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* Copyright (C) 2008 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
// Spaces used by misc partition are as below:
// 0 - 2K For bootloader_message
// 2K - 16K Used by Vendor's bootloader (the 2K - 4K range may be optionally used
// as bootloader_message_ab struct)
// 16K - 32K Used by uncrypt and recovery to store wipe_package for A/B devices
// 32K - 64K System space, used for miscellanious AOSP features. See below.
// Note that these offsets are admitted by bootloader,recovery and uncrypt, so they
// are not configurable without changing all of them.
constexpr size_t VENDOR_SPACE_OFFSET_IN_MISC = 2 * 1024;
constexpr size_t WIPE_PACKAGE_OFFSET_IN_MISC = 16 * 1024;
constexpr size_t SYSTEM_SPACE_OFFSET_IN_MISC = 32 * 1024;
constexpr size_t SYSTEM_SPACE_SIZE_IN_MISC = 32 * 1024;
/* Bootloader Message (2-KiB)
* This structure describes the content of a block in flash
* that is used for recovery and the bootloader to talk to
* each other.
* The command field is updated by linux when it wants to
* reboot into recovery or to update radio or bootloader firmware.
* It is also updated by the bootloader when firmware update
* is complete (to boot into recovery for any final cleanup)
* The status field was used by the bootloader after the completion
* of an "update-radio" or "update-hboot" command, which has been
* deprecated since Froyo.
* The recovery field is only written by linux and used
* for the system to send a message to recovery or the
* other way around.
* The stage field is written by packages which restart themselves
* multiple times, so that the UI can reflect which invocation of the
* package it is. If the value is of the format "#/#" (eg, "1/3"),
* the UI will add a simple indicator of that status.
* We used to have slot_suffix field for A/B boot control metadata in
* this struct, which gets unintentionally cleared by recovery or
* uncrypt. Move it into struct bootloader_message_ab to avoid the
* issue.
struct bootloader_message {
char command[32];
char status[32];
char recovery[768];
// 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];
// The 'reserved' field used to be 224 bytes when it was initially
// carved off from the 1024-byte recovery field. Bump it up to
// 1184-byte so that the entire bootloader_message struct rounds up
// to 2048-byte.
char reserved[1184];
// Holds Virtual A/B merge status information. Current version is 1. New fields
// must be added to the end.
struct misc_virtual_ab_message {
uint8_t version;
uint32_t magic;
uint8_t merge_status; // IBootControl 1.1, MergeStatus enum.
uint8_t source_slot; // Slot number when merge_status was written.
uint8_t reserved[57];
} __attribute__((packed));
struct misc_memtag_message {
uint8_t version;
uint32_t magic; // magic string for treble compat
uint32_t memtag_mode;
uint8_t reserved[55];
} __attribute__((packed));
#define MISC_MEMTAG_MAGIC_HEADER 0x5afefe5a
// This is set when the state was overridden forcibly. This does not need to be
// interpreted by the bootloader but is only for bookkeeping purposes so
// userspace knows what to do when the override is undone.
// See system/extras/mtectrl in AOSP for more information.
#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus)
static_assert(sizeof(struct misc_virtual_ab_message) == 64,
"struct misc_virtual_ab_message has wrong size");
static_assert(sizeof(struct misc_memtag_message) == 64,
"struct misc_memtag_message has wrong size");
// This struct is not meant to be used directly, rather, it is to make
// computation of offsets easier. New fields must be added to the end.
struct misc_system_space_layout {
misc_virtual_ab_message virtual_ab_message;
misc_memtag_message memtag_message;
} __attribute__((packed));
#ifdef __cplusplus
#include <string>
#include <vector>
// Gets the block device name of /misc partition.
std::string get_misc_blk_device(std::string* err);
// 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);
// Writes |size| bytes of data from buffer |p| to |misc_blk_device| at |offset|. If the write fails,
// sets the error message in |err|.
bool write_misc_partition(const void* p, size_t size, const std::string& misc_blk_device,
size_t offset, 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);
// Read bootloader message from the specified misc device into boot.
bool read_bootloader_message_from(bootloader_message* boot, const std::string& misc_blk_device,
std::string* err);
// Write bootloader message to BCB.
bool write_bootloader_message(const bootloader_message& boot, std::string* err);
// Write bootloader message to the specified BCB device.
bool write_bootloader_message_to(const bootloader_message& boot,
const std::string& misc_blk_device, std::string* err);
// Write bootloader message (boots into recovery with the options) to BCB. Will
// set the command and recovery fields, and reset the rest.
bool write_bootloader_message(const std::vector<std::string>& options, std::string* err);
// Write bootloader message (boots into recovery with the options) to the specific BCB device. Will
// set the command and recovery fields, and reset the rest.
bool write_bootloader_message_to(const std::vector<std::string>& options,
const std::string& misc_blk_device, std::string* err);
// Update bootloader message (boots into recovery with the options) to BCB. Will
// only update the command and recovery fields.
bool update_bootloader_message(const std::vector<std::string>& options, std::string* err);
// Update bootloader message (boots into recovery with the |options|) in |boot|. Will only update
// the command and recovery fields.
bool update_bootloader_message_in_struct(bootloader_message* boot,
const std::vector<std::string>& options);
// Clear BCB.
bool clear_bootloader_message(std::string* err);
// Writes the reboot-bootloader reboot reason to the bootloader_message.
bool write_reboot_bootloader(std::string* err);
// Read the wipe package from BCB (from offset WIPE_PACKAGE_OFFSET_IN_MISC).
bool read_wipe_package(std::string* package_data, size_t size, std::string* err);
// Write the wipe package into BCB (to offset WIPE_PACKAGE_OFFSET_IN_MISC).
bool write_wipe_package(const std::string& package_data, std::string* err);
// Read or write the Virtual A/B message from system space in /misc.
bool ReadMiscVirtualAbMessage(misc_virtual_ab_message* message, std::string* err);
bool WriteMiscVirtualAbMessage(const misc_virtual_ab_message& message, std::string* err);
// Read or write the memtag message from system space in /misc.
bool ReadMiscMemtagMessage(misc_memtag_message* message, std::string* err);
bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err);
#include <stdbool.h>
// C Interface.
bool write_bootloader_message(const char* options);
bool write_reboot_bootloader(void);
#endif // ifdef __cplusplus