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Commit 22929da2 authored by Kelvin Zhang's avatar Kelvin Zhang
Browse files

Copy snapuserd to first_stage_ramdisk 

Certain binaries, such as snapuserd, are only available under
/system/bin. To make them accessible by first stage init, we copy
/system/bin/snapuserd to /first_stage_ramdisk/system/bin/snapuserd .

Test: th
Bug: 219841787
Change-Id: I913425a82905c745a05ac32d488f08506dc264ff
parent 1821237a

init/first_stage_init.cpp

+37 −3
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <sys/utsname.h>

#include <unistd.h>



#include <chrono>

#include <filesystem>

#include <string>

#include <vector>
@@ -107,6 +108,39 @@ bool ForceNormalBoot(const std::string& cmdline, const std::string& bootconfig) 
           cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;

}



static void Copy(const char* src, const char* dst) {

    if (link(src, dst) == 0) {

        LOG(INFO) << "hard linking " << src << " to " << dst << " succeeded";

        return;

    }

    PLOG(FATAL) << "hard linking " << src << " to " << dst << " failed, falling back to copy.";

}



// Move e2fsck before switching root, so that it is available at the same path

// after switching root.

void PrepareSwitchRoot() {

    constexpr const char* src = "/system/bin/snapuserd";

    constexpr const char* dst = "/first_stage_ramdisk/system/bin/snapuserd";



    if (access(dst, X_OK) == 0) {

        LOG(INFO) << dst << " already exists and it can be executed";

        return;

    }



    if (access(src, F_OK) != 0) {

        PLOG(INFO) << "Not moving " << src << " because it cannot be accessed";

        return;

    }



    auto dst_dir = android::base::Dirname(dst);

    std::error_code ec;

    if (access(dst_dir.c_str(), F_OK) != 0) {

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

            LOG(FATAL) << "Cannot create " << dst_dir << ": " << ec.message();

        }

    }

    Copy(src, dst);

}

}  // namespace



std::string GetModuleLoadList(bool recovery, const std::string& dir_path) {
@@ -304,7 +338,6 @@ int FirstStageMain(int argc, char** argv) { 
                  << module_elapse_time.count() << " ms";

    }





    bool created_devices = false;

    if (want_console == FirstStageConsoleParam::CONSOLE_ON_FAILURE) {

        if (!IsRecoveryMode()) {
@@ -352,10 +385,11 @@ int FirstStageMain(int argc, char** argv) { 


    if (ForceNormalBoot(cmdline, bootconfig)) {

        mkdir("/first_stage_ramdisk", 0755);

        PrepareSwitchRoot();

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

        // target directory to itself here.

        if (mount("/first_stage_ramdisk", "/first_stage_ramdisk", nullptr, MS_BIND, nullptr) != 0) {

            LOG(FATAL) << "Could not bind mount /first_stage_ramdisk to itself";

            PLOG(FATAL) << "Could not bind mount /first_stage_ramdisk to itself";

        }

        SwitchRoot("/first_stage_ramdisk");

    }

init/switch_root.cpp

+2 −1
Original line number Diff line number Diff line
@@ -78,7 +78,8 @@ void SwitchRoot(const std::string& new_root) { 
        auto new_mount_path = new_root + mount_path;

        mkdir(new_mount_path.c_str(), 0755);

        if (mount(mount_path.c_str(), new_mount_path.c_str(), nullptr, MS_MOVE, nullptr) != 0) {

            PLOG(FATAL) << "Unable to move mount at '" << mount_path << "'";

            PLOG(FATAL) << "Unable to move mount at '" << mount_path << "' to "

                        << "'" << new_mount_path << "'";

        }

    }