upstream/mercurial-mirror Files · mercurial/pure/base85.py

merge: fix race that could cause wrong size in dirstate...

merge: fix race that could cause wrong size in dirstate The problem is that hg merge/update/etc work the following way: 1. figure out what files to update 2. apply the update to disk 3. apply the update to in-memory dirstate 4. write dirstate where step3 looks at the filesystem and assumes it sees the result of step2. If a file is changed between step2 and step3, step3 will record incorrect information in the dirstate. I avoid this by passing the size step3 needs directly from step2, for the common path (not implemented for change/delete conflicts for instance). I didn't fix the same race for the exec bit for now, because it's less likely to be problematic and I had trouble due to the fact that the dirstate stores the permissions differently from the manifest (st_mode vs '' 'l' 'x'), in combination with tests that pretend that symlinks are not supported. However, I moved the lstat from step3 to step2, which should tighten the race window markedly, both for the exec bit and for the mtime. Differential Revision: https://phab.mercurial-scm.org/D6475

Pulkit Goyal - - Load All Authors

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             base85.py
        
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      # base85.py: pure python base85 codec

      #

      # Copyright (C) 2009 Brendan Cully <brendan@kublai.com>

      #

      # This software may be used and distributed according to the terms of the

      # GNU General Public License version 2 or any later version.

      from __future__ import absolute_import

      import struct

      from .. import pycompat

      _b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef"

                                   "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")

      _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]

      _b85dec = {}

      def _mkb85dec():

          for i, c in enumerate(_b85chars):

              _b85dec[c] = i

      def b85encode(text, pad=False):

          """encode text in base85 format"""

          l = len(text)

          r = l % 4

          if r:

              text += '\0' * (4 - r)

          longs = len(text) >> 2

          words = struct.unpack('>%dL' % (longs), text)

          out = ''.join(_b85chars[(word // 52200625) % 85] +

                        _b85chars2[(word // 7225) % 7225] +

                        _b85chars2[word % 7225]

                        for word in words)

          if pad:

              return out

          # Trim padding

          olen = l % 4

          if olen:

              olen += 1

          olen += l // 4 * 5

          return out[:olen]

      def b85decode(text):

          """decode base85-encoded text"""

          if not _b85dec:

              _mkb85dec()

          l = len(text)

          out = []

          for i in range(0, len(text), 5):

              chunk = text[i:i + 5]

              chunk = pycompat.bytestr(chunk)

              acc = 0

              for j, c in enumerate(chunk):

                  try:

                      acc = acc * 85 + _b85dec[c]

                  except KeyError:

                      raise ValueError('bad base85 character at position %d'

                                       % (i + j))

              if acc > 4294967295:

                  raise ValueError('Base85 overflow in hunk starting at byte %d' % i)

              out.append(acc)

          # Pad final chunk if necessary

          cl = l % 5

          if cl:

              acc *= 85 ** (5 - cl)

              if cl > 1:

                  acc += 0xffffff >> (cl - 2) * 8

              out[-1] = acc

          out = struct.pack('>%dL' % (len(out)), *out)

          if cl:

              out = out[:-(5 - cl)]

          return out

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				# base85.py: pure python base85 codec
				#
				# Copyright (C) 2009 Brendan Cully <brendan@kublai.com>
				#
				# This software may be used and distributed according to the terms of the
				# GNU General Public License version 2 or any later version.

				from __future__ import absolute_import

				import struct

				from .. import pycompat

				_b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef"
				"ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{\|}~")
				_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
				_b85dec = {}

				def _mkb85dec():
				for i, c in enumerate(_b85chars):
				_b85dec[c] = i

				def b85encode(text, pad=False):
				"""encode text in base85 format"""
				l = len(text)
				r = l % 4
				if r:
				text += '\0' * (4 - r)
				longs = len(text) >> 2
				words = struct.unpack('>%dL' % (longs), text)

				out = ''.join(_b85chars[(word // 52200625) % 85] +
				_b85chars2[(word // 7225) % 7225] +
				_b85chars2[word % 7225]
				for word in words)

				if pad:
				return out

				# Trim padding
				olen = l % 4
				if olen:
				olen += 1
				olen += l // 4 * 5
				return out[:olen]

				def b85decode(text):
				"""decode base85-encoded text"""
				if not _b85dec:
				_mkb85dec()

				l = len(text)
				out = []
				for i in range(0, len(text), 5):
				chunk = text[i:i + 5]
				chunk = pycompat.bytestr(chunk)
				acc = 0
				for j, c in enumerate(chunk):
				try:
				acc = acc * 85 + _b85dec[c]
				except KeyError:
				raise ValueError('bad base85 character at position %d'
				% (i + j))
				if acc > 4294967295:
				raise ValueError('Base85 overflow in hunk starting at byte %d' % i)
				out.append(acc)

				# Pad final chunk if necessary
				cl = l % 5
				if cl:
				acc = 85 * (5 - cl)
				if cl > 1:
				acc += 0xffffff >> (cl - 2) * 8
				out[-1] = acc

				out = struct.pack('>%dL' % (len(out)), *out)
				if cl:
				out = out[:-(5 - cl)]

				return out