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# 7from docutils import nodes 8import sphinx 9from sphinx import addnodes 10if sphinx.version_info[0] < 2 or \ 11 sphinx.version_info[0] == 2 and sphinx.version_info[1] < 1: 12 from sphinx.environment import NoUri 13else: 14 from sphinx.errors import NoUri 15import re 16from itertools import chain 17 18# 19# Python 2 lacks re.ASCII... 20# 21try: 22 ascii_p3 = re.ASCII 23except AttributeError: 24 ascii_p3 = 0 25 26# 27# Regex nastiness. Of course. 28# Try to identify "function()" that's not already marked up some 29# other way. Sphinx doesn't like a lot of stuff right after a 30# :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last 31# bit tries to restrict matches to things that won't create trouble. 32# 33RE_function = re.compile(r'\b(([a-zA-Z_]\w+)\(\))', flags=ascii_p3) 34 35# 36# Sphinx 2 uses the same :c:type role for struct, union, enum and typedef 37# 38RE_generic_type = re.compile(r'\b(struct|union|enum|typedef)\s+([a-zA-Z_]\w+)', 39 flags=ascii_p3) 40 41# 42# Sphinx 3 uses a different C role for each one of struct, union, enum and 43# typedef 44# 45RE_struct = re.compile(r'\b(struct)\s+([a-zA-Z_]\w+)', flags=ascii_p3) 46RE_union = re.compile(r'\b(union)\s+([a-zA-Z_]\w+)', flags=ascii_p3) 47RE_enum = re.compile(r'\b(enum)\s+([a-zA-Z_]\w+)', flags=ascii_p3) 48RE_typedef = re.compile(r'\b(typedef)\s+([a-zA-Z_]\w+)', flags=ascii_p3) 49 50# 51# Detects a reference to a documentation page of the form Documentation/... with 52# an optional extension 53# 54RE_doc = re.compile(r'(\bDocumentation/)?((\.\./)*[\w\-/]+)\.(rst|txt)') 55 56RE_namespace = re.compile(r'^\s*..\s*c:namespace::\s*(\S+)\s*$') 57 58# 59# Reserved C words that we should skip when cross-referencing 60# 61Skipnames = [ 'for', 'if', 'register', 'sizeof', 'struct', 'unsigned' ] 62 63 64# 65# Many places in the docs refer to common system calls. It is 66# pointless to try to cross-reference them and, as has been known 67# to happen, somebody defining a function by these names can lead 68# to the creation of incorrect and confusing cross references. So 69# just don't even try with these names. 70# 71Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap', 72 'select', 'poll', 'fork', 'execve', 'clone', 'ioctl', 73 'socket' ] 74 75c_namespace = '' 76 77def markup_refs(docname, app, node): 78 t = node.astext() 79 done = 0 80 repl = [ ] 81 # 82 # Associate each regex with the function that will markup its matches 83 # 84 markup_func_sphinx2 = {RE_doc: markup_doc_ref, 85 RE_function: markup_c_ref, 86 RE_generic_type: markup_c_ref} 87 88 markup_func_sphinx3 = {RE_doc: markup_doc_ref, 89 RE_function: markup_func_ref_sphinx3, 90 RE_struct: markup_c_ref, 91 RE_union: markup_c_ref, 92 RE_enum: markup_c_ref, 93 RE_typedef: markup_c_ref} 94 95 if sphinx.version_info[0] >= 3: 96 markup_func = markup_func_sphinx3 97 else: 98 markup_func = markup_func_sphinx2 99 100 match_iterators = [regex.finditer(t) for regex in markup_func] 101 # 102 # Sort all references by the starting position in text 103 # 104 sorted_matches = sorted(chain(*match_iterators), key=lambda m: m.start()) 105 for m in sorted_matches: 106 # 107 # Include any text prior to match as a normal text node. 108 # 109 if m.start() > done: 110 repl.append(nodes.Text(t[done:m.start()])) 111 112 # 113 # Call the function associated with the regex that matched this text and 114 # append its return to the text 115 # 116 repl.append(markup_func[m.re](docname, app, m)) 117 118 done = m.end() 119 if done < len(t): 120 repl.append(nodes.Text(t[done:])) 121 return repl 122 123# 124# Keep track of cross-reference lookups that failed so we don't have to 125# do them again. 126# 127failed_lookups = { } 128def failure_seen(target): 129 return (target) in failed_lookups 130def note_failure(target): 131 failed_lookups[target] = True 132 133# 134# In sphinx3 we can cross-reference to C macro and function, each one with its 135# own C role, but both match the same regex, so we try both. 136# 137def markup_func_ref_sphinx3(docname, app, match): 138 cdom = app.env.domains['c'] 139 # 140 # Go through the dance of getting an xref out of the C domain 141 # 142 base_target = match.group(2) 143 target_text = nodes.Text(match.group(0)) 144 xref = None 145 possible_targets = [base_target] 146 # Check if this document has a namespace, and if so, try 147 # cross-referencing inside it first. 