Init.c

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

#define likely(x) __builtin_expect((x), 1)
#define unlikely(x) __builtin_expect((x), 0)

void runService_Squid(void) {
  // Start Squid Proxy Server
  printf("\033[0;32m%s\033[0m%s\n", "INFO: ", "Starting Squid Proxy Server");
  fflush(stdout);

  pid_t pidSquidCache = fork();
  if (unlikely(pidSquidCache == -1)) {
    printf("\033[0;31m%s\033[0m%s\n", "ERROR: ", "Failed to Fork");
    exit(EXIT_FAILURE);
  } else if (pidSquidCache == 0) {
    fclose(stdin);
    freopen("/dev/null", "w", stdout);
    freopen("/dev/null", "w", stderr);
    execl("/usr/sbin/squid", "squid", "-z", NULL);
    exit(EXIT_FAILURE);
  }
  waitpid(pidSquidCache, NULL, 0);
  while (access("/var/run/squid.pid", F_OK) == 0) {
    sleep(1);
  }

  pid_t pidSquid = fork();
  if (unlikely(pidSquid == -1)) {
    printf("\033[0;31m%s\033[0m%s\n", "ERROR: ", "Failed to Fork");
    exit(EXIT_FAILURE);
  } else if (pidSquid == 0) {
    fclose(stdin);
    freopen("/dev/null", "w", stdout);
    freopen("/dev/null", "w", stderr);
    execl("/usr/sbin/squid", "squid", NULL);
    exit(EXIT_FAILURE);
  }
  waitpid(pidSquid, NULL, 0);
}

void runService_OpenConnect(void) {
  // Allocate Space for Variables
  char *RPI_RCSID = NULL;
  char *RPI_PASSWORD = NULL;

  // Get RCSID & Password from Environment
  RPI_RCSID = getenv("RPI_RCSID");
  if (unlikely(RPI_RCSID == NULL)) {
    printf("\033[0;31m%s\033[0m%s\n",
           "ERROR: ", "Failed to get \"RPI_RCSID\" from the Environment");
    exit(EXIT_FAILURE);
  }
  RPI_PASSWORD = getenv("RPI_PASSWORD");
  if (unlikely(RPI_PASSWORD == NULL)) {
    printf("\033[0;31m%s\033[0m%s\n",
           "ERROR: ", "Failed to get \"RPI_PASSWORD\" from the Environment");
    exit(EXIT_FAILURE);
  }
  if (unlikely(strcmp(RPI_RCSID, "REPLACE_ME") == 0)) {
    printf("\033[0;31m%s\033[0m%s\n",
           "ERROR: ", "\"RPI_RCSID\" not Set, Terminating");
    exit(EXIT_FAILURE);
  } else if (unlikely(strcmp(RPI_PASSWORD, "REPLACE_ME") == 0)) {
    printf("\033[0;31m%s\033[0m%s\n",
           "ERROR: ", "\"RPI_PASSWORD\" not Set, Terminating");
    exit(EXIT_FAILURE);
  }

  // Start OpenConnect
  printf("\033[0;32m%s\033[0m%s\n", "INFO: ", "Starting OpenConnect");
  fflush(stdout);

  int pipeDescriptor[2] = {};
  if (unlikely(pipe(pipeDescriptor) == -1)) {
    printf("\033[0;31m%s\033[0m%s\n", "ERROR: ", "Failed to Create Pipe");
    exit(EXIT_FAILURE);
  }
  pid_t pidOpenConnect = fork();
  if (unlikely(pidOpenConnect == -1)) {
    printf("\033[0;31m%s\033[0m%s\n", "ERROR: ", "Failed to Fork");
    exit(EXIT_FAILURE);
  } else if (pidOpenConnect == 0) {
    close(pipeDescriptor[1]);
    dup2(pipeDescriptor[0], 0);
    freopen("/dev/null", "w", stdout);
    freopen("/dev/null", "w", stderr);
    execl("/usr/bin/openconnect", "openconnect", "vpn.stu.rpi.edu", "--quiet",
          NULL);
    exit(EXIT_FAILURE);
  }
  close(pipeDescriptor[0]);
  dprintf(pipeDescriptor[1], "%s\n%s\npush\n", RPI_RCSID, RPI_PASSWORD);
  close(pipeDescriptor[1]);
}

void gracefully_exit(int signum) {
  printf("\033[0;32m%s\033[0m%s%d%s\n", "INFO: ", "Received signal ", signum, ", exiting");
  kill(-1, SIGTERM);
  exit(0);
}

void register_signals() {
  struct sigaction handle_exit = { 0 };
  handle_exit.sa_handler = &gracefully_exit;
  handle_exit.sa_flags = SA_NODEFER;
  if (sigaction(SIGTERM, &handle_exit, NULL) +
      sigaction(SIGINT , &handle_exit, NULL) < 0) {
    printf("\033[0;31m%s\033[0%s\n", "ERROR: ", "Signal failed to be registered");
  }
}

int main(void) {
  // Refuse to Start as Non-Pid=1 Program
  if (getpid() != 1) {
    printf("\033[0;31m%s\033[0m%s\n", "ERROR: ", "Must be Run as PID 1");
    exit(EXIT_FAILURE);
  }

  register_signals();

  runService_Squid();

  runService_OpenConnect();

  // Collect Zombine Process
  while (1) {
    waitpid(-1, NULL, 0);
  }

  return EXIT_SUCCESS;
}