How to intercept Java_java_lang_ClassLoader_defineClass0 from libjava.so?

Question

linux

Good afternoon. I am researching Linux and Java for general development for the future.
I read that you can use LD_PRELOADit to intercept dynamically linked functions, you just need to export them in your library and connect it with LD_PRELOAD. And then whoever first declares the function, "that and slippers."
Decided to replace the functions Java_java_lang_ClassLoader_defineClass0, Java_java_lang_ClassLoader_defineClass1, Java_java_lang_ClassLoader_defineClass2from libjava.so. The choice is made in order to further decrypt encrypted resources. I ask you to leave this goal out of the discussion.
Well. Wrote "Hello world" in Java from three classes and one resource. Checking:

#java -cp . Main
Hello world

I am writing a library. Since I'm somewhat fluent in C++, I decided to write in FreePascal:

library run;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes
  { you can add units after this };

procedure Java_java_lang_ClassLoader_defineClass0; cdecl; export;
begin
  Writeln('LibRun Java_java_lang_ClassLoader_defineClass0');
end;

procedure Java_java_lang_ClassLoader_defineClass1; cdecl; export;
begin
  Writeln('LibRun Java_java_lang_ClassLoader_defineClass1');
end;

procedure Java_java_lang_ClassLoader_defineClass2; cdecl; export;
begin
  Writeln('LibRun Java_java_lang_ClassLoader_defineClass2');
end;

exports
  Java_java_lang_ClassLoader_defineClass0,
  Java_java_lang_ClassLoader_defineClass1,
  Java_java_lang_ClassLoader_defineClass2;

initialization
  Writeln('LibRun loaded');
finalization
  Writeln('LibRun unloaded');
end.

I expect to see one of the messages LibRun Java_java_lang_ClassLoader_defineClass*, and then an error, because my implementations do nothing.
I run:

#LD_PRELOAD=/path/to/lib/librun.so java -cp . Main
LibRun loaded
Hello world
LibRun unloaded

As you can see, the library was connected, but the interception did not happen.
The question is what's wrong?

Answer 1

Java loads these files via dlopenand dlsym, so it is not intercepted.
It needs to be intercepted dlsym.

Answer 2

I read that using LD_PRELOAD you can intercept dynamically linked functions, you just need to export them in your library and connect it using LD_PRELOAD. And then whoever first declares the function, "that and slippers."

If it were that easy, why would you need MSHookFunction (Cydia)?

Answer 3

Because in the css file the path comes from the css file, there is no fonts folder in the css folder ---- specify the full path with the domain or ../

Answer 4

you do not have these fonts in the fonts folder!
you need what was this
and you only have this:

Answer 5

As a result, I connected it through Google fonts and it all worked.