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+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2019 Jonathan Corbet <corbet@lwn.net>
+#
+# Apply kernel-specific tweaks after the initial document processing
+# has been done.
+#
+from docutils import nodes
+import sphinx
+from sphinx import addnodes
+if sphinx.version_info[0] < 2 or \
+ sphinx.version_info[0] == 2 and sphinx.version_info[1] < 1:
+ from sphinx.environment import NoUri
+else:
+ from sphinx.errors import NoUri
+import re
+from itertools import chain
+
+#
+# Python 2 lacks re.ASCII...
+#
+try:
+ ascii_p3 = re.ASCII
+except AttributeError:
+ ascii_p3 = 0
+
+#
+# Regex nastiness. Of course.
+# Try to identify "function()" that's not already marked up some
+# other way. Sphinx doesn't like a lot of stuff right after a
+# :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
+# bit tries to restrict matches to things that won't create trouble.
+#
+RE_function = re.compile(r'\b(([a-zA-Z_]\w+)\(\))', flags=ascii_p3)
+
+#
+# Sphinx 2 uses the same :c:type role for struct, union, enum and typedef
+#
+RE_generic_type = re.compile(r'\b(struct|union|enum|typedef)\s+([a-zA-Z_]\w+)',
+ flags=ascii_p3)
+
+#
+# Sphinx 3 uses a different C role for each one of struct, union, enum and
+# typedef
+#
+RE_struct = re.compile(r'\b(struct)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
+RE_union = re.compile(r'\b(union)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
+RE_enum = re.compile(r'\b(enum)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
+RE_typedef = re.compile(r'\b(typedef)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
+
+#
+# Detects a reference to a documentation page of the form Documentation/... with
+# an optional extension
+#
+RE_doc = re.compile(r'(\bDocumentation/)?((\.\./)*[\w\-/]+)\.(rst|txt)')
+
+RE_namespace = re.compile(r'^\s*..\s*c:namespace::\s*(\S+)\s*$')
+
+#
+# Reserved C words that we should skip when cross-referencing
+#
+Skipnames = [ 'for', 'if', 'register', 'sizeof', 'struct', 'unsigned' ]
+
+
+#
+# Many places in the docs refer to common system calls. It is
+# pointless to try to cross-reference them and, as has been known
+# to happen, somebody defining a function by these names can lead
+# to the creation of incorrect and confusing cross references. So
+# just don't even try with these names.
+#
+Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap',
+ 'select', 'poll', 'fork', 'execve', 'clone', 'ioctl',
+ 'socket' ]
+
+c_namespace = ''
+
+def markup_refs(docname, app, node):
+ t = node.astext()
+ done = 0
+ repl = [ ]
+ #
+ # Associate each regex with the function that will markup its matches
+ #
+ markup_func_sphinx2 = {RE_doc: markup_doc_ref,
+ RE_function: markup_c_ref,
+ RE_generic_type: markup_c_ref}
+
+ markup_func_sphinx3 = {RE_doc: markup_doc_ref,
+ RE_function: markup_func_ref_sphinx3,
+ RE_struct: markup_c_ref,
+ RE_union: markup_c_ref,
+ RE_enum: markup_c_ref,
+ RE_typedef: markup_c_ref}
+
+ if sphinx.version_info[0] >= 3:
+ markup_func = markup_func_sphinx3
+ else:
+ markup_func = markup_func_sphinx2
+
+ match_iterators = [regex.finditer(t) for regex in markup_func]
+ #
+ # Sort all references by the starting position in text
+ #
+ sorted_matches = sorted(chain(*match_iterators), key=lambda m: m.start())
+ for m in sorted_matches:
+ #
+ # Include any text prior to match as a normal text node.
+ #
+ if m.start() > done:
+ repl.append(nodes.Text(t[done:m.start()]))
+
+ #
+ # Call the function associated with the regex that matched this text and
+ # append its return to the text
+ #
+ repl.append(markup_func[m.re](docname, app, m))
+
+ done = m.end()
+ if done < len(t):
+ repl.append(nodes.Text(t[done:]))
+ return repl
+
+#
+# Keep track of cross-reference lookups that failed so we don't have to
+# do them again.
+#
+failed_lookups = { }
+def failure_seen(target):
+ return (target) in failed_lookups
+def note_failure(target):
+ failed_lookups[target] = True
+
+#
+# In sphinx3 we can cross-reference to C macro and function, each one with its
+# own C role, but both match the same regex, so we try both.
+#
+def markup_func_ref_sphinx3(docname, app, match):
+ cdom = app.env.domains['c']
+ #
+ # Go through the dance of getting an xref out of the C domain
+ #
+ base_target = match.group(2)
+ target_text = nodes.Text(match.group(0))
+ xref = None
+ possible_targets = [base_target]
+ # Check if this document has a namespace, and if so, try
+ # cross-referencing inside it first.
