= 6 && p[5] == ':' && 'a' <= p[4] && p[4] <= 'z' {
|
|
p = p[:3] + string(p[4]+'A'-'a') + p[5:]
|
|
}
|
|
return filepath.Clean(p), nil
|
|
}
|
|
|
|
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)
|
|
}
|
|
|
|
// A path beginning with `\\?\` represents the root, so automatically
|
|
// skip that part and begin processing the next segment.
|
|
if strings.HasPrefix(path, longpath.Prefix) {
|
|
b.WriteString(longpath.Prefix)
|
|
path = path[4:]
|
|
continue
|
|
}
|
|
|
|
// 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(filepath.Separator)
|
|
}
|
|
continue
|
|
}
|
|
|
|
// If this is the first segment after the long path prefix, accept the
|
|
// current segment as a volume root or UNC share and move on to the next.
|
|
if b.String() == longpath.Prefix {
|
|
b.WriteString(p)
|
|
b.WriteRune(filepath.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(filepath.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 filepath.IsAbs(dest) || os.IsPathSeparator(dest[0]) {
|
|
b.Reset()
|
|
}
|
|
path = dest + string(filepath.Separator) + path
|
|
}
|
|
return filepath.Clean(b.String()), nil
|
|
}
|