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glibc/dlfcn/dlsym.c
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/* Look up a symbol in a shared object loaded by `dlopen'. | |
Copyright (C) 1995-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library 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 | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <dlfcn.h> | |
#include <stddef.h> | |
#include <ldsodefs.h> | |
#if !defined SHARED && IS_IN (libdl) | |
void * | |
dlsym (void *handle, const char *name) | |
{ | |
return __dlsym (handle, name, RETURN_ADDRESS (0)); | |
} | |
#else | |
struct dlsym_args | |
{ | |
/* The arguments to dlsym_doit. */ | |
void *handle; | |
const char *name; | |
void *who; | |
/* The return value of dlsym_doit. */ | |
void *sym; | |
}; | |
static void | |
dlsym_doit (void *a) | |
{ | |
struct dlsym_args *args = (struct dlsym_args *) a; | |
args->sym = _dl_sym (args->handle, args->name, args->who); | |
} | |
void * | |
__dlsym (void *handle, const char *name DL_CALLER_DECL) | |
{ | |
# ifdef SHARED | |
if (__glibc_unlikely (_dlfcn_hook != NULL)) | |
return _dlfcn_hook->dlsym (handle, name, DL_CALLER); | |
# endif | |
struct dlsym_args args; | |
args.who = DL_CALLER; | |
args.handle = handle; | |
args.name = name; | |
/* Protect against concurrent loads and unloads. */ | |
__rtld_lock_lock_recursive (GL(dl_load_lock)); | |
void *result = (_dlerror_run (dlsym_doit, &args) ? NULL : args.sym); | |
__rtld_lock_unlock_recursive (GL(dl_load_lock)); | |
return result; | |
} | |
# ifdef SHARED | |
strong_alias (__dlsym, dlsym) | |
# endif | |
#endif |