3 files changed, 45 insertions, 3 deletions

diff --git a/bootloader_message/Android.mk b/bootloader_message/Android.mk
index a8c50819b..0d84713c3 100644
--- a/bootloader_message/Android.mk
+++ b/bootloader_message/Android.mk
@@ -20,6 +20,10 @@ LOCAL_SRC_FILES := bootloader_message.cpp
 LOCAL_MODULE := libbootloader_message
 LOCAL_STATIC_LIBRARIES := libbase libfs_mgr
 LOCAL_CFLAGS := -Werror
+ifeq ($(shell test $(PLATFORM_SDK_VERSION) -lt 26; echo $$?),0)
+    TARGET_GLOBAL_CFLAGS += -DUSE_OLD_BOOTLOADER_MESSAGE
+    CLANG_TARGET_GLOBAL_CFLAGS += -DUSE_OLD_BOOTLOADER_MESSAGE
+endif
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
 include $(BUILD_STATIC_LIBRARY)
diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index d8086be28..dcaeb794f 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -24,19 +24,46 @@
 #include <vector>
 
 #include <android-base/file.h>
-#include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
 #include <fs_mgr.h>
 
+#ifdef USE_OLD_BOOTLOADER_MESSAGE
+#include <sys/system_properties.h>
+
+static struct fstab* read_fstab(std::string* err) {
+  // The fstab path is always "/fstab.${ro.hardware}".
+  std::string fstab_path = "/fstab.";
+  char value[PROP_VALUE_MAX];
+  if (__system_property_get("ro.hardware", value) == 0) {
+    *err = "failed to get ro.hardware";
+    return nullptr;
+  }
+  fstab_path += value;
+  struct fstab* fstab = fs_mgr_read_fstab(fstab_path.c_str());
+  if (fstab == nullptr) {
+    *err = "failed to read " + fstab_path;
+  }
+  return fstab;
+}
+#endif
+
 static std::string get_misc_blk_device(std::string* err) {
+#ifdef USE_OLD_BOOTLOADER_MESSAGE
+  struct fstab* fstab = read_fstab(err);
+#else
   std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
                                                              fs_mgr_free_fstab);
+#endif
   if (!fstab) {
     *err = "failed to read default fstab";
     return "";
   }
+#ifdef USE_OLD_BOOTLOADER_MESSAGE
+  fstab_rec* record = fs_mgr_get_entry_for_mount_point(fstab, "/misc");
+#else
   fstab_rec* record = fs_mgr_get_entry_for_mount_point(fstab.get(), "/misc");
+#endif
   if (record == nullptr) {
     *err = "failed to find /misc partition";
     return "";
diff --git a/bootloader_message/include/bootloader_message/bootloader_message.h b/bootloader_message/include/bootloader_message/bootloader_message.h
index bc5104ddf..4ad18f2d9 100644
--- a/bootloader_message/include/bootloader_message/bootloader_message.h
+++ b/bootloader_message/include/bootloader_message/bootloader_message.h
@@ -65,6 +65,16 @@ struct bootloader_message {
     char status[32];
     char recovery[768];
 
+#ifdef USE_OLD_BOOTLOADER_MESSAGE
+    // The 'recovery' field used to be 1024 bytes.  It has only ever
+    // been used to store the recovery command line, so 768 bytes
+    // should be plenty.  We carve off the last 256 bytes to store the
+    // stage string (for multistage packages) and possible future
+    // expansion.
+    char stage[32];
+    char slot_suffix[32];
+    char reserved[192];
+#else
     // The 'recovery' field used to be 1024 bytes.  It has only ever
     // been used to store the recovery command line, so 768 bytes
     // should be plenty.  We carve off the last 256 bytes to store the
@@ -77,13 +87,14 @@ struct bootloader_message {
     // 1184-byte so that the entire bootloader_message struct rounds up
     // to 2048-byte.
     char reserved[1184];
+#endif
 };
 
 /**
  * We must be cautious when changing the bootloader_message struct size,
  * because A/B-specific fields may end up with different offsets.
  */
-#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus)
+#if !defined(USE_OLD_BOOTLOADER_MESSAGE) && ((__STDC_VERSION__ >= 201112L) || defined(__cplusplus))
 static_assert(sizeof(struct bootloader_message) == 2048,
               "struct bootloader_message size changes, which may break A/B devices");
 #endif
@@ -116,7 +127,7 @@ struct bootloader_message_ab {
  * Be cautious about the struct size change, in case we put anything post
  * bootloader_message_ab struct (b/29159185).
  */
-#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus)
+#if !defined(USE_OLD_BOOTLOADER_MESSAGE) && ((__STDC_VERSION__ >= 201112L) || defined(__cplusplus))
 static_assert(sizeof(struct bootloader_message_ab) == 4096,
               "struct bootloader_message_ab size changes");
 #endif