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Commit d75f30a4 authored by Steve Muckle's avatar Steve Muckle
Browse files

first_stage_init: add console 

Start and wait on a console if androidboot.first_stage_console=1 is
present on the kernel command line. This only works on eng and
userdebug builds.

Change-Id: I978e9390a89509431b399ea58b284736b27eeb1b
parent c538656d

init/Android.bp

+3 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ cc_defaults { 
        "-Wextra",

        "-Wno-unused-parameter",

        "-Werror",

        "-DALLOW_FIRST_STAGE_CONSOLE=0",

        "-DALLOW_LOCAL_PROP_OVERRIDE=0",

        "-DALLOW_PERMISSIVE_SELINUX=0",

        "-DREBOOT_BOOTLOADER_ON_PANIC=0",
@@ -36,6 +37,8 @@ cc_defaults { 
    product_variables: {

        debuggable: {

            cppflags: [

                "-UALLOW_FIRST_STAGE_CONSOLE",

                "-DALLOW_FIRST_STAGE_CONSOLE=1",

                "-UALLOW_LOCAL_PROP_OVERRIDE",

                "-DALLOW_LOCAL_PROP_OVERRIDE=1",

                "-UALLOW_PERMISSIVE_SELINUX",

init/Android.mk

+2 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ LOCAL_PATH:= $(call my-dir) 


ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))

init_options += \

    -DALLOW_FIRST_STAGE_CONSOLE=1 \

    -DALLOW_LOCAL_PROP_OVERRIDE=1 \

    -DALLOW_PERMISSIVE_SELINUX=1 \

    -DREBOOT_BOOTLOADER_ON_PANIC=1 \
@@ -15,6 +16,7 @@ init_options += \ 
    -DDUMP_ON_UMOUNT_FAILURE=1

else

init_options += \

    -DALLOW_FIRST_STAGE_CONSOLE=0 \

    -DALLOW_LOCAL_PROP_OVERRIDE=0 \

    -DALLOW_PERMISSIVE_SELINUX=0 \

    -DREBOOT_BOOTLOADER_ON_PANIC=0 \

init/first_stage_init.cpp

+53 −4
Original line number Diff line number Diff line
@@ -24,10 +24,12 @@ 
#include <sys/stat.h>

#include <sys/sysmacros.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <unistd.h>



#include <filesystem>

#include <string>

#include <thread>

#include <vector>



#include <android-base/chrono_utils.h>
@@ -92,9 +94,50 @@ void FreeRamdisk(DIR* dir, dev_t dev) { 
    }

}



bool ForceNormalBoot() {

    std::string cmdline;

    android::base::ReadFileToString("/proc/cmdline", &cmdline);

void StartConsole() {

    if (mknod("/dev/console", S_IFCHR | 0600, makedev(5, 1))) {

        PLOG(ERROR) << "unable to create /dev/console";

        return;

    }

    pid_t pid = fork();

    if (pid != 0) {

        int status;

        waitpid(pid, &status, 0);

        LOG(ERROR) << "console shell exited with status " << status;

        return;

    }

    int fd = -1;

    int tries = 10;

    // The device driver for console may not be ready yet so retry for a while in case of failure.

    while (tries--) {

        fd = open("/dev/console", O_RDWR);

        if (fd != -1) {

            break;

        }

        std::this_thread::sleep_for(100ms);

    }

    if (fd == -1) {

        LOG(ERROR) << "Could not open /dev/console, errno = " << errno;

        _exit(127);

    }

    ioctl(fd, TIOCSCTTY, 0);

    dup2(fd, 0);

    dup2(fd, 1);

    dup2(fd, 2);

    close(fd);



    const char* path = "/system/bin/sh";

    const char* args[] = {path, nullptr};

    int rv = execv(path, const_cast<char**>(args));

    LOG(ERROR) << "unable to execv, returned " << rv << " errno " << errno;

    _exit(127);

}



bool FirstStageConsole(const std::string& cmdline) {

    return cmdline.find("androidboot.first_stage_console=1") != std::string::npos;

}



bool ForceNormalBoot(const std::string& cmdline) {

    return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;

}
@@ -127,6 +170,8 @@ int FirstStageMain(int argc, char** argv) { 
#undef MAKE_STR

    // Don't expose the raw commandline to unprivileged processes.

    CHECKCALL(chmod("/proc/cmdline", 0440));

    std::string cmdline;

    android::base::ReadFileToString("/proc/cmdline", &cmdline);

    gid_t groups[] = {AID_READPROC};

    CHECKCALL(setgroups(arraysize(groups), groups));

    CHECKCALL(mount("sysfs", "/sys", "sysfs", 0, NULL));
@@ -198,7 +243,11 @@ int FirstStageMain(int argc, char** argv) { 
        LOG(FATAL) << "Failed to load kernel modules";

    }



    if (ForceNormalBoot()) {

    if (ALLOW_FIRST_STAGE_CONSOLE && FirstStageConsole(cmdline)) {

        StartConsole();

    }



    if (ForceNormalBoot(cmdline)) {

        mkdir("/first_stage_ramdisk", 0755);

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

        // target directory to itself here.