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fb55c2fbf3
Previously the added/modified placeholder hash for manifests generated from the dirstate was a 21byte long string consisting of the p1 file hash plus a single character to indicate an add or a modify. Normal hashes are only 20 bytes long. This makes it complicated to implement more efficient manifest implementations which rely on the hashes being fixed length. Let's change this hash to just be 20 bytes long, and rely on the astronomical improbability of an actual hash being these 20 bytes (just like we rely on no hash every being the nullid). This changes the possible behavior slightly in that the hash for all added/modified entries in the dirstate manifest will now be the same (so simple node comparisons would say they are equal), but we should never be doing simple node comparisons on these nodes even with the old hashes, because they did not accurately represent the content (i.e. two files based off the same p1 file node, with different working copy contents would have the same hash (even with the appended character) in the old scheme too, so we couldn't depend on the hashes period).
35 lines
900 B
Python
35 lines
900 B
Python
# node.py - basic nodeid manipulation for mercurial
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#
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# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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from __future__ import absolute_import
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import binascii
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# This ugly style has a noticeable effect in manifest parsing
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hex = binascii.hexlify
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bin = binascii.unhexlify
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nullrev = -1
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nullid = b"\0" * 20
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nullhex = hex(nullid)
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# Phony node value to stand-in for new files in some uses of
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# manifests.
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newnodeid = '!' * 20
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addednodeid = ('0' * 15) + 'added'
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modifiednodeid = ('0' * 12) + 'modified'
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wdirnodes = set((newnodeid, addednodeid, modifiednodeid))
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# pseudo identifiers for working directory
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# (they are experimental, so don't add too many dependencies on them)
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wdirrev = 0x7fffffff
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wdirid = b"\xff" * 20
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def short(node):
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return hex(node[:6])
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