torvalds-linux/Documentation/sphinx/kernel_include.py

#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0
# pylint: disable=R0903, R0912, R0914, R0915, C0209,W0707

"""
    kernel-include
    ~~~~~~~~~~~~~~

    Implementation of the ``kernel-include`` reST-directive.

    :copyright:  Copyright (C) 2016  Markus Heiser
    :license:    GPL Version 2, June 1991 see linux/COPYING for details.

    The ``kernel-include`` reST-directive is a replacement for the ``include``
    directive. The ``kernel-include`` directive expand environment variables in
    the path name and allows to include files from arbitrary locations.

    .. hint::

      Including files from arbitrary locations (e.g. from ``/etc``) is a
      security risk for builders. This is why the ``include`` directive from
      docutils *prohibit* pathnames pointing to locations *above* the filesystem
      tree where the reST document with the include directive is placed.

    Substrings of the form $name or ${name} are replaced by the value of
    environment variable name. Malformed variable names and references to
    non-existing variables are left unchanged.

    This extension overrides Sphinx include directory, adding some extra
    arguments:

    1. :generate-cross-refs:

        If present, instead of reading the file, it calls ParseDataStructs()
        class, which converts C data structures into cross-references to
        be linked to ReST files containing a more comprehensive documentation;

    2. :exception-file:

        Used together with :generate-cross-refs

        Points to a file containing rules to ignore C data structs or to
        use a different reference name, optionally using a different
        reference type.

    3. :warn-broken:

        Used together with :generate-cross-refs:

        Detect if the auto-generated cross references doesn't exist.

"""

# ==============================================================================
# imports
# ==============================================================================

import os.path
import re
import sys

from docutils import io, nodes, statemachine
from docutils.statemachine import ViewList
from docutils.utils.error_reporting import SafeString, ErrorString
from docutils.parsers.rst import Directive, directives
from docutils.parsers.rst.directives.body import CodeBlock, NumberLines

from sphinx.util import logging

srctree = os.path.abspath(os.environ["srctree"])
sys.path.insert(0, os.path.join(srctree, "tools/docs/lib"))

from parse_data_structs import ParseDataStructs

__version__ = "1.0"
logger = logging.getLogger(__name__)

RE_DOMAIN_REF = re.compile(r'\\ :(ref|c:type|c:func):`([^<`]+)(?:<([^>]+)>)?`\\')
RE_SIMPLE_REF = re.compile(r'`([^`]+)`')


# ==============================================================================
class KernelInclude(Directive):
    """
    KernelInclude (``kernel-include``) directive

    Most of the stuff here came from Include directive defined at:
        docutils/parsers/rst/directives/misc.py

    Yet, overriding the class don't has any benefits: the original class
    only have run() and argument list. Not all of them are implemented,
    when checked against latest Sphinx version, as with time more arguments
    were added.

    So, keep its own list of supported arguments
    """

    required_arguments = 1
    optional_arguments = 0
    final_argument_whitespace = True
    option_spec = {
        'literal': directives.flag,
        'code': directives.unchanged,
        'encoding': directives.encoding,
        'tab-width': int,
        'start-line': int,
        'end-line': int,
        'start-after': directives.unchanged_required,
        'end-before': directives.unchanged_required,
        # ignored except for 'literal' or 'code':
        'number-lines': directives.unchanged,  # integer or None
        'class': directives.class_option,

        # Arguments that aren't from Sphinx Include directive
        'generate-cross-refs': directives.flag,
        'warn-broken': directives.flag,
        'toc': directives.flag,
        'exception-file': directives.unchanged,
    }

    def read_rawtext(self, path, encoding):
            """Read and process file content with error handling"""
            try:
                self.state.document.settings.record_dependencies.add(path)
                include_file = io.FileInput(source_path=path,
                                            encoding=encoding,
                                            error_handler=self.state.document.settings.input_encoding_error_handler)
            except UnicodeEncodeError:
                raise self.severe('Problems with directive path:\n'
                                'Cannot encode input file path "%s" '
                                '(wrong locale?).' % SafeString(path))
            except IOError as error:
                raise self.severe('Problems with directive path:\n%s.' % ErrorString(error))

            try:
                return include_file.read()
            except UnicodeError as error:
                raise self.severe('Problem with directive:\n%s' % ErrorString(error))

    def apply_range(self, rawtext):
        """
        Handles start-line, end-line, start-after and end-before parameters
        """

