1 /* simple.c -- BFD simple client routines
2    Copyright (C) 2002-2016 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       if (data)
246 	free (data);
247       _bfd_generic_link_hash_table_free (abfd);
248       abfd->link.next = link_next;
249       return NULL;
250     }
251   bfd_map_over_sections (abfd, simple_save_output_info, &saved_offsets);
252 
253   if (symbol_table == NULL)
254     {
255       _bfd_generic_link_add_symbols (abfd, &link_info);
256 
257       storage_needed = bfd_get_symtab_upper_bound (abfd);
258       symbol_table = (asymbol **) bfd_malloc (storage_needed);
259       bfd_canonicalize_symtab (abfd, symbol_table);
260     }
261   else
262     storage_needed = 0;
263 
264   contents = bfd_get_relocated_section_contents (abfd,
265 						 &link_info,
266 						 &link_order,
267 						 outbuf,
268 						 0,
269 						 symbol_table);
270   if (contents == NULL && data != NULL)
271     free (data);
272 
273   bfd_map_over_sections (abfd, simple_restore_output_info, &saved_offsets);
274   free (saved_offsets.sections);
275 
276   _bfd_generic_link_hash_table_free (abfd);
277   abfd->link.next = link_next;
278   return contents;
279 }
280