Booting Android over USB

gistfile1.txt

From e3e5afef1f357a86c1c5bc1386910ed3ed095d7b Mon Sep 17 00:00:00 2001
From: Pierre-Hugues Husson <phh@phh.me>
Date: Tue, 18 Jul 2023 15:01:17 +0200
Subject: [PATCH] Allow booting USB

This fixes boot USB (assuming androidboot.boot_device=ff500000.dwc3 in cmdline):
- Do prefix match rather than full match, because full path includes USB path which might be problematic
- Only take boot_devices' list of partitions to confirm that partitions are ready
(without it internal emmc's partitions will be enough to tell system that it's ready to boot, even though it isn't)

Change-Id: I7b7aa0eff1442054eef19679e05e7a0808dcfd9d
---
 init/block_dev_initializer.cpp | 17 +++++++++++++----
 init/block_dev_initializer.h   |  1 +
 init/devices.cpp               |  6 +++++-
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/init/block_dev_initializer.cpp b/init/block_dev_initializer.cpp
index 05e00edfda..1688bbf768 100644
--- a/init/block_dev_initializer.cpp
+++ b/init/block_dev_initializer.cpp
@@ -29,11 +29,10 @@ namespace init {
 using android::base::Timer;
 using namespace std::chrono_literals;
 
-BlockDevInitializer::BlockDevInitializer() : uevent_listener_(16 * 1024 * 1024) {
-    auto boot_devices = android::fs_mgr::GetBootDevices();
+BlockDevInitializer::BlockDevInitializer() : uevent_listener_(16 * 1024 * 1024), boot_devices_(android::fs_mgr::GetBootDevices()) {
     device_handler_ = std::make_unique<DeviceHandler>(
             std::vector<Permissions>{}, std::vector<SysfsPermissions>{}, std::vector<Subsystem>{},
-            std::move(boot_devices), false);
+            boot_devices_, false);
 }
 
 bool BlockDevInitializer::InitDeviceMapper() {
@@ -98,6 +97,16 @@ ListenerAction BlockDevInitializer::HandleUevent(const Uevent& uevent,
 
     LOG(VERBOSE) << __PRETTY_FUNCTION__ << ": found partition: " << name;
 
+    std::string device;
+    bool is_boot_device = false;
+    for(const auto& b: boot_devices_) {
+        if(uevent.path.find(b) != std::string::npos) {
+            is_boot_device = true;
+        }
+    }
+
+    if(!is_boot_device) return ListenerAction::kContinue;
+
     devices->erase(iter);
     device_handler_->HandleUevent(uevent);
     return devices->empty() ? ListenerAction::kStop : ListenerAction::kContinue;
@@ -116,7 +125,7 @@ bool BlockDevInitializer::InitDevices(std::set<std::string> devices) {
                   << ": partition(s) not found in /sys, waiting for their uevent(s): "
                   << android::base::Join(devices, ", ");
         Timer t;
-        uevent_listener_.Poll(uevent_callback, 10s);
+        uevent_listener_.Poll(uevent_callback, 100s);
         LOG(INFO) << "Wait for partitions returned after " << t;
     }
 
diff --git a/init/block_dev_initializer.h b/init/block_dev_initializer.h
index ec39ce084d..7732ce6598 100644
--- a/init/block_dev_initializer.h
+++ b/init/block_dev_initializer.h
@@ -40,6 +40,7 @@ class BlockDevInitializer final {
 
     std::unique_ptr<DeviceHandler> device_handler_;
     UeventListener uevent_listener_;
+    std::set<std::string> boot_devices_;
 };
 
 }  // namespace init
diff --git a/init/devices.cpp b/init/devices.cpp
index d4a3cb9d35..d81c6a4216 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -403,7 +403,11 @@ std::vector<std::string> DeviceHandler::GetBlockDeviceSymlinks(const Uevent& uev
 
     auto link_path = "/dev/block/" + type + "/" + device;
 
-    bool is_boot_device = boot_devices_.find(device) != boot_devices_.end();
+    bool is_boot_device = false;
+    for(const auto& b: boot_devices_) {
+        if(device.find(b) == 0)
+            is_boot_device = true;
+    }
     if (!uevent.partition_name.empty()) {
         std::string partition_name_sanitized(uevent.partition_name);
         SanitizePartitionName(&partition_name_sanitized);
-- 
2.41.0