1 /* ELF attributes support (based on ARM EABI attributes).
2 Copyright (C) 2005-2014 Free Software Foundation, Inc.
3
4 This file is part of BFD, the Binary File Descriptor library.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19 MA 02110-1301, USA. */
20
21 #include "sysdep.h"
22 #include "bfd.h"
23 #include "libiberty.h"
24 #include "libbfd.h"
25 #include "elf-bfd.h"
26
27 /* Return the number of bytes needed by I in uleb128 format. */
28 static int
uleb128_size(unsigned int i)29 uleb128_size (unsigned int i)
30 {
31 int size;
32 size = 1;
33 while (i >= 0x80)
34 {
35 i >>= 7;
36 size++;
37 }
38 return size;
39 }
40
41 /* Return TRUE if the attribute has the default value (0/""). */
42 static bfd_boolean
is_default_attr(obj_attribute * attr)43 is_default_attr (obj_attribute *attr)
44 {
45 if (ATTR_TYPE_HAS_INT_VAL (attr->type) && attr->i != 0)
46 return FALSE;
47 if (ATTR_TYPE_HAS_STR_VAL (attr->type) && attr->s && *attr->s)
48 return FALSE;
49 if (ATTR_TYPE_HAS_NO_DEFAULT (attr->type))
50 return FALSE;
51
52 return TRUE;
53 }
54
55 /* Return the size of a single attribute. */
56 static bfd_vma
obj_attr_size(int tag,obj_attribute * attr)57 obj_attr_size (int tag, obj_attribute *attr)
58 {
59 bfd_vma size;
60
61 if (is_default_attr (attr))
62 return 0;
63
64 size = uleb128_size (tag);
65 if (ATTR_TYPE_HAS_INT_VAL (attr->type))
66 size += uleb128_size (attr->i);
67 if (ATTR_TYPE_HAS_STR_VAL (attr->type))
68 size += strlen ((char *)attr->s) + 1;
69 return size;
70 }
71
72 /* Return the vendor name for a given object attributes section. */
73 static const char *
vendor_obj_attr_name(bfd * abfd,int vendor)74 vendor_obj_attr_name (bfd *abfd, int vendor)
75 {
76 return (vendor == OBJ_ATTR_PROC
77 ? get_elf_backend_data (abfd)->obj_attrs_vendor
78 : "gnu");
79 }
80
81 /* Return the size of the object attributes section for VENDOR
82 (OBJ_ATTR_PROC or OBJ_ATTR_GNU), or 0 if there are no attributes
83 for that vendor to record and the vendor is OBJ_ATTR_GNU. */
84 static bfd_vma
vendor_obj_attr_size(bfd * abfd,int vendor)85 vendor_obj_attr_size (bfd *abfd, int vendor)
86 {
87 bfd_vma size;
88 obj_attribute *attr;
89 obj_attribute_list *list;
90 int i;
91 const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
92
93 if (!vendor_name)
94 return 0;
95
96 attr = elf_known_obj_attributes (abfd)[vendor];
97 size = 0;
98 for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
99 size += obj_attr_size (i, &attr[i]);
100
101 for (list = elf_other_obj_attributes (abfd)[vendor];
102 list;
103 list = list->next)
104 size += obj_attr_size (list->tag, &list->attr);
105
106 /* <size> <vendor_name> NUL 0x1 <size> */
107 return ((size || vendor == OBJ_ATTR_PROC)
108 ? size + 10 + strlen (vendor_name)
109 : 0);
110 }
111
112 /* Return the size of the object attributes section. */
113 bfd_vma
bfd_elf_obj_attr_size(bfd * abfd)114 bfd_elf_obj_attr_size (bfd *abfd)
115 {
116 bfd_vma size;
117
118 size = vendor_obj_attr_size (abfd, OBJ_ATTR_PROC);
119 size += vendor_obj_attr_size (abfd, OBJ_ATTR_GNU);
120
121 /* 'A' <sections for each vendor> */
122 return (size ? size + 1 : 0);
123 }
124
125 /* Write VAL in uleb128 format to P, returning a pointer to the
