/*
* Helper header for LD_PRELOAD related headers macros. Must be loaded _first_
* (for RTLD_NEXT)!
*
* Copyright (C) 2012-2013 Simon Ruderich
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
#ifndef LDPRELOAD_H
#define LDPRELOAD_H 1
/* Necessary for RTLD_NEXT. */
#define _GNU_SOURCE
/* abort() */
#include
/* dlsym() */
#include
#include
static void *dlsym_function(char const *name) noinline;
/* Load the function name using dlsym() and return it. Terminate program on
* failure. Split in function and macro to reduce code inserted into the
* function using the macro. */
static void *dlsym_function(char const *name) {
void *result;
int saved_errno = errno; /* just in case */
/* Clear possibly existing error. */
dlerror();
result = dlsym(RTLD_NEXT, name);
/* Not much we can do. Most likely the other output functions failed to
* load too. */
if (dlerror() != NULL) {
abort();
}
errno = saved_errno;
return result;
}
#define DLSYM_FUNCTION(pointer, name) \
if (unlikely(!(pointer))) { \
*(void **) (&(pointer)) = dlsym_function(name); \
}
#endif