How do I implement a shell to my OS

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C

operating-systems

<pre>#include <stdbool.h>
#include <kernel/tty.h>
#include <stdint.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <stdarg.h>
#include "GDTandIDT.h"
#include "mm.h"
#include "schedule.h"
#include "fs.h"
#include "initrd.h"

#define MAX_INPUT_LENGTH 256

char read_char() {}

void print_char(char c) {}

int strcmp(const char* str1, const char* str2) {
    while (*str1 && (*str1 == *str2)) {
        str1++;
        str2++; }
    return *(unsigned char*)str1 - *(unsigned char*)str2; }

void read_command(char* buffer, size_t size) {
    size_t i = 0;
    char c;
    while (i < size - 1 && (c = read_char()) != '\n') {
        buffer[i++] = c;
        print_char(c); }
    buffer[i] = '\0';
    print_char('\n'); }

void execute_command(char* command) {
    if (strcmp(command, "help") == 0) {
        printf("Available commands:\n");
        printf(" - help: Display available commands\n");
        printf(" - version: Display kernel version\n"); }
    else if (strcmp(command, "version") == 0) {
        printf("Kernel version 1.0\n"); }
    else { printf("Unknown command. Type 'help' to see available commands.\n"); } }

void print_prompt() {
    printf("> "); }

void kernel_main(void) {
    init_gdt();
    init_idt();
    terminal_initialize();
    init_dynamic_mem();
    
    size_t allocation_size = 1024;
    void* allocated_memory;
    int allocation_count = 0;
    char command[MAX_INPUT_LENGTH];
    
    while ((allocated_memory = malloc(allocation_size)) != NULL) {
        allocation_count++;
        allocation_size *= 2; }
    
    if (allocated_memory != NULL) {
        *(int*)allocated_memory = 42; }
    
    free(allocated_memory);
    
    while (1) {
        print_prompt();
        read_command(command, MAX_INPUT_LENGTH);
        execute_command(command);
        schedule();
        kbd(); } }

It show me something like this when I type

> Unknown command. Type 'help' to see available commands.
a> Unknown command. Type 'help' to see available commands.

What I have tried:

I was try to fix it but I only make spaghetti code :"(