[delphizip] Re: Memory leak in Inflate.c in Unzip.dll
- From: "James Turner" <james.d.h.turner@xxxxxxxxxxxx>
- To: <delphizip@xxxxxxxxxxxxx>
- Date: Thu, 8 May 2003 20:47:31 +0100
Roger,
I don't have any reference code, but I have included the password checking
code I use in Zipfusion.
I arrived at this solution partially from code analysis and partially from
experimentation using the debugger to watch variables.
James Turner
SKARO.NET
procedure EnterPassword(WND:HWND; Attempts:integer);
{ The file pointer is assumed to be located at the start }
{ of the file data or the 12-byte encryption prefix. }
{ Failure will raise an exception. }
type TCryptBlock = array [0..(SizeOf(TZipCryptKey) div 2) - 1] of Word;
function Decrypt(CryptBlock:TCryptBlock):Boolean;
{ CryptBlock must be passed as a value parameter otherwise the }
{ password has to be entered correctly at the first attempt. }
const InitKey : TZipCryptKey = (305419896,591751049,878082192);
var i : integer;
w : Word;
begin
Result := False; if Password = '' then exit;
CryptKey := InitKey;
for i := 1 to Length(Password) do UpdateCryptKey(byte(Password[i]));
DecryptBuff(@CryptBlock,SizeOf(CryptBlock));
w := CryptBlock[High(CryptBlock)];
with Header do if Flags and 8 = 0 then result := w = HiWord(CRC32)
else result := w = LoWord(FileDate);
end;
var CryptBlock : TCryptBlock;
begin { EnterPassword }
if (Header.Flags and 1) = 0 then exit; { Not password protected }
{ If AutoRun is true, SkipFile should always be called }
if not AutoRun then begin
InfileRead(CryptBlock,SizeOf(CryptBlock));
if Password <> '' then inc(Attempts);
repeat
if Decrypt(CryptBlock) then Exit;
if (Attempts > 0) then begin
dec(Attempts);
case DialogBoxParam(HInstance,'DIALOG_Password',WND,@DP_Password,0)
of
ID_OK : Continue;
ID_No : Break; { Skip button : return false }
ID_Cancel : SkipFile('',sfAbort);
else end;
end
else Break;
until false;
end;
SkipFile(SourceFileName,sfWrongPassword);
end;
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