dlfcn/dlerror.h

   1 /* Memory management for dlerror messages.
   2    Copyright (C) 2021-2022 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 void __libc_dlerror_result_free (void) attribute_hidden;
  91
  92 #endif /* _DLERROR_H */