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|
# frozen_string_literal: true
require_relative "../vendored_fileutils"
require "rubygems/package"
module Bundler
class CompactIndexClient
# write cache files in a way that is robust to concurrent modifications
# if digests are given, the checksums will be verified
class CacheFile
DEFAULT_FILE_MODE = 0o644
private_constant :DEFAULT_FILE_MODE
class Error < RuntimeError; end
class ClosedError < Error; end
class DigestMismatchError < Error
def initialize(digests, expected_digests)
super "Calculated checksums #{digests.inspect} did not match expected #{expected_digests.inspect}."
end
end
# Initialize with a copy of the original file, then yield the instance.
def self.copy(path, &block)
new(path) do |file|
file.initialize_digests
SharedHelpers.filesystem_access(path, :read) do
path.open("rb") do |s|
file.open {|f| IO.copy_stream(s, f) }
end
end
yield file
end
end
# Write data to a temp file, then replace the original file with it verifying the digests if given.
def self.write(path, data, digests = nil)
return unless data
new(path) do |file|
file.digests = digests
file.write(data)
end
end
attr_reader :original_path, :path
def initialize(original_path, &block)
@original_path = original_path
@perm = original_path.file? ? original_path.stat.mode : DEFAULT_FILE_MODE
@path = original_path.sub(/$/, ".#{$$}.tmp")
return unless block_given?
begin
yield self
ensure
close
end
end
def size
path.size
end
# initialize the digests using CompactIndexClient::SUPPORTED_DIGESTS, or a subset based on keys.
def initialize_digests(keys = nil)
@digests = keys ? SUPPORTED_DIGESTS.slice(*keys) : SUPPORTED_DIGESTS.dup
@digests.transform_values! {|algo_class| SharedHelpers.digest(algo_class).new }
end
# reset the digests so they don't contain any previously read data
def reset_digests
@digests&.each_value(&:reset)
end
# set the digests that will be verified at the end
def digests=(expected_digests)
@expected_digests = expected_digests
if @expected_digests.nil?
@digests = nil
elsif @digests
@digests = @digests.slice(*@expected_digests.keys)
else
initialize_digests(@expected_digests.keys)
end
end
def digests?
@digests&.any?
end
# Open the temp file for writing, reusing original permissions, yielding the IO object.
def open(write_mode = "wb", perm = @perm, &block)
raise ClosedError, "Cannot reopen closed file" if @closed
SharedHelpers.filesystem_access(path, :write) do
path.open(write_mode, perm) do |f|
yield digests? ? Gem::Package::DigestIO.new(f, @digests) : f
end
end
end
# Returns false without appending when no digests since appending is too error prone to do without digests.
def append(data)
return false unless digests?
open("a") {|f| f.write data }
verify && commit
end
def write(data)
reset_digests
open {|f| f.write data }
commit!
end
def commit!
verify || raise(DigestMismatchError.new(@base64digests, @expected_digests))
commit
end
# Verify the digests, returning true on match, false on mismatch.
def verify
return true unless @expected_digests && digests?
@base64digests = @digests.transform_values!(&:base64digest)
@digests = nil
@base64digests.all? {|algo, digest| @expected_digests[algo] == digest }
end
# Replace the original file with the temp file without verifying digests.
# The file is permanently closed.
def commit
raise ClosedError, "Cannot commit closed file" if @closed
SharedHelpers.filesystem_access(original_path, :write) do
FileUtils.mv(path, original_path)
end
@closed = true
end
# Remove the temp file without replacing the original file.
# The file is permanently closed.
def close
return if @closed
FileUtils.remove_file(path) if @path&.file?
@closed = true
end
end
end
end
|
