1  /* Macros for using symbol sets for running lists of functions.
       2     Copyright (C) 1994-2023 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 _SET_HOOKS_H
      20  #define _SET_HOOKS_H 1
      21  
      22  #define __need_size_t
      23  #include <stddef.h>
      24  #include <sys/cdefs.h>
      25  #include <libc-symbols.h>
      26  
      27  #include "set-hooks-arch.h"
      28  
      29  #ifdef symbol_set_define
      30  /* Define a hook variable called NAME.  Functions put on this hook take
      31     arguments described by PROTO.  Use `text_set_element (NAME, FUNCTION)'
      32     from include/libc-symbols.h to add a function to the hook.  */
      33  
      34  # define DEFINE_HOOK(NAME, PROTO)		\
      35    typedef void __##NAME##_hook_function_t PROTO; \
      36    symbol_set_define (NAME)
      37  
      38  # define DECLARE_HOOK(NAME, PROTO)		\
      39    typedef void __##NAME##_hook_function_t PROTO;\
      40    symbol_set_declare (NAME)
      41  
      42  /* Run all the functions hooked on the set called NAME.
      43     Each function is called like this: `function ARGS'.  */
      44  
      45  # define RUN_HOOK(NAME, ARGS)						      \
      46  do {									      \
      47    void *const *ptr;						      \
      48    for (ptr = (void *const *) symbol_set_first_element (NAME);		      \
      49         ! symbol_set_end_p (NAME, ptr); ++ptr)				      \
      50      (*(__##NAME##_hook_function_t *) *ptr) ARGS;			      \
      51  } while (0)
      52  
      53  /* Define a hook variable with NAME and PROTO, and a function called RUNNER
      54     which calls each function on the hook in turn, with ARGS.  */
      55  
      56  # define DEFINE_HOOK_RUNNER(name, runner, proto, args) \
      57  DEFINE_HOOK (name, proto); \
      58  extern void runner proto; void runner proto { RUN_HOOK (name, args); }
      59  
      60  # ifdef SET_RELHOOK
      61  /* This is similar to RUN_RELHOOK, but the hooks were registered with
      62   * SET_RELHOOK so that a relative offset was computed by the linker
      63   * rather than an absolute address by the dynamic linker. */
      64  #  define RUN_RELHOOK(NAME, ARGS)				      \
      65  do {								      \
      66    void *const *ptr;						      \
      67    for (ptr = (void *const *) symbol_set_first_element (NAME);	      \
      68         ! symbol_set_end_p (NAME, ptr); ++ptr) {			      \
      69      __##NAME##_hook_function_t *f =				      \
      70  	(void*) ((uintptr_t) ptr + (ptrdiff_t) *ptr);		      \
      71      (*f) ARGS;							      \
      72    } \
      73  } while (0)
      74  # else
      75  #  define SET_RELHOOK(NAME, HOOK) text_set_element (NAME, HOOK)
      76  #  define RUN_RELHOOK(NAME, ARGS) RUN_HOOK(NAME, ARGS)
      77  # endif
      78  
      79  #else
      80  
      81  /* The system does not provide necessary support for this.  */
      82  # define DEFINE_HOOK(NAME, PROTO)
      83  
      84  # define DECLARE_HOOK(NAME, PROTO)
      85  
      86  # define RUN_HOOK(NAME, ARGS)
      87  
      88  # define DEFINE_HOOK_RUNNER(name, runner, proto, args)
      89  
      90  # define SET_RELHOOK(NAME, HOOK)
      91  
      92  # define RUN_RELHOOK(NAME, ARGS)
      93  
      94  #endif
      95  
      96  #endif /* set-hooks.h */