64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
/* This file is part of the sample code and exercises
|
|
* used by the class "Advanced Programming in the UNIX
|
|
* Environment" taught by Jan Schaumann
|
|
* <jschauma@netmeister.org> at Stevens Institute of
|
|
* Technology.
|
|
*
|
|
* This file is in the public domain.
|
|
*
|
|
* You don't have to, but if you feel like
|
|
* acknowledging where you got this code, you may
|
|
* reference me by name, email address, or point
|
|
* people to the course website:
|
|
* https://stevens.netmeister.org/631/
|
|
*/
|
|
|
|
/* This program can be used to illustrate that we can load symbols from
|
|
* dynamic libraries at runtime without actually linking against them.
|
|
*
|
|
* Since (some) Linux versions don't use getprogname(3)/setprogname(3), we
|
|
* extract these function definitions from the BSD compatibility library, but
|
|
* unlike in the 'setget' example, we are _not_ linking against the library.
|
|
*
|
|
* Compile with 'cc -Wall -rdynamic dlopenex.c -dl'; compare with 'cc
|
|
* -Wall setget.c -lbsd'.
|
|
*/
|
|
|
|
#include <dlfcn.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
int
|
|
main(int argc, char **argv) {
|
|
void *handle;
|
|
void (*setprogname)(const char *);
|
|
char *(*getprogname)(void);
|
|
char *error;
|
|
|
|
handle = dlopen("libbsd.so", RTLD_LAZY);
|
|
if (!handle) {
|
|
fprintf(stderr, "%s\n", dlerror());
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
(void)dlerror();
|
|
|
|
*(void **) (&setprogname) = dlsym(handle, "setprogname");
|
|
if ((error = dlerror()) != NULL) {
|
|
fprintf(stderr, "%s\n", error);
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
*(void **) (&getprogname) = dlsym(handle, "getprogname");
|
|
if ((error = dlerror()) != NULL) {
|
|
fprintf(stderr, "%s\n", error);
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
|
|
setprogname("dlopenex");
|
|
printf("My name is '%s'.\n", getprogname());
|
|
dlclose(handle);
|
|
exit(EXIT_SUCCESS);
|
|
}
|