Merge pull request #196 from gilles-peskine-arm/config-checks-generator-framework

Introduce config_checks_generator.py

scripts/make_generated_files.py

@@ -10,6 +10,7 @@ Generate the TF-PSA-Crypto generated files
 """
 import argparse
 import filecmp
+import os
 import shutil
 import subprocess
 import sys
@@ -66,6 +67,18 @@ def get_generation_script_files(generation_script: str):
 
     return files
 
+COMMON_GENERATION_SCRIPTS = [
+]
+
+# Once the script has been added to both Mbed TLS and TF-PSA-Crypto,
+# we can include this unconditionally.
+# https://github.com/Mbed-TLS/mbedtls/issues/10305
+if os.path.exists("scripts/generate_config_checks.py"):
+    COMMON_GENERATION_SCRIPTS.append(GenerationScript(
+        Path("scripts/generate_config_checks.py"),
+        get_generation_script_files("scripts/generate_config_checks.py"),
+        "", None))
+
 if build_tree.looks_like_tf_psa_crypto_root("."):
     TF_PSA_CRYPTO_GENERATION_SCRIPTS = [
         GenerationScript(
@@ -244,6 +257,7 @@ def main():
         generation_scripts = MBEDTLS_GENERATION_SCRIPTS
     else:
         raise Exception("No support for Mbed TLS 3.6")
+    generation_scripts += COMMON_GENERATION_SCRIPTS
 
     if args.list:
         files = get_generated_files(generation_scripts)

