bfd/simple.c

   1 /* simple.c -- BFD simple client routines
   2    Copyright (C) 2002-2021 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_add_to_set (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  29                          struct bfd_link_hash_entry *entry ATTRIBUTE_UNUSED,
  30                          bfd_reloc_code_real_type reloc ATTRIBUTE_UNUSED,
  31                          bfd *abfd ATTRIBUTE_UNUSED,
  32                          asection *sec ATTRIBUTE_UNUSED,
  33                          bfd_vma value ATTRIBUTE_UNUSED)
  34 {
  35 }
  36
  37 static  void
  38 simple_dummy_constructor (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  39                           bool constructor ATTRIBUTE_UNUSED,
  40                           const char *name ATTRIBUTE_UNUSED,
  41                           bfd *abfd ATTRIBUTE_UNUSED,
  42                           asection *sec ATTRIBUTE_UNUSED,
  43                           bfd_vma value ATTRIBUTE_UNUSED)
  44 {
  45 }
  46
  47 static void
  48 simple_dummy_multiple_common (struct bfd_link_info * info ATTRIBUTE_UNUSED,
  49                               struct bfd_link_hash_entry * entry ATTRIBUTE_UNUSED,
  50                               bfd * abfd ATTRIBUTE_UNUSED,
  51                               enum bfd_link_hash_type type ATTRIBUTE_UNUSED,
  52                               bfd_vma size ATTRIBUTE_UNUSED)
  53 {
  54 }
  55
  56 static void
  57 simple_dummy_warning (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  58                       const char *warning ATTRIBUTE_UNUSED,
  59                       const char *symbol ATTRIBUTE_UNUSED,
  60                       bfd *abfd ATTRIBUTE_UNUSED,
  61                       asection *section ATTRIBUTE_UNUSED,
  62                       bfd_vma address ATTRIBUTE_UNUSED)
  63 {
  64 }
  65
  66 static void
  67 simple_dummy_undefined_symbol (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  68                                const char *name ATTRIBUTE_UNUSED,
  69                                bfd *abfd ATTRIBUTE_UNUSED,
  70                                asection *section ATTRIBUTE_UNUSED,
  71                                bfd_vma address ATTRIBUTE_UNUSED,
  72                                bool fatal ATTRIBUTE_UNUSED)
  73 {
  74 }
  75
  76 static void
  77 simple_dummy_reloc_overflow (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  78                              struct bfd_link_hash_entry *entry ATTRIBUTE_UNUSED,
  79                              const char *name ATTRIBUTE_UNUSED,
  80                              const char *reloc_name ATTRIBUTE_UNUSED,
  81                              bfd_vma addend ATTRIBUTE_UNUSED,
  82                              bfd *abfd ATTRIBUTE_UNUSED,
  83                              asection *section ATTRIBUTE_UNUSED,
  84                              bfd_vma address ATTRIBUTE_UNUSED)
  85 {
  86 }
  87
  88 static void
  89 simple_dummy_reloc_dangerous (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  90                               const char *message ATTRIBUTE_UNUSED,
  91                               bfd *abfd ATTRIBUTE_UNUSED,
  92                               asection *section ATTRIBUTE_UNUSED,
  93                               bfd_vma address ATTRIBUTE_UNUSED)
  94 {
  95 }
  96
  97 static void
  98 simple_dummy_unattached_reloc (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
  99                                const char *name ATTRIBUTE_UNUSED,
 100                                bfd *abfd ATTRIBUTE_UNUSED,
 101                                asection *section ATTRIBUTE_UNUSED,
 102                                bfd_vma address ATTRIBUTE_UNUSED)
 103 {
 104 }
 105
 106 static void
 107 simple_dummy_multiple_definition (struct bfd_link_info *link_info ATTRIBUTE_UNUSED,
 108                                   struct bfd_link_hash_entry *h ATTRIBUTE_UNUSED,
 109                                   bfd *nbfd ATTRIBUTE_UNUSED,
 110                                   asection *nsec ATTRIBUTE_UNUSED,
 111                                   bfd_vma nval ATTRIBUTE_UNUSED)
 112 {
 113 }
 114
 115 static void
 116 simple_dummy_einfo (const char *fmt ATTRIBUTE_UNUSED, ...)
 117 {
 118 }
 119
 120 struct saved_output_info
 121 {
 122   bfd_vma offset;
 123   asection *section;
 124 };
 125
 126 struct saved_offsets
 127 {
 128   unsigned int section_count;
 129   struct saved_output_info *sections;
 130 };
 131
 132 /* The sections in ABFD may already have output sections and offsets
 133    set if we are here during linking.
 134
 135    DWARF-2 specifies offsets into debug sections in many cases and
 136    bfd_simple_get_relocated_section_contents is called to relocate
 137    debug info for a single relocatable object file.  So we want
 138    offsets relative to that object file's sections, not offsets in the
 139    output file.  For that reason, reset a debug section->output_offset
 140    to zero.
