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