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1 | #! @PYTHON@ |
2 | ### | |
3 | ### Parse a profile definition file and emit a particular section | |
4 | ### | |
5 | ### (c) 2011 Mark Wooding | |
6 | ### | |
7 | ||
8 | ###----- Licensing notice --------------------------------------------------- | |
9 | ### | |
10 | ### This file is part of the distorted.org.uk key management suite. | |
11 | ### | |
12 | ### distorted-keys is free software; you can redistribute it and/or modify | |
13 | ### it under the terms of the GNU General Public License as published by | |
14 | ### the Free Software Foundation; either version 2 of the License, or | |
15 | ### (at your option) any later version. | |
16 | ### | |
17 | ### distorted-keys is distributed in the hope that it will be useful, | |
18 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ### GNU General Public License for more details. | |
21 | ### | |
22 | ### You should have received a copy of the GNU General Public License | |
23 | ### along with distorted-keys; if not, write to the Free Software Foundation, | |
24 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
26 | from __future__ import with_statement | |
27 | ||
28 | import sys as SYS | |
29 | import os as OS | |
30 | import UserDict as UD | |
31 | import optparse as O | |
32 | from cStringIO import StringIO | |
33 | ||
34 | PACKAGE = "@PACKAGE@" | |
35 | VERSION = "@VERSION@" | |
36 | ||
37 | ###-------------------------------------------------------------------------- | |
38 | ### Utilities. | |
39 | ||
40 | class struct (object): | |
41 | def __init__(me, **kw): | |
42 | me.__dict__.update(kw) | |
43 | ||
44 | class UserError (Exception): pass | |
45 | ||
46 | ###-------------------------------------------------------------------------- | |
47 | ### Configuration section management. | |
48 | ||
49 | class prop (struct): pass | |
50 | ||
51 | class Section (object, UD.DictMixin): | |
52 | """ | |
53 | A section of a profile configuration file. | |
54 | """ | |
55 | ||
56 | ## States for depth-first traversal. | |
57 | V_WHITE = 0 # Not yet visited. | |
58 | V_GREY = 1 # Currently being visited. | |
59 | V_BLACK = 2 # Visited previously and processed. | |
60 | ||
61 | def __init__(me, name, dict = None): | |
62 | """ | |
63 | Initialize a Section object. | |
64 | ||
65 | The DICT provides the initial (direct) contents of the Section. The NAME | |
66 | is used for presentation purposes, e.g., when reporting error conditions. | |
67 | """ | |
68 | super(Section, me).__init__() | |
69 | if dict is None: me._dict = {} | |
70 | else: me._dict = dict | |
71 | me._visited = me.V_WHITE | |
72 | me.name = name | |
73 | me.includes = set() | |
74 | me.inferiors = set() | |
75 | me.inherited = {} | |
76 | ||
77 | ## Dictionary methods for UD.DictMixin. The built-in `dict' class provides | |
78 | ## equality, and is therefore not hashable. By doing things this way, we | |
79 | ## can retain reference equality and stay hashable, which will be useful | |
80 | ## later. | |
81 | def __getitem__(me, key): | |
82 | return me._dict[key] | |
83 | def __setitem__(me, key, value): | |
84 | me._dict[key] = value | |
85 | def __delitem__(me, key): | |
86 | del me._dict[key] | |
87 | def keys(me): | |
88 | return me._dict.keys() | |
89 | def __contains__(me, key): | |
90 | return key in me._dict | |
91 | def __iter__(me): | |
92 | return me._dict.__iter__() | |
93 | def iteritems(me): | |
94 | return me._dict.iteritems() | |
95 | def __repr__(me): | |
96 | return 'Section(%r, %r)' % (me.name, me.inherited) | |
97 | ||
98 | def transit(me, seen = None, path = None): | |
99 | """ | |
100 | Visit the Section for the purposes of computing transitive inclusion. | |
101 | ||
102 | If this completes successfully, the Section's inferiors slot is set up to | |
103 | contain all of its (non-strict) inferiors. A section's inferiors consist | |
104 | of itself, together with the union of the inferiors of all of its | |
105 | included Sections. | |
106 | ||
107 | If the Section's visited state is black, nothing happens; if it's white | |
108 | then it will be coloured grey temporarily, and its included Sections | |
109 | processed recursively; if it's grey to begin with then we have | |
110 | encountered a cycle. | |
111 | ||
