Hi to all,

I'm writing a patch to can use an external .dbg file during the debugging process.

All works fine but when an unhandled exception is raised the RTL show stacktrace without debug info (no sources line).

How I can instruct the RTL to search the debug symbols in a project.dbg file (if not found in the executable)?

Write support for it in the lineinfo and lnfodwrf units. You can find those units in fpc\rtl\inc.

Vincent

See http://sourceware.org/gdb/download/onlinedocs/gdb_16.html#SEC154 how to find the external .dbg file from the .gnu_debuglink section.

Note that the build-id support still needs to be added to fpc and thus the crc checksum verification needs to be implemented to verify that the correct .dbg is found. In the final situation both options shall be implemented.

If you are going to implement something first refactor the part that handles the opening and reading of the executable file and can find the position of sections. Most of these routines are already available in lineinfo.pp for multiple platforms. Both lineinfo and lnfodwrf shall use the new unit. Keep also in mind that only routines from the system unit can be used, so no streams from classes unit.

Peter

Hi,

2008/1/17, Vincent Snijders :

These 2 units uses the "f" and "infile" files to read the debug data, but I cannot find the unit that assign these files. Where can I looking for?

See function openstabs in lineinfo:

function OpenStabs:boolean;
var
  ofm : word;
begin
  OpenStabs:=false;
  assign(f,paramstr(0));

and for dwarf in lnfodwarf there is OpenDwarf:

function OpenDwarf() : Boolean;
var
  oldfilemode : Word;
begin
  OpenDwarf := false;
  { open input file }
  assign(infile, paramstr(0));
  {$I-}

Michael.

Hi,

2008/1/17, Michael Van Canneyt :

Thank you very much! :)

I'm working on. ;)

Bogusław Brandys wrote

I think it should by default look for program.dbg file , and then if not exists for paramstr(0). Is that enough ? If so,please explain how to check if file exists , which function could be used here.

No, as Peter described, you should look in the executable for a link to the file with debug info.

Vincent

I think it should by default look for program.dbg file , and then if not exists for paramstr(0). Is that enough ? If so,please explain how to check if file exists , which function could be used here.

Regards
Boguslaw

Moreover, if the debug information is included within the executable file directly, there's probably no need to look for an external file, IMHO, so if the proper link isn't available and we would want to support external files anyway, the preference should be probably the other way round (first paramstr(0), then paramstr(0) with extension changed to .dbg or something like that).

Tomas

I don't agree. We should not support looking implicitly for a .dbg without a gnu_debuglink section. Because there is no garauntee that the .dbg and the .exe will match. The gnu_debuglink is the only reliable way, because it uses a build-id or a checksum verification.

Peter

I see - this is the perfect situation.I thought about fast hack ;-)

Hi,

2008/1/17, Peter Vreman :

I'm sorry but I'm NOT ABLE to create a patch to read and verify the gnu_debuglink section.
I'm ONLY able to search for an external .dbg file (the same of the .exe but simply renamed).

So I think others must write this path, I'm really sorry to cannot help! :(

A voluntary? ;)

I don't think there's a contradiction - I wrote "if ... we would want to support external files". I understand very well that we might not want to support that for reasons you just mentioned.

Tomas