bfd/simple.c

   1 /* simple.c -- BFD simple client routines
   2    Copyright (C) 2002-2020 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
  27 static void
  28 simple_dummy_warning (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  29                       const char *warning ATTRIBUTE_UNUSED,
  30                       const char *symbol ATTRIBUTE_UNUSED,
  31                       bfd *abfd ATTRIBUTE_UNUSED,
  32                       asection *section ATTRIBUTE_UNUSED,
  33                       bfd_vma address ATTRIBUTE_UNUSED)
  34 {
  35 }
  36
  37 static void
  38 simple_dummy_undefined_symbol (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  39                                const char *name ATTRIBUTE_UNUSED,
  40                                bfd *abfd ATTRIBUTE_UNUSED,
  41                                asection *section ATTRIBUTE_UNUSED,
  42                                bfd_vma address ATTRIBUTE_UNUSED,
  43                                bfd_boolean fatal ATTRIBUTE_UNUSED)
  44 {
  45 }
  46
  47 static void
  48 simple_dummy_reloc_overflow (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  49                              struct bfd_link_hash_entry *entry ATTRIBUTE_UNUSED,
  50                              const char *name ATTRIBUTE_UNUSED,
  51                              const char *reloc_name ATTRIBUTE_UNUSED,
  52                              bfd_vma addend ATTRIBUTE_UNUSED,
  53                              bfd *abfd ATTRIBUTE_UNUSED,
  54                              asection *section ATTRIBUTE_UNUSED,
  55                              bfd_vma address ATTRIBUTE_UNUSED)
  56 {
  57 }
  58
  59 static void
  60 simple_dummy_reloc_dangerous (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  61                               const char *message ATTRIBUTE_UNUSED,
  62                               bfd *abfd ATTRIBUTE_UNUSED,
  63                               asection *section ATTRIBUTE_UNUSED,
  64                               bfd_vma address ATTRIBUTE_UNUSED)
  65 {
  66 }
  67
  68 static void
  69 simple_dummy_unattached_reloc (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  70                                const char *name ATTRIBUTE_UNUSED,
  71                                bfd *abfd ATTRIBUTE_UNUSED,
  72                                asection *section ATTRIBUTE_UNUSED,
  73                                bfd_vma address ATTRIBUTE_UNUSED)
  74 {
  75 }
  76
  77 static void
  78 simple_dummy_multiple_definition (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  79                                   struct bfd_link_hash_entry *h ATTRIBUTE_UNUSED,
  80                                   bfd *nbfd ATTRIBUTE_UNUSED,
  81                                   asection *nsec ATTRIBUTE_UNUSED,
  82                                   bfd_vma nval ATTRIBUTE_UNUSED)
  83 {
  84 }
  85
  86 static void
  87 simple_dummy_einfo (const char *fmt ATTRIBUTE_UNUSED, ...)
  88 {
  89 }
  90
  91 struct saved_output_info
  92 {
  93   bfd_vma offset;
  94   asection *section;
  95 };
  96
  97 struct saved_offsets
  98 {
  99   unsigned int section_count;
 100   struct saved_output_info *sections;
 101 };
 102
 103 /* The sections in ABFD may already have output sections and offsets
 104    set if we are here during linking.
 105
 106    DWARF-2 specifies offsets into debug sections in many cases and
 107    bfd_simple_get_relocated_section_contents is called to relocate
 108    debug info for a single relocatable object file.  So we want
 109    offsets relative to that object file's sections, not offsets in the
 110    output file.  For that reason, reset a debug section->output_offset
 111    to zero.
 112
 113    If not called during linking then set section->output_section to
 114    point back to the input section, because output_section must not be
 115    NULL when calling the relocation routines.
 116
 117    Save the original output offset and section to restore later.  */
 118
 119 static void
 120 simple_save_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 121                          asection *section,
 122                          void *ptr)
 123 {
 124   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 125   struct saved_output_info *output_info;
 126
 127   output_info = &saved_offsets->sections[section->index];
 128   output_info->offset = section->output_offset;
 129   output_info->section = section->output_section;
 130   if ((section->flags & SEC_DEBUGGING) != 0
 131       || section->output_section == NULL)
 132     {
 133       section->output_offset = 0;
 134       section->output_section = section;
 135     }
 136 }
 137
 138 static void
 139 simple_restore_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 140                             asection *section,
 141                             void *ptr)
 142 {
 143   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 144   struct saved_output_info *output_info;
 145
 146   if (section->index >= saved_offsets->section_count)
 147     return;
 148
 149   output_info = &saved_offsets->sections[section->index];
 150   section->output_offset = output_info->offset;
 151   section->output_section = output_info->section;
 152 }
 153
 154 /*
 155 FUNCTION
 156         bfd_simple_relocate_secton
 157
 158 SYNOPSIS
 159         bfd_byte *bfd_simple_get_relocated_section_contents
 160           (bfd *abfd, asection *sec, bfd_byte *outbuf, asymbol **symbol_table);
 161
 162 DESCRIPTION
 163         Returns the relocated contents of section @var{sec}.  The symbols in
 164         @var{symbol_table} will be used, or the symbols from @var{abfd} if
 165         @var{symbol_table} is NULL.  The output offsets for debug sections will
 166         be temporarily reset to 0.  The result will be stored at @var{outbuf}
 167         or allocated with @code{bfd_malloc} if @var{outbuf} is @code{NULL}.
