42_KFS/src/shell/exec.c

#include "kprintf.h"
#include "shell.h"
#include "string.h"
#include "terminal.h"

#define NB_CMDS 8
#define BORDER  "==========================================================="
#define HEADER  "Welcome to bozOShell - Available Commands"

extern struct screen *screen;

struct shell_command {
	char name[16];
	char description[256];
	void (*fn)(void);
};

static void help(void);

static const struct shell_command commands[NB_CMDS] = {
    {"help", "Print this help menu", help},
    {"reboot", "Reboot the system", reboot},
    {"poweroff", "Shut down the system", halt},
    {"halt", "Stop all CPU functions", halt},
    {"stack", "Print the stack trace", print_stack},
    {"clear", "Clear the current terminal", terminal_clear},
    {"date", "Display the current time and date (UTC+0)", date},
    {"merdella", "Surprise", merdella},
};

static void help(void)
{
	const size_t padding = 15;

	kprintf("%s\n", BORDER);
	kprintf(" %s\n", HEADER);
	kprintf("%s\n", BORDER);

	for (size_t i = 0; i < sizeof(commands) / sizeof(commands[0]); i++) {
		kprintf(" %s", commands[i].name);
		for (size_t j = 0; j < (padding - strlen(commands[i].name));
		     j++)
			kprintf(" ");
		kprintf(": %s\n", commands[i].description);
	}

	kprintf("%s\n", BORDER);
}

static void auto_complete(void)
{
	const size_t len = strlen(screen->line);
	int nb_matches = 0;
	const char *last_match;

	for (size_t i = 0; i < NB_CMDS; i++) {
		if (!strncmp(screen->line, commands[i].name, len)) {
			nb_matches++;
			last_match = commands[i].name;
		}
	}
	if (nb_matches != 1)
		return;
	for (size_t i = len; last_match[i]; i++) {
		screen->line[i] = last_match[i];
		kprintf("%c", screen->line[i]);
	}
}

static void read_line(void)
{
	size_t i = 0;
	struct key_event ev;
	uint8_t prev_scan_code = 0;

	while (1) {
		ev = terminal_getkey();
		if (ev.c == '\n')
			break;
		char *buf = screen->line;
		i = strlen(screen->line);
		const size_t size = sizeof(screen->line);
		if (prev_scan_code != ev.scan_code && ev.scan_code) {
			if (ev.scan_code == KEY_BACKSPACE && i) {
				buf[--i] = '\0';
				move_cursor(LEFT);
				terminal_putchar(' ');
				move_cursor(LEFT);
			} else if (ev.scan_code == KEY_TAB && i) {
				auto_complete();
			} else if (ev.c && i < size - 1) {
				kprintf("%c", ev.c);
				buf[i++] = ev.c;
			}
			if (i >= size)
				break;
		}
		prev_scan_code = ev.scan_code;
	}
	kprintf("\n");
	screen->line[i] = '\0';
}

void shell_init(void)
{
	while (1) {
		kprintf(PROMPT);
		read_line();
		bool invalid = true;
		for (int i = 0; i < NB_CMDS; i++) {
			if (!strcmp(commands[i].name, screen->line)) {
				commands[i].fn();
				invalid = false;
				break;
			}
		}
		if (invalid && screen->line[0])
			kprintf(KERN_WARNING "invalid command: %s\n",
			        screen->line);
		memset(screen->line, '\0', sizeof(screen->line));
	}
}