#include<cctype>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<initializer_list>
#include<dirent.h>
#include<fcntl.h>
#include<grp.h>
#include<linux/rtc.h>
#include<net/if.h>
#include<netinet/in.h>
#include<spawn.h>
#include<sys/mount.h>
#include<sys/reboot.h>
#include<sys/resource.h>
#include<sys/socket.h>
#include<sys/stat.h>
#include<sys/swap.h>
#include<sys/syscall.h>
#include<sys/utsname.h>
#include<sys/wait.h>
#include<unistd.h>
using namespace std;

#define exec(...)do{const char*const c[]={__VA_ARGS__,0};execvp(*c,(char*const*)c);}while(0)
#define run(...)do{const char*const c[]={__VA_ARGS__,0};posix_spawnp(0,*c,0,0,(char*const*)c,environ);}while(0)
static auto open2(const char*a,int b){return open(a,b|O_CLOEXEC,S_IRUSR|S_IWUSR);}

int main(){
const auto xlk="/tmp/.X0-lock",hor="/root",hou="/home/xxx",_0="0",_1="1";const auto pol=100000;

for(auto i=(const char*const[]){"/dev/pts","devpts","gid=5,mode=600","/dev/shm","tmpfs","mode=1777,size=2g","/proc","proc","hidepid=2","/sys","sysfs",0,0};*i;i+=3)
  mount(0,*i,i[1],MS_MGC_VAL|MS_NOEXEC|MS_NOSUID,i[2]);

auto ti=open2("/dev/shm/init.log",O_CREAT|O_RDWR);
dup2(ti,STDERR_FILENO);
dup2(ti,STDOUT_FILENO);
dup2(open2("/dev/null",0),STDIN_FILENO);

char ts[100];dirent*ent;
auto dir=opendir("/sys/fs/ext4");
while((ent=readdir(dir))&&memcmp(ent->d_name,"sd",2));
snprintf(ts,sizeof ts,"/dev/%s",ent->d_name);
run("/usr/bin/e2fsck","-fvy",ts);

utsname unm;
uname(&unm);
snprintf(ts,sizeof ts,"/lib/modules/%s/extra/nvidia.ko",unm.release);
syscall(SYS_finit_module,open2(ts,0),"NVreg_ModifyDeviceFiles=0",0);

setsid();
umask(S_IRWXG|S_IRWXO);
for(auto i=(const rlim_t[]){RLIMIT_MEMLOCK,0,RLIMIT_NPROC,300,0};*i;i+=2)
  setrlimit(*i,&(const rlimit&){i[1],i[1]});
for(auto i=(const char*const[]){"DBUS_SESSION_BUS_ADDRESS",_0,"DISPLAY",":0","__GL_SYNC_TO_VBLANK",_0,"HOME",hou,"LADSPA_PATH","/usr/lib/ladspa","LANG","ru_RU.UTF-8","NO_AT_BRIDGE",_1,"PATH","/usr/bin:/opt/bin",0};*i;i+=2)
  setenv(*i,i[1],1);

ti=0;
wait(&ti);
if(ti<2)
  mount(0,"/",0,MS_MGC_VAL|MS_LAZYTIME|MS_NOATIME|MS_REMOUNT,"dioread_nolock,errors=remount-ro,lazytime,nobarrier,noblock_validity");
else{
  sync();
  reboot(RB_AUTOBOOT);}

remove(xlk);
if(!fork()){
  const gid_t grp[]={1000,10};
  chdir(hou);
  setgroups(sizeof grp/sizeof*grp,grp);
  setgid(*grp);
  setuid(*grp);
  while(access(xlk,F_OK))
    usleep(pol);
  for(const auto&i:(const char*const[][6]){
  {"/usr/bin/openbox",0},
  //skip
    })posix_spawnp(0,*i,0,0,(char*const*)i,environ);
  return 0;}

run("/usr/lib/xorg-server/Xorg","-noreset","-novtswitch","vt1","-config","/root/.config/xorg.conf");
for(const auto&i:{"/run/metalog.pid","/run/ppp0.pid"})
  remove(i);
chdir(hor);
setenv("HOME",hor,1);
ti=socket(AF_INET,SOCK_CLOEXEC|SOCK_DGRAM,IPPROTO_IP);
ioctl(ti,SIOCSIFFLAGS,&(const ifreq&){"eth0",IFF_RUNNING|IFF_UP|IFF_BROADCAST|IFF_MULTICAST});
ioctl(ti,SIOCSIFFLAGS,&(const ifreq&){"lo",IFF_RUNNING|IFF_UP|IFF_LOOPBACK});
for(const auto&i:(const char*const[][5]){
{"/usr/bin/metalog","--configfile",".config/metalog.conf",0},
{"/usr/bin/pppd",0},
{"/usr/bin/pdnsd","--nodaemon","--config-file",".config/pdnsd.conf",0},
  })posix_spawnp(0,*i,0,0,(char*const*)i,environ);
swapon("/swap",0);

for(auto i=(const char*const[]){
"/proc/sys/kernel/ctrl-alt-del",_0,
//skip
  0};*i;i+=2)write(open2(*i,O_RDWR),i[1],strlen(i[1]));

dir=opendir("/proc");
while((ent=readdir(dir)))
  if(isdigit(*ent->d_name)){
    snprintf(ts,sizeof ts,"/proc/%s/comm",ent->d_name);// /proc/*/task/*
    if(read(open2(ts,0),ts,sizeof ts)>0){
      ti=atoi(ent->d_name);
      if(!memcmp(ts,"kswapd0",7))
        setpriority(PRIO_PROCESS,ti,20);
      if(!memcmp(ts,"Xorg",1))
        setpriority(PRIO_PROCESS,ti,-20);
      }}

while(open2("/sys/class/sound/pcmC0D0p",0)<0)
  usleep(pol);
run("/usr/bin/alsactl","restore");
//run("/usr/bin/nvidia-smi","--power-limit=113");

ti=open2("/dev/tty2",O_RDWR);
dup2(ti,STDERR_FILENO);
dup2(ti,STDOUT_FILENO);
dup2(ti,STDIN_FILENO);
exec("/usr/bin/bash","--login");

while(1)
  wait(0);}