Create heaps_of_knowledge.c

heaps_of_knowledge/heaps_of_knowledge.c

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