Boot control HAL based on the A/B headers.

The added bootctrl.bcb module implement the legacy interface for the
bootctrl HAL based on the Boot Control Block (BCB) and the headers
already specified in the booloader_message library.

This serves as a reference implementation of the boot_control HAL.

Bug: 32707546
Test: Tested internally that a device can use this HAL to flip slots and
recovery from a /misc wipe.

Change-Id: Ic02e5aaf4de7d0a1780eac4e8705dae20d0b3e10

2 files changed, 12 insertions, 0 deletions

diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index d8086be2..f91446b4 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -117,6 +117,13 @@ static bool write_misc_partition(const void* p, size_t size, const std::string&
   return true;
 }
 
+std::string get_bootloader_message_blk_device(std::string* err) {
+  std::string misc_blk_device = get_misc_blk_device(err);
+  if (misc_blk_device.empty()) return "";
+  if (!wait_for_device(misc_blk_device, err)) return "";
+  return misc_blk_device;
+}
+
 bool read_bootloader_message_from(bootloader_message* boot, const std::string& misc_blk_device,
                                   std::string* err) {
   return read_misc_partition(boot, sizeof(*boot), misc_blk_device,
diff --git a/bootloader_message/include/bootloader_message/bootloader_message.h b/bootloader_message/include/bootloader_message/bootloader_message.h
index bc5104dd..2ffbfc9e 100644
--- a/bootloader_message/include/bootloader_message/bootloader_message.h
+++ b/bootloader_message/include/bootloader_message/bootloader_message.h
@@ -180,6 +180,11 @@ static_assert(sizeof(struct bootloader_control) ==
 #include <string>
 #include <vector>
 
+// Return the block device name for the bootloader message partition and waits
+// for the device for up to 10 seconds. In case of error returns the empty
+// string.
+std::string get_bootloader_message_blk_device(std::string* err);
+
 // Read bootloader message into boot. Error message will be set in err.
 bool read_bootloader_message(bootloader_message* boot, std::string* err);