Relocation Error

[PBaswat]

Hi,
while compiling a program i am getting relocation error as follows

What is exact cause behind this error????

[PBaswat]

Any update on these?????????????

[ghaith]

Hi @PBaswat,
Since we are an open source project it's not always possible to answer all questions right away.
We also don't have enough information to go on for the problem.
Here are possible ideas on how to better formulate the questions:
https://madelinemiller.dev/blog/open-source-software-support/
https://developer.mozilla.org/en-US/docs/MDN/Community/Open_source_etiquette

[mhasel]

Hi.
Can you give us some more information about what you are trying to compile/link and the commands you used? This error can trigger when the linker expects a shared object (needed for PIC/PIE compilation) but finds a static one instead. In other words, this might be a "file not found" error in disguise.

[PBaswat]

Here i am attaching zip file, which will invoke program from helloWorld.ST.
after extracting if u tried to build sample project using build.sh, it gives relocation error as below

if you comment line no 49 on inProgram.ST,it will build successfull.
Sample.zip
build Command

[ghaith]

I just tried this with the latest version (from master) and I can compile and run normally. I believe the version you are using must have had an issue where it requires all linked objects to be compiled with --pic

[eddkhfjgdkhgkjfbhnfguh]

We have one Program and two function block in our project.

inProgram.ST

   var_global
      ExternalIfval : dint; 
   end_var

program inProgram

   var_temp
      asign1 : dint ;
      asign2 : dint ;
      asign3 : dint ;
   end_var	
 
   var
      fb1 : function_block1; 
      fb2 : function_block2;  
   end_var
   
   if ExternalIfval = 0 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   elsif ExternalIfval = 1 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   elsif ExternalIfval = 2 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   elsif ExternalIfval = 3 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	fb1(I2 := asign1);
   elsif ExternalIfval = 4 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	fb1(I2 := asign1);
   else
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;    
   	fb1();
  end_if;

   fb2(IO2 := asign2, IO1 := asign3);
end_program

function_block1.ST

FUNCTION_BLOCK function_block1

	VAR_INPUT
		I1 : BOOL ;
		I2 : dint := 25;
	END_VAR

	VAR_OUTPUT
		Q2 : dint ;
	END_VAR

	var_temp
		temp_var : dint ;
	end_var

	Q2 := I2 ;
	if I2 = 25 then
        temp_var := I2;
	end_if;
	
END_FUNCTION_BLOCK

function_block2.ST

FUNCTION_BLOCK function_block2

	var_in_out
		IO1 : dint ;
		IO2 : dint ;
	end_var

	VAR_INPUT
		I1 : BOOL ;
	END_VAR

	VAR_OUTPUT
		Q1 : BOOL ;
		Q3 : dint ;
		Q4 : dint ;
	END_VAR

	if IO1 > 4 then
        Q3 := IO1 ;
        Q4 := IO2 ;
	else
        Q3 := IO1 ;
        Q4 := IO2 ;
	end_if;


END_FUNCTION_BLOCK

main.ST

FUNCTION main : DINT
	inProgram();
END_FUNCTION

When we build the above code with

rustyc function_block1.ST function_block2.ST inProgram.ST  main.ST --linker=clang -o Test -L$LD_LIBRARY_PATH -liec61131std 

we get below error

/usr/bin/ld: /tmp/.tmp9msZ5z/Test: relocation R_X86_64_32S against `.rodata' can not be used when making a PIE object; recompile with -fPIE
/usr/bin/ld: failed to set dynamic section sizes: bad value
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: GeneralError { message: "An error occured during linking", err_no: linker__generic_error }

But if we add --pic the above error is removed and binary is generated. But when we run the binary it gives Segmentation fault .

We tried to build the project by removing below lines from inProgram.ST, the project build successfully with out using --pic flag and binary is generated. When we run the binary it also run successfully.

  elsif ExternalIfval = 2 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   elsif ExternalIfval = 3 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	fb1(I2 := asign1);
   elsif ExternalIfval = 4 then
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	fb1(I2 := asign1);
   else
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;
   	asign1 := ExternalIfval + 1;
   	asign2 := ExternalIfval + 2;
   	asign3 := ExternalIfval + 3;    
   	fb1();

But when the same commented code is run with --pic flag the build is successful but while running the binary we get Segmentation fault

Are we doing something wrong ?. Please let us know if more information is required.

Thank You

[ghaith]

Hello, I'll try to reproduce the issue locally but from what i see in the comments I think you are running one of the alphas. (The binray name changed from rustyc to plc). Do you mind trying this on the latest master branch?

[ghaith]

I just tried the code in the example with the newest branch and it does not break. You can download the latest binaries from here:
https://github.com/PLC-lang/rusty/actions/workflows/rust.yml?query=branch%3Amaster by going to the latest build and scrolling down to the Artifacts section

[eddkhfjgdkhgkjfbhnfguh]

Thanks for the help.
We have used a tag v0.2.0 to build the code. Will build with latest code and let you know.

[eddkhfjgdkhgkjfbhnfguh]

With new master branch we are able to build with our code with commenting and without using --pic flag. Output binaries are also running successfully.
But if we use --pic flag to build the code, it build successfully but when running the binary we are still getting Segmentation fault while running the code.

[ghaith]

I'll open an issue with that. By default on master we always use pic. But i'll need to investigate

[mhasel]

edit: moved answer here to the tracking issue #1033