Fix: lab3 on-board problems

kernel/lib/shell.c

@@ -159,20 +159,41 @@ void _reboot(void)
   _reset(1 << 16);
 }
 
+char *_shell_buf = (char *)0x0;
+int _shell_sz = 0;
+
+static inline
+int _shell_operations(char ch)
+{
+  switch (ch) {
+  case 0x7f:
+    if (_shell_sz > 0) {
+      --_shell_sz;
+      uart_puts("\b \b");
+    }
+    return true;
+  default:
+  }
+  return false;
+}
+
 int shell(file_node_t *initrd_root)
 {
   uart_puts("# ");
-  char *buf = kmalloc(INPUT_BUFLEN * sizeof(char)), ch;
-  int sz = 0;
+  char ch;
+  _shell_buf = kmalloc(INPUT_BUFLEN * sizeof(char));
+  _shell_sz = 0;
   while ((ch = uart_getc()) != '\n') {
-    buf[sz++] = ch;
+    if (_shell_operations(ch))
+      continue;
+    _shell_buf[_shell_sz++] = ch;
     uart_putb((const uint8_t *)&ch, 1);
   }
   uart_puts(ENDL);
-  buf[sz] = ' ';
+  _shell_buf[_shell_sz] = ' ';
 
   vector_t *args = make_vector(0);
-  for (char *saveptr = 0x0, *tok = strtok_r(buf, " ", &saveptr);
+  for (char *saveptr = 0x0, *tok = strtok_r(_shell_buf, " ", &saveptr);
        tok; tok = strtok_r((char *)0x0, " ", &saveptr)) {
     VEC_PUSH(args, tok);
     LOG(tok);