From 59b6e618166871a5feea46b72f1617048fba6afe Mon Sep 17 00:00:00 2001
From: ed <s@ocv.me>
Date: Wed, 6 Jul 2022 02:28:34 +0200
Subject: [PATCH] build fstab from relabels when mtab is unreadable

---
 copyparty/fsutil.py | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/copyparty/fsutil.py b/copyparty/fsutil.py
index 06979ec9..b1d3f3cd 100644
--- a/copyparty/fsutil.py
+++ b/copyparty/fsutil.py
@@ -3,6 +3,7 @@ from __future__ import print_function, unicode_literals
 
 import ctypes
 import re
+import os
 import time
 
 from .__init__ import ANYWIN, MACOS
@@ -21,6 +22,7 @@ class Fstab(object):
     def __init__(self, log: RootLogger):
         self.log_func = log
 
+        self.trusted = False
         self.tab: Optional[VFS] = None
         self.cache: dict[str, str] = {}
         self.age = 0.0
@@ -49,6 +51,7 @@ class Fstab(object):
                 self.log(msg.format(path, fs, min_ex()), 3)
                 return fs
 
+        path = path.lstrip("/")
         try:
             return self.cache[path]
         except:
@@ -92,21 +95,44 @@ class Fstab(object):
 
     def relabel(self, path: str, nval: str) -> None:
         assert self.tab
+        self.cache = {}
+        path = path.lstrip("/")
         ptn = re.compile(r"^[^\\/]*")
-        vn, _ = self.tab._find(path)
+        vn, rem = self.tab._find(path)
+        if not self.trusted:
+            # no mtab access; have to build as we go
+            if "/" in rem:
+                self.tab.add("idk", os.path.join(vn.vpath, rem.split("/")[0]))
+            if rem:
+                self.tab.add(nval, path)
+            else:
+                vn.realpath = nval
+
+            return
+
         visit = [vn]
         while visit:
             vn = visit.pop()
             vn.realpath = ptn.sub(nval, vn.realpath)
             visit.extend(list(vn.nodes.values()))
-        self.cache = {}
 
     def get_unix(self, path: str) -> str:
         if not self.tab:
-            self.build_tab()
+            try:
+                self.build_tab()
+                self.trusted = True
+            except:
+                # prisonparty or other restrictive environment
+                self.log("failed to build tab:\n{}".format(min_ex()), 3)
+                self.tab = VFS(self.log_func, "idk", "/", AXS(), {})
+                self.trusted = False
 
         assert self.tab
-        return self.tab._find(path)[0].realpath.split("/")[0]
+        ret = self.tab._find(path)[0]
+        if self.trusted or path == ret.vpath:
+            return ret.realpath.split("/")[0]
+        else:
+            return "idk"
 
     def get_w32(self, path: str) -> str:
         # list mountpoints: fsutil fsinfo drives