From 1aade8f8a8ddf2cdd207e2e1bdd304d3e5f8a4d3 Mon Sep 17 00:00:00 2001
From: LoveSy <shana@zju.edu.cn>
Date: Fri, 3 Mar 2023 22:53:53 +0800
Subject: [PATCH] No greedy match to find parent mount point

This fixes /sys is considered as a parent mount point of /system
---
 native/src/core/bootstages.cpp    | 17 ++++++++++-------
 native/src/zygisk/deny/revert.cpp |  7 ++++---
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/native/src/core/bootstages.cpp b/native/src/core/bootstages.cpp
index cf3041974..804a1aa75 100644
--- a/native/src/core/bootstages.cpp
+++ b/native/src/core/bootstages.cpp
@@ -3,7 +3,7 @@
 #include <sys/sysmacros.h>
 #include <linux/input.h>
 #include <libgen.h>
-#include <vector>
+#include <set>
 #include <string>
 
 #include <magisk.hpp>
@@ -54,14 +54,17 @@ static void mount_mirrors() {
     if (auto mirror_dir = MAGISKTMP + "/" MIRRDIR; !mount_mirror("/", mirror_dir)) {
         LOGI("fallback to mount subtree\n");
         // rootfs may fail, fallback to bind mount each mount point
-        std::vector<string> mounted_dirs {{ MAGISKTMP }};
+        set<string, greater<>> mounted_dirs {{ MAGISKTMP }};
         for (const auto &info: parse_mount_info("self")) {
             if (info.type == "rootfs"sv) continue;
-            bool mounted = std::any_of(mounted_dirs.begin(), mounted_dirs.end(), [&](const auto &dir) {
-                return str_starts(info.target, dir);
-            });
-            if (!mounted && mount_mirror(info.target, mirror_dir + info.target)) {
-                mounted_dirs.emplace_back(info.target);
+            // the greatest mount point that less than info.target, which is possibly a parent
+            if (auto last_mount = mounted_dirs.upper_bound(info.target);
+                last_mount != mounted_dirs.end() && info.target.starts_with(*last_mount + '/')) {
+                continue;
+            }
+            if (mount_mirror(info.target, mirror_dir + info.target)) {
+                LOGD("%-8s: %s <- %s\n", "rbind", (mirror_dir + info.target).data(), info.target.data());
+                mounted_dirs.insert(info.target);
             }
         }
     }
diff --git a/native/src/zygisk/deny/revert.cpp b/native/src/zygisk/deny/revert.cpp
index 47ccd7634..01cdcf01a 100644
--- a/native/src/zygisk/deny/revert.cpp
+++ b/native/src/zygisk/deny/revert.cpp
@@ -27,11 +27,12 @@ void revert_unmount() {
 
     if (targets.empty()) return;
 
-    for (auto last_target = targets.cbegin(), iter = next(targets.cbegin()); iter != targets.cend();) {
-        if (iter->starts_with(*last_target)) {
+    auto last_target = *targets.cbegin() + '/';
+    for (auto iter = next(targets.cbegin()); iter != targets.cend();) {
+        if (iter->starts_with(last_target)) {
             iter = targets.erase(iter);
         } else {
-            last_target = iter++;
+            last_target = *iter++ + '/';
         }
     }