1  /* Memory management for dlerror messages.
       2     Copyright (C) 2021-2023 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  #ifndef _DLERROR_H
      20  #define _DLERROR_H
      21  
      22  #include <dlfcn.h>
      23  #include <ldsodefs.h>
      24  #include <stdbool.h>
      25  #include <stdint.h>
      26  #include <stdlib.h>
      27  
      28  /* Source of the errstring member in struct dl_action_result, for
      29     finding the right deallocation routine.  */
      30  enum dl_action_result_errstring_source
      31    {
      32     dl_action_result_errstring_constant, /* String literal, no deallocation.  */
      33     dl_action_result_errstring_rtld, /* libc in the primary namespace.  */
      34     dl_action_result_errstring_local, /* libc in the current namespace.  */
      35    };
      36  
      37  struct dl_action_result
      38  {
      39    int errcode;
      40    char errstring_source;
      41    bool returned;
      42    const char *objname;
      43    char *errstring;
      44  };
      45  
      46  /* Used to free the errstring member of struct dl_action_result in the
      47     dl_action_result_errstring_rtld case.  */
      48  static inline void
      49  dl_error_free (void *ptr)
      50  {
      51  #ifdef SHARED
      52    /* In the shared case, ld.so may use a different malloc than this
      53       namespace.  */
      54    GLRO (dl_error_free (ptr));
      55  #else
      56    /* Call the implementation directly.  It still has to check for
      57       pointers which cannot be freed, so do not call free directly
      58       here.  */
      59    _dl_error_free (ptr);
      60  #endif
      61  }
      62  
      63  /* Deallocate RESULT->errstring, leaving *RESULT itself allocated.  */
      64  static inline void
      65  dl_action_result_errstring_free (struct dl_action_result *result)
      66  {
      67    switch (result->errstring_source)
      68      {
      69      case dl_action_result_errstring_constant:
      70        break;
      71      case dl_action_result_errstring_rtld:
      72        dl_error_free (result->errstring);
      73        break;
      74      case dl_action_result_errstring_local:
      75        free (result->errstring);
      76        break;
      77      }
      78  }
      79  
      80  /* Stand-in for an error result object whose allocation failed.  No
      81     precise message can be reported for this, but an error must still
      82     be signaled.  */
      83  static struct dl_action_result *const dl_action_result_malloc_failed
      84    __attribute__ ((unused)) = (struct dl_action_result *) (intptr_t) -1;
      85  
      86  /* Thread-local variable for storing dlfcn failures for subsequent
      87     reporting via dlerror.  */
      88  extern __thread struct dl_action_result *__libc_dlerror_result
      89    attribute_tls_model_ie;
      90  
      91  #endif /* _DLERROR_H */