1 # SPDX-License-Identifier: GPL-2.0
2 # Copyright 2019 Jonathan Corbet <corbet@lwn.net>
3 #
4 # Apply kernel-specific tweaks after the initial document processing
5 # has been done.
6 #
7 from docutils import nodes
8 import sphinx
9 from sphinx import addnodes
10 from sphinx.errors import NoUri
11 import re
12 from itertools import chain
13
14 #
15 # Python 2 lacks re.ASCII...
16 #
17 try:
18 ascii_p3 = re.ASCII
19 except AttributeError:
20 ascii_p3 = 0
21
22 #
23 # Regex nastiness. Of course.
24 # Try to identify "function()" that's not already marked up some
25 # other way. Sphinx doesn't like a lot of stuff right after a
26 # :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
27 # bit tries to restrict matches to things that won't create trouble.
28 #
29 RE_function = re.compile(r'\b(([a-zA-Z_]\w+)\(\))', flags=ascii_p3)
30
31 #
32 # Sphinx 2 uses the same :c:type role for struct, union, enum and typedef
33 #
34 RE_generic_type = re.compile(r'\b(struct|union|enum|typedef)\s+([a-zA-Z_]\w+)',
35 flags=ascii_p3)
36
37 #
38 # Sphinx 3 uses a different C role for each one of struct, union, enum and
39 # typedef
40 #
41 RE_struct = re.compile(r'\b(struct)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
42 RE_union = re.compile(r'\b(union)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
43 RE_enum = re.compile(r'\b(enum)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
44 RE_typedef = re.compile(r'\b(typedef)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
45
46 #
47 # Detects a reference to a documentation page of the form Documentation/... with
48 # an optional extension
49 #
50 RE_doc = re.compile(r'(\bDocumentation/)?((\.\./)*[\w\-/]+)\.(rst|txt)')
51
52 RE_namespace = re.compile(r'^\s*..\s*c:namespace::\s*(\S+)\s*$')
53
54 #
55 # Reserved C words that we should skip when cross-referencing
56 #
57 Skipnames = [ 'for', 'if', 'register', 'sizeof', 'struct', 'unsigned' ]
58
59
60 #
61 # Many places in the docs refer to common system calls. It is
62 # pointless to try to cross-reference them and, as has been known
63 # to happen, somebody defining a function by these names can lead
64 # to the creation of incorrect and confusing cross references. So
65 # just don't even try with these names.
66 #
67 Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap',
68 'select', 'poll', 'fork', 'execve', 'clone', 'ioctl',
69 'socket' ]
70
71 c_namespace = ''
72
73 #
74 # Detect references to commits.
75 #
76 RE_git = re.compile(r'commit\s+(?P<rev>[0-9a-f]{12,40})(?:\s+\(".*?"\))?',
77 flags=re.IGNORECASE | re.DOTALL)
78
79 def markup_refs(docname, app, node):
80 t = node.astext()
81 done = 0
82 repl = [ ]
83 #
84 # Associate each regex with the function that will markup its matches
85 #
86 markup_func_sphinx2 = {RE_doc: markup_doc_ref,
87 RE_function: markup_c_ref,
88 RE_generic_type: markup_c_ref}
89
90 markup_func_sphinx3 = {RE_doc: markup_doc_ref,
91 RE_function: markup_func_ref_sphinx3,
92 RE_struct: markup_c_ref,
93 RE_union: markup_c_ref,
94 RE_enum: markup_c_ref,
95 RE_typedef: markup_c_ref,
96 RE_git: markup_git}
97
98 if sphinx.version_info[0] >= 3:
99 markup_func = markup_func_sphinx3
100 else:
101 markup_func = markup_func_sphinx2
102
103 match_iterators = [regex.finditer(t) for regex in markup_func]
104 #
105 # Sort all references by the starting position in text
106 #
107 sorted_matches = sorted(chain(*match_iterators), key=lambda m: m.start())
108 for m in sorted_matches:
109 #
110 # Include any text prior to match as a normal text node.
111 #
112 if m.start() > done:
113 repl.append(nodes.Text(t[done:m.start()]))
114
115 #
116 # Call the function associated with the regex that matched this text and
117 # append its return to the text
118 #
119 repl.append(markup_func[m.re](docname, app, m))
120
121 done = m.end()
122 if done < len(t):
123 repl.append(nodes.Text(t[done:]))
124 return repl
125
126 #
127 # Keep track of cross-reference lookups that failed so we don't have to
128 # do them again.
129 #
130 failed_lookups = { }
131 def failure_seen(target):
132 return (target) in failed_lookups
133 def note_failure(target):
134 failed_lookups[target] = True
135
136 #
137 # In sphinx3 we can cross-reference to C macro and function, each one with its
138 # own C role, but both match the same regex, so we try both.
139 #
140 def markup_func_ref_sphinx3(docname, app, match):
141 cdom = app.env.domains['c']
142 #
143 # Go through the dance of getting an xref out of the C domain
144 #
145 base_target = match.group(2)
146 target_text = nodes.Text(match.group(0))
147 xref = None
148 possible_targets = [base_target]
149 # Check if this document has a namespace, and if so, try
150 # cross-referencing inside it first.