 168
 169         Returns @code{NULL} on a fatal error; ignores errors applying
 170         particular relocations.
 171 */
 172
 173 bfd_byte *
 174 bfd_simple_get_relocated_section_contents (bfd *abfd,
 175                                            asection *sec,
 176                                            bfd_byte *outbuf,
 177                                            asymbol **symbol_table)
 178 {
 179   struct bfd_link_info link_info;
 180   struct bfd_link_order link_order;
 181   struct bfd_link_callbacks callbacks;
 182   bfd_byte *contents, *data;
 183   int storage_needed;
 184   struct saved_offsets saved_offsets;
 185   bfd *link_next;
 186
 187   /* Don't apply relocation on executable and shared library.  See
 188      PR 4756.  */
 189   if ((abfd->flags & (HAS_RELOC | EXEC_P | DYNAMIC)) != HAS_RELOC
 190       || ! (sec->flags & SEC_RELOC))
 191     {
 192       contents = outbuf;
 193       if (!bfd_get_full_section_contents (abfd, sec, &contents))
 194         return NULL;
 195       return contents;
 196     }
 197
 198   /* In order to use bfd_get_relocated_section_contents, we need
 199      to forge some data structures that it expects.  */
 200
 201   /* Fill in the bare minimum number of fields for our purposes.  */
 202   memset (&link_info, 0, sizeof (link_info));
 203   link_info.output_bfd = abfd;
 204   link_info.input_bfds = abfd;
 205   link_info.input_bfds_tail = &abfd->link.next;
 206
 207   link_next = abfd->link.next;
 208   abfd->link.next = NULL;
 209   link_info.hash = _bfd_generic_link_hash_table_create (abfd);
 210   link_info.callbacks = &callbacks;
 211   callbacks.warning = simple_dummy_warning;
 212   callbacks.undefined_symbol = simple_dummy_undefined_symbol;
 213   callbacks.reloc_overflow = simple_dummy_reloc_overflow;
 214   callbacks.reloc_dangerous = simple_dummy_reloc_dangerous;
 215   callbacks.unattached_reloc = simple_dummy_unattached_reloc;
 216   callbacks.multiple_definition = simple_dummy_multiple_definition;
 217   callbacks.einfo = simple_dummy_einfo;
 218
 219   memset (&link_order, 0, sizeof (link_order));
 220   link_order.next = NULL;
 221   link_order.type = bfd_indirect_link_order;
 222   link_order.offset = 0;
 223   link_order.size = sec->size;
 224   link_order.u.indirect.section = sec;
 225
 226   data = NULL;
 227   if (outbuf == NULL)
 228     {
 229       bfd_size_type amt = sec->rawsize > sec->size ? sec->rawsize : sec->size;
 230       data = (bfd_byte *) bfd_malloc (amt);
 231       if (data == NULL)
 232         {
 233           _bfd_generic_link_hash_table_free (abfd);
 234           abfd->link.next = link_next;
 235           return NULL;
 236         }
 237       outbuf = data;
 238     }
 239
 240   saved_offsets.section_count = abfd->section_count;
 241   saved_offsets.sections = malloc (sizeof (*saved_offsets.sections)
 242                                    * saved_offsets.section_count);
 243   if (saved_offsets.sections == NULL)
 244     {
 245       free (data);
 246       _bfd_generic_link_hash_table_free (abfd);
 247       abfd->link.next = link_next;
 248       return NULL;
 249     }
 250   bfd_map_over_sections (abfd, simple_save_output_info, &saved_offsets);
 251
 252   if (symbol_table == NULL)
 253     {
 254       _bfd_generic_link_add_symbols (abfd, &link_info);
 255
 256       storage_needed = bfd_get_symtab_upper_bound (abfd);
 257       symbol_table = (asymbol **) bfd_malloc (storage_needed);
 258       bfd_canonicalize_symtab (abfd, symbol_table);
 259     }
 260   else
 261     storage_needed = 0;
 262
 263   contents = bfd_get_relocated_section_contents (abfd,
 264                                                  &link_info,
 265                                                  &link_order,
 266                                                  outbuf,
 267                                                  0,
 268                                                  symbol_table);
 269   if (contents == NULL)
 270     free (data);
 271
 272   bfd_map_over_sections (abfd, simple_restore_output_info, &saved_offsets);
 273   free (saved_offsets.sections);
 274
 275   _bfd_generic_link_hash_table_free (abfd);
 276   abfd->link.next = link_next;
 277   return contents;
 278 }