add: hold down key && core: create get_key to simplify keyboard usage

src/shell/exec.c

@@ -75,11 +75,44 @@ void auto_complete(void)
 	}
 }
 
-void shell_init(void)
+static char *get_line(void)
 {
-	char *line;
-	kprintf(PROMPT);
-	while ((line = get_line())) {
+	size_t i = 0;
+	struct key_event ev;
+
+	while (1) {
+		ev = get_key();
+		// kprintf("%d %d\n", ev.scan_code, ev.c);
+		if (ev.c == '\n')
+			break;
+		char *buf = screen->line;
+		i = strlen(screen->line);
+		const size_t size = sizeof(screen->line);
+		if (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;
+		}
+	}
+	kprintf("\n");
+	screen->line[i] = '\0';
+}
+
+void shell_init()
+{
+	while (1) {
+		kprintf(PROMPT);
+		get_line();
 		bool invalid = true;
 		for (unsigned i = 0; i < NB_CMDS; i++) {
 			if (!strncmp(cmds[i].name, screen->line,
@@ -96,6 +129,5 @@ void shell_init(void)
 			kprintf(KERN_WARNING "invalid command: %s\n",
 			        screen->line);
 		memset(screen->line, '\0', sizeof(screen->line));
-		kprintf(PROMPT);
 	}
 }