151 if c_namespace:
152 possible_targets.insert(0, c_namespace + "." + base_target)
153
154 if base_target not in Skipnames:
155 for target in possible_targets:
156 if (target not in Skipfuncs) and not failure_seen(target):
157 lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
158 lit_text += target_text
159 pxref = addnodes.pending_xref('', refdomain = 'c',
160 reftype = 'function',
161 reftarget = target,
162 modname = None,
163 classname = None)
164 #
165 # XXX The Latex builder will throw NoUri exceptions here,
166 # work around that by ignoring them.
167 #
168 try:
169 xref = cdom.resolve_xref(app.env, docname, app.builder,
170 'function', target, pxref,
171 lit_text)
172 except NoUri:
173 xref = None
174
175 if xref:
176 return xref
177 note_failure(target)
178
179 return target_text
180
181 def markup_c_ref(docname, app, match):
182 class_str = {# Sphinx 2 only
183 RE_function: 'c-func',
184 RE_generic_type: 'c-type',
185 # Sphinx 3+ only
186 RE_struct: 'c-struct',
187 RE_union: 'c-union',
188 RE_enum: 'c-enum',
189 RE_typedef: 'c-type',
190 }
191 reftype_str = {# Sphinx 2 only
192 RE_function: 'function',
193 RE_generic_type: 'type',
194 # Sphinx 3+ only
195 RE_struct: 'struct',
196 RE_union: 'union',
197 RE_enum: 'enum',
198 RE_typedef: 'type',
199 }
200
201 cdom = app.env.domains['c']
202 #
203 # Go through the dance of getting an xref out of the C domain
204 #
205 base_target = match.group(2)
206 target_text = nodes.Text(match.group(0))
207 xref = None
208 possible_targets = [base_target]
209 # Check if this document has a namespace, and if so, try
210 # cross-referencing inside it first.
211 if c_namespace:
212 possible_targets.insert(0, c_namespace + "." + base_target)
213
214 if base_target not in Skipnames:
215 for target in possible_targets:
216 if not (match.re == RE_function and target in Skipfuncs):
217 lit_text = nodes.literal(classes=['xref', 'c', class_str[match.re]])
218 lit_text += target_text
219 pxref = addnodes.pending_xref('', refdomain = 'c',
220 reftype = reftype_str[match.re],
221 reftarget = target, modname = None,
222 classname = None)
223 #
224 # XXX The Latex builder will throw NoUri exceptions here,
225 # work around that by ignoring them.
226 #
227 try:
228 xref = cdom.resolve_xref(app.env, docname, app.builder,
229 reftype_str[match.re], target, pxref,
230 lit_text)
231 except NoUri:
232 xref = None
233
234 if xref:
235 return xref
236
237 return target_text
238
239 #
240 # Try to replace a documentation reference of the form Documentation/... with a
241 # cross reference to that page
242 #
243 def markup_doc_ref(docname, app, match):
244 stddom = app.env.domains['std']
245 #
246 # Go through the dance of getting an xref out of the std domain
247 #
248 absolute = match.group(1)
249 target = match.group(2)
250 if absolute:
251 target = "/" + target
252 xref = None
253 pxref = addnodes.pending_xref('', refdomain = 'std', reftype = 'doc',
254 reftarget = target, modname = None,
255 classname = None, refexplicit = False)
256 #
257 # XXX The Latex builder will throw NoUri exceptions here,
258 # work around that by ignoring them.
259 #
260 try:
261 xref = stddom.resolve_xref(app.env, docname, app.builder, 'doc',
262 target, pxref, None)
263 except NoUri:
264 xref = None
265 #
266 # Return the xref if we got it; otherwise just return the plain text.
267 #
268 if xref:
269 return xref
270 else:
271 return nodes.Text(match.group(0))
272
273 def get_c_namespace(app, docname):
274 source = app.env.doc2path(docname)
275 with open(source) as f:
276 for l in f:
277 match = RE_namespace.search(l)
278 if match:
279 return match.group(1)
280 return ''
281
282 def markup_git(docname, app, match):
283 # While we could probably assume that we are running in a git
284 # repository, we can't know for sure, so let's just mechanically
285 # turn them into git.kernel.org links without checking their
286 # validity. (Maybe we can do something in the future to warn about
287 # these references if this is explicitly requested.)
288 text = match.group(0)
289 rev = match.group('rev')
290 return nodes.reference('', nodes.Text(text),
291 refuri=f'https://git.kernel.org/torvalds/c/{rev}')
292
293 def auto_markup(app, doctree, name):
294 global c_namespace
295 c_namespace = get_c_namespace(app, name)
296 def text_but_not_a_reference(node):
297 # The nodes.literal test catches ``literal text``, its purpose is to
298 # avoid adding cross-references to functions that have been explicitly
299 # marked with cc:func:.
300 if not isinstance(node, nodes.Text) or isinstance(node.parent, nodes.literal):
301 return False
302
303 child_of_reference = False
304 parent = node.parent
305 while parent:
306 if isinstance(parent, nodes.Referential):
307 child_of_reference = True
308 break
309 parent = parent.parent
310 return not child_of_reference
311
312 #
313 # This loop could eventually be improved on. Someday maybe we
314 # want a proper tree traversal with a lot of awareness of which
315 # kinds of nodes to prune. But this works well for now.
316 #
317 for para in doctree.traverse(nodes.paragraph):
318 for node in para.traverse(condition=text_but_not_a_reference):
319 node.parent.replace(node, markup_refs(name, app, node))
320
321 def setup(app):
322 app.connect('doctree-resolved', auto_markup)
323 return {
324 'parallel_read_safe': True,
325 'parallel_write_safe': True,
326 }
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