+ if c_namespace:
+ possible_targets.insert(0, c_namespace + "." + base_target)
+
+ if base_target not in Skipnames:
+ for target in possible_targets:
+ if (target not in Skipfuncs) and not failure_seen(target):
+ lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
+ lit_text += target_text
+ pxref = addnodes.pending_xref('', refdomain = 'c',
+ reftype = 'function',
+ reftarget = target,
+ modname = None,
+ classname = None)
+ #
+ # XXX The Latex builder will throw NoUri exceptions here,
+ # work around that by ignoring them.
+ #
+ try:
+ xref = cdom.resolve_xref(app.env, docname, app.builder,
+ 'function', target, pxref,
+ lit_text)
+ except NoUri:
+ xref = None
+
+ if xref:
+ return xref
+ note_failure(target)
+
+ return target_text
+
+def markup_c_ref(docname, app, match):
+ class_str = {# Sphinx 2 only
+ RE_function: 'c-func',
+ RE_generic_type: 'c-type',
+ # Sphinx 3+ only
+ RE_struct: 'c-struct',
+ RE_union: 'c-union',
+ RE_enum: 'c-enum',
+ RE_typedef: 'c-type',
+ }
+ reftype_str = {# Sphinx 2 only
+ RE_function: 'function',
+ RE_generic_type: 'type',
+ # Sphinx 3+ only
+ RE_struct: 'struct',
+ RE_union: 'union',
+ RE_enum: 'enum',
+ RE_typedef: 'type',
+ }
+
+ cdom = app.env.domains['c']
+ #
+ # Go through the dance of getting an xref out of the C domain
+ #
+ base_target = match.group(2)
+ target_text = nodes.Text(match.group(0))
+ xref = None
+ possible_targets = [base_target]
+ # Check if this document has a namespace, and if so, try
+ # cross-referencing inside it first.
+ if c_namespace:
+ possible_targets.insert(0, c_namespace + "." + base_target)
+
+ if base_target not in Skipnames:
+ for target in possible_targets:
+ if not (match.re == RE_function and target in Skipfuncs):
+ lit_text = nodes.literal(classes=['xref', 'c', class_str[match.re]])
+ lit_text += target_text
+ pxref = addnodes.pending_xref('', refdomain = 'c',
+ reftype = reftype_str[match.re],
+ reftarget = target, modname = None,
+ classname = None)
+ #
+ # XXX The Latex builder will throw NoUri exceptions here,
+ # work around that by ignoring them.
+ #
+ try:
+ xref = cdom.resolve_xref(app.env, docname, app.builder,
+ reftype_str[match.re], target, pxref,
+ lit_text)
+ except NoUri:
+ xref = None
+
+ if xref:
+ return xref
+
+ return target_text
+
+#
+# Try to replace a documentation reference of the form Documentation/... with a
+# cross reference to that page
+#
+def markup_doc_ref(docname, app, match):
+ stddom = app.env.domains['std']
+ #
+ # Go through the dance of getting an xref out of the std domain
+ #
+ absolute = match.group(1)
+ target = match.group(2)
+ if absolute:
+ target = "/" + target
+ xref = None
+ pxref = addnodes.pending_xref('', refdomain = 'std', reftype = 'doc',
+ reftarget = target, modname = None,
+ classname = None, refexplicit = False)
+ #
+ # XXX The Latex builder will throw NoUri exceptions here,
+ # work around that by ignoring them.
+ #
+ try:
+ xref = stddom.resolve_xref(app.env, docname, app.builder, 'doc',
+ target, pxref, None)
+ except NoUri:
+ xref = None
+ #
+ # Return the xref if we got it; otherwise just return the plain text.
+ #
+ if xref:
+ return xref
+ else:
+ return nodes.Text(match.group(0))
+
+def get_c_namespace(app, docname):
+ source = app.env.doc2path(docname)
+ with open(source) as f:
+ for l in f:
+ match = RE_namespace.search(l)
+ if match:
+ return match.group(1)
+ return ''
+
+def auto_markup(app, doctree, name):
+ global c_namespace
+ c_namespace = get_c_namespace(app, name)
+ def text_but_not_a_reference(node):
+ # The nodes.literal test catches ``literal text``, its purpose is to
+ # avoid adding cross-references to functions that have been explicitly
+ # marked with cc:func:.
+ if not isinstance(node, nodes.Text) or isinstance(node.parent, nodes.literal):
+ return False
+
+ child_of_reference = False
+ parent = node.parent
+ while parent:
+ if isinstance(parent, nodes.Referential):
+ child_of_reference = True
+ break
+ parent = parent.parent
+ return not child_of_reference
+
+ #
+ # This loop could eventually be improved on. Someday maybe we
+ # want a proper tree traversal with a lot of awareness of which
+ # kinds of nodes to prune. But this works well for now.
+ #
+ for para in doctree.traverse(nodes.paragraph):
+ for node in para.traverse(condition=text_but_not_a_reference):
+ node.parent.replace(node, markup_refs(name, app, node))
+
+def setup(app):
+ app.connect('doctree-resolved', auto_markup)
+ return {
+ 'parallel_read_safe': True,
+ 'parallel_write_safe': True,
+ }