mORMot Open Source

tbo

Member

Registered: 2015-04-20

Posts: 375

EAccessViolation in function LogHeaderNoRecursion

Delphi 13.0, Windows 64 Bit
Lazarus 4.1, FPC 3.3.1, Windows 64 Bit
mORMot 2, Commit 2.3.12723

The problem arises in unit mormot.core.log. Function SynLogException is called.

procedure SynLogException(const Ctxt: TSynLogExceptionContext);
...
      // minimal exception logging to all other TSynLog files (to ease debug)
      for i := 0 to high(SynLogFamily) do
      begin
        fam := SynLogFamily[i];
        if (fam <> HandleExceptionFamily) and // if not already logged above
           (Ctxt.ELevel in fam.Level) then
        try
          DoLogException(fam.fGlobalLog, Ctxt);
        except

Function DoLogException calls LogHeaderNoRecursion(Log.fWriter, Ctxt.ELevel, @nfo^.CurrentTimeAndThread). Log.fWriter is Nil here. The LogHeaderNoRecursion function looks like this:

 
procedure LogHeaderNoRecursion(WR: TJsonWriter; const Level: TSynLogLevel;
  TimeStampAndThreadNum: PShortString);
  {$ifdef HASINLINE} inline; {$endif}
begin
  WR.AddShort(TimeStampAndThreadNum^);

Here, WR is not checked for Nil and EAccessViolation is triggered. The same behaviour occurs with Lazarus/FPC Windows 64-bit. The call stack shows that it starts via the SynLogVectoredHandler function. Delphi Windows 32-bit runs with the same source code without any problems because this function is not called.

With best regards
Thomas

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 15,226

Website

Re: EAccessViolation in function LogHeaderNoRecursion

How did you define your several TSynLog classes?
I can't reproduce the issue here.

Anyway, it should be better now with:
https://github.com/synopse/mORMot2/commit/2536799c6

Thanks for the feedback!