126 following byte. */
127 static bfd_byte *
write_uleb128(bfd_byte * p,unsigned int val)128 write_uleb128 (bfd_byte *p, unsigned int val)
129 {
130 bfd_byte c;
131 do
132 {
133 c = val & 0x7f;
134 val >>= 7;
135 if (val)
136 c |= 0x80;
137 *(p++) = c;
138 }
139 while (val);
140 return p;
141 }
142
143 /* Write attribute ATTR to butter P, and return a pointer to the following
144 byte. */
145 static bfd_byte *
write_obj_attribute(bfd_byte * p,int tag,obj_attribute * attr)146 write_obj_attribute (bfd_byte *p, int tag, obj_attribute *attr)
147 {
148 /* Suppress default entries. */
149 if (is_default_attr (attr))
150 return p;
151
152 p = write_uleb128 (p, tag);
153 if (ATTR_TYPE_HAS_INT_VAL (attr->type))
154 p = write_uleb128 (p, attr->i);
155 if (ATTR_TYPE_HAS_STR_VAL (attr->type))
156 {
157 int len;
158
159 len = strlen (attr->s) + 1;
160 memcpy (p, attr->s, len);
161 p += len;
162 }
163
164 return p;
165 }
166
167 /* Write the contents of the object attributes section (length SIZE)
168 for VENDOR to CONTENTS. */
169 static void
vendor_set_obj_attr_contents(bfd * abfd,bfd_byte * contents,bfd_vma size,int vendor)170 vendor_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size,
171 int vendor)
172 {
173 bfd_byte *p;
174 obj_attribute *attr;
175 obj_attribute_list *list;
176 int i;
177 const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
178 size_t vendor_length = strlen (vendor_name) + 1;
179
180 p = contents;
181 bfd_put_32 (abfd, size, p);
182 p += 4;
183 memcpy (p, vendor_name, vendor_length);
184 p += vendor_length;
185 *(p++) = Tag_File;
186 bfd_put_32 (abfd, size - 4 - vendor_length, p);
187 p += 4;
188
189 attr = elf_known_obj_attributes (abfd)[vendor];
190 for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
191 {
192 int tag = i;
193 if (get_elf_backend_data (abfd)->obj_attrs_order)
194 tag = get_elf_backend_data (abfd)->obj_attrs_order (i);
195 p = write_obj_attribute (p, tag, &attr[tag]);
196 }
197
198 for (list = elf_other_obj_attributes (abfd)[vendor];
199 list;
200 list = list->next)
201 p = write_obj_attribute (p, list->tag, &list->attr);
202 }
203
204 /* Write the contents of the object attributes section to CONTENTS. */
205 void
bfd_elf_set_obj_attr_contents(bfd * abfd,bfd_byte * contents,bfd_vma size)206 bfd_elf_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size)
207 {
208 bfd_byte *p;
209 int vendor;
210 bfd_vma my_size;
211
212 p = contents;
213 *(p++) = 'A';
214 my_size = 1;
215 for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
216 {
217 bfd_vma vendor_size = vendor_obj_attr_size (abfd, vendor);
218 if (vendor_size)
219 vendor_set_obj_attr_contents (abfd, p, vendor_size, vendor);
220 p += vendor_size;
221 my_size += vendor_size;
222 }
223
224 if (size != my_size)
225 abort ();
226 }
227
228 /* Allocate/find an object attribute. */
229 static obj_attribute *
elf_new_obj_attr(bfd * abfd,int vendor,int tag)230 elf_new_obj_attr (bfd *abfd, int vendor, int tag)
231 {
232 obj_attribute *attr;
233 obj_attribute_list *list;
234 obj_attribute_list *p;
235 obj_attribute_list **lastp;
236
237
238 if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
239 {
240 /* Known tags are preallocated. */
