Move dead submodules in-tree

Signed-off-by: swurl <swurl@swurl.xyz>

externals/mbedtls/tests/scripts/test_zeroize.gdb

@@ -0,0 +1,103 @@
+# test_zeroize.gdb
+#
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+#
+# This file is provided under the Apache License 2.0, or the
+# GNU General Public License v2.0 or later.
+#
+# **********
+# Apache License 2.0:
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# **********
+#
+# **********
+# GNU General Public License v2.0 or later:
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# **********
+#
+# Purpose
+#
+# Run a test using the debugger to check that the mbedtls_platform_zeroize()
+# function in platform_util.h is not being optimized out by the compiler. To do
+# so, the script loads the test program at programs/test/zeroize.c and sets a
+# breakpoint at the last return statement in main(). When the breakpoint is
+# hit, the debugger manually checks the contents to be zeroized and checks that
+# it is actually cleared.
+#
+# The mbedtls_platform_zeroize() test is debugger driven because there does not
+# seem to be a mechanism to reliably check whether the zeroize calls are being
+# eliminated by compiler optimizations from within the compiled program. The
+# problem is that a compiler would typically remove what it considers to be
+# "unnecessary" assignments as part of redundant code elimination. To identify
+# such code, the compilar will create some form dependency graph between
+# reads and writes to variables (among other situations). It will then use this
+# data structure to remove redundant code that does not have an impact on the
+# program's observable behavior. In the case of mbedtls_platform_zeroize(), an
+# intelligent compiler could determine that this function clears a block of
+# memory that is not accessed later in the program, so removing the call to
+# mbedtls_platform_zeroize() does not have an observable behavior. However,
+# inserting a test after a call to mbedtls_platform_zeroize() to check whether
+# the block of memory was correctly zeroed would force the compiler to not
+# eliminate the mbedtls_platform_zeroize() call. If this does not occur, then
+# the compiler potentially has a bug.
+#
+# Note: This test requires that the test program is compiled with -g3.
+
+set confirm off
+
+file ./programs/test/zeroize
+
+search GDB_BREAK_HERE
+break $_
+
+set args ./programs/test/zeroize.c
+run
+
+set $i = 0
+set $len = sizeof(buf)
+set $buf = buf
+
+while $i < $len
+    if $buf[$i++] != 0
+        echo The buffer at was not zeroized\n
+        quit 1
+    end
+end
+
+echo The buffer was correctly zeroized\n
+
+continue
+
+if $_exitcode != 0
+    echo The program did not terminate correctly\n
+    quit 1
+end
+
+quit 0