platform_system_core/init/util.h
Yu Ning c01022a62e Allow the use of a custom Android DT directory
On platforms that use ACPI instead of Device Tree (DT), such as
Ranchu x86/x86_64, /proc/device-tree/firmware/android/ does not
exist. As a result, Android O is unable to mount /system, etc.
at the first stage of init:

 init: First stage mount skipped (missing/incompatible fstab in
 device tree)

Those platforms may create another directory that mimics the layout
of the standard DT directory in procfs, and store early mount
configuration there. E.g., Ranchu x86/x86_64 creates one in sysfs
using information encoded in the ACPI tables:

 https://android-review.googlesource.com/442472
 https://android-review.googlesource.com/443432
 https://android-review.googlesource.com/442393
 https://android-review.googlesource.com/442395

Therefore, instead of hardcoding the Android DT path, load it from
the kernel command line using a new Android-specific property key
("androidboot.android_dt_dir"). If no such property exists, fall
back to the standard procfs path (so no change is needed for DT-
aware platforms).

Note that init/ and fs_mgr/ each have their own copy of the Android
DT path, because they do not share any global state. A future CL
should remove the duplication by refactoring.

With this CL as well as the above ones, the said warning is gone,
but early mount fails. That is a separate bug, though, and will be
addressed by another CL.

Test: Boot patched sdk_phone_x86-userdebug system image with patched
      Goldfish 3.18 x86 kernel in patched Android Emulator, verify
      the "init: First stage mount skipped" warning no longer shows
      in dmesg.

Change-Id: Ib6df577319503ec1ca778de2b5458cc72ce07415
Signed-off-by: Yu Ning <yu.ning@intel.com>
2017-07-28 11:10:48 +08:00

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2.5 KiB
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/*
* Copyright (C) 2010 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.
*/
#ifndef _INIT_UTIL_H_
#define _INIT_UTIL_H_
#include <sys/stat.h>
#include <sys/types.h>
#include <chrono>
#include <functional>
#include <ostream>
#include <string>
#include <android-base/chrono_utils.h>
#include <selinux/label.h>
#define COLDBOOT_DONE "/dev/.coldboot_done"
using android::base::boot_clock;
using namespace std::chrono_literals;
namespace android {
namespace init {
int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
const char* socketcon, selabel_handle* sehandle);
bool ReadFile(const std::string& path, std::string* content, std::string* err);
bool WriteFile(const std::string& path, const std::string& content, std::string* err);
bool DecodeUid(const std::string& name, uid_t* uid, std::string* err);
int mkdir_recursive(const std::string& pathname, mode_t mode, selabel_handle* sehandle);
int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);
void import_kernel_cmdline(bool in_qemu,
const std::function<void(const std::string&, const std::string&, bool)>&);
int make_dir(const char* path, mode_t mode, selabel_handle* sehandle);
std::string bytes_to_hex(const uint8_t *bytes, size_t bytes_len);
bool is_dir(const char* pathname);
bool expand_props(const std::string& src, std::string* dst);
void panic() __attribute__((__noreturn__));
// Returns the platform's Android DT directory as specified in the kernel cmdline.
// If the platform does not configure a custom DT path, returns the standard one (based in procfs).
const std::string& get_android_dt_dir();
// Reads or compares the content of device tree file under the platform's Android DT directory.
bool read_android_dt_file(const std::string& sub_path, std::string* dt_content);
bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content);
} // namespace init
} // namespace android
#endif