241 attr = &elf_known_obj_attributes (abfd)[vendor][tag];
242 }
243 else
244 {
245 /* Create a new tag. */
246 list = (obj_attribute_list *)
247 bfd_alloc (abfd, sizeof (obj_attribute_list));
248 memset (list, 0, sizeof (obj_attribute_list));
249 list->tag = tag;
250 /* Keep the tag list in order. */
251 lastp = &elf_other_obj_attributes (abfd)[vendor];
252 for (p = *lastp; p; p = p->next)
253 {
254 if (tag < p->tag)
255 break;
256 lastp = &p->next;
257 }
258 list->next = *lastp;
259 *lastp = list;
260 attr = &list->attr;
261 }
262
263 return attr;
264 }
265
266 /* Return the value of an integer object attribute. */
267 int
bfd_elf_get_obj_attr_int(bfd * abfd,int vendor,int tag)268 bfd_elf_get_obj_attr_int (bfd *abfd, int vendor, int tag)
269 {
270 obj_attribute_list *p;
271
272 if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
273 {
274 /* Known tags are preallocated. */
275 return elf_known_obj_attributes (abfd)[vendor][tag].i;
276 }
277 else
278 {
279 for (p = elf_other_obj_attributes (abfd)[vendor];
280 p;
281 p = p->next)
282 {
283 if (tag == p->tag)
284 return p->attr.i;
285 if (tag < p->tag)
286 break;
287 }
288 return 0;
289 }
290 }
291
292 /* Add an integer object attribute. */
293 void
bfd_elf_add_obj_attr_int(bfd * abfd,int vendor,int tag,unsigned int i)294 bfd_elf_add_obj_attr_int (bfd *abfd, int vendor, int tag, unsigned int i)
295 {
296 obj_attribute *attr;
297
298 attr = elf_new_obj_attr (abfd, vendor, tag);
299 attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag) | ATTR_TYPE_FLAG_EXIST;
300 attr->i = i;
301 }
302
303 /* Duplicate an object attribute string value. */
304 char *
_bfd_elf_attr_strdup(bfd * abfd,const char * s)305 _bfd_elf_attr_strdup (bfd *abfd, const char * s)
306 {
307 char * p;
308 int len;
309
310 len = strlen (s) + 1;
311 p = (char *) bfd_alloc (abfd, len);
312 return (char *) memcpy (p, s, len);
313 }
314
315 /* Add a string object attribute. */
316 void
bfd_elf_add_obj_attr_string(bfd * abfd,int vendor,int tag,const char * s)317 bfd_elf_add_obj_attr_string (bfd *abfd, int vendor, int tag, const char *s)
318 {
319 obj_attribute *attr;
320
321 attr = elf_new_obj_attr (abfd, vendor, tag);
322 attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag) | ATTR_TYPE_FLAG_EXIST;
323 attr->s = _bfd_elf_attr_strdup (abfd, s);
324 }
325
326 /* Add a int+string object attribute. */
327 void
bfd_elf_add_obj_attr_int_string(bfd * abfd,int vendor,int tag,unsigned int i,const char * s)328 bfd_elf_add_obj_attr_int_string (bfd *abfd, int vendor, int tag,
329 unsigned int i, const char *s)
330 {
331 obj_attribute *attr;
332
333 attr = elf_new_obj_attr (abfd, vendor, tag);
334 attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag) | ATTR_TYPE_FLAG_EXIST;
335 attr->i = i;
336 attr->s = _bfd_elf_attr_strdup (abfd, s);
337 }
338
339 /* Copy the object attributes from IBFD to OBFD. */
340 void
_bfd_elf_copy_obj_attributes(bfd * ibfd,bfd * obfd)341 _bfd_elf_copy_obj_attributes (bfd *ibfd, bfd *obfd)
342 {
343 obj_attribute *in_attr;
344 obj_attribute *out_attr;
345 obj_attribute_list *list;
346 int i;
347 int vendor;
348
349 if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
