bfd/simple.c

   1 /* simple.c -- BFD simple client routines
   2    Copyright (C) 2002-2023 Free Software Foundation, Inc.
   3    Contributed by MontaVista Software, Inc.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #include "sysdep.h"
  23 #include "bfd.h"
  24 #include "libbfd.h"
  25 #include "bfdlink.h"
  26 #include "genlink.h"
  27
  28 static void
  29 simple_dummy_add_to_set (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  30                          struct bfd_link_hash_entry *entry ATTRIBUTE_UNUSED,
  31                          bfd_reloc_code_real_type reloc ATTRIBUTE_UNUSED,
  32                          bfd *abfd ATTRIBUTE_UNUSED,
  33                          asection *sec ATTRIBUTE_UNUSED,
  34                          bfd_vma value ATTRIBUTE_UNUSED)
  35 {
  36 }
  37
  38 static  void
  39 simple_dummy_constructor (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  40                           bool constructor ATTRIBUTE_UNUSED,
  41                           const char *name ATTRIBUTE_UNUSED,
  42                           bfd *abfd ATTRIBUTE_UNUSED,
  43                           asection *sec ATTRIBUTE_UNUSED,
  44                           bfd_vma value ATTRIBUTE_UNUSED)
  45 {
  46 }
  47
  48 static void
  49 simple_dummy_multiple_common (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  50                               struct bfd_link_hash_entry * entry ATTRIBUTE_UNUSED,
  51                               bfd * abfd ATTRIBUTE_UNUSED,
  52                               enum bfd_link_hash_type type ATTRIBUTE_UNUSED,
  53                               bfd_vma size ATTRIBUTE_UNUSED)
  54 {
  55 }
  56
  57 static void
  58 simple_dummy_warning (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  59                       const char *warning ATTRIBUTE_UNUSED,
  60                       const char *symbol ATTRIBUTE_UNUSED,
  61                       bfd *abfd ATTRIBUTE_UNUSED,
  62                       asection *section ATTRIBUTE_UNUSED,
  63                       bfd_vma address ATTRIBUTE_UNUSED)
  64 {
  65 }
  66
  67 static void
  68 simple_dummy_undefined_symbol (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  69                                const char *name ATTRIBUTE_UNUSED,
  70                                bfd *abfd ATTRIBUTE_UNUSED,
  71                                asection *section ATTRIBUTE_UNUSED,
  72                                bfd_vma address ATTRIBUTE_UNUSED,
  73                                bool fatal ATTRIBUTE_UNUSED)
  74 {
  75 }
  76
  77 static void
  78 simple_dummy_reloc_overflow (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  79                              struct bfd_link_hash_entry *entry ATTRIBUTE_UNUSED,
  80                              const char *name ATTRIBUTE_UNUSED,
  81                              const char *reloc_name ATTRIBUTE_UNUSED,
  82                              bfd_vma addend ATTRIBUTE_UNUSED,
  83                              bfd *abfd ATTRIBUTE_UNUSED,
  84                              asection *section ATTRIBUTE_UNUSED,
  85                              bfd_vma address ATTRIBUTE_UNUSED)
  86 {
  87 }
  88
  89 static void
  90 simple_dummy_reloc_dangerous (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  91                               const char *message ATTRIBUTE_UNUSED,
  92                               bfd *abfd ATTRIBUTE_UNUSED,
  93                               asection *section ATTRIBUTE_UNUSED,
  94                               bfd_vma address ATTRIBUTE_UNUSED)
  95 {
  96 }
  97
  98 static void
  99 simple_dummy_unattached_reloc (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
 100                                const char *name ATTRIBUTE_UNUSED,
 101                                bfd *abfd ATTRIBUTE_UNUSED,
 102                                asection *section ATTRIBUTE_UNUSED,
 103                                bfd_vma address ATTRIBUTE_UNUSED)
 104 {
 105 }
 106
 107 static void
 108 simple_dummy_multiple_definition (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
 109                                   struct bfd_link_hash_entry *h ATTRIBUTE_UNUSED,
 110                                   bfd *nbfd ATTRIBUTE_UNUSED,
 111                                   asection *nsec ATTRIBUTE_UNUSED,
 112                                   bfd_vma nval ATTRIBUTE_UNUSED)
 113 {
 114 }
 115
 116 static void
 117 simple_dummy_einfo (const char *fmt ATTRIBUTE_UNUSED, ...)
 118 {
 119 }
 120
 121 struct saved_output_info
 122 {
 123   bfd_vma offset;
 124   asection *section;
 125 };
 126
 127 struct saved_offsets
 128 {
 129   unsigned int section_count;
 130   struct saved_output_info *sections;
 131 };
 132
 133 /* The sections in ABFD may already have output sections and offsets
 134    set if we are here during linking.
 135
 136    DWARF-2 specifies offsets into debug sections in many cases and
 137    bfd_simple_get_relocated_section_contents is called to relocate
 138    debug info for a single relocatable object file.  So we want
 139    offsets relative to that object file's sections, not offsets in the
 140    output file.  For that reason, reset a debug section->output_offset
 141    to zero.
