include/elf/reloc-macros.h

   1 /* Generic relocation support for BFD.
   2    Copyright (C) 1998-2022 Free Software Foundation, Inc.
   3
   4    This file is part of BFD, the Binary File Descriptor library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 /* These macros are used by the various *.h target specific header
  21    files to either generate an enum containing all the known relocations
  22    for that target, or if RELOC_MACROS_GEN_FUNC is defined, a recognition
  23    function is generated instead.  (This is used by binutils/readelf.c)
  24
  25    Given a header file like this:
  26
  27         START_RELOC_NUMBERS (foo)
  28             RELOC_NUMBER (R_foo_NONE,    0)
  29             RELOC_NUMBER (R_foo_32,      1)
  30             EMPTY_RELOC  (R_foo_good)
  31             FAKE_RELOC   (R_foo_illegal, 9)
  32         END_RELOC_NUMBERS (R_foo_count)
  33
  34    Then the following will be produced by default (ie if
  35    RELOC_MACROS_GEN_FUNC is *not* defined).
  36
  37         enum foo
  38         {
  39           R_foo_NONE = 0,
  40           R_foo_32 = 1,
  41           R_foo_good,
  42           R_foo_illegal = 9,
  43           R_foo_count
  44         };
  45
  46    Note: The value of the symbol defined in the END_RELOC_NUMBERS
  47    macro (R_foo_count in the case of the example above) will be
  48    set to the value of the whichever *_RELOC macro precedes it plus
  49    one.  Therefore if you intend to use the symbol as a sentinel for
  50    the highest valid macro value you should make sure that the
  51    preceding *_RELOC macro is the highest valid number.  ie a
  52    declaration like this:
  53
  54         START_RELOC_NUMBERS (foo)
  55             RELOC_NUMBER (R_foo_NONE,    0)
  56             RELOC_NUMBER (R_foo_32,      1)
  57             FAKE_RELOC   (R_foo_illegal, 9)
  58             FAKE_RELOC   (R_foo_synonym, 0)
  59         END_RELOC_NUMBERS (R_foo_count)
  60
  61    will result in R_foo_count having a value of 1 (R_foo_synonym + 1)
  62    rather than 10 or 2 as might be expected.
  63
  64    Alternatively you can assign a value to END_RELOC_NUMBERS symbol
  65    explicitly, like this:
  66
  67         START_RELOC_NUMBERS (foo)
  68             RELOC_NUMBER (R_foo_NONE,    0)
  69             RELOC_NUMBER (R_foo_32,      1)
  70             FAKE_RELOC   (R_foo_illegal, 9)
  71             FAKE_RELOC   (R_foo_synonym, 0)
  72         END_RELOC_NUMBERS (R_foo_count = 2)
  73
  74    If RELOC_MACROS_GEN_FUNC *is* defined, then instead the
  75    following function will be generated:
  76
  77         static const char *foo (unsigned long rtype);
  78         static const char *
  79         foo (unsigned long rtype)
  80         {
  81            switch (rtype)
  82            {
  83            case 0: return "R_foo_NONE";
  84            case 1: return "R_foo_32";
  85            default: return NULL;
  86            }
  87         }
  88    */
  89
  90 #ifndef _RELOC_MACROS_H
  91 #define _RELOC_MACROS_H
  92
  93 #ifdef RELOC_MACROS_GEN_FUNC
  94
  95 /* This function takes the relocation number and returns the
  96    string version name of the name of that relocation.  If
  97    the relocation is not recognised, NULL is returned.  */
  98
  99 #define START_RELOC_NUMBERS(name)                               \
 100 static const char *name (unsigned long rtype);                  \
 101 static const char *                                             \
 102 name (unsigned long rtype)                                      \
 103 {                                                               \
 104   switch (rtype)                                                \
 105     {
 106
 107 #define RELOC_NUMBER(name, number) \
 108     case number: return #name;
 109
 110 #define FAKE_RELOC(name, number)
 111 #define EMPTY_RELOC(name)
 112
 113 #define END_RELOC_NUMBERS(name) \
 114     default: return NULL;       \
 115     }                           \
 116 }
 117
 118
 119 #else /* Default to generating enum.  */
 120
 121 #define START_RELOC_NUMBERS(name)   enum name {
 122 #define RELOC_NUMBER(name, number)  name = number,
 123 #define FAKE_RELOC(name, number)    name = number,
 124 #define EMPTY_RELOC(name)           name,
 125 #define END_RELOC_NUMBERS(name)     name };
 126
 127 #endif
 128
 129 #endif /* _RELOC_MACROS_H */