Jacek Laskowski

Quote:

unit System.Generics.Defaults;

[...]

function GetHashCode_Class(Inst: PSimpleInstance; const Value: TObject): Integer;
begin
  if Value = nil then
    Result := 42
  else
    Result := Value.GetHashCode;
end;

What is this? Why 42? 🙂

ps. Delphi Tokyo, maybe other too

FastReport is also missing...

1 hour ago, Dmitry Arefiev said:

Do we have a report for this ? 

https://quality.embarcadero.com/browse/RSP-21770

Bug exist in System.Net.HttpClient.Win.pas file. This is not exactly REST Library like I wrote previous, but REST uses this subsystem too.

Bad function with my changes:

function ReadHeader(ARequest: HINTERNET; AHeaderFlag: DWORD; const AHeaderName: string = ''): string;
var
  LSize: Cardinal;
  LFlags: DWORD;
  LHeaderName: PWideChar;
begin
  LFLags := AHeaderFlag;
  if AHeaderName <> '' then
  begin
    LFLags := LFLags or WINHTTP_QUERY_CUSTOM;
    LHeaderName := PWideChar(AHeaderName);
  end
  else
    LHeaderName := WINHTTP_HEADER_NAME_BY_INDEX;

  LSize := 0;
  WinHttpQueryHeaders(ARequest, LFLags, LHeaderName, nil, LSize, WINHTTP_NO_HEADER_INDEX);

  if GetLastError = ERROR_WINHTTP_HEADER_NOT_FOUND then
    Result := ''
  else
  begin
    if GetLastError <> ERROR_INSUFFICIENT_BUFFER then
      raise ENetHTTPException.CreateResFmt(@SNetHttpHeadersError, [GetLastError, SysErrorMessage(GetLastError, TWinHttpLib.Handle)]);

    SetLength(Result, LSize div SizeOf(Char) - 1);
    
    // ----------------------  my changes begin
    if Length(Result) = 0 then
    begin
      SetLength(Result, 1);
    end;
    // ---------------------- my changes end
    
    if WinHttpQueryHeaders(ARequest, LFLags, LHeaderName, PChar(Result), LSize, WINHTTP_NO_HEADER_INDEX) = False then
      raise ENetHTTPException.CreateResFmt(@SNetHttpHeadersError, [GetLastError, SysErrorMessage(GetLastError, TWinHttpLib.Handle)]);
  end;
end;

The problem occurs when a zero-length string (SetLength) is created and passed by the PChar to the WinHttpQueryHeaders() method as Nil.

SetLength(Result, LSize div SizeOf(Char) - 1);  //when LSize = 2 then Result is empty string

I can't reproduce this case now, because I don't have access to that site that caused the error on the hackathon, and on a few other ones that I checked right now, this situation doesn't occur (the header row with 2 characters).

The REST Library in Delphi Rio has a serious error. I was last weekend at the world's largest HackYeah hackathon, where I needed to use the Delphi Rio to connect to the rest service. However, I could not. REST Debbuger did not return any error or response after calling the request (button Send Request). I lost a lot of time on the verification of network connections and the operation of the server itself (I thought that a heavy load on the hackatone participants "killed" the server) but it turned out to be a mistake in the REST Library. When I tried to call the request directly from Delphi (request.Execute ()) I got an error in KERNELBASE. There is no error in Delphi Tokyo, the same code worked there, but on my laptop I only had Rio. So I was looking for a solution. Eventually, I found the place and the reason, corrected RTL file (after copy to project directory) and the code runed, but the bad taste remained.

Later I will publish where the error lies.

Yes, it's good idea!

The code is correct, compiles, but the editor highlights errors 😞

Next example of use inline variable to improve code clarity:

Instead of unclear:

fRecipients := TCollections.CreateList<TRecipient>(True);

we can write:

  fRecipients := TCollections.CreateList<TRecipient>(var OwnsObjects = True);

Based on this thread:

https://stackoverflow.com/questions/29958168/are-integer-reads-atomic-in-delphi

it can be assumed that writing or reading Integer values (4 bytes) does not have to be atomic. It depends on the alignment.
Questions:
Is writing and reading 1 byte (type Byte) always atomic (and safe) operation?

Is writing and reading 2 byte (type Word) always atomic (and safe) operation?