1 /* BFD back-end for binary objects.
2 Copyright (C) 1994-2023 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Cygnus Support, <ian@cygnus.com>
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 /* This is a BFD backend which may be used to read or write binary
23 objects. Historically, it was used as an output format for objcopy
24 in order to generate raw binary data, but is now used for other
25 purposes as well.
26
27 This is very simple. The only complication is that the real data
28 will start at some address X, and in some cases we will not want to
29 include X zeroes just to get to that point. Since the start
30 address is not meaningful for this object file format, we use it
31 instead to indicate the number of zeroes to skip at the start of
32 the file. objcopy cooperates by specially setting the start
33 address to zero by default. */
34
35 #include "sysdep.h"
36 #include "bfd.h"
37 #include "safe-ctype.h"
38 #include "libbfd.h"
39
40 /* Any bfd we create by reading a binary file has three symbols:
41 a start symbol, an end symbol, and an absolute length symbol. */
42 #define BIN_SYMS 3
43
44 /* Create a binary object. Invoked via bfd_set_format. */
45
46 static bool
47 binary_mkobject (bfd *abfd ATTRIBUTE_UNUSED)
48 {
49 return true;
50 }
51
52 /* Any file may be considered to be a binary file, provided the target
53 was not defaulted. That is, it must be explicitly specified as
54 being binary. */
55
56 static bfd_cleanup
57 binary_object_p (bfd *abfd)
58 {
59 struct stat statbuf;
60 asection *sec;
61 flagword flags;
62
63 if (abfd->target_defaulted)
64 {
65 bfd_set_error (bfd_error_wrong_format);
66 return NULL;
67 }
68
69 abfd->symcount = BIN_SYMS;
70
71 /* Find the file size. */
72 if (bfd_stat (abfd, &statbuf) < 0)
73 {
74 bfd_set_error (bfd_error_system_call);
75 return NULL;
76 }
77
78 /* One data section. */
79 flags = SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_HAS_CONTENTS;
80 sec = bfd_make_section_with_flags (abfd, ".data", flags);
81 if (sec == NULL)
82 return NULL;
83 sec->vma = 0;
84 sec->size = statbuf.st_size;
85 sec->filepos = 0;
86
87 abfd->tdata.any = (void *) sec;
88
89 return _bfd_no_cleanup;
90 }
91
92 #define binary_close_and_cleanup _bfd_generic_close_and_cleanup
93 #define binary_bfd_free_cached_info _bfd_generic_bfd_free_cached_info
94 #define binary_new_section_hook _bfd_generic_new_section_hook
95
96 /* Get contents of the only section. */
97
98 static bool
99 binary_get_section_contents (bfd *abfd,
100 asection *section,
101 void * location,
102 file_ptr offset,
103 bfd_size_type count)
104 {
105 if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0
106 || bfd_bread (location, count, abfd) != count)
107 return false;
108 return true;
109 }
110
111 /* Return the amount of memory needed to read the symbol table. */
112
113 static long
114 binary_get_symtab_upper_bound (bfd *abfd ATTRIBUTE_UNUSED)
115 {
116 return (BIN_SYMS + 1) * sizeof (asymbol *);
117 }
118
119 /* Create a symbol name based on the bfd's filename. */
120
121 static char *
122 mangle_name (bfd *abfd, char *suffix)
123 {
124 bfd_size_type size;
125 char *buf;
126 char *p;
127
128 size = (strlen (bfd_get_filename (abfd))
129 + strlen (suffix)
130 + sizeof "_binary__");
131
132 buf = (char *) bfd_alloc (abfd, size);
133 if (buf == NULL)
134 return "";
135
136 sprintf (buf, "_binary_%s_%s", bfd_get_filename (abfd), suffix);
137
138 /* Change any non-alphanumeric characters to underscores. */
139 for (p = buf; *p; p++)
140 if (! ISALNUM (*p))
141 *p = '_';
142
143 return buf;
144 }
145
146 /* Return the symbol table. */
147
148 static long
149 binary_canonicalize_symtab (bfd *abfd, asymbol **alocation)
150 {
151 asection *sec = (asection *) abfd->tdata.any;
152 asymbol *syms;
153 unsigned int i;
154 size_t amt = BIN_SYMS * sizeof (asymbol);
155
