docs: import Linux kernel-doc script and extension

Import Linux's kernel-doc script as of commit 15e2544ed38a1e, as well
as the Sphinx extension to call kernel-doc according to the arguments
and parameters given to a reStructuredText directive.

The kernel-doc extension accepts a filename, which is relative to
the QEMU source tree root.  The extension also notifies Sphinx about the
document dependency on the file, causing the document to be rebuilt when
the file has been changed.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/sphinx/kerneldoc.py

@@ -0,0 +1,172 @@
+# coding=utf-8
+#
+# Copyright © 2016 Intel Corporation
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice (including the next
+# paragraph) shall be included in all copies or substantial portions of the
+# Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+#
+# Authors:
+#    Jani Nikula <jani.nikula@intel.com>
+#
+# Please make sure this works on both python2 and python3.
+#
+
+import codecs
+import os
+import subprocess
+import sys
+import re
+import glob
+
+from docutils import nodes, statemachine
+from docutils.statemachine import ViewList
+from docutils.parsers.rst import directives, Directive
+
+#
+# AutodocReporter is only good up to Sphinx 1.7
+#
+import sphinx
+
+Use_SSI = sphinx.__version__[:3] >= '1.7'
+if Use_SSI:
+    from sphinx.util.docutils import switch_source_input
+else:
+    from sphinx.ext.autodoc import AutodocReporter
+
+import kernellog
+
+__version__  = '1.0'
+
+class KernelDocDirective(Directive):
+    """Extract kernel-doc comments from the specified file"""
+    required_argument = 1
+    optional_arguments = 4
+    option_spec = {
+        'doc': directives.unchanged_required,
+        'functions': directives.unchanged,
+        'export': directives.unchanged,
+        'internal': directives.unchanged,
+    }
+    has_content = False
+
+    def run(self):
+        env = self.state.document.settings.env
+        cmd = [env.config.kerneldoc_bin, '-rst', '-enable-lineno']
+
+        filename = env.config.kerneldoc_srctree + '/' + self.arguments[0]
+        export_file_patterns = []
+
+        # Tell sphinx of the dependency
+        env.note_dependency(os.path.abspath(filename))
+
+        tab_width = self.options.get('tab-width', self.state.document.settings.tab_width)
+
+        # FIXME: make this nicer and more robust against errors
+        if 'export' in self.options:
+            cmd += ['-export']
+            export_file_patterns = str(self.options.get('export')).split()
+        elif 'internal' in self.options:
+            cmd += ['-internal']
+            export_file_patterns = str(self.options.get('internal')).split()
+        elif 'doc' in self.options:
+            cmd += ['-function', str(self.options.get('doc'))]
+        elif 'functions' in self.options:
+            functions = self.options.get('functions').split()
+            if functions:
+                for f in functions:
+                    cmd += ['-function', f]
+            else:
+                cmd += ['-no-doc-sections']
+
+        for pattern in export_file_patterns:
+            for f in glob.glob(env.config.kerneldoc_srctree + '/' + pattern):
+                env.note_dependency(os.path.abspath(f))
+                cmd += ['-export-file', f]
+
+        cmd += [filename]
+
+        try:
+            kernellog.verbose(env.app,
+                              'calling kernel-doc \'%s\'' % (" ".join(cmd)))
+
+            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            out, err = p.communicate()
+
+            out, err = codecs.decode(out, 'utf-8'), codecs.decode(err, 'utf-8')
+
+            if p.returncode != 0:
+                sys.stderr.write(err)
+
+                kernellog.warn(env.app,
+                               'kernel-doc \'%s\' failed with return code %d' % (" ".join(cmd), p.returncode))
+                return [nodes.error(None, nodes.paragraph(text = "kernel-doc missing"))]
+            elif env.config.kerneldoc_verbosity > 0:
+                sys.stderr.write(err)
+
+            lines = statemachine.string2lines(out, tab_width, convert_whitespace=True)
+            result = ViewList()
+
+            lineoffset = 0;
+            line_regex = re.compile("^#define LINENO ([0-9]+)$")
+            for line in lines:
+                match = line_regex.search(line)
+                if match:
+                    # sphinx counts lines from 0
+                    lineoffset = int(match.group(1)) - 1
+                    # we must eat our comments since the upset the markup
+                else:
+                    result.append(line, filename, lineoffset)
+                    lineoffset += 1
+
+            node = nodes.section()
+            self.do_parse(result, node)
+
+            return node.children
+
+        except Exception as e:  # pylint: disable=W0703
+            kernellog.warn(env.app, 'kernel-doc \'%s\' processing failed with: %s' %
+                           (" ".join(cmd), str(e)))
+            return [nodes.error(None, nodes.paragraph(text = "kernel-doc missing"))]
+
+    def do_parse(self, result, node):
+        if Use_SSI:
+            with switch_source_input(self.state, result):
+                self.state.nested_parse(result, 0, node, match_titles=1)
+        else:
+            save = self.state.memo.title_styles, self.state.memo.section_level, self.state.memo.reporter
+            self.state.memo.reporter = AutodocReporter(result, self.state.memo.reporter)
+            self.state.memo.title_styles, self.state.memo.section_level = [], 0
+            try:
+                self.state.nested_parse(result, 0, node, match_titles=1)
+            finally:
+                self.state.memo.title_styles, self.state.memo.section_level, self.state.memo.reporter = save
+
+
+def setup(app):
+    app.add_config_value('kerneldoc_bin', None, 'env')
+    app.add_config_value('kerneldoc_srctree', None, 'env')
+    app.add_config_value('kerneldoc_verbosity', 1, 'env')
+
+    app.add_directive('kernel-doc', KernelDocDirective)
+
+    return dict(
+        version = __version__,
+        parallel_read_safe = True,
+        parallel_write_safe = True
+    )

docs/sphinx/kernellog.py

@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Sphinx has deprecated its older logging interface, but the replacement
+# only goes back to 1.6.  So here's a wrapper layer to keep around for
+# as long as we support 1.4.
+#
+import sphinx
+
+if sphinx.__version__[:3] >= '1.6':
+    UseLogging = True
+    from sphinx.util import logging
+    logger = logging.getLogger('kerneldoc')
+else:
+    UseLogging = False
+
+def warn(app, message):
+    if UseLogging:
+        logger.warning(message)
+    else:
+        app.warn(message)
+
+def verbose(app, message):
+    if UseLogging:
+        logger.verbose(message)
+    else:
+        app.verbose(message)
+
+