a315e6865c
Our rudimentary check for whether a file path is entirely contained under a directory had a false negative when the parent directory is "/".
76 lines
1.4 KiB
Go
76 lines
1.4 KiB
Go
package download
|
|
|
|
import (
|
|
"archive/zip"
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
"path/filepath"
|
|
"strings"
|
|
)
|
|
|
|
const (
|
|
dirMode os.FileMode = 0755
|
|
fileMode os.FileMode = 0644
|
|
execMode os.FileMode = 0755
|
|
)
|
|
|
|
func extractZip(zr *zip.Reader, destDir string) error {
|
|
for _, zf := range zr.File {
|
|
fpath := filepath.Join(destDir, filepath.FromSlash(zf.Name))
|
|
if !filepathDescendsFrom(fpath, destDir) {
|
|
continue
|
|
}
|
|
if err := extractZipFile(zf, fpath); err != nil {
|
|
return fmt.Errorf("error extracting %q: %w", zf.Name, err)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func extractZipFile(zf *zip.File, dest string) error {
|
|
zm := zf.Mode()
|
|
if zm.IsDir() {
|
|
return os.MkdirAll(dest, dirMode)
|
|
}
|
|
|
|
f, err := zf.Open()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer f.Close()
|
|
|
|
if dir := filepath.Dir(dest); dir != "." {
|
|
if err := os.MkdirAll(dir, dirMode); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
df, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE|os.O_EXCL, getPerm(zm))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer df.Close()
|
|
|
|
_, err = io.Copy(df, f)
|
|
return err
|
|
}
|
|
|
|
func getPerm(m os.FileMode) os.FileMode {
|
|
if m&0111 == 0 {
|
|
return fileMode
|
|
}
|
|
return execMode
|
|
}
|
|
|
|
func filepathDescendsFrom(p, dir string) bool {
|
|
p = filepath.Clean(p)
|
|
dir = filepath.Clean(dir)
|
|
if dir == "." && !filepath.IsAbs(p) {
|
|
return !strings.HasPrefix(p, ".."+string(filepath.Separator))
|
|
}
|
|
if !strings.HasSuffix(dir, string(filepath.Separator)) {
|
|
dir += string(filepath.Separator)
|
|
}
|
|
return strings.HasPrefix(p, dir)
|
|
}
|