156 syms = (asymbol *) bfd_alloc (abfd, amt);
157 if (syms == NULL)
158 return -1;
159
160 /* Start symbol. */
161 syms[0].the_bfd = abfd;
162 syms[0].name = mangle_name (abfd, "start");
163 syms[0].value = 0;
164 syms[0].flags = BSF_GLOBAL;
165 syms[0].section = sec;
166 syms[0].udata.p = NULL;
167
168 /* End symbol. */
169 syms[1].the_bfd = abfd;
170 syms[1].name = mangle_name (abfd, "end");
171 syms[1].value = sec->size;
172 syms[1].flags = BSF_GLOBAL;
173 syms[1].section = sec;
174 syms[1].udata.p = NULL;
175
176 /* Size symbol. */
177 syms[2].the_bfd = abfd;
178 syms[2].name = mangle_name (abfd, "size");
179 syms[2].value = sec->size;
180 syms[2].flags = BSF_GLOBAL;
181 syms[2].section = bfd_abs_section_ptr;
182 syms[2].udata.p = NULL;
183
184 for (i = 0; i < BIN_SYMS; i++)
185 *alocation++ = syms++;
186 *alocation = NULL;
187
188 return BIN_SYMS;
189 }
190
191 #define binary_make_empty_symbol _bfd_generic_make_empty_symbol
192 #define binary_print_symbol _bfd_nosymbols_print_symbol
193 #define binary_get_symbol_version_string \
194 _bfd_nosymbols_get_symbol_version_string
195
196 /* Get information about a symbol. */
197
198 static void
199 binary_get_symbol_info (bfd *ignore_abfd ATTRIBUTE_UNUSED,
200 asymbol *symbol,
201 symbol_info *ret)
202 {
203 bfd_symbol_info (symbol, ret);
204 }
205
206 #define binary_bfd_is_local_label_name bfd_generic_is_local_label_name
207 #define binary_get_lineno _bfd_nosymbols_get_lineno
208 #define binary_find_nearest_line _bfd_nosymbols_find_nearest_line
209 #define binary_find_nearest_line_with_alt _bfd_nosymbols_find_nearest_line_with_alt
210 #define binary_find_line _bfd_nosymbols_find_line
211 #define binary_find_inliner_info _bfd_nosymbols_find_inliner_info
212 #define binary_bfd_make_debug_symbol _bfd_nosymbols_bfd_make_debug_symbol
213 #define binary_read_minisymbols _bfd_generic_read_minisymbols
214 #define binary_minisymbol_to_symbol _bfd_generic_minisymbol_to_symbol
215 #define binary_bfd_is_target_special_symbol _bfd_bool_bfd_asymbol_false
216
217 /* Set the architecture of a binary file. */
218 #define binary_set_arch_mach _bfd_generic_set_arch_mach
219
220 /* Write section contents of a binary file. */
221
222 static bool
223 binary_set_section_contents (bfd *abfd,
224 asection *sec,
225 const void * data,
226 file_ptr offset,
227 bfd_size_type size)
228 {
229 if (size == 0)
230 return true;
231
232 if (! abfd->output_has_begun)
233 {
234 bool found_low;
235 bfd_vma low;
236 asection *s;
237
238 /* The lowest section LMA sets the virtual address of the start
239 of the file. We use this to set the file position of all the
240 sections. */
241 found_low = false;
242 low = 0;
243 for (s = abfd->sections; s != NULL; s = s->next)
244 if (((s->flags
245 & (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC | SEC_NEVER_LOAD))
246 == (SEC_HAS_CONTENTS | SEC_LOAD | SEC_ALLOC))
247 && (s->size > 0)
248 && (! found_low || s->lma < low))
249 {
250 low = s->lma;
251 found_low = true;
252 }
253
254 for (s = abfd->sections; s != NULL; s = s->next)
255 {
256 unsigned int opb = bfd_octets_per_byte (abfd, s);
257
258 s->filepos = (s->lma - low) * opb;
259
260 /* Skip following warning check for sections that will not
261 occupy file space. */
262 if ((s->flags
263 & (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_NEVER_LOAD))
264 != (SEC_HAS_CONTENTS | SEC_ALLOC)
265 || (s->size == 0))
266 continue;
267
268 /* If attempting to generate a binary file from a bfd with
269 LMA's all over the place, huge (sparse?) binary files may
270 result. This condition attempts to detect this situation
271 and print a warning. Better heuristics would be nice to
272 have. */
273
274 if (s->filepos < 0)
275 _bfd_error_handler
276 /* xgettext:c-format */
277 (_("warning: writing section `%pA' at huge (ie negative) "
278 "file offset"),
279 s);