112 | The SEEN dictionary and PATH list are used for detecting and reporting | |
113 | cycles. The PATH contains a list of the currently grey Sections, in the | |
114 | order in which they were encountered; SEEN maps Section names to their | |
115 | indices in the PATH list. | |
116 | ||
117 | It is possible to make this work in the presence of cycles, but it's more | |
118 | effort than it's worth. | |
119 | """ | |
120 | ||
121 | ## Extend the path to include us. This will be useful when reporting | |
122 | ## cycles. | |
123 | if seen is None: seen = {} | |
124 | if path is None: path = [] | |
125 | path.append(me) | |
126 | ||
127 | ## Already been here: nothing to do. | |
128 | if me._visited == me.V_BLACK: | |
129 | pass | |
130 | ||
131 | ## We've found a cycle: report it to the user. | |
132 | elif me._visited == me.V_GREY: | |
133 | raise UserError, 'detected inclusion cycle:\n\t%s' % \ | |
134 | ' -> '.join(["`%s'" % s.name for s in path[seen[me]:]]) | |
135 | ||
136 | ## Not done this one yet: process my included Sections, and compute the | |
137 | ## union of their inferiors. | |
138 | else: | |
139 | seen[me] = len(path) - 1 | |
140 | me._visited = me.V_GREY | |
141 | me.inferiors = set([me]) | |
142 | for s in me.includes: | |
143 | s.transit(seen, path) | |
144 | me.inferiors.update(s.inferiors) | |
145 | me._visited = me.V_BLACK | |
146 | ||
147 | ## Remove myself from the path. | |
148 | path.pop() | |
149 | ||
150 | def inherit(me): | |
151 | """ | |
152 | Compute the inherited properties for this Section. | |
153 | ||
154 | A Section has an inherited property named P if any inferior has a direct | |
155 | property named P. The value of the property is determined as follows. | |
156 | Firstly, determine the set A of all inferiors which have a direct | |
157 | property P. Secondly, determine a /reduced/ set containing only the | |
158 | maximal elements of A: if R contains a pair of distinct inferiors I and J | |
159 | such that I is an inferior of J, then R does not contain I; R contains | |
160 | all elements A not so excluded. If all inferiors in R define the same | |
161 | value for the property, then that is the value of the inherited property; | |
162 | if two inferiors disagree, then the situation is erroneous. | |
163 | ||
164 | Note that if a Section defines a direct property then it has an inherited | |
165 | property with the same value: in this case, the reduced set is a | |
166 | singleton. | |
167 | """ | |
168 | ||
169 | ## First pass: for each property name, determine the reduced set of | |
170 | ## inferiors defining that property, and the values they have for it. | |
171 | ## Here, D maps property names to lists of `prop' records. | |
172 | d = {} | |
173 | for s in me.inferiors: | |
174 | ||
175 | ## Work through the direct properties of inferior S. | |
176 | for k, v in s.iteritems(): | |
177 | ||
178 | ## Ignore `special' properties. | |
179 | if k.startswith('@'): | |
180 | continue | |
181 | ||
182 | ## Work through the current reduced set. Discard entries from | |
183 | ## sections inferior to S. If an entry exists for a section T to | |
184 | ## which S is inferior, then don't add S itself. | |
185 | addp = True | |
186 | pp = [] | |
187 | try: | |
188 | for q in d[k]: | |
189 | if s in q.source.inferiors: | |
190 | addp = False | |
191 | if q.source not in s.inferiors: | |
192 | pp.append(q) | |
193 | except KeyError: | |
194 | pass | |
195 | if addp: | |
196 | pp.append(prop(value = v, source = s)) | |
197 | d[k] = pp | |
198 | ||
199 | ## Second pass: check that the reduced set defines a unique value for | |
200 | ## each inherited property. | |
201 | for k, vv in d.iteritems(): | |
202 | c = {} | |
203 | ||
204 | ## Build in C a dictionary mapping candidate values to lists of | |
205 | ## inferiors asserting those values. | |
206 | for p in vv: | |
207 | c.setdefault(p.value, []).append(p.source) | |
208 | ||
209 | ## Now C should have only one key. If not, C records enough | |
210 | ## information that we can give a useful error report. | |
211 | if len(c) != 1: | |
212 | raise UserError, \ | |
213 | "inconsistent values for property `%s' in section `%s': %s" % \ | |
214 | (k, me.name, | |
215 | ''.join(["\n\t`%s' via %s" % | |
216 | (v, ', '.join(["`%s'" % s.name for s in ss])) | |
