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/* Look up a symbol in a shared object loaded by `dlopen'.
Copyright (C) 1995-2022 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
<https://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <ldsodefs.h>
#include <shlib-compat.h>
#include <stddef.h>
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);
}
static void *
dlsym_implementation (void *handle, const char *name, void *dl_caller)
{
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
void *
___dlsym (void *handle, const char *name)
{
if (!rtld_active ())
return GLRO (dl_dlfcn_hook)->dlsym (handle, name, RETURN_ADDRESS (0));
else
return dlsym_implementation (handle, name, RETURN_ADDRESS (0));
}
versioned_symbol (libc, ___dlsym, dlsym, GLIBC_2_34);
# if OTHER_SHLIB_COMPAT (libdl, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libdl, ___dlsym, dlsym, GLIBC_2_0);
# endif
#else /* !SHARED */
/* Also used with _dlfcn_hook. */
void *
__dlsym (void *handle, const char *name, void *dl_caller)
{
return dlsym_implementation (handle, name, dl_caller);
}
void *
___dlsym (void *handle, const char *name)
{
return __dlsym (handle, name, RETURN_ADDRESS (0));
}
weak_alias (___dlsym, dlsym)
#endif /* !SHARED */
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