[ruby-core:51747] [ruby-trunk - Feature #7525] How to avoid memory leak when something gets wrong and throw exception when using win32api?

Issue #7525 has been updated by mghomn (Justin Peal).


Thank you for the resource release schema!
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Feature #7525: How to avoid memory leak when something gets wrong and throw exception when using win32api?
https://bugs.ruby-lang.org/issues/7525#change-35711

Author: mghomn (Justin Peal)
Status: Rejected
Priority: Normal
Assignee: usa (Usaku NAKAMURA)
Category: 
Target version: 2.0.0


require 'win32api'

module Crypto
  # Common API
  NULL = 0
  @GetLastError = Win32API.new('kernel32', 'GetLastError', '', 'I')
  @lstrlen = Win32API.new('kernel32', 'lstrlenW', 'L', 'I')

  # Memory API
  @RtlMoveMemory = Win32API.new('kernel32', 'RtlMoveMemory', 'PLL', 'I')
  @LocalFree = Win32API.new('kernel32', 'LocalFree', 'L', 'I')

  # Crypto API
  CRYPTPROTECT_UI_FORBIDDEN = 0x01
  @CryptProtectData = Win32API.new('crypt32', 'CryptProtectData', 'PPPPPLP', 'I')
  @CryptUnprotectData = Win32API.new('crypt32', 'CryptUnprotectData', 'PPPPPLP', 'I')

  def self.error func
    puts "#{func} Error = #{@GetLastError.call()}"
  end

  def self.encrypt str, entropy, desc
    pDataIn = [str.bytesize, str].pack('Lp')
    szDataDescr = (desc + "\0").encode(Encoding::UTF_16LE)
    pOptionalEntropy = [entropy.bytesize, entropy].pack('Lp')
    pvReserved = pPromptStruct = NULL
    dwFlags = CRYPTPROTECT_UI_FORBIDDEN
    pDataOut = [0, ''].pack('Lp')
    return error('CryptProtectData') if @CryptProtectData.call(pDataIn, szDataDescr, pOptionalEntropy, pvReserved, pPromptStruct, dwFlags, pDataOut) == 0
    cbData, pbData = pDataOut.unpack('LL')
    ret = ' '.encode(Encoding::BINARY) * cbData
    return error('RtlMoveMemory') if @RtlMoveMemory.call(ret, pbData, cbData) == 0
    return error('LocalFree') if @LocalFree.call(pbData) != NULL
    ret
  end

  def self.decrypt str, entropy, desc
    pDataIn = [str.bytesize, str].pack('Lp')
    ppszDataDescr = [NULL].pack('L')
    pOptionalEntropy = [entropy.bytesize, entropy].pack('Lp')
    pvReserved = pPromptStruct = NULL
    dwFlags = CRYPTPROTECT_UI_FORBIDDEN
    pDataOut = [0, ''].pack('Lp')
    return error('CryptUnprotectData') if @CryptUnprotectData.call(pDataIn, ppszDataDescr, pOptionalEntropy, pvReserved, pPromptStruct, dwFlags, pDataOut) == 0
    pszDataDescr = ppszDataDescr.unpack('L').first
    szDataDescr = ' '.encode(Encoding::UTF_16LE) * @lstrlen.call(pszDataDescr)
    return error('RtlMoveMemory') if @RtlMoveMemory.call(szDataDescr, pszDataDescr, szDataDescr.bytesize) == 0
    return error('LocalFree') if @LocalFree.call(pszDataDescr) != NULL
    szDataDescr.encode!(Encoding::UTF_8)
    cbData, pbData = pDataOut.unpack('LL')
    ret = ' '.encode(Encoding::BINARY) * cbData
    return error('RtlMoveMemory') if @RtlMoveMemory.call(ret, pbData, cbData) == 0
    return error('LocalFree') if @LocalFree.call(pbData) != NULL
    desc = '' unless desc
    return error('Unmatched description') unless desc == szDataDescr
    ret.force_encoding(Encoding::UTF_8)
  end
end

if $0 == __FILE__
  def test plain, entropy, desc
    puts "plain = #{plain}, entropy = #{entropy}, desc = #{desc}"
    cipher = Crypto.encrypt(plain, entropy, desc)
    puts "cipher = #{cipher.unpack('H*').first}"
    recover = Crypto.decrypt(cipher, entropy, desc)
    puts "recover = #{recover}"
  end

  begin
    test('abcd', 'efgh', 'ijkl')
  rescue
    puts $!.to_s.force_encoding(Encoding::UTF_8), $!.backtrace.join($/)
  end
end


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