Move get_c_expression_values into a separate module
Create a directory mbedtls_dev intended to contain various Python
module for use by Python scripts located anywhere in the Mbed TLS
source tree.
Move get_c_expression_values and its auxiliary functions into a new
Python module mbedtls_dev.c_build_helper.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/mbedtls_dev/c_build_helper.py b/scripts/mbedtls_dev/c_build_helper.py
new file mode 100644
index 0000000..6807602
--- /dev/null
+++ b/scripts/mbedtls_dev/c_build_helper.py
@@ -0,0 +1,138 @@
+"""Generate and run C code.
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-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.
+
+import os
+import platform
+import subprocess
+import sys
+import tempfile
+
+def remove_file_if_exists(filename):
+ """Remove the specified file, ignoring errors."""
+ if not filename:
+ return
+ try:
+ os.remove(filename)
+ except OSError:
+ pass
+
+def create_c_file(file_label):
+ """Create a temporary C file.
+
+ * ``file_label``: a string that will be included in the file name.
+
+ Return ```(c_file, c_name, exe_name)``` where ``c_file`` is a Python
+ stream open for writing to the file, ``c_name`` is the name of the file
+ and ``exe_name`` is the name of the executable that will be produced
+ by compiling the file.
+ """
+ c_fd, c_name = tempfile.mkstemp(prefix='tmp-{}-'.format(file_label),
+ suffix='.c')
+ exe_suffix = '.exe' if platform.system() == 'Windows' else ''
+ exe_name = c_name[:-2] + exe_suffix
+ remove_file_if_exists(exe_name)
+ c_file = os.fdopen(c_fd, 'w', encoding='ascii')
+ return c_file, c_name, exe_name
+
+def generate_c_printf_expressions(c_file, cast_to, printf_format, expressions):
+ """Generate C instructions to print the value of ``expressions``.
+
+ Write the code with ``c_file``'s ``write`` method.
+
+ Each expression is cast to the type ``cast_to`` and printed with the
+ printf format ``printf_format``.
+ """
+ for expr in expressions:
+ c_file.write(' printf("{}\\n", ({}) {});\n'
+ .format(printf_format, cast_to, expr))
+
+def generate_c_file(c_file,
+ caller, header,
+ main_generator):
+ """Generate a temporary C source file.
+
+ * ``c_file`` is an open stream on the C source file.
+ * ``caller``: an informational string written in a comment at the top
+ of the file.
+ * ``header``: extra code to insert before any function in the generated
+ C file.
+ * ``main_generator``: a function called with ``c_file`` as its sole argument
+ to generate the body of the ``main()`` function.
+ """
+ c_file.write('/* Generated by {} */'
+ .format(caller))
+ c_file.write('''
+#include <stdio.h>
+''')
+ c_file.write(header)
+ c_file.write('''
+int main(void)
+{
+''')
+ main_generator(c_file)
+ c_file.write(''' return 0;
+}
+''')
+
+def get_c_expression_values(
+ cast_to, printf_format,
+ expressions,
+ caller=__name__, file_label='',
+ header='', include_path=None,
+ keep_c=False,
+): # pylint: disable=too-many-arguments
+ """Generate and run a program to print out numerical values for expressions.
+
+ * ``cast_to``: a C type.
+ * ``printf_format``: a printf format suitable for the type ``cast_to``.
+ * ``header``: extra code to insert before any function in the generated
+ C file.
+ * ``expressions``: a list of C language expressions that have the type
+ ``type``.
+ * ``include_path``: a list of directories containing header files.
+ * ``keep_c``: if true, keep the temporary C file (presumably for debugging
+ purposes).
+
+ Return the list of values of the ``expressions``.
+ """
+ if include_path is None:
+ include_path = []
+ c_name = None
+ exe_name = None
+ try:
+ c_file, c_name, exe_name = create_c_file(file_label)
+ generate_c_file(
+ c_file, caller, header,
+ lambda c_file: generate_c_printf_expressions(c_file,
+ cast_to, printf_format,
+ expressions)
+ )
+ c_file.close()
+ cc = os.getenv('CC', 'cc')
+ subprocess.check_call([cc] +
+ ['-I' + dir for dir in include_path] +
+ ['-o', exe_name, c_name])
+ if keep_c:
+ sys.stderr.write('List of {} tests kept at {}\n'
+ .format(caller, c_name))
+ else:
+ os.remove(c_name)
+ output = subprocess.check_output([exe_name])
+ return output.decode('ascii').strip().split('\n')
+ finally:
+ remove_file_if_exists(exe_name)