1  /* Look up a versioned symbol in a shared object loaded by `dlopen'.
       2     Copyright (C) 1995-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <dlfcn.h>
      20  #include <ldsodefs.h>
      21  #include <shlib-compat.h>
      22  #include <stddef.h>
      23  
      24  struct dlvsym_args
      25  {
      26    /* The arguments to dlvsym_doit.  */
      27    void *handle;
      28    const char *name;
      29    const char *version;
      30    void *who;
      31  
      32    /* The return values of dlvsym_doit.  */
      33    void *sym;
      34  };
      35  
      36  static void
      37  dlvsym_doit (void *a)
      38  {
      39    struct dlvsym_args *args = (struct dlvsym_args *) a;
      40  
      41    args->sym = _dl_vsym (args->handle, args->name, args->version, args->who);
      42  }
      43  
      44  static void *
      45  dlvsym_implementation (void *handle, const char *name, const char *version,
      46  		       void *dl_caller)
      47  {
      48    struct dlvsym_args args;
      49    args.who = dl_caller;
      50    args.handle = handle;
      51    args.name = name;
      52    args.version = version;
      53  
      54    /* Protect against concurrent loads and unloads.  */
      55    __rtld_lock_lock_recursive (GL(dl_load_lock));
      56  
      57    void *result = (_dlerror_run (dlvsym_doit, &args) ? NULL : args.sym);
      58  
      59    __rtld_lock_unlock_recursive (GL(dl_load_lock));
      60  
      61    return result;
      62  }
      63  
      64  #ifdef SHARED
      65  void *
      66  ___dlvsym (void *handle, const char *name, const char *version)
      67  {
      68    if (GLRO (dl_dlfcn_hook) != NULL)
      69      return GLRO (dl_dlfcn_hook)->dlvsym (handle, name, version,
      70  					 RETURN_ADDRESS (0));
      71    else
      72      return dlvsym_implementation (handle, name, version, RETURN_ADDRESS (0));
      73  }
      74  versioned_symbol (libc, ___dlvsym, dlvsym, GLIBC_2_34);
      75  
      76  # if OTHER_SHLIB_COMPAT (libdl, GLIBC_2_1, GLIBC_2_34)
      77  compat_symbol (libdl, ___dlvsym, dlvsym, GLIBC_2_1);
      78  # endif
      79  
      80  #else /* !SHARED */
      81  /* Also used with _dlfcn_hook.  */
      82  void *
      83  __dlvsym (void *handle, const char *name, const char *version, void *dl_caller)
      84  {
      85    return dlvsym_implementation (handle, name, version, dl_caller);
      86  }
      87  
      88  void *
      89  ___dlvsym (void *handle, const char *name, const char *version)
      90  {
      91    return __dlvsym (handle, name, version, RETURN_ADDRESS (0));
      92  }
      93  weak_alias (___dlvsym, dlvsym)
      94  #endif /* !SHARED */