Mercurial > public > mercurial-scm > hg-stable
comparison mercurial/utils/storageutil.py @ 40325:b0fbd1792e2d
storageutil: extract most of peek_censored from revlog
This function is super hacky and isn't correct 100% of the time. I'm going
to need this functionality on a future non-revlog store.
Let's copy things to storageutil so this code only exists once.
Differential Revision: https://phab.mercurial-scm.org/D5118
| author | Gregory Szorc <gregory.szorc@gmail.com> |
|---|---|
| date | Tue, 16 Oct 2018 15:36:19 +0200 |
| parents | 6994a8be3663 |
| children | 634b45317459 59a870a4ad6e |
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| 40324:6637b079ae45 | 40325:b0fbd1792e2d |
|---|---|
| 7 | 7 |
| 8 from __future__ import absolute_import | 8 from __future__ import absolute_import |
| 9 | 9 |
| 10 import hashlib | 10 import hashlib |
| 11 import re | 11 import re |
| 12 import struct | |
| 12 | 13 |
| 13 from ..i18n import _ | 14 from ..i18n import _ |
| 14 from ..node import ( | 15 from ..node import ( |
| 15 bin, | 16 bin, |
| 16 nullid, | 17 nullid, |
| 447 baserevisionsize=baserevisionsize, | 448 baserevisionsize=baserevisionsize, |
| 448 revision=revision, | 449 revision=revision, |
| 449 delta=delta) | 450 delta=delta) |
| 450 | 451 |
| 451 prevrev = rev | 452 prevrev = rev |
| 453 | |
| 454 def deltaiscensored(delta, baserev, baselenfn): | |
| 455 """Determine if a delta represents censored revision data. | |
| 456 | |
| 457 ``baserev`` is the base revision this delta is encoded against. | |
| 458 ``baselenfn`` is a callable receiving a revision number that resolves the | |
| 459 length of the revision fulltext. | |
| 460 | |
| 461 Returns a bool indicating if the result of the delta represents a censored | |
| 462 revision. | |
| 463 """ | |
| 464 # Fragile heuristic: unless new file meta keys are added alphabetically | |
| 465 # preceding "censored", all censored revisions are prefixed by | |
| 466 # "\1\ncensored:". A delta producing such a censored revision must be a | |
| 467 # full-replacement delta, so we inspect the first and only patch in the | |
| 468 # delta for this prefix. | |
| 469 hlen = struct.calcsize(">lll") | |
| 470 if len(delta) <= hlen: | |
| 471 return False | |
| 472 | |
| 473 oldlen = baselenfn(baserev) | |
| 474 newlen = len(delta) - hlen | |
| 475 if delta[:hlen] != mdiff.replacediffheader(oldlen, newlen): | |
| 476 return False | |
| 477 | |
| 478 add = "\1\ncensored:" | |
| 479 addlen = len(add) | |
| 480 return newlen >= addlen and delta[hlen:hlen + addlen] == add |