challenge.c.j2

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stddef.h>

// definitions
//
#define FLAG_PATH "{{ flag_path }}"
#define BUFSZ (128-8)

char *cp = NULL;
char *item_list = NULL;

enum {
    RUNNING,
    STOPPED,
    PROBE_FILE
};
unsigned char state = STOPPED;

char default_list[] = {
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
};

// prototypes
//
void jobmgmt(void);
void read_flag(void);
void start_polling(void (*)(void));

// implementation
//

void jobmgmt(void)
{
    if(state == STOPPED) {
	printf("running job.\n");
	state = RUNNING;
    } else if(state == RUNNING) {
	printf("ending job.\n");
	state = STOPPED;
    } else if(state == PROBE_FILE) {
	printf("reading flag file.\n");
	read_flag();
	state = STOPPED;
    } else {
	printf("unknown state %d.. bailing.\n", state);
	exit(1);
    }
}

void read_flag(void)
{
    FILE *fp = NULL;
    char buffer[BUFSZ] = {0};

    fp = fopen(FLAG_PATH, "r");
    if(fp) {
	fgets(buffer, sizeof(buffer), fp);
	fclose(fp);
	printf("%s\n", buffer);
    } else {
	perror("fopen " FLAG_PATH " failed");
    }

    exit(1);
}

void start_polling(void (*state_change)(void))
{
    int cnt = 0xdeadbeef;
    char buffer[BUFSZ] = {0x41};

    cp = buffer;

    state_change(); // running

    for(cnt = 0; cnt <= BUFSZ; cnt++) {
	*cp++ = item_list[cnt];
    }

    state_change(); // stopped
}

int main(int argc, char **argv)
{
    void (*cb)(void) = jobmgmt;

    item_list = (argc <= 1 ? default_list : argv[1]);
    start_polling(cb);

    return 0;
}