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06-29-2006
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export-dynamic
I load some dynamic libraries from main module (with dlopen). These libraries use 1 function from main module, therefore in Makefile I must use
gcc -g -Wl,--export-dynamic,-rpath,./lib -o not not.o db.o -ldl -ldb -lpcap Note option --export-dynamic that is passed to the ELF linker. The question is how can I determine which symbols must be put to the dynamic symbol table. I do not want to put all symbols, but putting only used once the function called by dynamically loaded libraries is not visible for these libraries. 
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06-29-2006
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If I understand your question:
dynamic loading means you know the symbol names and the libraries names ahead of time - for the all the entrypoints you are going to map dynamically by calling dlopen yourself... Right? Code:
nm myexcutablefile Am I on track so far?
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06-30-2006
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This is not what I meant
Suppose I have 2 files: main.c, lib.c Function func1() is defined in main.c, and lib.so is loaded from main.c: dlopen("lib.so", RTLD_LAZY) Then func1() is called from lib.c. Becouse of this I need to put all symbols to the dynamic symbol table: gcc -g -Wl,--export-dynamic,-rpath,. -o main main.o -ldl How can put only func1() to the dynamic symbol table (omitting other symbols)?
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06-30-2006
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Sorry. I did not understand.
Since you are in a GNU development environment do you know about libltdl? This allows you to handle what you are doing. See: http://www.gnu.org/software/libtool/...#Using-libltdl If you don't like that - what you have to do in code: do not directly reference the module you want by name, this is how you "hide" it from ld. Example: Code:
#include <stdlib.h>
#include <stdio.h>
#include <dlfcn.h>
int main(int argc, char **argv) {
void *libhandle=NULL;
double (*myfunc)(double);
char *errormsg=NULL;
libhandle = dlopen ("/lib/libwhatever.so.1", RTLD_LAZY);
if (!libhandle) {
fputs (dlerror(), stderr);
exit(EXIT_FAILURE);
}
myfunc = dlsym(libhandle, "myfunction");
if ((errormsg = dlerror()) != NULL) {
fputs(errormsg, stderr);
exit(EXIT_FAILURE);
}
printf ("%f\n", (*myfunc)(1.0));
dlclose(libhandle);
return 0;
}
Again, this is what I think you are saying: you have not "hidden" all the symbols. Correct me if I'm wrong. You can't play mix-n-match, some hidden, some not.
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