148 if c_namespace: 149 possible_targets.insert(0, c_namespace + "." + base_target) 150 151 if base_target not in Skipnames: 152 for target in possible_targets: 153 if (target not in Skipfuncs) and not failure_seen(target): 154 lit_text = nodes.literal(classes=['xref', 'c', 'c-func']) 155 lit_text += target_text 156 pxref = addnodes.pending_xref('', refdomain = 'c', 157 reftype = 'function', 158 reftarget = target, 159 modname = None, 160 classname = None) 161 # 162 # XXX The Latex builder will throw NoUri exceptions here, 163 # work around that by ignoring them. 164 # 165 try: 166 xref = cdom.resolve_xref(app.env, docname, app.builder, 167 'function', target, pxref, 168 lit_text) 169 except NoUri: 170 xref = None 171 172 if xref: 173 return xref 174 note_failure(target) 175 176 return target_text 177 178def markup_c_ref(docname, app, match): 179 class_str = {# Sphinx 2 only 180 RE_function: 'c-func', 181 RE_generic_type: 'c-type', 182 # Sphinx 3+ only 183 RE_struct: 'c-struct', 184 RE_union: 'c-union', 185 RE_enum: 'c-enum', 186 RE_typedef: 'c-type', 187 } 188 reftype_str = {# Sphinx 2 only 189 RE_function: 'function', 190 RE_generic_type: 'type', 191 # Sphinx 3+ only 192 RE_struct: 'struct', 193 RE_union: 'union', 194 RE_enum: 'enum', 195 RE_typedef: 'type', 196 } 197 198 cdom = app.env.domains['c'] 199 # 200 # Go through the dance of getting an xref out of the C domain 201 # 202 base_target = match.group(2) 203 target_text = nodes.Text(match.group(0)) 204 xref = None 205 possible_targets = [base_target] 206 # Check if this document has a namespace, and if so, try 207 # cross-referencing inside it first. 208 if c_namespace: 209 possible_targets.insert(0, c_namespace + "." + base_target) 210 211 if base_target not in Skipnames: 212 for target in possible_targets: 213 if not (match.re == RE_function and target in Skipfuncs): 214 lit_text = nodes.literal(classes=['xref', 'c', class_str[match.re]]) 215 lit_text += target_text 216 pxref = addnodes.pending_xref('', refdomain = 'c', 217 reftype = reftype_str[match.re], 218 reftarget = target, modname = None, 219 classname = None) 220 # 221 # XXX The Latex builder will throw NoUri exceptions here, 222 # work around that by ignoring them. 223 # 224 try: 225 xref = cdom.resolve_xref(app.env, docname, app.builder, 226 reftype_str[match.re], target, pxref, 227 lit_text) 228 except NoUri: 229 xref = None 230 231 if xref: 232 return xref 233 234 return target_text 235 236# 237# Try to replace a documentation reference of the form Documentation/... with a 238# cross reference to that page 239# 240def markup_doc_ref(docname, app, match): 241 stddom = app.env.domains['std'] 242 # 243 # Go through the dance of getting an xref out of the std domain 244 # 245 absolute = match.group(1) 246 target = match.group(2) 247 if absolute: 248 target = "/" + target 249 xref = None 250 pxref = addnodes.pending_xref('', refdomain = 'std', reftype = 'doc', 251 reftarget = target, modname = None, 252 classname = None, refexplicit = False) 253 # 254 # XXX The Latex builder will throw NoUri exceptions here, 255 # work around that by ignoring them. 256 # 257 try: 258 xref = stddom.resolve_xref(app.env, docname, app.builder, 'doc', 259 target, pxref, None) 260 except NoUri: 261 xref = None 262 # 263 # Return the xref if we got it; otherwise just return the plain text. 264 # 265 if xref: 266 return xref 267 else: 268 return nodes.Text(match.group(0)) 269 270def get_c_namespace(app, docname): 271 source = app.env.doc2path(docname) 272 with open(source) as f: 273 for l in f: 274 match = RE_namespace.search(l) 275 if match: 276 return match.group(1) 277 return '' 278 279def auto_markup(app, doctree, name): 280 global c_namespace 281 c_namespace = get_c_namespace(app, name) 282 def text_but_not_a_reference(node): 283 # The nodes.literal test catches ``literal text``, its purpose is to 284 # avoid adding cross-references to functions that have been explicitly 285 # marked with cc:func:. 286 if not isinstance(node, nodes.Text) or isinstance(node.parent, nodes.literal): 287 return False 288 289 child_of_reference = False 290 parent = node.parent 291 while parent: 292 if isinstance(parent, nodes.Referential): 293 child_of_reference = True 294 break 295 parent = parent.parent 296 return not child_of_reference 297 298 # 299 # This loop could eventually be improved on. Someday maybe we 300 # want a proper tree traversal with a lot of awareness of which 301 # kinds of nodes to prune. But this works well for now. 302 # 303 for para in doctree.traverse(nodes.paragraph): 304 for node in para.traverse(condition=text_but_not_a_reference): 305 node.parent.replace(node, markup_refs(name, app, node)) 306 307def setup(app): 308 app.connect('doctree-resolved', auto_markup) 309 return { 310 'parallel_read_safe': True, 311 'parallel_write_safe': True, 312 } 313