350 || bfd_get_flavour (obfd) != bfd_target_elf_flavour)
351 return;
352
353 for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
354 {
355 in_attr
356 = &elf_known_obj_attributes (ibfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
357 out_attr
358 = &elf_known_obj_attributes (obfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
359 for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
360 {
361 out_attr->type = in_attr->type;
362 out_attr->i = in_attr->i;
363 if (in_attr->s && *in_attr->s)
364 out_attr->s = _bfd_elf_attr_strdup (obfd, in_attr->s);
365 in_attr++;
366 out_attr++;
367 }
368
369 for (list = elf_other_obj_attributes (ibfd)[vendor];
370 list;
371 list = list->next)
372 {
373 in_attr = &list->attr;
374 switch (in_attr->type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
375 {
376 case ATTR_TYPE_FLAG_INT_VAL:
377 bfd_elf_add_obj_attr_int (obfd, vendor, list->tag, in_attr->i);
378 break;
379 case ATTR_TYPE_FLAG_STR_VAL:
380 bfd_elf_add_obj_attr_string (obfd, vendor, list->tag,
381 in_attr->s);
382 break;
383 case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
384 bfd_elf_add_obj_attr_int_string (obfd, vendor, list->tag,
385 in_attr->i, in_attr->s);
386 break;
387 default:
388 abort ();
389 }
390 }
391 }
392 }
393
394 /* Determine whether a GNU object attribute tag takes an integer, a
395 string or both. */
396 static int
gnu_obj_attrs_arg_type(int tag)397 gnu_obj_attrs_arg_type (int tag)
398 {
399 /* Except for Tag_compatibility, for GNU attributes we follow the
400 same rule ARM ones > 32 follow: odd-numbered tags take strings
401 and even-numbered tags take integers. In addition, tag & 2 is
402 nonzero for architecture-independent tags and zero for
403 architecture-dependent ones. */
404 if (tag == Tag_compatibility)
405 return 3;
406 else
407 return (tag & 1) != 0 ? 2 : 1;
408 }
409
410 /* Determine what arguments an attribute tag takes. */
411 int
_bfd_elf_obj_attrs_arg_type(bfd * abfd,int vendor,int tag)412 _bfd_elf_obj_attrs_arg_type (bfd *abfd, int vendor, int tag)
413 {
414 switch (vendor)
415 {
416 case OBJ_ATTR_PROC:
417 return get_elf_backend_data (abfd)->obj_attrs_arg_type (tag);
418 break;
419 case OBJ_ATTR_GNU:
420 return gnu_obj_attrs_arg_type (tag);
421 break;
422 default:
423 abort ();
424 }
425 }
426
427 /* Parse an object attributes section. */
428 void
_bfd_elf_parse_attributes(bfd * abfd,Elf_Internal_Shdr * hdr)429 _bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
430 {
431 bfd_byte *contents;
432 bfd_byte *p;
433 bfd_vma len;
434 const char *std_sec;
435
436 contents = (bfd_byte *) bfd_malloc (hdr->sh_size);
437 if (!contents)
438 return;
439 if (!bfd_get_section_contents (abfd, hdr->bfd_section, contents, 0,
440 hdr->sh_size))
441 {
442 free (contents);
443 return;
444 }
445 p = contents;
446 std_sec = get_elf_backend_data (abfd)->obj_attrs_vendor;
447 if (*(p++) == 'A')
448 {
449 len = hdr->sh_size - 1;
450 while (len > 0)
451 {
452 unsigned namelen;
453 bfd_vma section_len;
454 int vendor;
455
456 section_len = bfd_get_32 (abfd, p);
457 p += 4;
458 if (section_len == 0)
459 break;
460 if (section_len > len)
461 section_len = len;
462 len -= section_len;
