Add new build command avd_patch

native/jni/init/getinfo.cpp

@@ -180,6 +180,8 @@ void BootConfig::set(const kv_pairs &kv) {
             strlcpy(hardware_plat, value.data(), sizeof(hardware_plat));
         } else if (key == "androidboot.fstab_suffix") {
             strlcpy(fstab_suffix, value.data(), sizeof(fstab_suffix));
+        } else if (key == "qemu") {
+            emulator = true;
         }
     }
 }
@@ -193,6 +195,7 @@ void BootConfig::print() {
     LOGD("fstab_suffix=[%s]\n", fstab_suffix);
     LOGD("hardware=[%s]\n", hardware);
     LOGD("hardware.platform=[%s]\n", hardware_plat);
+    LOGD("emulator=[%d]\n", emulator);
 }
 
 #define read_dt(name, key)                                          \
@@ -230,7 +233,7 @@ void load_kernel_info(BootConfig *config) {
     parse_prop_file("/.backup/.magisk", [=](auto key, auto value) -> bool {
         if (key == "RECOVERYMODE" && value == "true") {
             LOGD("Running in recovery mode, waiting for key...\n");
-            config->skip_initramfs = !check_key_combo();
+            config->skip_initramfs = config->emulator || !check_key_combo();
             return false;
         }
         return true;

native/jni/init/init.hpp

@@ -6,6 +6,7 @@ struct BootConfig {
     bool skip_initramfs;
     bool force_normal_boot;
     bool rootwait;
+    bool emulator;
     char slot[3];
     char dt_dir[64];
     char fstab_suffix[32];
@@ -66,6 +67,10 @@ protected:
     mmap_data magisk_config;
     std::string custom_rules_dir;
 
+    // When this boolean is set, this means we are currently
+    // running magiskinit on legacy SAR AVD emulator
+    bool avd_hack = false;
+
     void mount_with_dt();
     bool patch_sepolicy(const char *file);
     void setup_tmp(const char *path);

native/jni/init/mount.cpp

@@ -158,12 +158,19 @@ 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")
+            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);
-        mount_list.push_back(entry.mnt_point);
+        // 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)
+            mount_list.push_back(entry.mnt_point);
     }
 }
 
@@ -372,6 +379,7 @@ void SARInit::early_mount() {
         xmkdir("/dev", 0755);
         xmount("tmpfs", "/dev", "tmpfs", 0, "mode=755");
         mount_list.emplace_back("/dev");
+        avd_hack = config->emulator;
         mount_with_dt();
     }
 }
@@ -399,7 +407,7 @@ bool SecondStageInit::prepare() {
 void BaseInit::exec_init() {
     // Unmount in reverse order
     for (auto &p : reversed(mount_list)) {
-        if (xumount(p.data()) == 0)
+        if (xumount2(p.data(), MNT_DETACH) == 0)
             LOGD("Unmount [%s]\n", p.data());
     }
     execv("/init", argv);

native/jni/init/rootdir.cpp

@@ -234,6 +234,10 @@ void SARBase::patch_rootdir() {
             make_pair(SPLIT_PLAT_CIL, "xxx"), /* Force loading monolithic sepolicy */
             make_pair(MONOPOLICY, sepol)      /* Redirect /sepolicy to custom path */
          });
+        if (avd_hack) {
+            // Force disable early mount on original init
+            init.patch({ make_pair("android,fstab", "xxx") });
+        }
         xmkdir(ROOTOVL, 0);
         int dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC, 0);
         xwrite(dest, init.buf, init.sz);