intro misctrl am: 1dba6a8129

Original change: https://android-review.googlesource.com/c/platform/bootable/recovery/+/2966070

Change-Id: I39bc4b1309e82064234a8f6d3c63e91e8e98d4ba
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

bootloader_message/Android.bp

@@ -39,6 +39,17 @@ cc_defaults {
     export_include_dirs: ["include"],
 }
 
+cc_binary {
+    name: "misctrl",
+    shared_libs: [
+        "libbase",
+        "libbootloader_message",
+        "liblog",
+    ],
+    init_rc: ["misctrl.rc"],
+    srcs: ["misctrl_main.cpp"],
+}
+
 cc_library {
     name: "libbootloader_message",
     defaults: [

bootloader_message/bootloader_message.cpp

@@ -26,6 +26,7 @@
 #include <vector>
 
 #include <android-base/file.h>
+#include <android-base/hex.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
@@ -324,6 +325,23 @@ bool WriteMiscKcmdlineMessage(const misc_kcmdline_message& message, std::string*
                                        offsetof(misc_system_space_layout, kcmdline_message), err);
 }
 
+bool CheckReservedSystemSpaceEmpty(bool* empty, std::string* err) {
+  constexpr size_t kReservedSize = SYSTEM_SPACE_SIZE_IN_MISC - sizeof(misc_system_space_layout);
+
+  uint8_t space[kReservedSize];
+  if (!ReadMiscPartitionSystemSpace(&space, kReservedSize, sizeof(misc_system_space_layout), err)) {
+    return false;
+  }
+
+  *empty = space[0] == 0 && 0 == memcmp(space, space + 1, kReservedSize - 1);
+
+  if (!*empty) {
+    *err = android::base::HexString(space, kReservedSize);
+  }
+
+  return true;
+}
+
 extern "C" bool write_reboot_bootloader(void) {
   std::string err;
   return write_reboot_bootloader(&err);

bootloader_message/include/bootloader_message/bootloader_message.h

@@ -216,6 +216,10 @@ bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err
 // Read or write the kcmdline message from system space in /misc.
 bool ReadMiscKcmdlineMessage(misc_kcmdline_message* message, std::string* err);
 bool WriteMiscKcmdlineMessage(const misc_kcmdline_message& message, std::string* err);
+
+// Check reserved system space.
+bool CheckReservedSystemSpaceEmpty(bool* empty, std::string* err);
+
 #else
 
 #include <stdbool.h>

bootloader_message/misctrl.rc

@@ -0,0 +1,4 @@
+service misctrl /system/bin/misctrl
+    user root # for misc partition access
+    class core
+    oneshot

bootloader_message/misctrl_main.cpp

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <bootloader_message/bootloader_message.h>
+#include <log/log.h>
+
+#include <string>
+
+#include <cstdio>
+
+static void log(const char* fmt, ...) __attribute__((format(printf, 1, 2)));
+static void log(const char* fmt, ...) {
+  va_list va;
+  va_start(va, fmt);
+
+  va_list vb;
+  va_copy(vb, va);
+
+  __android_log_vprint(ANDROID_LOG_ERROR, "misctrl", fmt, va);
+  va_end(va);
+
+  vfprintf(stderr, fmt, vb);
+  fprintf(stderr, "\n");
+  va_end(vb);
+}
+
+static int check_reserved_space() {
+  bool empty;
+  std::string err;
+  bool success = CheckReservedSystemSpaceEmpty(&empty, &err);
+  if (!success) {
+    log("Could not read reserved space: %s", err.c_str());
+    return 1;
+  }
+  log("System reserved space empty? %d.", empty);
+
+  if (!err.empty()) {
+    constexpr size_t kPrintChunkSize = 256;
+    for (size_t i = 0; i < err.size(); i += kPrintChunkSize) {
+      log("DATA: %s", err.substr(i, kPrintChunkSize).c_str());
+    }
+  }
+
+  return empty ? 0 : 1;
+}
+
+int main() {
+  return check_reserved_space();
+}