结构中的字符串被覆盖，我不知道为什么

Question

I've had this problem for the last two hours and I can't understand what's happening. I expect it to print this

ROBCO INDUSTRIES UNIFIED OPERATING SYSTEM
COPYRIGHT 2075-2077 ROBCO INDUSTRIES
-Server 6-

But instead it displays this

ROBCO INDUSTRIES UNIFIED OPERATING SYSTEM
COPYRIGHT Testing testing 123

I have no clue why this is happening but hopefully you will be able to help me. (If you want to know what this is for it's a Fallout Terminal Emulator). Just ask if you nned any more details. Thanks!

It's being compiled like this if you need to know

gcc test.c configParser.c -lconfig

test.c

#include <stdio.h>
#include "robco.h"

int main() {
  struct config_struct config;
  config = getConfig("test_config.cfg");

  printf("%s", config.banner);

  return 0;
}

configParser.c

#include <stdio.h>
#include <libconfig.h>
#include <string.h>
#include "robco.h"

int cap(int num, int cap) {
  return (num > cap) ? cap : num;
}

struct config_struct getConfig(const char *filename)
{
  config_t cfg;
  config_setting_t *root, *menu, *options, *option;

  // Read the file. If there is an error, report it and exit.
  config_init(&cfg);
  config_read_file(&cfg, filename);

  root = config_root_setting(&cfg);

  // Get the banner from the config file if it exists, if not use the default set in robco.h
  const char *banner;

  if (! config_setting_lookup_string(root, "banner", &banner) ) {
    banner = DEFAULT_BANNER;
  }

  // Create the config struct and fill in the banner
  struct config_struct config;
  strcpy(config.banner, banner);

  // Get the menu
  menu = config_lookup(&cfg, "menu");

  // If it can't fetch the menu for any reason return -1
  if(! menu) {
    return;
  }

  // Get the options
  options = config_setting_get_member(menu, "options");

  if(! options) {
    return;
  }

  // Get number of options
  config.menu.num_options = cap(config_setting_length(options), MAX_OPTIONS);

  // Get the title. If it doesn't exist use the default
  const char *title;

  if (! config_setting_lookup_string(menu, "title", &title) ) {
    title = DEFAULT_TITLE;
  }

  strcpy(config.menu.title, title);

  // Loop through and get the text for all the options
  for(int i = 0; i < config.menu.num_options; ++i)
  {
    option = config_setting_get_elem(options, i);
    const char *text;

    config_setting_lookup_string(option, "text", &text);

    strcpy(config.menu.options[i].text, text);
  }

  return config;
}

robco.h

#define MAX_STRING_LENGTH 52
#define MAX_OPTIONS 5
#define DEFAULT_BANNER "ROBCO INDUSTRIES UNIFIED OPERATING SYSTEM\nCOPYRIGHT 2075-2077 ROBCO INDUSTRIES\n-Server 6-"
#define DEFAULT_TITLE "-=- TEST TITLE -=-"

struct option_struct {
  char text[MAX_STRING_LENGTH];
};

struct menu_struct {
  struct option_struct options[MAX_OPTIONS];
  int num_options;
  int selected;
  char title[MAX_STRING_LENGTH];
};

struct config_struct {
  char banner[MAX_STRING_LENGTH];
  struct menu_struct menu;
};

void printCenter(char msg[], int startRow);
void printMenuOption(char msg[], int startRow);
void drawMenu(struct menu_struct menu, int startRow);
void init_graphics();
struct config_struct getConfig(const char *filename);

test_config.cfg

menu: {
   title: "Super Secret Valve Control Panel";
   options: (
    { 
      text: "Testing testing 123";
    },
    { 
      text: "THE SUN IS A DEADLY LASER";
    }
  );
};

Answer 1

Your default banner text is longer than MAX_STRING_LENGTH , so when you copy it to config.banner you write past the end of the array, leading to undefined behavior.

Make sure all your buffers are large enough to store the longest string you expect (accounting for the terminator), or truncate strings to the length of the buffer, or use dynamic memory and size the buffers as you need to.

Answer 2

I bet your MAX_STRING_LENGTH is too little and that you don't test for lengths. You must use strncpy and then don't forget to set the terminating null, which strncpy doesn't do.

You must also turn the warnings of your compiler on. I see struct config_struct getConfig but in that function you do some return s without a return value. The compiler should warn about that.