challenge.c.j2

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <fmtmsg.h>
#include <sys/time.h>

void (*f)(int);
char *msg;

#define SAFE_FREE(x)                                                           \
  do {                                                                         \
    if (x) {                                                                   \
      free(x);                                                                 \
    }                                                                          \
  } while (0);

#define FLAG "{{ flag_path }}"

void read_flag()
{
	int fd = -1;
	char buf[512] = {0};

	fd = open(FLAG, O_RDONLY);
	if(fd == -1) return;

	read(fd, &buf, sizeof(buf)-1);
	printf("%s\n", buf);
	close(fd);
	exit(0);
}

void sh(int num) {
  SAFE_FREE(msg);
  fmtmsg(MM_PRINT | MM_SOFT | MM_OPSYS | MM_NRECOV, "challenge:sh", MM_ERROR,
         "interrupted with signal", MM_NULLACT, MM_NULLTAG);
  f(EXIT_FAILURE);
}

int main(int argc, char **argv) {
  struct sigaction newaction;

  if (argc <= 1) {
    fprintf(stderr, "%s <message>\n",
            argv[0] == NULL ? "./challenge" : argv[0]);
    return EXIT_FAILURE;
  }

  f = _exit;

  newaction.sa_handler = sh;
  sigemptyset(&newaction.sa_mask);
  newaction.sa_flags = SA_RESETHAND;
  sigaction(SIGTERM, &newaction, NULL);

  msg = strdup(argv[1]);
  puts(msg);
  SAFE_FREE(msg);

  return EXIT_SUCCESS;
}