upstream/mercurial-mirror Files · mercurial/cffi/mpatch.py

revlog: enforce chunk slicing down to a certain size...

revlog: enforce chunk slicing down to a certain size Limit maximum chunk size to 4x final size when reading a revision from a revlog. We only apply this logic when the target size is known from the revlog. Ideally, revlog's delta chain would be written in a way that does not trigger this extra slicing often. However, having this second guarantee that we won't read unexpectedly large amounts of memory in all cases is important for the future. Future delta chain building algorithms might have good reason to create delta chain with such characteristics. Including this code in core as soon as possible will make Mercurial 4.7 forward-compatible with such improvement.

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      # mpatch.py - CFFI implementation of mpatch.c

      #

      # Copyright 2016 Maciej Fijalkowski <fijall@gmail.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

      from ..pure.mpatch import *

      from ..pure.mpatch import mpatchError  # silence pyflakes

      from . import _mpatch

      ffi = _mpatch.ffi

      lib = _mpatch.lib

      @ffi.def_extern()

      def cffi_get_next_item(arg, pos):

          all, bins = ffi.from_handle(arg)

          container = ffi.new("struct mpatch_flist*[1]")

          to_pass = ffi.new("char[]", str(bins[pos]))

          all.append(to_pass)

          r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)

          if r < 0:

              return ffi.NULL

          return container[0]

      def patches(text, bins):

          lgt = len(bins)

          all = []

          if not lgt:

              return text

          arg = (all, bins)

          patch = lib.mpatch_fold(ffi.new_handle(arg),

                                  lib.cffi_get_next_item, 0, lgt)

          if not patch:

              raise mpatchError("cannot decode chunk")

          outlen = lib.mpatch_calcsize(len(text), patch)

          if outlen < 0:

              lib.mpatch_lfree(patch)

              raise mpatchError("inconsistency detected")

          buf = ffi.new("char[]", outlen)

          if lib.mpatch_apply(buf, text, len(text), patch) < 0:

              lib.mpatch_lfree(patch)

              raise mpatchError("error applying patches")

          res = ffi.buffer(buf, outlen)[:]

          lib.mpatch_lfree(patch)

          return res

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				# mpatch.py - CFFI implementation of mpatch.c
				#
				# Copyright 2016 Maciej Fijalkowski <fijall@gmail.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

				from ..pure.mpatch import *
				from ..pure.mpatch import mpatchError # silence pyflakes
				from . import _mpatch

				ffi = _mpatch.ffi
				lib = _mpatch.lib

				@ffi.def_extern()
				def cffi_get_next_item(arg, pos):
				all, bins = ffi.from_handle(arg)
				container = ffi.new("struct mpatch_flist*[1]")
				to_pass = ffi.new("char[]", str(bins[pos]))
				all.append(to_pass)
				r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)
				if r < 0:
				return ffi.NULL
				return container[0]

				def patches(text, bins):
				lgt = len(bins)
				all = []
				if not lgt:
				return text
				arg = (all, bins)
				patch = lib.mpatch_fold(ffi.new_handle(arg),
				lib.cffi_get_next_item, 0, lgt)
				if not patch:
				raise mpatchError("cannot decode chunk")
				outlen = lib.mpatch_calcsize(len(text), patch)
				if outlen < 0:
				lib.mpatch_lfree(patch)
				raise mpatchError("inconsistency detected")
				buf = ffi.new("char[]", outlen)
				if lib.mpatch_apply(buf, text, len(text), patch) < 0:
				lib.mpatch_lfree(patch)
				raise mpatchError("error applying patches")
				res = ffi.buffer(buf, outlen)[:]
				lib.mpatch_lfree(patch)
				return res