463 section_len -= 4;
464 namelen = strnlen ((char *) p, section_len) + 1;
465 if (namelen == 0 || namelen >= section_len)
466 break;
467 section_len -= namelen;
468 if (std_sec && strcmp ((char *) p, std_sec) == 0)
469 vendor = OBJ_ATTR_PROC;
470 else if (strcmp ((char *) p, "gnu") == 0)
471 vendor = OBJ_ATTR_GNU;
472 else
473 {
474 /* Other vendor section. Ignore it. */
475 p += namelen + section_len;
476 continue;
477 }
478
479 p += namelen;
480 while (section_len > 0)
481 {
482 int tag;
483 unsigned int n;
484 unsigned int val;
485 bfd_vma subsection_len;
486 bfd_byte *end;
487
488 tag = read_unsigned_leb128 (abfd, p, &n);
489 p += n;
490 subsection_len = bfd_get_32 (abfd, p);
491 p += 4;
492 if (subsection_len == 0)
493 break;
494 if (subsection_len > section_len)
495 subsection_len = section_len;
496 section_len -= subsection_len;
497 subsection_len -= n + 4;
498 end = p + subsection_len;
499 switch (tag)
500 {
501 case Tag_File:
502 while (p < end)
503 {
504 int type;
505
506 tag = read_unsigned_leb128 (abfd, p, &n);
507 p += n;
508 type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
509 switch (type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
510 {
511 case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
512 val = read_unsigned_leb128 (abfd, p, &n);
513 p += n;
514 bfd_elf_add_obj_attr_int_string (abfd, vendor, tag,
515 val, (char *)p);
516 p += strlen ((char *)p) + 1;
517 break;
518 case ATTR_TYPE_FLAG_STR_VAL:
519 bfd_elf_add_obj_attr_string (abfd, vendor, tag,
520 (char *)p);
521 p += strlen ((char *)p) + 1;
522 break;
523 case ATTR_TYPE_FLAG_INT_VAL:
524 val = read_unsigned_leb128 (abfd, p, &n);
525 p += n;
526 bfd_elf_add_obj_attr_int (abfd, vendor, tag, val);
527 break;
528 default:
529 abort ();
530 }
531 }
532 break;
533 case Tag_Section:
534 case Tag_Symbol:
535 /* Don't have anywhere convenient to attach these.
536 Fall through for now. */
537 default:
538 /* Ignore things we don't kow about. */
539 p += subsection_len;
540 subsection_len = 0;
541 break;
542 }
543 }
544 }
545 }
546 free (contents);
547 }
548
549 /* Merge common object attributes from IBFD into OBFD. Raise an error
550 if there are conflicting attributes. Any processor-specific
551 attributes have already been merged. This must be called from the
552 bfd_elfNN_bfd_merge_private_bfd_data hook for each individual
553 target, along with any target-specific merging. Because there are
554 no common attributes other than Tag_compatibility at present, and
555 non-"gnu" Tag_compatibility is not expected in "gnu" sections, this
556 is not presently called for targets without their own
557 attributes. */
558
559 bfd_boolean
_bfd_elf_merge_object_attributes(bfd * ibfd,bfd * obfd)560 _bfd_elf_merge_object_attributes (bfd *ibfd, bfd *obfd)
561 {
562 obj_attribute *in_attr;
563 obj_attribute *out_attr;
564 int vendor;
565
566 /* The only common attribute is currently Tag_compatibility,
567 accepted in both processor and "gnu" sections. */
568 for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
569 {
570 /* Handle Tag_compatibility. The tags are only compatible if the flags
571 are identical and, if the flags are '1', the strings are identical.
