elf/dlfcn.h

   1 /* User functions for run-time dynamic loading.
   2    Copyright (C) 1995, 1996, 1997, 1998 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #ifndef _DLFCN_H
  21 #define _DLFCN_H 1
  22
  23 #include <features.h>
  24
  25 /* Collect various system dependand definitions and declarations.  */
  26 #include <bits/dlfcn.h>
  27
  28 /* If the first argument of `dlsym' is set to RTLD_NEXT the run-time
  29    address of the symbol called NAME in the next shared object is
  30    returned.  The "next" relation is defined by the order the shared
  31    objects were loaded.  */
  32 #define RTLD_NEXT       ((void *) -1l)
  33
  34 __BEGIN_DECLS
  35
  36 /* Open the shared object FILE and map it in; return a handle that can be
  37    passed to `dlsym' to get symbol values from it.  */
  38 extern void *dlopen __P ((__const char *__file, int __mode));
  39
  40 /* Unmap and close a shared object opened by `dlopen'.
  41    The handle cannot be used again after calling `dlclose'.  */
  42 extern int dlclose __P ((void *__handle));
  43
  44 /* Find the run-time address in the shared object HANDLE refers to
  45    of the symbol called NAME.  */
  46 extern void *dlsym __P ((void *__handle, __const char *__name));
  47
  48 #ifdef __USE_GNU
  49 /* Find the run-time address in the shared object HANDLE refers to
  50    of the symbol called NAME with VERSION.  */
  51 extern void *dlvsym __P ((void *__handle, __const char *__name,
  52                           __const char *__version));
  53 #endif
  54
  55 /* When any of the above functions fails, call this function
  56    to return a string describing the error.  Each call resets
  57    the error string so that a following call returns null.  */
  58 extern char *dlerror __P ((void));
  59
  60 /* Fill in *INFO with the following information about ADDRESS.
  61    Returns 0 iff no shared object's segments contain that address.  */
  62 typedef struct
  63   {
  64     __const char *dli_fname;    /* File name of defining object.  */
  65     void *dli_fbase;            /* Load address of that object.  */
  66     __const char *dli_sname;    /* Name of nearest symbol.  */
  67     void *dli_saddr;            /* Exact value of nearest symbol.  */
  68   } Dl_info;
  69 extern int dladdr __P ((const void *__address, Dl_info *__info));
  70
  71 #ifdef __USE_GNU
  72 /* To support profiling of shared objects it is a good idea to call
  73    the function found using `dlsym' using the following macro since
  74    these calls do not use the PLT.  But this would mean the dynamic
  75    loader has no chance to find out when the function is called.  The
  76    macro applies the necessary magic so that profiling is possible.
  77    Rewrite
  78         foo = (*fctp) (arg1, arg2);
  79    into
  80         foo = DL_CALL_FCT (fctp, (arg1, arg2));
  81 */
  82 # define DL_CALL_FCT(fctp, args) \
  83   (_dl_mcount_wrapper_check (fctp), (*(fctp)) args)
  84
  85 /* This function calls the profiling functions.  */
  86 extern void _dl_mcount_wrapper_check __P ((void *__selfpc));
  87 #endif
  88
  89 __END_DECLS
  90
  91 #endif  /* dlfcn.h */