// SPDX-License-Identifier: MPL-2.0
// Fixed-command local broker; camera access is confined to Android UID 1006.
#define _GNU_SOURCE
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <grp.h>
#include <signal.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define SOCKET_DIR "/data/local/vulpes-beatles/camera-ipc"
#define SOCKET_PATH SOCKET_DIR "/camera.sock"
#define WORKER "/data/local/tmp/vulpes-beatles-camera-worker"

static volatile sig_atomic_t stopping;
static void stop_now(int signal_number) { (void)signal_number; stopping = 1; }

int main(void) {
  if (setpgid(0,0) && errno != EACCES) return 1;
  struct sigaction action = {0}; action.sa_handler = stop_now;
  sigemptyset(&action.sa_mask); sigaction(SIGTERM,&action,NULL); sigaction(SIGINT,&action,NULL);
  umask(0);
  if (mkdir(SOCKET_DIR,0777) && errno != EEXIST) return 2;
  chmod(SOCKET_DIR,0777); unlink(SOCKET_PATH);
  int server=socket(AF_UNIX,SOCK_STREAM,0); if(server<0) return 3;
  struct sockaddr_un address={0}; address.sun_family=AF_UNIX;
  strncpy(address.sun_path,SOCKET_PATH,sizeof(address.sun_path)-1);
  if(bind(server,(struct sockaddr *)&address,sizeof(address)) || chmod(SOCKET_PATH,0666) || listen(server,2)) return 4;
  printf("camera broker ready uid=%d socket=%s\n",getuid(),SOCKET_PATH); fflush(stdout);
  while(!stopping) {
    int client=accept(server,NULL,NULL);
    if(client<0) { if(errno==EINTR) continue; break; }
    pid_t child=fork();
    if(child==0) {
      close(server);
      fprintf(stderr,"camera worker accepted pid=%d\n",getpid()); fflush(stderr);
      gid_t groups[]={1006};
      if(setgroups(1,groups) || setgid(1006) || setuid(1006)) _exit(120);
      if(dup2(client,STDIN_FILENO)<0 || dup2(client,STDOUT_FILENO)<0) _exit(121);
      if(client>STDOUT_FILENO) close(client);
      setenv("LD_LIBRARY_PATH","/system/lib:/data/local/tmp",1);
      execl(WORKER,"vulpes-beatles-camera-worker",(char *)NULL);
      _exit(127);
    }
    close(client);
    while(waitpid(-1,NULL,WNOHANG)>0) {}
  }
  close(server); unlink(SOCKET_PATH); return 0;
}