Add a one-command history to the Nulix shell

When hitting enter, the command buffer is copied to another
buffer before the command split.

On left arrow press, the oldbuffer is copied to the actual one
and the screen is updated

Signed-off-by: lfalkau <[email protected]>

kernel/nsh/nsh.c

@@ -6,7 +6,7 @@
  * Nulix shell
  *
  * created: 2022/12/07 - xlmod <[email protected]>
- * updated: 2022/12/16 - glafond- <glafond-@student.42.fr>
+ * updated: 2022/12/19 - lfalkau <lfalkau@student.42.fr>
  */
 
 #include <kernel/string.h>
@@ -21,6 +21,7 @@ extern struct screenbuf *sb_current;
 
 // Buffer where the user input is stored
 char nsh_buf[NSH_BUFSIZE];
+char nsh_old[NSH_BUFSIZE];
 // Buffer where the splitted cmd is stored
 char *nsh_cmd[NSH_BUFSIZE / 2 + 1];
 
@@ -80,6 +81,9 @@ static void nsh_createcmd() {
 	char c;
 	int ibuf = 0;
 	int icmd = 0;
+
+	memset(nsh_old, 0, NSH_BUFSIZE);
+	memcpy(nsh_old, nsh_buf, nsh_bufindex);
 	while (ibuf < nsh_bufindex) {
 		c = nsh_buf[ibuf];
 		if (c != ' ' && c != 0) {
@@ -129,6 +133,13 @@ static void nsh_shortcut(struct kbd_event *evt) {
 		case KEY_PAGE_UP:
 			sb_scroll_top(sb_current);
 			break;
+		case KEY_CURSOR_LEFT:
+			for (int i = 0; i < nsh_bufindex; i++)
+				sb_putchar(sb_current, '\b');
+			nsh_bufindex = strlen(nsh_old);
+			memcpy(nsh_buf, nsh_old, nsh_bufindex);
+			sb_putstr(sb_current, nsh_buf);
+			break;
 		default:
 			break;
 	}