        # Get to-be-included content
        startline = self.options.get('start-line', None)
        endline = self.options.get('end-line', None)
        try:
            if startline or (endline is not None):
                lines = rawtext.splitlines()
                rawtext = '\n'.join(lines[startline:endline])
        except UnicodeError as error:
            raise self.severe(f'Problem with "{self.name}" directive:\n'
                              + io.error_string(error))
        # start-after/end-before: no restrictions on newlines in match-text,
        # and no restrictions on matching inside lines vs. line boundaries
        after_text = self.options.get("start-after", None)
        if after_text:
            # skip content in rawtext before *and incl.* a matching text
            after_index = rawtext.find(after_text)
            if after_index < 0:
                raise self.severe('Problem with "start-after" option of "%s" '
                                  "directive:\nText not found." % self.name)
            rawtext = rawtext[after_index + len(after_text) :]
        before_text = self.options.get("end-before", None)
        if before_text:
            # skip content in rawtext after *and incl.* a matching text
            before_index = rawtext.find(before_text)
            if before_index < 0:
                raise self.severe('Problem with "end-before" option of "%s" '
                                  "directive:\nText not found." % self.name)
            rawtext = rawtext[:before_index]

        return rawtext

    def xref_text(self, env, path, tab_width):
        """
        Read and add contents from a C file parsed to have cross references.

        There are two types of supported output here:
        - A C source code with cross-references;
        - a TOC table containing cross references.
        """
        parser = ParseDataStructs()
        parser.parse_file(path)

        if 'exception-file' in self.options:
            source_dir = os.path.dirname(os.path.abspath(
                self.state_machine.input_lines.source(
                    self.lineno - self.state_machine.input_offset - 1)))
            exceptions_file = os.path.join(source_dir, self.options['exception-file'])
            parser.process_exceptions(exceptions_file)

        # Store references on a symbol dict to be used at check time
        if 'warn-broken' in self.options:
            env._xref_files.add(path)

        if "toc" not in self.options:

            rawtext = ".. parsed-literal::\n\n" + parser.gen_output()
            self.apply_range(rawtext)

            include_lines = statemachine.string2lines(rawtext, tab_width,
                                                      convert_whitespace=True)

            # Sphinx always blame the ".. <directive>", so placing
            # line numbers here won't make any difference

            self.state_machine.insert_input(include_lines, path)
            return []

        # TOC output is a ReST file, not a literal. So, we can add line
        # numbers

        rawtext = parser.gen_toc()

        include_lines = statemachine.string2lines(rawtext, tab_width,
                                                  convert_whitespace=True)

        # Append line numbers data

        startline = self.options.get('start-line', None)

        result = ViewList()
        if startline and startline > 0:
            offset = startline - 1
        else:
            offset = 0

        for ln, line in enumerate(include_lines, start=offset):
            result.append(line, path, ln)

        self.state_machine.insert_input(result, path)

        return []

    def literal(self, path, tab_width, rawtext):
        """Output a literal block"""

        # Convert tabs to spaces, if `tab_width` is positive.
        if tab_width >= 0:
            text = rawtext.expandtabs(tab_width)
        else:
            text = rawtext
        literal_block = nodes.literal_block(rawtext, source=path,
                                            classes=self.options.get("class", []))
        literal_block.line = 1
        self.add_name(literal_block)
        if "number-lines" in self.options:
            try:
                startline = int(self.options["number-lines"] or 1)
            except ValueError:
                raise self.error(":number-lines: with non-integer start value")
            endline = startline + len(include_lines)
            if text.endswith("\n"):
                text = text[:-1]
            tokens = NumberLines([([], text)], startline, endline)
            for classes, value in tokens:
                if classes:
                    literal_block += nodes.inline(value, value,
                                                    classes=classes)
                else:
                    literal_block += nodes.Text(value, value)
        else:
            literal_block += nodes.Text(text, text)
        return [literal_block]

