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