Set ownership on directories in chroot

Also support getOwner on all Unixes as they all have `Stat_t.{U,G}id`

client/allocdir/alloc_dir.go

@@ -17,6 +17,12 @@ import (
 	"github.com/hpcloud/tail/watch"
 )
 
+const (
+	// idUnsupported is what the uid/gid will be set to on platforms (eg
+	// Windows) that don't support integer ownership identifiers.
+	idUnsupported = -1
+)
+
 var (
 	// The name of the directory that is shared across tasks in a task group.
 	SharedAllocName = "alloc"
@@ -405,7 +411,7 @@ func fileCopy(src, dst string, uid, gid int, perm os.FileMode) error {
 		return fmt.Errorf("Couldn't copy %q to %q: %v", src, dst, err)
 	}
 
-	if uid >= 0 && gid >= 0 {
+	if uid != idUnsupported && gid != idUnsupported {
 		if err := dstFile.Chown(uid, gid); err != nil {
 			return fmt.Errorf("Couldn't copy %q to %q: %v", src, dst, err)
 		}
@@ -456,6 +462,12 @@ func createDir(basePath, relPath string) error {
 		if err := os.MkdirAll(destDir, fi.Perm); err != nil {
 			return err
 		}
+
+		if fi.Uid != idUnsupported && fi.Gid != idUnsupported {
+			if err := os.Chown(destDir, fi.Uid, fi.Gid); err != nil {
+				return err
+			}
+		}
 	}
 	return nil
 }
@@ -464,24 +476,30 @@ func createDir(basePath, relPath string) error {
 type fileInfo struct {
 	Name string
 	Perm os.FileMode
+
+	// Uid and Gid are unsupported on Windows
+	Uid int
+	Gid int
 }
 
 // splitPath stats each subdirectory of a path. The first element of the array
 // is the file passed to this function, and the last element is the root of the
 // path.
 func splitPath(path string) ([]fileInfo, error) {
 	var mode os.FileMode
-	i, err := os.Stat(path)
+	fi, err := os.Stat(path)
 
 	// If the path is not present in the host then we respond with the most
 	// flexible permission.
+	uid, gid := idUnsupported, idUnsupported
 	if err != nil {
 		mode = os.ModePerm
 	} else {
-		mode = i.Mode()
+		uid, gid = getOwner(fi)
+		mode = fi.Mode()
 	}
 	var dirs []fileInfo
-	dirs = append(dirs, fileInfo{Name: path, Perm: mode})
+	dirs = append(dirs, fileInfo{Name: path, Perm: mode, Uid: uid, Gid: gid})
 	currentDir := path
 	for {
 		dir := filepath.Dir(filepath.Clean(currentDir))
@@ -491,13 +509,15 @@ func splitPath(path string) ([]fileInfo, error) {
 
 		// We try to find the permission of the file in the host. If the path is not
 		// present in the host then we respond with the most flexible permission.
-		i, err = os.Stat(dir)
+		uid, gid := idUnsupported, idUnsupported
+		fi, err := os.Stat(dir)
 		if err != nil {
 			mode = os.ModePerm
 		} else {
-			mode = i.Mode()
+			uid, gid = getOwner(fi)
+			mode = fi.Mode()
 		}
-		dirs = append(dirs, fileInfo{Name: dir, Perm: mode})
+		dirs = append(dirs, fileInfo{Name: dir, Perm: mode, Uid: uid, Gid: gid})
 		currentDir = dir
 	}
 	return dirs, nil

client/allocdir/fs_darwin.go

@@ -24,8 +24,3 @@ func createSecretDir(dir string) error {
 func removeSecretDir(dir string) error {
 	return os.RemoveAll(dir)
 }
-
-// getOwner isn't implemented for Darwin
-func getOwner(os.FileInfo) (int, int) {
-	return -1, -1
-}

client/allocdir/fs_freebsd.go

@@ -24,8 +24,3 @@ func createSecretDir(dir string) error {
 func removeSecretDir(dir string) error {
 	return os.RemoveAll(dir)
 }
-
-// getOwner isn't implemented for FreeBSD
-func getOwner(os.FileInfo) (int, int) {
-	return -1, -1
-}

client/allocdir/fs_linux.go

@@ -88,11 +88,3 @@ func removeSecretDir(dir string) error {
 	}
 	return os.RemoveAll(dir)
 }
-
-func getOwner(fi os.FileInfo) (int, int) {
-	stat, ok := fi.Sys().(*syscall.Stat_t)
-	if !ok {
-		return -1, -1
-	}
-	return int(stat.Uid), int(stat.Gid)
-}

client/allocdir/fs_solaris.go

@@ -25,8 +25,3 @@ func createSecretDir(dir string) error {
 func removeSecretDir(dir string) error {
 	return os.RemoveAll(dir)
 }
-
-// getOwner isn't implemented for Solaris
-func getOwner(os.FileInfo) (int, int) {
-	return -1, -1
-}

client/allocdir/fs_unix.go

@@ -8,6 +8,7 @@ import (
 	"os/user"
 	"path/filepath"
 	"strconv"
+	"syscall"
 
 	"golang.org/x/sys/unix"
 )
@@ -96,3 +97,11 @@ func linkOrCopy(src, dst string, uid, gid int, perm os.FileMode) error {
 
 	return fileCopy(src, dst, uid, gid, perm)
 }
+
+func getOwner(fi os.FileInfo) (int, int) {
+	stat, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return -1, -1
+	}
+	return int(stat.Uid), int(stat.Gid)
+}

client/allocdir/fs_windows.go

@@ -73,5 +73,5 @@ func unmountSpecialDirs(taskDir string) error {
 
 // getOwner doesn't work on Windows as Windows doesn't use int user IDs
 func getOwner(os.FileInfo) (int, int) {
-	return -1, -1
+	return idUnsupported, idUnsupported
 }