[squeak-dev] dlopen: I'm stumped
Schwab,Wilhelm K
bschwab at anest.ufl.edu
Fri Apr 2 12:24:18 UTC 2010
Hello all,
Attached is my attempt at calling dlopen() from Pharo, and it is not going well. The C code below works as expected, so the problem has to be either in my code or something in Pharo or the VM itself.
I am fairly certain that loading the attached is safe, but
DynamicLinkingLibrary
getProcAddress:'cos'
from:'libm.so'.
crashes the vm in my experience. Any ideas?
Bill
/*
http://www.unix.com/man-page/All/3/dlopen/
Build as:
gcc -rdynamic -o fubar fubar.c -ldl
*/
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
int
main(int argc, char **argv)
{
void *handle;
double (*cosine)(double);
char *error;
handle = dlopen("libm.so", RTLD_LAZY);
if (!handle) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
dlerror(); /* Clear any existing error */
/* Writing: cosine = (double (*)(double)) dlsym(handle, "cos");
would seem more natural, but the C99 standard leaves
casting from "void *" to a function pointer undefined.
The assignment used below is the POSIX.1-2003 (Technical
Corrigendum 1) workaround; see the Rationale for the
POSIX specification of dlsym(). */
*(void **) (&cosine) = dlsym(handle, "cos");
if ((error = dlerror()) != NULL) {
fprintf(stderr, "%s\n", error);
exit(EXIT_FAILURE);
}
printf("%f\n", (*cosine)(2.0));
dlclose(handle);
exit(EXIT_SUCCESS);
}
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