Create heaps_of_knowledge.c
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Ankur Sundara
GitHub
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1 changed files with 207 additions and 0 deletions
207
heaps_of_knowledge/heaps_of_knowledge.c
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207
heaps_of_knowledge/heaps_of_knowledge.c
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//gcc -m32 -std=c99 -Wall -fno-stack-protector heaps_of_knowledge.c -o heaps_of_knowledge
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#define _GNU_SOURCE
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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struct chapter {
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struct chapter *prev_chapter;
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struct chapter *next_chapter;
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char *title;
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char *content;
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void (* print_ch)(int, struct chapter *);
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};
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typedef struct chapter chapter;
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typedef struct book {
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char *title;
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int num_chapters;
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chapter *first_chapter;
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} book;
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book *create_book(char *title) {
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book *b = malloc(sizeof(book));
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b->title = strdup(title);
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b->first_chapter = NULL;
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b->num_chapters = 0;
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return b;
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}
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void print_chapter(int num, chapter *ch) {
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printf("---------------\n");
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printf("Chapter %i: %s", num, ch->title);
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printf("---------------\n");
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printf("%s\n", ch->content);
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}
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int success = 0x1337;
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void validate(int ans) {
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if ((ans ^ 0xDEADBEEF) == 0xDEADBEAF) {
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success = 0x13371337;
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}
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}
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void give_flag() {
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if (success==0x13371337) {
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FILE *f = fopen("flag.txt", "r");
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gid_t gid = getegid();
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setresgid(gid, gid, gid);
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if (f != NULL) {
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char c;
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while ((c = fgetc(f)) != EOF) {
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putchar(c);
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}
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fclose(f);
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}
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else {
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printf("Failed to open flag file!\n");
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}
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}
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else {
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printf("nope! \n");
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}
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}
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int i;
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int num_ch;
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char option[4];
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int option_val;
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int main(int argc, char *argv[]) {
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printf("Please enter the title of the book you would like to write: ");
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char title[50];
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char text[256];
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fgets(title, 50, stdin);
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//get rid of newline
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title[strlen(title)-1] = '\0';
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printf("You have started writing the book '%s'. Please select an option to get started!\n", title);
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book *book = create_book(title);
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while(1) {
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printf("1. Edit chapter\n");
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printf("2. Delete chapter\n");
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printf("3. Publish book\n");
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i=0;
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num_ch = book->num_chapters;
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chapter *curr_ch;
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fgets(option, 4, stdin);
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option_val = atoi(option);
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switch(option_val) {
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case 1: //edit
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printf("Enter chapter number to edit: ");
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fgets(option, 4, stdin);
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option_val = atoi(option);
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if (option_val > 0 && option_val <= num_ch) {
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printf("Editing chapter\n");
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printf("Enter new chapter text: \n");
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curr_ch = book->first_chapter;
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for (i=1; i<option_val; i++) {
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curr_ch = curr_ch->next_chapter;
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}
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gets(curr_ch->content);
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}
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else if (option_val == num_ch+1) {
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printf("Adding new chapter\n");
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printf("Enter chapter title: \n");
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fgets(title, 50, stdin);
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printf("Enter chapter text: \n");
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fgets(text, 256, stdin);
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chapter *ch = malloc(sizeof(chapter));
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ch->title = strdup(title);
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ch->content = strdup(text);
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ch->print_ch = &print_chapter;
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curr_ch = book->first_chapter;
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book->num_chapters++;
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if (curr_ch == NULL) {
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book->first_chapter = ch;
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}
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else {
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while (curr_ch->next_chapter != NULL) {
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curr_ch = curr_ch->next_chapter;
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}
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curr_ch->next_chapter = ch;
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ch->prev_chapter = curr_ch;
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}
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}
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else {
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printf("Invalid chapter number!\n");
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return 0;
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}
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break;
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case 2: //delete
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printf("Enter chapter number to delete: ");
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fgets(option, 4, stdin);
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option_val = atoi(option);
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if (option_val > 0 && option_val <= num_ch) {
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printf("deleting chapter\n");
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book->num_chapters--;
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if (option_val == 1) {
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chapter *old_first = book->first_chapter;
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book->first_chapter = old_first->next_chapter;
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free(old_first->title);
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free(old_first->content);
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free(old_first);
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if (book->first_chapter != NULL)
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book->first_chapter->prev_chapter = NULL;
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}
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else {
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curr_ch = book->first_chapter;
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for(i=2;i<option_val;i++) {
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curr_ch = curr_ch->next_chapter;
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}
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chapter *to_del = curr_ch->next_chapter;
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curr_ch->next_chapter = to_del->next_chapter;
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if (to_del->next_chapter != NULL)
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to_del->next_chapter->prev_chapter = to_del->prev_chapter;
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free(to_del->title);
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free(to_del->content);
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free(to_del);
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}
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}
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else {
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printf("Invalid chapter number!\n");
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return 0;
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}
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break;
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default: //publish
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printf("Book published! Here it is:\n");
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printf("===============\n");
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printf("%s\n", book->title);
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printf("===============\n");
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i = 1;
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curr_ch = book->first_chapter;
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while (curr_ch != NULL) {
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curr_ch->print_ch(i, curr_ch);
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curr_ch = curr_ch->next_chapter;
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i++;
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}
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return 0;
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}
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}
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return 0;
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}
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