Re: [Tinycc-devel] Problem with libtcc DLL + MEMORY output

[Amaury Bouchard]

Hi all,

So, nobody here ever tried to use TinyCC library to compile some code, then generate a .so/.dll file, then execute this code?

Some help would be really appreciated.

Thank you in advance for your answer.

Amaury

2016-11-21 15:27 GMT+01:00 Amaury Bouchard <address@hidden>:

Hi all,

I have a problem using libtcc. It works perfectly when I want to compile some code on the fly (setting the output type to MEMORY and then fetching a pointer to the desired function); it seems to work fine too when I use it to generate a shared object file (DLL output type).

But when I try to compile some code, then write the .so file, then execute the code on the fly, I get errors at the first call to tcc_relocate().

Here is an example:

<<

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <libtcc.h>

void main(int argc, char **argv)

{

   // the C code that will be compiled

   char *code = "int wrapper() { printf(\"OK\\n\"); }";

   TCCState *state;

   int (*wrapper)(void);

   int size;

   void *memory;

   printf("+ create TCC context\n");

   state = tcc_new();

   printf("+ code compilation\n");

   tcc_compile_string(state, code);

   if (argc == 2)

   {

      printf("+ set output type to DLL\n");

      tcc_set_output_type(state, TCC_OUTPUT_DLL);

      printf("+ write shared object file\n");

      tcc_output_file(state, "demo.so");

   }    

   printf("+ set output type to MEMORY\n");

   tcc_set_output_type(state, TCC_OUTPUT_MEMORY);

   printf("+ phony memory relocation\n");

   size = tcc_relocate(state, NULL);

   if (size == -1)

   {

      printf("+ tcc_relocate() error\n");

      exit(2);  

   }    

   printf("+ destination memory allocation\n");

   memory = malloc(size);

   printf("+ memory relocation\n");

   tcc_relocate(state, memory);

   printf("+ get a pointer to the function\n");

   wrapper = tcc_get_symbol(state, "wrapper");

   printf("+ release the allocated memory\n");

   tcc_delete(state);

   printf("+ execution of the function\n");

   wrapper();

   printf("+ release the memory that contains the binary code\n");

   free(memory);

}

>>

When I execute this program without any parameter (the .so file is not generated), everything is fine. Here is the output:

<<

+ create TCC context

+ code compilation

+ set output type to MEMORY

+ phony memory relocation

+ destination memory allocation

+ memory relocation

+ get a pointer to the function

+ release the allocated memory

+ execution of the function

OK

+ release the memory that contains the binary code

>>

But when I want to generate the .so file and execute the function, I get some errors (and a core dump):

<<

+ create TCC context

+ code compilation

+ set output type to DLL

+ write shared object file

+ set output type to MEMORY

+ phony memory relocation

tcc: error: '_etext' defined twice

tcc: error: '_edata' defined twice

tcc: error: '_end' defined twice

tcc: error: '__preinit_array_start' defined twice

tcc: error: '__preinit_array_end' defined twice

tcc: error: '__init_array_start' defined twice

tcc: error: '__init_array_end' defined twice

tcc: error: '__fini_array_start' defined twice

tcc: error: '__fini_array_end' defined twice

*** Error in `./demo': realloc(): invalid old size: 0x0000000001055220 ***

Abandon (core dumped)

>>

Any idea? What am I doing wrong ?

Best regards,

Amaury