shd-lib.h

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

typedef struct {
    size_t len;
    char content[];
} page_t;

typedef struct {
    size_t len;
    page_t **pages;
} notebook_t;

#define MAX_PAGES 0x100

/**
 * Create an empty notebook with space for a fixed number of pages.
 * All pages are initially unallocated (invalid).
 *
 * @param len The number of pages in the notebook. Must be less than MAX_PAGES.
 *
 * @return A pointer to the newly created notebook if successful, or NULL.
 */
notebook_t *create_notebook(size_t len);

/**
 * Free all memory associated with a notebook, including its pages.
 *
 * @param nb The notebook to destroy. Assume non-null.
 */
void destroy_notebook(notebook_t *nb);

/**
 * Look up a page by index and return a pointer to its stored content.
 *
 * @param nb Notebook object. Assume non-null.
 * @param page_nr The page # to read.
 *
 * @return A pointer to the page's content if the page exists, else NULL.
 *         A non-existent page is considered a failure case.
 */
char *read_page(notebook_t *nb, int page_nr);

/**
 * Create or replace a page's content with the provided message.
 *
 * @param nb Notebook object. Assume non-null.
 * @param page_nr The page # to write to.
 * @param msg The message to write. Assume non-null.
 *
 * @return 0 on success, -1 otherwise.
 *         If a page_nr already exists, overwrite it with this new msg.
 *         If page_nr is in bounds and does not exist, create a new page with the provided msg.
 */
int write_page(notebook_t *nb, int page_nr, const char *msg);

/**
 * Increase the allocated size of an existing page by a byte amount.
 *
 * @param nb Notebook object. Assume non-null.
 * @param page_nr The page to grow.
 * @param msg The amount to grow the page by in bytes.
 *
 * @return 0 on success, -1 otherwise
 *         A non-existent page is considered a failure case.
 *         A new size greater than the maximum unsigned 64-bit value is a failure case.
 */
int grow_page(notebook_t *nb, int page_nr, size_t amount);

/**
 * Remove a page from the notebook and release its storage.
 *
 * @param nb Notebook object. Assume non-null.
 * @param page_nr The page to delete.
 *
 * @return 0 on success, -1 otherwise.
 *         A non-existent page is considered a failure case.
 */
int delete_page(notebook_t *nb, int page_nr);

/**
 * Append additional text to the end of an existing page's content.
 *
 * @param nb Notebook object. Assume non-null.
 * @param page_nr The page to append to.
 * @param msg The message to append. Assume non-null.
 *
 * @return 0 on success, -1 otherwise.
 *         A non-existent page is considered a failure case.
 */
int append_page(notebook_t *nb, int page_nr, const char *msg);