217 | for v, ss in c.iteritems()])) | |
218 | ||
219 | ## Insert the computed property value. | |
220 | me.inherited[k] = c.keys()[0] | |
221 | ||
222 | def expand(me, string, seen = None, path = None): | |
223 | """ | |
224 | Expand placeholders in STRING and return the result. | |
225 | ||
226 | A placeholder has the form $PROP or ${PROP} (the latter syntax identifies | |
227 | the property name unambiguously), and is replaced by the value of the | |
228 | (inherited) property named PROP. A token $$ is replaced with a single $. | |
229 | ||
230 | The SEEN and PATH parameters work the same way as in the `transit' | |
231 | method. | |
232 | """ | |
233 | ||
234 | if seen is None: seen = {} | |
235 | if path is None: path = [] | |
236 | ||
237 | ## Prepare stuff for the loop. | |
238 | out = StringIO() | |
239 | left = 0 | |
240 | n = len(string) | |
241 | ||
242 | ## Pick out placeholders and expand them. | |
243 | while True: | |
244 | ||
245 | ## Find a placeholder. | |
246 | dol = string.find('$', left) | |
247 | ||
248 | ## None: commit the rest of the string and we're done. | |
249 | if dol < 0: | |
250 | out.write(string[left:]) | |
251 | break | |
252 | ||
253 | ## Commit the portion before the placeholder. | |
254 | out.write(string[left:dol]) | |
255 | ||
256 | ## Check for a trailing `$'. After this, we can be sure of at least | |
257 | ## one more character. | |
258 | if dol + 1 >= n: | |
259 | prop = '' | |
260 | ||
261 | ## If there's a left brace, find a right brace: the property name is | |
262 | ## between them. | |
263 | elif string[dol + 1] == '{': | |
264 | ace = string.find('}', dol + 2) | |
265 | if ace < 0: | |
266 | raise UserError, \ | |
267 | "invalid placeholder (missing `}') in `%s'" % string | |
268 | prop = string[dol + 2:ace] | |
269 | left = ace + 1 | |
270 | ||
271 | ## If there's a dollar, just commit it and go round again. | |
272 | elif string[dol + 1] == '$': | |
273 | left = dol + 2 | |
274 | out.write('$') | |
275 | continue | |
276 | ||
277 | ## Otherwise take as many constituent characters as we can. | |
278 | else: | |
279 | left = dol + 1 | |
280 | while left < n and (string[left].isalnum() or string[left] in '-_'): | |
281 | left += 1 | |
282 | prop = string[dol + 1:left].replace('-', '_') | |
283 | ||
284 | ## If we came up empty, report an error. | |
285 | if prop == '': | |
286 | raise UserError, \ | |
287 | "invalid placeholder (empty name) in `%s'" % string | |
288 | ||
289 | ## Extend the path: we're going to do a recursive expansion. | |
290 | path.append(prop) | |
291 | ||
292 | ## Report a cycle if we found one. | |
293 | if prop in seen: | |
294 | raise UserError, 'substitution cycle:\n\t%s' % \ | |
295 | (' -> '.join(["`%s'" % p for p in path[seen[prop]:]])) | |
296 | ||
297 | ## Look up the raw value. | |
298 | try: | |
299 | value = me.inherited[prop] | |
300 | except KeyError: | |
301 | raise UserError, "unknown property `%s'" % prop | |
302 | ||
303 | ## Recursively expand, and unwind the PATH and SEEN stuff. | |
304 | seen[prop] = len(path) - 1 | |
305 | out.write(me.expand(value, seen, path)) | |
306 | path.pop() | |
307 | del seen[prop] | |
308 | ||
309 | ## Done: return the accumulated result. | |
310 | return out.getvalue() | |
311 | ||
312 | def link(d): | |
313 | """ | |
314 | Link together the Sections in D according to their inclusions. | |
315 | ||
316 | If a Section S has an `@include' special property, then set S's `includes' | |
317 | slot to be the set of sections named in that property's value. Then | |
318 | compute the inferiors and inherited properties for all of the Sections. | |
319 | """ | |
320 | ||
321 | ## Capture the global section. | |
322 | g = d['@GLOBAL'] | |
323 | ||
324 | ## Walk through all of the sections. | |
325 | for sect in d.itervalues(): | |
326 | ||
327 | ## If this isn't the global section, then add the global section as an | |
328 | ## implicit inclusion. | |
329 | if sect is not g: | |
330 | sect.includes.add(g) | |
331 | ||
332 | ## If there are explicit inclusions, then add them to the included set. | |
333 | try: | |
334 | inc = sect['@include'] | |
335 | except KeyError: | |
336 | pass | |
337 | else: | |
338 | for s in inc.split(): | |
339 | try: | |
340 | sect.includes.add(d[s]) | |