scripts/mbedtls_framework/config_checks_generator.py

@@ -0,0 +1,228 @@
+"""Generate C preprocessor code to check for bad configurations.
+
+The headers are meant to be included in a specific way in PROJECT_config.c.
+See framework/docs/architecture/config-check-framework.md for information.
+"""
+
+## Copyright The Mbed TLS Contributors
+## SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+
+import argparse
+import enum
+import os
+import re
+import sys
+import textwrap
+import typing
+from typing import Iterator, List
+
+from . import build_tree
+from . import typing_util
+
+
+class Position(enum.Enum):
+    BEFORE = 0 # Before build_info.h
+    USER = 1 # Just after reading PROJECT_CONFIG_FILE (*config.h) and PROJECT_USER_CONFIG_FILE
+    FINAL = 2 # After *adjust*.h and the rest of build_info.h
+
+
+class Checker:
+    """Description of checks for one option.
+
+    By default, this class triggers an error if the option is set after
+    reading the user configuration. To change the behavior, override
+    the methods `before`, `user` and `final` as needed.
+    """
+
+    def __init__(self, name: str, suggestion: str = '') -> None:
+        """Construct a checker for the given preprocessor macro name.
+
+        If suggestion is given, it is appended to the error message.
+        It should be a short sentence intended for human readers.
+        This sentence follows a sentence like "<macro_name> is not
+        a valid configuration option".
+        """
+        self.name = name
+        self.suggestion = suggestion
+
+    def _basic_message(self) -> str:
+        """The first sentence of the message to display on error.
+
+        It should end with a full stop or other sentence-ending punctuation.
+        """
+        return f'{self.name} is not a valid configuration option.'
+
+    def message(self) -> str:
+        """The message to display on error."""
+        message = self._basic_message()
+        if self.suggestion:
+            message += ' Suggestion: ' + self.suggestion
+        return message
+
+    def _quoted_message(self) -> str:
+        """Quote message() in double quotes. Useful for #error directives."""
+        return ('"' +
+                str.replace(str.replace(self.message(),
+                                        '\\', '\\\\'),
+                            '"', '\\"') +
+                '"')
+
+    def before(self, _prefix: str) -> str:
+        """C code to inject before including the config."""
+        #pylint: disable=no-self-use
+        # Derived classes will add content where needed.
+        return ''
+
+    def user(self, _prefix: str) -> str:
+        """C code to inject immediately after including the user config."""
+        return f'''
+        #if defined({self.name})
+        #  error {self._quoted_message()}
+        #endif
+        '''
+
+    def final(self, _prefix: str) -> str:
+        """C code to inject after finalizing the config."""
+        #pylint: disable=no-self-use
+        # Derived classes will add content where needed.
+        return ''
+
+    def code(self, position: Position, prefix: str) -> str:
+        """C code to inject at the given position.
+
+        Use the given prefix for auxiliary macro names.
+        """
+        methods = {
+            Position.BEFORE: self.before,
+            Position.USER: self.user,
+            Position.FINAL: self.final,
+        }
+        method = methods[position]
+        snippet = method(prefix)
+        return textwrap.dedent(snippet)
+
+
+class Internal(Checker):
+    """Checker for an internal-only option."""
+
+
+class Removed(Checker):
+    """Checker for an option that has been removed."""
+
+    def __init__(self, name: str, version: str, suggestion: str = '') -> None:
+        super().__init__(name, suggestion)
+        self.version = version
+
+    def _basic_message(self) -> str:
+        """The first sentence of the message to display on error.
+
+        It should end with a full stop or other sentence-ending punctuation.
+        """
+        return f'{self.name} was removed in {self.version}.'
+
+    def user(self, prefix: str) -> str:
+        """C code to inject immediately after including the user config."""
+        # A removed option is forbidden, just like an internal option.
+        # But since we're checking a macro that is not defined anywhere,
+        # we need to tell check_names.py that this is a false positive.
+        code = super().user(prefix)
+        return re.sub(rf'^ *# *\w+.*\b{self.name}\b.*$',
+                      lambda m: m.group(0) + ' //no-check-names',
+                      code, flags=re.M)
+
+
+class BranchData(typing.NamedTuple):
+    """The relevant aspects of the configuration on a branch."""
+
+    # Subdirectory where the generated headers will be located.
+    header_directory: str
+
+    # Prefix used for the generated headers' basename.
+    header_prefix: str
+
+    # Prefix used for C preprocessor macros.
+    project_cpp_prefix: str
+
+    # Options to check
+    checkers: List[Checker]
+
+
+class HeaderGenerator:
+    """Generate a header to include before or after the user config."""
+
+    def __init__(self, branch_data: BranchData, position: Position) -> None:
+        self.branch_data = branch_data
+        self.position = position
+        self.prefix = branch_data.project_cpp_prefix + '_CONFIG_CHECK'
+        self.bypass_checks = self.prefix + '_BYPASS'
+
+    def write_stanza(self, out: typing_util.Writable, checker: Checker) -> None:
+        """Write the part of the output corresponding to one config option."""
+        code = checker.code(self.position, self.prefix)
+        out.write(code)
+
+    def write_content(self, out: typing_util.Writable) -> None:
+        """Write the output for all config options to be processed."""
+        for checker in self.branch_data.checkers:
+            self.write_stanza(out, checker)
+
+    def output_file_name(self) -> str:
+        """The base name of the output file."""
+        return ''.join([self.branch_data.header_prefix,
+                        'config_check_',
+                        self.position.name.lower(),
+                        '.h'])
+
+    def write(self, directory: str) -> None:
+        """Write the whole output file."""
+        basename = self.output_file_name()
+        with open(os.path.join(directory, basename), 'w') as out:
+            out.write(f'''\
+/* {basename} (generated part of {self.branch_data.header_prefix}config.c). */
+/* Automatically generated by {os.path.basename(sys.argv[0])}. Do not edit! */
+
+#if !defined({self.bypass_checks}) //no-check-names
+
+/* *INDENT-OFF* */
+''')
+            self.write_content(out)
+            out.write(f'''
+/* *INDENT-ON* */
+
+#endif /* !defined({self.bypass_checks}) */ //no-check-names
+
+/* End of automatically generated {basename} */
+''')
+
+
+def generate_header_files(branch_data: BranchData,
+                          directory: str,
+                          list_only: bool = False) -> Iterator[str]:
+    """Generate the header files to include before and after *config.h."""
+    for position in Position:
+        generator = HeaderGenerator(branch_data, position)
+        yield os.path.join(directory, generator.output_file_name())
+        if not list_only:
+            generator.write(directory)
+
+
+def main(branch_data: BranchData) -> None:
+    root = build_tree.guess_project_root()
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--list', action='store_true',
+                        help='List generated files and exit')
+    parser.add_argument('--list-for-cmake', action='store_true',
+                        help='List generated files in CMake-friendly format and exit')
+    parser.add_argument('output_directory', metavar='DIR', nargs='?',
+                        default=os.path.join(root, branch_data.header_directory),
+                        help='output file location (default: %(default)s)')
+    options = parser.parse_args()
+    list_only = options.list or options.list_for_cmake
+    output_files = generate_header_files(branch_data,
+                                         options.output_directory,
+                                         list_only=list_only)
+    if options.list_for_cmake:
+        sys.stdout.write(';'.join(output_files))
+    elif options.list:
+        for filename in output_files:
+            print(filename)