From 519bd2f30f5d74fe08d655cab0b5b9b5db3a42ab Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Wed, 19 Jan 2022 20:28:01 -0800
Subject: [PATCH] Disable AVD hacks by default

---
 native/jni/init/init.hpp  | 10 ++++++++++
 native/jni/init/mount.cpp | 16 ++++++++++------
 scripts/avd_magisk.sh     |  2 +-
 scripts/avd_patch.sh      |  6 ++++++
 4 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/native/jni/init/init.hpp b/native/jni/init/init.hpp
index f3217890b..46927fee3 100644
--- a/native/jni/init/init.hpp
+++ b/native/jni/init/init.hpp
@@ -2,6 +2,11 @@
 
 using kv_pairs = std::vector<std::pair<std::string, std::string>>;
 
+// For API 28 AVD, it uses legacy SAR setup that requires
+// special hacks in magiskinit to work properly. We do not
+// necessarily want this enabled in production builds.
+#define ENABLE_AVD_HACK 0
+
 struct BootConfig {
     bool skip_initramfs;
     bool force_normal_boot;
@@ -67,9 +72,14 @@ protected:
     mmap_data magisk_config;
     std::string custom_rules_dir;
 
+#if ENABLE_AVD_HACK
     // When this boolean is set, this means we are currently
     // running magiskinit on legacy SAR AVD emulator
     bool avd_hack = false;
+#else
+    // Make it const so compiler can optimize hacks out of the code
+    static const bool avd_hack = false;
+#endif
 
     void mount_with_dt();
     bool patch_sepolicy(const char *file);
diff --git a/native/jni/init/mount.cpp b/native/jni/init/mount.cpp
index 06410a318..779221d35 100644
--- a/native/jni/init/mount.cpp
+++ b/native/jni/init/mount.cpp
@@ -158,19 +158,21 @@ void MagiskInit::mount_with_dt() {
     for (const auto &entry : fstab) {
         if (is_lnk(entry.mnt_point.data()))
             continue;
-        // When we force AVD to disable SystemAsRoot, it will always add system
-        // to dt fstab, which we actually have already mounted as root
-        if (avd_hack && entry.mnt_point == "/system")
+        if (avd_hack && entry.mnt_point == "/system") {
+            // When we force AVD to disable SystemAsRoot, it will always add system
+            // to dt fstab. We actually already mounted it as root, so skip this one.
             continue;
+        }
         // Derive partname from dev
         sprintf(blk_info.partname, "%s%s", basename(entry.dev.data()), config->slot);
         setup_block(true);
         xmkdir(entry.mnt_point.data(), 0755);
         xmount(blk_info.block_dev, entry.mnt_point.data(), entry.type.data(), MS_RDONLY, nullptr);
-        // When avd_hack is true, do not add any early mount partitions to mount_list
-        // as we will actually forcefully disable original init's early mount
-        if (!avd_hack)
+        if (!avd_hack) {
+            // When avd_hack is true, do not add any early mount partitions to mount_list
+            // as we will actually forcefully disable original init's early mount
             mount_list.push_back(entry.mnt_point);
+        }
     }
 }
 
@@ -379,7 +381,9 @@ void SARInit::early_mount() {
         xmkdir("/dev", 0755);
         xmount("tmpfs", "/dev", "tmpfs", 0, "mode=755");
         mount_list.emplace_back("/dev");
+#if ENABLE_AVD_HACK
         avd_hack = config->emulator;
+#endif
         mount_with_dt();
     }
 }
diff --git a/scripts/avd_magisk.sh b/scripts/avd_magisk.sh
index 2c5baaa31..a8b388ea7 100755
--- a/scripts/avd_magisk.sh
+++ b/scripts/avd_magisk.sh
@@ -16,7 +16,7 @@
 # the official Android emulator (AVD) instead of a real device.
 #
 # This only covers the "core" features of Magisk. For testing
-# magiskinit, please checkout avd_init.sh.
+# magiskinit, please checkout avd_patch.sh.
 #
 #####################################################################
 
diff --git a/scripts/avd_patch.sh b/scripts/avd_patch.sh
index f73bc1855..dcb00a973 100644
--- a/scripts/avd_patch.sh
+++ b/scripts/avd_patch.sh
@@ -14,6 +14,10 @@
 # After patching ramdisk.img, close the emulator, then select
 # "Cold Boot Now" in AVD Manager to force a full reboot.
 #
+# P.S. If running against the API 28 image, modify init.hpp and set
+# ENABLE_AVD_HACK to 1 to enable special hacks designed specifically
+# for this use case.
+#
 #####################################################################
 # AVD Init Configurations:
 #
@@ -39,6 +43,8 @@ if [ -z "$FIRST_STAGE" ]; then
   exec ./busybox sh $0
 fi
 
+pm install -r $(pwd)/app-debug.apk
+
 # Extract files from APK
 unzip -oj app-debug.apk 'assets/util_functions.sh'
 . ./util_functions.sh