117 lines
2.3 KiB
Go
117 lines
2.3 KiB
Go
|
// This software is distributed under the MIT License.
|
||
|
|
//
|
||
|
|
// You should have received a copy of the MIT License along with this program.
|
||
|
|
// If not, see <https://opensource.org/licenses/MIT>
|
||
|
|
|
||
|
|
package realpath
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"os"
|
||
|
|
"path/filepath"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Realpath returns the real path of a given file in the os
|
||
|
|
func Realpath(fpath string) (string, error) {
|
||
|
|
|
||
|
|
if len(fpath) == 0 {
|
||
|
|
return "", os.ErrInvalid
|
||
|
|
}
|
||
|
|
|
||
|
|
if !filepath.IsAbs(fpath) {
|
||
|
|
pwd, err := os.Getwd()
|
||
|
|
if err != nil {
|
||
|
|
return "", err
|
||
|
|
}
|
||
|
|
fpath = filepath.Join(pwd, fpath)
|
||
|
|
}
|
||
|
|
|
||
|
|
path := []byte(fpath)
|
||
|
|
nlinks := 0
|
||
|
|
start := 1
|
||
|
|
prev := 1
|
||
|
|
for start < len(path) {
|
||
|
|
c := nextComponent(path, start)
|
||
|
|
cur := c[start:]
|
||
|
|
|
||
|
|
switch {
|
||
|
|
|
||
|
|
case len(cur) == 0:
|
||
|
|
copy(path[start:], path[start+1:])
|
||
|
|
path = path[0 : len(path)-1]
|
||
|
|
|
||
|
|
case len(cur) == 1 && cur[0] == '.':
|
||
|
|
if start+2 < len(path) {
|
||
|
|
copy(path[start:], path[start+2:])
|
||
|
|
}
|
||
|
|
path = path[0 : len(path)-2]
|
||
|
|
|
||
|
|
case len(cur) == 2 && cur[0] == '.' && cur[1] == '.':
|
||
|
|
copy(path[prev:], path[start+2:])
|
||
|
|
path = path[0 : len(path)+prev-(start+2)]
|
||
|
|
prev = 1
|
||
|
|
start = 1
|
||
|
|
|
||
|
|
default:
|
||
|
|
|
||
|
|
fi, err := os.Lstat(string(c))
|
||
|
|
if err != nil {
|
||
|
|
return "", err
|
||
|
|
}
|
||
|
|
if isSymlink(fi) {
|
||
|
|
|
||
|
|
nlinks++
|
||
|
|
if nlinks > 16 {
|
||
|
|
return "", os.ErrInvalid
|
||
|
|
}
|
||
|
|
|
||
|
|
var link string
|
||
|
|
link, err = os.Readlink(string(c))
|
||
|
|
after := string(path[len(c):])
|
||
|
|
|
||
|
|
// switch symlink component with its real path
|
||
|
|
path = switchSymlinkCom(path, start, link, after)
|
||
|
|
|
||
|
|
prev = 1
|
||
|
|
start = 1
|
||
|
|
} else {
|
||
|
|
// Directories
|
||
|
|
prev = start
|
||
|
|
start = len(c) + 1
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
for len(path) > 1 && path[len(path)-1] == os.PathSeparator {
|
||
|
|
path = path[0 : len(path)-1]
|
||
|
|
}
|
||
|
|
return string(path), nil
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
// test if a link is symbolic link
|
||
|
|
func isSymlink(fi os.FileInfo) bool {
|
||
|
|
return fi.Mode()&os.ModeSymlink == os.ModeSymlink
|
||
|
|
}
|
||
|
|
|
||
|
|
// switch a symbolic link component to its real path
|
||
|
|
func switchSymlinkCom(path []byte, start int, link, after string) []byte {
|
||
|
|
|
||
|
|
if link[0] == os.PathSeparator {
|
||
|
|
// Absolute links
|
||
|
|
return []byte(filepath.Join(link, after))
|
||
|
|
}
|
||
|
|
|
||
|
|
// Relative links
|
||
|
|
return []byte(filepath.Join(string(path[0:start]), link, after))
|
||
|
|
}
|
||
|
|
|
||
|
|
// get the next component
|
||
|
|
func nextComponent(path []byte, start int) []byte {
|
||
|
|
v := bytes.IndexByte(path[start:], os.PathSeparator)
|
||
|
|
if v < 0 {
|
||
|
|
return path
|
||
|
|
}
|
||
|
|
return path[0 : start+v]
|
||
|
|
}
|