libtasn1: Import libtasn1-4.19.0

Import a very trimmed-down set of libtasn1 files:

  curl -L -O https://ftp.gnu.org/gnu/libtasn1/libtasn1-4.19.0.tar.gz
  tar xvzf libtasn1-4.19.0.tar.gz
  rm -rf grub-core/lib/libtasn1
  mkdir -p grub-core/lib/libtasn1/lib
  mkdir -p grub-core/lib/libtasn1/tests
  cp libtasn1-4.19.0/{README.md,COPYING} grub-core/lib/libtasn1
  cp libtasn1-4.19.0/lib/{coding.c,decoding.c,element.c,element.h,errors.c,gstr.c,gstr.h,int.h,parser_aux.c,parser_aux.h,structure.c,structure.h} grub-core/libtasn1/lib
  cp libtasn1-4.19.0/lib/includes/libtasn1.h grub-core/lib/libtasn1
  cp libtasn1-4.19.0/tests/{CVE-2018-1000654-1_asn1_tab.h,CVE-2018-1000654-2_asn1_tab.h,CVE-2018-1000654.c,object-id-decoding.c,object-id-encoding.c,octet-string.c,reproducers.c,Test_overflow.c,Test_simple.c,Test_strings.c} grub-core/lib/libtasn1/tests
  rm -rf libtasn1-4.19.0*

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>

grub-core/lib/libtasn1/lib/gstr.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2002-2022 Free Software Foundation, Inc.
+ *
+ * This file is part of LIBTASN1.
+ *
+ * The LIBTASN1 library is free software; you can redistribute it
+ * and/or modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#ifndef GSTR_H
+# define GSTR_H
+
+unsigned int _asn1_str_cpy (char *dest, size_t dest_tot_size,
+			    const char *src);
+void _asn1_str_cat (char *dest, size_t dest_tot_size, const char *src);
+
+# define Estrcpy(x,y) _asn1_str_cpy(x,ASN1_MAX_ERROR_DESCRIPTION_SIZE,y)
+# define Estrcat(x,y) _asn1_str_cat(x,ASN1_MAX_ERROR_DESCRIPTION_SIZE,y)
+
+inline static void
+safe_memset (void *data, int c, size_t size)
+{
+  volatile unsigned volatile_zero = 0;
+  volatile char *vdata = (volatile char *) data;
+
+  /* This is based on a nice trick for safe memset,
+   * sent by David Jacobson in the openssl-dev mailing list.
+   */
+
+  if (size > 0)
+    do
+      {
+	memset (data, c, size);
+      }
+    while (vdata[volatile_zero] != c);
+}
+
+#endif /* GSTR_H */