341 | except KeyError: | |
342 | raise UserError, \ | |
343 | "unknown section `%s' included in `%s'" % (s, sect.name) | |
344 | ||
345 | ## Compute the inferiors and inherited properties. | |
346 | for sect in d.itervalues(): | |
347 | sect.transit() | |
348 | for sect in d.itervalues(): | |
349 | sect.inherit() | |
350 | ||
351 | ###-------------------------------------------------------------------------- | |
352 | ### Parsing input files. | |
353 | ||
354 | ## Names of special properties. All of these begin with an `@' sign. | |
355 | SPECIALS = set(['@include']) | |
356 | ||
357 | def parse(filename, d): | |
358 | """ | |
359 | Parse a profile file FILENAME, updating dictionary D. | |
360 | ||
361 | Each entry in the dictionary maps a section name to the section's contents; | |
362 | the contents are in turn represented as a dictionary mapping properties to | |
363 | values. Inter-section references, defaults, and so on are not processed | |
364 | here. | |
365 | """ | |
366 | ||
367 | sect = '@GLOBAL' | |
368 | ||
369 | with open(filename) as f: | |
370 | n = 0 | |
371 | for line in f: | |
372 | n += 1 | |
373 | line = line.strip() | |
374 | if not line or line[0] in ';#': | |
375 | continue | |
376 | if line[0] == '[' and line[-1] == ']': | |
377 | sect = line[1:-1] | |
378 | continue | |
379 | ||
380 | ## Parse an assignment. | |
381 | eq = line.find('=') | |
382 | colon = line.find(':') | |
383 | if eq < 0 or 0 <= colon < eq: eq = colon | |
384 | if eq < 0: raise UserError, '%s:%d: no assignment' % (filename, n) | |
385 | name, value = line[:eq].strip(), line[eq + 1:].strip() | |
386 | ||
387 | ## Check that the name is well-formed. | |
388 | name = name.replace('-', '_') | |
389 | if not (name and | |
390 | (name in SPECIALS or | |
391 | all(map(lambda ch: ch == '_' or ch.isalnum(), name)))): | |
392 | raise UserError, "%s:%d: bad name `%s'" % (filename, n, name) | |
393 | ||
394 | ## Store the assignment. | |
395 | try: | |
396 | d[sect][name] = value | |
397 | except KeyError: | |
398 | s = Section(sect) | |
399 | d[sect] = s | |
400 | s[name] = value | |
401 | ||
402 | ###-------------------------------------------------------------------------- | |
403 | ### Main program. | |
404 | ||
405 | OP = O.OptionParser( | |
406 | usage = '%prog FILE|DIRECTORY ... SECTION', | |
407 | version = '%%prog, version %s' % VERSION, | |
408 | description = '''\ | |
409 | Parse the configurations FILE and DIRECTORY contents, and output the named | |
410 | SECTION as a sequence of simple assignments. | |
411 | ''') | |
412 | ||
413 | def main(args): | |
414 | try: | |
415 | ||
416 | ## Check the arguments. | |
417 | opts, args = OP.parse_args(args[1:]) | |
418 | if len(args) < 2: | |
419 | OP.error('not enough positional parameters') | |
420 | files = args[:-1] | |
421 | sect = args[-1] | |
422 | ||
423 | ## Read in the inputs. | |
424 | d = { '@GLOBAL': Section('@GLOBAL') } | |
425 | for f in files: | |
426 | ||
427 | ## It's a directory: pick out the files contained. | |
428 | if OS.path.isdir(f): | |
429 | for sf in sorted(OS.listdir(f)): | |
430 | if not all(map(lambda ch: ch in '_-' or ch.isalnum(), sf)): | |
431 | continue | |
432 | ff = OS.path.join(f, sf) | |
433 | if not OS.path.isfile(ff): | |
434 | continue | |
435 | parse(ff, d) | |
436 | ||
437 | ## Not a directory: just try to parse it. | |
438 | else: | |
439 | parse(f, d) | |
440 | ||
441 | ## Print the contents. | |
442 | link(d) | |
443 | try: | |
444 | s = d[sect] | |
445 | except KeyError: | |
446 | raise UserError, "unknown section `%s'" % sect | |
447 | for k, v in s.inherited.iteritems(): | |
448 | print '%s=%s' % (k, s.expand(v)) | |
449 | ||
450 | ## Report errors for expected problems. | |
451 | except UserError, e: | |
452 | SYS.stderr.write('%s: %s\n' % (OP.get_prog_name(), e.args[0])) | |
453 | SYS.exit(1) | |
454 | except OSError, e: | |
455 | SYS.stderr.write('%s: %s\n' % (OP.get_prog_name(), e.args[1])) | |
456 | SYS.exit(1) | |
457 | except IOError, e: | |
458 | SYS.stderr.write('%s: %s: %s\n' % | |
459 | (OP.get_prog_name(), e.filename, e.strerror)) | |
460 | SYS.exit(1) | |
461 | ||
462 | if __name__ == '__main__': | |
463 | main(SYS.argv) | |
464 | ||
465 | ###----- That's all, folks -------------------------------------------------- |