280 }
281
282 abfd->output_has_begun = true;
283 }
284
285 /* We don't want to output anything for a section that is neither
286 loaded nor allocated. The contents of such a section are not
287 meaningful in the binary format. */
288 if ((sec->flags & (SEC_LOAD | SEC_ALLOC)) == 0)
289 return true;
290 if ((sec->flags & SEC_NEVER_LOAD) != 0)
291 return true;
292
293 return _bfd_generic_set_section_contents (abfd, sec, data, offset, size);
294 }
295
296 /* No space is required for header information. */
297
298 static int
299 binary_sizeof_headers (bfd *abfd ATTRIBUTE_UNUSED,
300 struct bfd_link_info *info ATTRIBUTE_UNUSED)
301 {
302 return 0;
303 }
304
305 #define binary_bfd_get_relocated_section_contents bfd_generic_get_relocated_section_contents
306 #define binary_bfd_relax_section bfd_generic_relax_section
307 #define binary_bfd_gc_sections bfd_generic_gc_sections
308 #define binary_bfd_lookup_section_flags bfd_generic_lookup_section_flags
309 #define binary_bfd_merge_sections bfd_generic_merge_sections
310 #define binary_bfd_is_group_section bfd_generic_is_group_section
311 #define binary_bfd_group_name bfd_generic_group_name
312 #define binary_bfd_discard_group bfd_generic_discard_group
313 #define binary_section_already_linked _bfd_generic_section_already_linked
314 #define binary_bfd_define_common_symbol bfd_generic_define_common_symbol
315 #define binary_bfd_link_hide_symbol _bfd_generic_link_hide_symbol
316 #define binary_bfd_define_start_stop bfd_generic_define_start_stop
317 #define binary_bfd_link_hash_table_create _bfd_generic_link_hash_table_create
318 #define binary_bfd_link_just_syms _bfd_generic_link_just_syms
319 #define binary_bfd_copy_link_hash_symbol_type _bfd_generic_copy_link_hash_symbol_type
320 #define binary_bfd_link_add_symbols _bfd_generic_link_add_symbols
321 #define binary_bfd_final_link _bfd_generic_final_link
322 #define binary_bfd_link_split_section _bfd_generic_link_split_section
323 #define binary_get_section_contents_in_window _bfd_generic_get_section_contents_in_window
324 #define binary_bfd_link_check_relocs _bfd_generic_link_check_relocs
325
326 const bfd_target binary_vec =
327 {
328 "binary", /* name */
329 bfd_target_unknown_flavour, /* flavour */
330 BFD_ENDIAN_UNKNOWN, /* byteorder */
331 BFD_ENDIAN_UNKNOWN, /* header_byteorder */
332 EXEC_P, /* object_flags */
333 (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE | SEC_DATA
334 | SEC_ROM | SEC_HAS_CONTENTS), /* section_flags */
335 0, /* symbol_leading_char */
336 ' ', /* ar_pad_char */
337 16, /* ar_max_namelen */
338 255, /* match priority. */
339 TARGET_KEEP_UNUSED_SECTION_SYMBOLS, /* keep unused section symbols. */
340 bfd_getb64, bfd_getb_signed_64, bfd_putb64,
341 bfd_getb32, bfd_getb_signed_32, bfd_putb32,
342 bfd_getb16, bfd_getb_signed_16, bfd_putb16, /* data */
343 bfd_getb64, bfd_getb_signed_64, bfd_putb64,
344 bfd_getb32, bfd_getb_signed_32, bfd_putb32,
345 bfd_getb16, bfd_getb_signed_16, bfd_putb16, /* hdrs */
346 { /* bfd_check_format */
347 _bfd_dummy_target,
348 binary_object_p,
349 _bfd_dummy_target,
350 _bfd_dummy_target,
351 },
352 { /* bfd_set_format */
353 _bfd_bool_bfd_false_error,
354 binary_mkobject,
355 _bfd_bool_bfd_false_error,
356 _bfd_bool_bfd_false_error,
357 },
358 { /* bfd_write_contents */
359 _bfd_bool_bfd_false_error,
360 _bfd_bool_bfd_true,
361 _bfd_bool_bfd_false_error,
362 _bfd_bool_bfd_false_error,
363 },
364
365 BFD_JUMP_TABLE_GENERIC (binary),
366 BFD_JUMP_TABLE_COPY (_bfd_generic),
367 BFD_JUMP_TABLE_CORE (_bfd_nocore),
368 BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
369 BFD_JUMP_TABLE_SYMBOLS (binary),
370 BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
371 BFD_JUMP_TABLE_WRITE (binary),
372 BFD_JUMP_TABLE_LINK (binary),
373 BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
374
375 NULL,
376
377 NULL
378 };