 142
 143    If not called during linking then set section->output_section to
 144    point back to the input section, because output_section must not be
 145    NULL when calling the relocation routines.
 146
 147    Save the original output offset and section to restore later.  */
 148
 149 static void
 150 simple_save_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 151                          asection *section,
 152                          void *ptr)
 153 {
 154   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 155   struct saved_output_info *output_info;
 156
 157   output_info = &saved_offsets->sections[section->index];
 158   output_info->offset = section->output_offset;
 159   output_info->section = section->output_section;
 160   if ((section->flags & SEC_DEBUGGING) != 0
 161       || section->output_section == NULL)
 162     {
 163       section->output_offset = 0;
 164       section->output_section = section;
 165     }
 166 }
 167
 168 static void
 169 simple_restore_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 170                             asection *section,
 171                             void *ptr)
 172 {
 173   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 174   struct saved_output_info *output_info;
 175
 176   if (section->index >= saved_offsets->section_count)
 177     return;
 178
 179   output_info = &saved_offsets->sections[section->index];
 180   section->output_offset = output_info->offset;
 181   section->output_section = output_info->section;
 182 }
 183
 184 /*
 185 FUNCTION
 186         bfd_simple_relocate_secton
 187
 188 SYNOPSIS
 189         bfd_byte *bfd_simple_get_relocated_section_contents
 190           (bfd *abfd, asection *sec, bfd_byte *outbuf, asymbol **symbol_table);
 191
 192 DESCRIPTION
 193         Returns the relocated contents of section @var{sec}.  The symbols in
 194         @var{symbol_table} will be used, or the symbols from @var{abfd} if
 195         @var{symbol_table} is NULL.  The output offsets for debug sections will
 196         be temporarily reset to 0.  The result will be stored at @var{outbuf}
 197         or allocated with @code{bfd_malloc} if @var{outbuf} is @code{NULL}.
 198
 199         Returns @code{NULL} on a fatal error; ignores errors applying
 200         particular relocations.
 201 */
 202
 203 bfd_byte *
 204 bfd_simple_get_relocated_section_contents (bfd *abfd,
 205                                            asection *sec,
 206                                            bfd_byte *outbuf,
 207                                            asymbol **symbol_table)
 208 {
 209   struct bfd_link_info link_info;
 210   struct bfd_link_order link_order;
 211   struct bfd_link_callbacks callbacks;
 212   bfd_byte *contents;
 213   struct saved_offsets saved_offsets;
 214   bfd *link_next;
 215
 216   /* Don't apply relocation on executable and shared library.  See
 217      PR 4756.  */
 218   if ((abfd->flags & (HAS_RELOC | EXEC_P | DYNAMIC)) != HAS_RELOC
 219       || ! (sec->flags & SEC_RELOC))
 220     {
 221       if (!bfd_get_full_section_contents (abfd, sec, &outbuf))
 222         return NULL;
 223       return outbuf;
 224     }
 225
 226   /* In order to use bfd_get_relocated_section_contents, we need
 227      to forge some data structures that it expects.  */
 228
 229   /* Fill in the bare minimum number of fields for our purposes.  */
 230   memset (&link_info, 0, sizeof (link_info));
 231   link_info.output_bfd = abfd;
 232   link_info.input_bfds = abfd;
 233   link_info.input_bfds_tail = &abfd->link.next;
 234
 235   link_next = abfd->link.next;
 236   abfd->link.next = NULL;
 237   link_info.hash = _bfd_generic_link_hash_table_create (abfd);
 238   link_info.callbacks = &callbacks;
 239   /* Make sure that any fields not initialised below do not
 240      result in a potential indirection via a random address.  */
 241   memset (&callbacks, 0, sizeof callbacks);
 242   callbacks.warning = simple_dummy_warning;
 243   callbacks.undefined_symbol = simple_dummy_undefined_symbol;
 244   callbacks.reloc_overflow = simple_dummy_reloc_overflow;
 245   callbacks.reloc_dangerous = simple_dummy_reloc_dangerous;
 246   callbacks.unattached_reloc = simple_dummy_unattached_reloc;
 247   callbacks.multiple_definition = simple_dummy_multiple_definition;
 248   callbacks.einfo = simple_dummy_einfo;
 249   callbacks.multiple_common = simple_dummy_multiple_common;
 250   callbacks.constructor = simple_dummy_constructor;
 251   callbacks.add_to_set = simple_dummy_add_to_set;
 252
 253   memset (&link_order, 0, sizeof (link_order));
 254   link_order.next = NULL;
 255   link_order.type = bfd_indirect_link_order;
 256   link_order.offset = 0;
 257   link_order.size = sec->size;
 258   link_order.u.indirect.section = sec;
 259
 260   contents = NULL;
 261
 262   saved_offsets.section_count = abfd->section_count;
 263   saved_offsets.sections = malloc (sizeof (*saved_offsets.sections)
 264                                    * saved_offsets.section_count);
 265   if (saved_offsets.sections == NULL)
 266     goto out1;
 267   bfd_map_over_sections (abfd, simple_save_output_info, &saved_offsets);
 268
 269   if (symbol_table == NULL)
 270     {
 271       if (!bfd_generic_link_read_symbols (abfd))
 272         goto out2;
 273       symbol_table = _bfd_generic_link_get_symbols (abfd);
 274     }
 275
 276   contents = bfd_get_relocated_section_contents (abfd,
 277                                                  &link_info,
 278                                                  &link_order,
 279                                                  outbuf,
 280                                                  false,
 281                                                  symbol_table);
 282  out2:
 283   bfd_map_over_sections (abfd, simple_restore_output_info, &saved_offsets);
 284   free (saved_offsets.sections);
 285  out1:
 286   _bfd_generic_link_hash_table_free (abfd);
 287   abfd->link.next = link_next;
 288   return contents;
 289 }