android_bootable_recovery/firmware.c

/*
 * 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
 *
 *      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.h"
#include "common.h"
#include "firmware.h"
#include "roots.h"

#include <errno.h>
#include <string.h>
#include <sys/reboot.h>

static const char *update_type = NULL;
static const char *update_data = NULL;
static int update_length = 0;

int remember_firmware_update(const char *type, const char *data, int length) {
    if (update_type != NULL || update_data != NULL) {
        LOGE("Multiple firmware images\n");
        return -1;
    }

    update_type = type;
    update_data = data;
    update_length = length;
    return 0;
}

// Return true if there is a firmware update pending.
int firmware_update_pending() {
  return update_data != NULL && update_length > 0;
}

/* Bootloader / Recovery Flow
 *
 * On every boot, the bootloader will read the bootloader_message
 * from flash and check the command field.  The bootloader should
 * deal with the command field not having a 0 terminator correctly
 * (so as to not crash if the block is invalid or corrupt).
 *
 * The bootloader will have to publish the partition that contains
 * the bootloader_message to the linux kernel so it can update it.
 *
 * if command == "boot-recovery" -> boot recovery.img
 * else if command == "update-radio" -> update radio image (below)
 * else if command == "update-hboot" -> update hboot image (below)
 * else -> boot boot.img (normal boot)
 *
 * Radio/Hboot Update Flow
 * 1. the bootloader will attempt to load and validate the header
 * 2. if the header is invalid, status="invalid-update", goto #8
 * 3. display the busy image on-screen
 * 4. if the update image is invalid, status="invalid-radio-image", goto #8
 * 5. attempt to update the firmware (depending on the command)
 * 6. if successful, status="okay", goto #8
 * 7. if failed, and the old image can still boot, status="failed-update"
 * 8. write the bootloader_message, leaving the recovery field
 *    unchanged, updating status, and setting command to
 *    "boot-recovery"
 * 9. reboot
 *
 * The bootloader will not modify or erase the cache partition.
 * It is recovery's responsibility to clean up the mess afterwards.
 */

int maybe_install_firmware_update(const char *send_intent) {
    if (update_data == NULL || update_length == 0) return 0;

    /* We destroy the cache partition to pass the update image to the
     * bootloader, so all we can really do afterwards is wipe cache and reboot.
     * Set up this instruction now, in case we're interrupted while writing.
     */

    struct bootloader_message boot;
    memset(&boot, 0, sizeof(boot));
    strlcpy(boot.command, "boot-recovery", sizeof(boot.command));
    strlcpy(boot.recovery, "recovery\n--wipe_cache\n", sizeof(boot.command));
    if (send_intent != NULL) {
        strlcat(boot.recovery, "--send_intent=", sizeof(boot.recovery));
        strlcat(boot.recovery, send_intent, sizeof(boot.recovery));
        strlcat(boot.recovery, "\n", sizeof(boot.recovery));
    }
    if (set_bootloader_message(&boot)) return -1;

    int width = 0, height = 0, bpp = 0;
    char *busy_image = ui_copy_image(
        BACKGROUND_ICON_FIRMWARE_INSTALLING, &width, &height, &bpp);
    char *fail_image = ui_copy_image(
        BACKGROUND_ICON_FIRMWARE_ERROR, &width, &height, &bpp);

    ui_print("Writing %s image...\n", update_type);
    if (write_update_for_bootloader(
            update_data, update_length,
            width, height, bpp, busy_image, fail_image)) {
        LOGE("Can't write %s image\n(%s)\n", update_type, strerror(errno));
        format_volume("/cache");  // Attempt to clean cache up, at least.
        return -1;
    }

    free(busy_image);
    free(fail_image);

    /* The update image is fully written, so now we can instruct the bootloader
     * to install it.  (After doing so, it will come back here, and we will
     * wipe the cache and reboot into the system.)
     */
    snprintf(boot.command, sizeof(boot.command), "update-%s", update_type);
    if (set_bootloader_message(&boot)) {
        format_volume("/cache");
        return -1;
    }

    reboot(RB_AUTOBOOT);

    // Can't reboot?  WTF?
    LOGE("Can't reboot\n");
    return -1;
}