 141
 142    If not called during linking then set section->output_section to
 143    point back to the input section, because output_section must not be
 144    NULL when calling the relocation routines.
 145
 146    Save the original output offset and section to restore later.  */
 147
 148 static void
 149 simple_save_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 150                          asection *section,
 151                          void *ptr)
 152 {
 153   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 154   struct saved_output_info *output_info;
 155
 156   output_info = &saved_offsets->sections[section->index];
 157   output_info->offset = section->output_offset;
 158   output_info->section = section->output_section;
 159   if ((section->flags & SEC_DEBUGGING) != 0
 160       || section->output_section == NULL)
 161     {
 162       section->output_offset = 0;
 163       section->output_section = section;
 164     }
 165 }
 166
 167 static void
 168 simple_restore_output_info (bfd *abfd ATTRIBUTE_UNUSED,
 169                             asection *section,
 170                             void *ptr)
 171 {
 172   struct saved_offsets *saved_offsets = (struct saved_offsets *) ptr;
 173   struct saved_output_info *output_info;
 174
 175   if (section->index >= saved_offsets->section_count)
 176     return;
 177
 178   output_info = &saved_offsets->sections[section->index];
 179   section->output_offset = output_info->offset;
 180   section->output_section = output_info->section;
 181 }
 182
 183 /*
 184 FUNCTION
 185         bfd_simple_relocate_secton
 186
 187 SYNOPSIS
 188         bfd_byte *bfd_simple_get_relocated_section_contents
 189           (bfd *abfd, asection *sec, bfd_byte *outbuf, asymbol **symbol_table);
 190
 191 DESCRIPTION
 192         Returns the relocated contents of section @var{sec}.  The symbols in
 193         @var{symbol_table} will be used, or the symbols from @var{abfd} if
 194         @var{symbol_table} is NULL.  The output offsets for debug sections will
 195         be temporarily reset to 0.  The result will be stored at @var{outbuf}
 196         or allocated with @code{bfd_malloc} if @var{outbuf} is @code{NULL}.
 197
 198         Returns @code{NULL} on a fatal error; ignores errors applying
 199         particular relocations.
 200 */
 201
 202 bfd_byte *
 203 bfd_simple_get_relocated_section_contents (bfd *abfd,
 204                                            asection *sec,
 205                                            bfd_byte *outbuf,
 206                                            asymbol **symbol_table)
 207 {
 208   struct bfd_link_info link_info;
 209   struct bfd_link_order link_order;
 210   struct bfd_link_callbacks callbacks;
 211   bfd_byte *contents, *data;
 212   int storage_needed;
 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       contents = outbuf;
 222       if (!bfd_get_full_section_contents (abfd, sec, &contents))
 223         return NULL;
 224       return contents;
 225     }
 226
 227   /* In order to use bfd_get_relocated_section_contents, we need
 228      to forge some data structures that it expects.  */
 229
 230   /* Fill in the bare minimum number of fields for our purposes.  */
 231   memset (&link_info, 0, sizeof (link_info));
 232   link_info.output_bfd = abfd;
 233   link_info.input_bfds = abfd;
 234   link_info.input_bfds_tail = &abfd->link.next;
 235
 236   link_next = abfd->link.next;
 237   abfd->link.next = NULL;
 238   link_info.hash = _bfd_generic_link_hash_table_create (abfd);
 239   link_info.callbacks = &callbacks;
 240   /* Make sure that any fields not initialised below do not
 241      result in a potential indirection via a random address.  */
 242   memset (&callbacks, 0, sizeof callbacks);
 243   callbacks.warning = simple_dummy_warning;
 244   callbacks.undefined_symbol = simple_dummy_undefined_symbol;
 245   callbacks.reloc_overflow = simple_dummy_reloc_overflow;
 246   callbacks.reloc_dangerous = simple_dummy_reloc_dangerous;
 247   callbacks.unattached_reloc = simple_dummy_unattached_reloc;
 248   callbacks.multiple_definition = simple_dummy_multiple_definition;
 249   callbacks.einfo = simple_dummy_einfo;
 250   callbacks.multiple_common = simple_dummy_multiple_common;
 251   callbacks.constructor = simple_dummy_constructor;
 252   callbacks.add_to_set = simple_dummy_add_to_set;
 253
 254   memset (&link_order, 0, sizeof (link_order));
 255   link_order.next = NULL;
 256   link_order.type = bfd_indirect_link_order;
 257   link_order.offset = 0;
 258   link_order.size = sec->size;
 259   link_order.u.indirect.section = sec;
 260
 261   data = NULL;
 262   if (outbuf == NULL)
 263     {
 264       bfd_size_type amt = sec->rawsize > sec->size ? sec->rawsize : sec->size;
 265       data = (bfd_byte *) bfd_malloc (amt);
 266       if (data == NULL)
 267         {
 268           _bfd_generic_link_hash_table_free (abfd);
 269           abfd->link.next = link_next;
 270           return NULL;
 271         }
 272       outbuf = data;
 273     }
 274
 275   saved_offsets.section_count = abfd->section_count;
 276   saved_offsets.sections = malloc (sizeof (*saved_offsets.sections)
 277                                    * saved_offsets.section_count);
 278   if (saved_offsets.sections == NULL)
 279     {
 280       free (data);
 281       _bfd_generic_link_hash_table_free (abfd);
 282       abfd->link.next = link_next;
 283       return NULL;
 284     }
 285   bfd_map_over_sections (abfd, simple_save_output_info, &saved_offsets);
 286
 287   if (symbol_table == NULL)
 288     {
 289       _bfd_generic_link_add_symbols (abfd, &link_info);
 290
 291       storage_needed = bfd_get_symtab_upper_bound (abfd);
 292       symbol_table = (asymbol **) bfd_malloc (storage_needed);
 293       bfd_canonicalize_symtab (abfd, symbol_table);
 294     }
 295   else
 296     storage_needed = 0;
 297
 298   contents = bfd_get_relocated_section_contents (abfd,
 299                                                  &link_info,
 300                                                  &link_order,
 301                                                  outbuf,
 302                                                  0,
 303                                                  symbol_table);
 304   if (contents == NULL)
 305     free (data);
 306
 307   bfd_map_over_sections (abfd, simple_restore_output_info, &saved_offsets);
 308   free (saved_offsets.sections);
 309
 310   _bfd_generic_link_hash_table_free (abfd);
 311   abfd->link.next = link_next;
 312   return contents;
 313 }