Implement the 'full' and 'baremetal' configurations

Also fix 'realfull' to only affect the appropriate sections.

Tested to produce the same results as config.pl on the default
configuration. This commit deliberately contains a direct copy the
lists of symbol names from config.pl.

scripts/config.py

@@ -35,12 +35,14 @@ class Setting:
       with no value.
     * active: True if name is defined, False if a #define for name is
       present in config.h but commented out.
+    * section: the name of the section that contains this symbol.
     """
     # pylint: disable=too-few-public-methods
-    def __init__(self, active, name, value=''):
+    def __init__(self, active, name, value='', section=None):
         self.active = active
         self.name = name
         self.value = value
+        self.section = section
 
 class Config:
     """Representation of the Mbed TLS configuration.
@@ -137,18 +139,93 @@ class Config:
         """Run adapter on each known symbol and (de)activate it accordingly.
 
         `adapter` must be a function that returns a boolean. It is called as
-        `adapter(name, active)` for each setting, where `active` is `True`
-        if `name` is set and `False` if `name` is known but unset. If
+        `adapter(name, active, section)` for each setting, where `active` is
+        `True` if `name` is set and `False` if `name` is known but unset,
+        and `section` is the name of the section containing `name`. If
         `adapter` returns `True`, then set `name` (i.e. make it active),
         otherwise unset `name` (i.e. make it known but inactive).
         """
         for setting in self.settings.values():
-            setting.active = adapter(setting.name, setting.active)
+            setting.active = adapter(setting.name, setting.active,
+                                     setting.section)
 
-def realfull_adapter(_name, _set):
-    """Uncomment everything."""
+def is_full_section(section):
+    """Is this section affected by "config.py full" and friends?"""
+    return section.endswith('support') or section.endswith('modules')
+
+def realfull_adapter(_name, active, section):
+    """Uncomment everything in the system and feature sections."""
+    if not is_full_section(section):
+        return active
     return True
 
+def include_in_full(name):
+    """Rules for symbols in the "full" configuration."""
+    if re.search(r'PLATFORM_[A-Z0-9]+_ALT', name):
+        return True
+    if name in [
+            'MBEDTLS_TEST_NULL_ENTROPY',
+            'MBEDTLS_DEPRECATED_REMOVED',
+            'MBEDTLS_HAVE_SSE2',
+            'MBEDTLS_PLATFORM_NO_STD_FUNCTIONS',
+            'MBEDTLS_CTR_DRBG_USE_128_BIT_KEY',
+            'MBEDTLS_ECP_DP_M221_ENABLED',
+            'MBEDTLS_ECP_DP_M383_ENABLED',
+            'MBEDTLS_ECP_DP_M511_ENABLED',
+            'MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES',
+            'MBEDTLS_NO_PLATFORM_ENTROPY',
+            'MBEDTLS_RSA_NO_CRT',
+            'MBEDTLS_NO_UDBL_DIVISION',
+            'MBEDTLS_NO_64BIT_MULTIPLICATION',
+            'MBEDTLS_PSA_CRYPTO_SE_C',
+            'MBEDTLS_PSA_CRYPTO_SPM',
+            'MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER',
+            'MBEDTLS_PSA_INJECT_ENTROPY',
+            'MBEDTLS_ECP_RESTARTABLE',
+            'MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED',
+    ]:
+        return False
+    if name.endswith('_ALT'):
+        return False
+    return True
+
+def full_adapter(name, active, section):
+    """Config adapter for "full"."""
+    if not is_full_section(section):
+        return active
+    return include_in_full(name)
+
+def keep_in_baremetal(name):
+    """Rules for symbols in the "baremetal" configuration."""
+    if name in [
+            'MBEDTLS_TIMING_C',
+            'MBEDTLS_FS_IO',
+            'MBEDTLS_ENTROPY_NV_SEED',
+            'MBEDTLS_HAVE_TIME',
+            'MBEDTLS_HAVE_TIME_DATE',
+            'MBEDTLS_DEPRECATED_WARNING',
+            'MBEDTLS_HAVEGE_C',
+            'MBEDTLS_THREADING_C',
+            'MBEDTLS_THREADING_PTHREAD',
+            'MBEDTLS_MEMORY_BACKTRACE',
+            'MBEDTLS_MEMORY_BUFFER_ALLOC_C',
+            'MBEDTLS_PLATFORM_TIME_ALT',
+            'MBEDTLS_PLATFORM_FPRINTF_ALT',
+            'MBEDTLS_PSA_ITS_FILE_C',
+            'MBEDTLS_PSA_CRYPTO_SE_C',
+            'MBEDTLS_PSA_CRYPTO_STORAGE_C',
+    ]:
+        return False
+    return True
+
+def baremetal_adapter(name, active, section):
+    """Config adapter for "baremetal"."""
+    if not is_full_section(section):
+        return active
+    if name == 'MBEDTLS_NO_PLATFORM_ENTROPY':
+        return True
+    return include_in_full(name) and keep_in_baremetal(name)
+
 class ConfigFile(Config):
     """Representation of the Mbed TLS configuration read for a file.
 
@@ -164,8 +241,10 @@ class ConfigFile(Config):
             filename = self.default_path
         super().__init__()
         self.filename = filename
+        self.current_section = 'header'
         with open(filename) as file:
             self.templates = [self._parse_line(line) for line in file]
+        self.current_section = None
 
     def set(self, name, value=None):
         if name not in self.settings:
@@ -179,11 +258,20 @@ class ConfigFile(Config):
                            r'(?P<arguments>(?:\((?:\w|\s|,)*\))?)' +
                            r'(?P<separator>\s*)' +
                            r'(?P<value>.*)')
+    _section_line_regexp = (r'\s*/?\*+\s*[\\@]name\s+SECTION:\s*' +
+                            r'(?P<section>.*)[ */]*')
+    _config_line_regexp = re.compile(r'|'.join([_define_line_regexp,
+                                                _section_line_regexp]))
     def _parse_line(self, line):
         """Parse a line in config.h and return the corresponding template."""
         line = line.rstrip('\r\n')
-        m = re.match(self._define_line_regexp, line)
-        if m:
+        m = re.match(self._config_line_regexp, line)
+        if m is None:
+            return line
+        elif m.group('section'):
+            self.current_section = m.group('section')
+            return line
+        else:
             active = not m.group('commented_out')
             name = m.group('name')
             value = m.group('value')
@@ -191,10 +279,9 @@ class ConfigFile(Config):
                         m.group('indentation'),
                         m.group('define') + name +
                         m.group('arguments') + m.group('separator'))
-            self.settings[name] = Setting(active, name, value)
+            self.settings[name] = Setting(active, name, value,
+                                          self.current_section)
             return template
-        else:
-            return line
 
     def _format_template(self, name, indent, middle):
         """Build a line for config.h for the given setting.
@@ -267,8 +354,17 @@ if __name__ == '__main__':
         def add_adapter(name, function, description):
             subparser = subparsers.add_parser(name, help=description)
             subparser.set_defaults(adapter=function)
+        add_adapter('baremetal', baremetal_adapter,
+                    """Like full, but exclude features that require platform
+                    features such as file input-output.""")
+        add_adapter('full', full_adapter,
+                    """Uncomment most features.
+                    Exclude alternative implementations and platform support
+                    options, as well as some options that are awkward to test.
+                    """)
         add_adapter('realfull', realfull_adapter,
-                    """Uncomment all #defines. No exceptions.""")
+                    """Uncomment all boolean #defines.
+                    Suitable for generating documentation, but not for building.""")
 
         args = parser.parse_args()
         config = ConfigFile(args.file)