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Commit a68ee762 authored by Yifan Hong's avatar Yifan Hong
Browse files

Load boot image props. 

This change does the following:

- Create /second_stage_resources empty dir at root.
- At runtime:
  - At first stage init:
    - mount tmpfs to /second_stage_resources.
    - Copy /system/etc/ramdisk/build.prop to
      /second_stage_resources/system/etc/ramdisk/build.prop
  - At second stage init:
    - Load prop from the above path
    - umount /second_stage_resources

Test: getprop -Z
Test: getprop
Bug: 169169031

Change-Id: I18b16aa5fd42fa44686c858982a17791b2d43489
parent 909219cc

init/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ LOCAL_POST_INSTALL_CMD := mkdir -p \ 
    $(TARGET_RAMDISK_OUT)/dev \

    $(TARGET_RAMDISK_OUT)/mnt \

    $(TARGET_RAMDISK_OUT)/proc \

    $(TARGET_RAMDISK_OUT)/second_stage_resources \

    $(TARGET_RAMDISK_OUT)/sys \



LOCAL_STATIC_LIBRARIES := \

init/first_stage_init.cpp

+20 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include "first_stage_console.h"

#include "first_stage_mount.h"

#include "reboot_utils.h"

#include "second_stage_resources.h"

#include "switch_root.h"

#include "util.h"
@@ -235,6 +236,11 @@ int FirstStageMain(int argc, char** argv) { 
    // /debug_ramdisk is used to preserve additional files from the debug ramdisk

    CHECKCALL(mount("tmpfs", "/debug_ramdisk", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,

                    "mode=0755,uid=0,gid=0"));



    // /second_stage_resources is used to preserve files from first to second

    // stage init

    CHECKCALL(mount("tmpfs", kSecondStageRes, "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,

                    "mode=0755,uid=0,gid=0"))

#undef CHECKCALL



    SetStdioToDevNull(argv);
@@ -276,6 +282,20 @@ int FirstStageMain(int argc, char** argv) { 
        StartConsole();

    }



    if (access(kBootImageRamdiskProp, F_OK) == 0) {

        std::string dest = GetRamdiskPropForSecondStage();

        std::string dir = android::base::Dirname(dest);

        std::error_code ec;

        if (!fs::create_directories(dir, ec)) {

            LOG(FATAL) << "Can't mkdir " << dir << ": " << ec.message();

        }

        if (!fs::copy_file(kBootImageRamdiskProp, dest, ec)) {

            LOG(FATAL) << "Can't copy " << kBootImageRamdiskProp << " to " << dest << ": "

                       << ec.message();

        }

        LOG(INFO) << "Copied ramdisk prop to " << dest;

    }



    if (ForceNormalBoot(cmdline)) {

        mkdir("/first_stage_ramdisk", 0755);

        // SwitchRoot() must be called with a mount point as the target, so we bind mount the

init/init.cpp

+10 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ 
#include "proto_utils.h"

#include "reboot.h"

#include "reboot_utils.h"

#include "second_stage_resources.h"

#include "security.h"

#include "selabel.h"

#include "selinux.h"
@@ -668,6 +669,12 @@ static void UmountDebugRamdisk() { 
    }

}



static void UmountSecondStageRes() {

    if (umount(kSecondStageRes) != 0) {

        PLOG(ERROR) << "Failed to umount " << kSecondStageRes;

    }

}



static void MountExtraFilesystems() {

#define CHECKCALL(x) \

    if ((x) != 0) PLOG(FATAL) << #x " failed.";
@@ -776,6 +783,9 @@ int SecondStageMain(int argc, char** argv) { 


    PropertyInit();



    // Umount second stage resources after property service has read the .prop files.

    UmountSecondStageRes();



    // Umount the debug ramdisk after property service has read the .prop files when it means to.

    if (load_debug_prop) {

        UmountDebugRamdisk();

init/property_service.cpp

+11 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ 
#include "persistent_properties.h"

#include "property_type.h"

#include "proto_utils.h"

#include "second_stage_resources.h"

#include "selinux.h"

#include "subcontext.h"

#include "system/core/init/property_service.pb.h"
@@ -745,6 +746,15 @@ static bool load_properties_from_file(const char* filename, const char* filter, 
    return true;

}



static void LoadPropertiesFromSecondStageRes(std::map<std::string, std::string>* properties) {

    std::string prop = GetRamdiskPropForSecondStage();

    if (access(prop.c_str(), R_OK) != 0) {

        CHECK(errno == ENOENT) << "Cannot access " << prop << ": " << strerror(errno);

        return;

    }

    load_properties_from_file(prop.c_str(), nullptr, properties);

}



// persist.sys.usb.config values can't be combined on build-time when property

// files are split into each partition.

// So we need to apply the same rule of build/make/tools/post_process_props.py
@@ -933,6 +943,7 @@ void PropertyLoadBootDefaults() { 


    // Order matters here. The more the partition is specific to a product, the higher its

    // precedence is.

    LoadPropertiesFromSecondStageRes(&properties);

    load_properties_from_file("/system/build.prop", nullptr, &properties);

    load_properties_from_partition("system_ext", /* support_legacy_path_until */ 30);

    // TODO(b/117892318): uncomment the following condition when vendor.imgs for aosp_* targets are

init/second_stage_resources.h

0 → 100644
+32 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2020 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.

 */



#pragma once



#include <string>



namespace android {

namespace init {



constexpr const char kSecondStageRes[] = "/second_stage_resources";

constexpr const char kBootImageRamdiskProp[] = "/system/etc/ramdisk/build.prop";



inline std::string GetRamdiskPropForSecondStage() {

    return std::string(kSecondStageRes) + kBootImageRamdiskProp;

}



}  // namespace init

}  // namespace android