124 lines
4.2 KiB
Ruby
124 lines
4.2 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module EncodingHelper
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extend self
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# This threshold is carefully tweaked to prevent usage of encodings detected
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# by CharlockHolmes with low confidence. If CharlockHolmes confidence is low,
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# we're better off sticking with utf8 encoding.
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# Reason: git diff can return strings with invalid utf8 byte sequences if it
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# truncates a diff in the middle of a multibyte character. In this case
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# CharlockHolmes will try to guess the encoding and will likely suggest an
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# obscure encoding with low confidence.
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# There is a lot more info with this merge request:
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# https://gitlab.com/gitlab-org/gitlab_git/merge_requests/77#note_4754193
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ENCODING_CONFIDENCE_THRESHOLD = 50
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def encode!(message)
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message = force_encode_utf8(message)
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return message if message.valid_encoding?
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# return message if message type is binary
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detect = detect_encoding(message)
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return message.force_encoding("BINARY") if detect_binary?(message, detect)
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if detect && detect[:encoding] && detect[:confidence] > ENCODING_CONFIDENCE_THRESHOLD
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# force detected encoding if we have sufficient confidence.
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message.force_encoding(detect[:encoding])
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end
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# encode and clean the bad chars
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message.replace clean(message)
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rescue ArgumentError => e
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return unless e.message.include?('unknown encoding name')
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encoding = detect ? detect[:encoding] : "unknown"
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"--broken encoding: #{encoding}"
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end
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def detect_encoding(data, limit: CharlockHolmes::EncodingDetector::DEFAULT_BINARY_SCAN_LEN, cache_key: nil)
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return if data.nil?
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if Feature.enabled?(:cached_encoding_detection, type: :development, default_enabled: :yaml)
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return CharlockHolmes::EncodingDetector.new(limit).detect(data) unless cache_key.present?
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Rails.cache.fetch([:detect_binary, CharlockHolmes::VERSION, cache_key], expires_in: 1.week) do
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CharlockHolmes::EncodingDetector.new(limit).detect(data)
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end
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else
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CharlockHolmes::EncodingDetector.new(limit).detect(data)
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end
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end
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def detect_binary?(data, detect = nil)
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detect ||= detect_encoding(data)
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detect && detect[:type] == :binary && detect[:confidence] == 100
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end
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# EncodingDetector checks the first 1024 * 1024 bytes for NUL byte, libgit2 checks
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# only the first 8000 (https://github.com/libgit2/libgit2/blob/2ed855a9e8f9af211e7274021c2264e600c0f86b/src/filter.h#L15),
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# which is what we use below to keep a consistent behavior.
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def detect_libgit2_binary?(data, cache_key: nil)
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detect = detect_encoding(data, limit: 8000, cache_key: cache_key)
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detect && detect[:type] == :binary
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end
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def encode_utf8(message, replace: "")
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message = force_encode_utf8(message)
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return message if message.valid_encoding?
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detect = detect_encoding(message)
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if detect && detect[:encoding]
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begin
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CharlockHolmes::Converter.convert(message, detect[:encoding], 'UTF-8')
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rescue ArgumentError => e
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Gitlab::AppLogger.warn("Ignoring error converting #{detect[:encoding]} into UTF8: #{e.message}")
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''
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end
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else
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clean(message, replace: replace)
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end
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rescue ArgumentError
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nil
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end
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def encode_binary(str)
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return "" if str.nil?
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str.dup.force_encoding(Encoding::ASCII_8BIT)
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end
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def binary_io(str_or_io)
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io = str_or_io.to_io.dup if str_or_io.respond_to?(:to_io)
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io ||= StringIO.new(str_or_io.to_s.freeze)
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io.tap { |io| io.set_encoding(Encoding::ASCII_8BIT) }
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end
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private
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def force_encode_utf8(message)
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raise ArgumentError unless message.respond_to?(:force_encoding)
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return message if message.encoding == Encoding::UTF_8 && message.valid_encoding?
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message = message.dup if message.respond_to?(:frozen?) && message.frozen?
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message.force_encoding("UTF-8")
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end
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def clean(message, replace: "")
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message.encode(
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"UTF-16BE",
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undef: :replace,
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invalid: :replace,
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replace: replace.encode("UTF-16BE")
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)
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.encode("UTF-8")
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.gsub("\0".encode("UTF-8"), "")
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end
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end
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end
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