    def code(self, path, tab_width):
        """Output a code block"""

        include_lines = statemachine.string2lines(rawtext, tab_width,
                                                  convert_whitespace=True)

        self.options["source"] = path
        codeblock = CodeBlock(self.name,
                                [self.options.pop("code")],  # arguments
                                self.options,
                                include_lines,
                                self.lineno,
                                self.content_offset,
                                self.block_text,
                                self.state,
                                self.state_machine)
        return codeblock.run()

    def run(self):
        """Include a file as part of the content of this reST file."""
        env = self.state.document.settings.env
        path = os.path.realpath(os.path.expandvars(self.arguments[0]))

        # to get a bit security back, prohibit /etc:
        if path.startswith(os.sep + "etc"):
            raise self.severe('Problems with "%s" directive, prohibited path: %s' %
                              (self.name, path))

        self.arguments[0] = path

        env.note_dependency(os.path.abspath(path))

        # HINT: I had to copy&paste the whole Include.run method. I'am not happy
        # with this, but due to security reasons, the Include.run method does
        # not allow absolute or relative pathnames pointing to locations *above*
        # the filesystem tree where the reST document is placed.

        if not self.state.document.settings.file_insertion_enabled:
            raise self.warning('"%s" directive disabled.' % self.name)
        source = self.state_machine.input_lines.source(self.lineno -
                                                       self.state_machine.input_offset - 1)
        source_dir = os.path.dirname(os.path.abspath(source))
        path = directives.path(self.arguments[0])
        if path.startswith("<") and path.endswith(">"):
            path = os.path.join(self.standard_include_path, path[1:-1])
        path = os.path.normpath(os.path.join(source_dir, path))

        # HINT: this is the only line I had to change / commented out:
        # path = utils.relative_path(None, path)

        encoding = self.options.get("encoding",
                                    self.state.document.settings.input_encoding)
        tab_width = self.options.get("tab-width",
                                     self.state.document.settings.tab_width)

        # Get optional arguments to related to cross-references generation
        if "generate-cross-refs" in self.options:
            return self.xref_text(env, path, tab_width)

        rawtext = self.read_rawtext(path, encoding)
        rawtext = self.apply_range(rawtext)

        if "code" in self.options:
            return self.code(path, tab_width, rawtext)

        return self.literal(path, tab_width, rawtext)

# ==============================================================================

reported = set()

def check_missing_refs(app, env, node, contnode):
    """Check broken refs for the files it creates xrefs"""
    if not node.source:
        return None

    try:
        xref_files = env._xref_files
    except AttributeError:
        logger.critical("FATAL: _xref_files not initialized!")
        raise

    # Only show missing references for kernel-include reference-parsed files
    if node.source not in xref_files:
        return None

    target = node.get('reftarget', '')
    domain = node.get('refdomain', 'std')
    reftype = node.get('reftype', '')

    msg = f"can't link to: {domain}:{reftype}:: {target}"

    # Don't duplicate warnings
    data = (node.source, msg)
    if data in reported:
        return None
    reported.add(data)

    logger.warning(msg, location=node, type='ref', subtype='missing')

    return None

def merge_xref_info(app, env, docnames, other):
    """
    As each process modify env._xref_files, we need to merge them back.
    """
    if not hasattr(other, "_xref_files"):
        return
    env._xref_files.update(getattr(other, "_xref_files", set()))

def init_xref_docs(app, env, docnames):
    """Initialize a list of files that we're generating cross references¨"""
    app.env._xref_files = set()

# ==============================================================================

def setup(app):
    """Setup Sphinx exension"""

    app.connect("env-before-read-docs", init_xref_docs)
    app.connect("env-merge-info", merge_xref_info)
    app.add_directive("kernel-include", KernelInclude)
    app.connect("missing-reference", check_missing_refs)

    return {
        "version": __version__,
        "parallel_read_safe": True,
        "parallel_write_safe": True,
    }