572 If the flags are non-zero, then we can only use the string "gnu". */
573 in_attr = &elf_known_obj_attributes (ibfd)[vendor][Tag_compatibility];
574 out_attr = &elf_known_obj_attributes (obfd)[vendor][Tag_compatibility];
575
576 if (in_attr->i > 0 && strcmp (in_attr->s, "gnu") != 0)
577 {
578 _bfd_error_handler
579 (_("error: %B: Object has vendor-specific contents that "
580 "must be processed by the '%s' toolchain"),
581 ibfd, in_attr->s);
582 return FALSE;
583 }
584
585 if (in_attr->i != out_attr->i
586 || (in_attr->i != 0 && strcmp (in_attr->s, out_attr->s) != 0))
587 {
588 _bfd_error_handler (_("error: %B: Object tag '%d, %s' is "
589 "incompatible with tag '%d, %s'"),
590 ibfd,
591 in_attr->i, in_attr->s ? in_attr->s : "",
592 out_attr->i, out_attr->s ? out_attr->s : "");
593 return FALSE;
594 }
595 }
596
597 return TRUE;
598 }
599
600 /* Merge an unknown processor-specific attribute TAG, within the range
601 of known attributes, from IBFD into OBFD; return TRUE if the link
602 is OK, FALSE if it must fail. */
603
604 bfd_boolean
_bfd_elf_merge_unknown_attribute_low(bfd * ibfd,bfd * obfd,int tag)605 _bfd_elf_merge_unknown_attribute_low (bfd *ibfd, bfd *obfd, int tag)
606 {
607 obj_attribute *in_attr;
608 obj_attribute *out_attr;
609 bfd *err_bfd = NULL;
610 bfd_boolean result = TRUE;
611
612 in_attr = elf_known_obj_attributes_proc (ibfd);
613 out_attr = elf_known_obj_attributes_proc (obfd);
614
615 if (out_attr[tag].i != 0 || out_attr[tag].s != NULL)
616 err_bfd = obfd;
617 else if (in_attr[tag].i != 0 || in_attr[tag].s != NULL)
618 err_bfd = ibfd;
619
620 if (err_bfd != NULL)
621 result
622 = get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd, tag);
623
624 /* Only pass on attributes that match in both inputs. */
625 if (in_attr[tag].i != out_attr[tag].i
626 || (in_attr[tag].s == NULL) != (out_attr[tag].s == NULL)
627 || (in_attr[tag].s != NULL && out_attr[tag].s != NULL
628 && strcmp (in_attr[tag].s, out_attr[tag].s) != 0))
629 {
630 out_attr[tag].i = 0;
631 out_attr[tag].s = NULL;
632 }
633
634 return result;
635 }
636
637 /* Merge the lists of unknown processor-specific attributes, outside
638 the known range, from IBFD into OBFD; return TRUE if the link is
639 OK, FALSE if it must fail. */
640
641 bfd_boolean
_bfd_elf_merge_unknown_attribute_list(bfd * ibfd,bfd * obfd)642 _bfd_elf_merge_unknown_attribute_list (bfd *ibfd, bfd *obfd)
643 {
644 obj_attribute_list *in_list;
645 obj_attribute_list *out_list;
646 obj_attribute_list **out_listp;
647 bfd_boolean result = TRUE;
648
649 in_list = elf_other_obj_attributes_proc (ibfd);
650 out_listp = &elf_other_obj_attributes_proc (obfd);
651 out_list = *out_listp;
652
653 for (; in_list || out_list; )
654 {
655 bfd *err_bfd = NULL;
656 int err_tag = 0;
657
658 /* The tags for each list are in numerical order. */
659 /* If the tags are equal, then merge. */
660 if (out_list && (!in_list || in_list->tag > out_list->tag))
661 {
662 /* This attribute only exists in obfd. We can't merge, and we don't
663 know what the tag means, so delete it. */
664 err_bfd = obfd;
665 err_tag = out_list->tag;
666 *out_listp = out_list->next;
667 out_list = *out_listp;
668 }
669 else if (in_list && (!out_list || in_list->tag < out_list->tag))
670 {
671 /* This attribute only exists in ibfd. We can't merge, and we don't
672 know what the tag means, so ignore it. */
673 err_bfd = ibfd;
674 err_tag = in_list->tag;
675 in_list = in_list->next;
676 }
677 else /* The tags are equal. */
678 {
679 /* As present, all attributes in the list are unknown, and
680 therefore can't be merged meaningfully. */
681 err_bfd = obfd;
682 err_tag = out_list->tag;
683
684 /* Only pass on attributes that match in both inputs. */
685 if (in_list->attr.i != out_list->attr.i
686 || (in_list->attr.s == NULL) != (out_list->attr.s == NULL)
687 || (in_list->attr.s && out_list->attr.s
688 && strcmp (in_list->attr.s, out_list->attr.s) != 0))
689 {
690 /* No match. Delete the attribute. */
691 *out_listp = out_list->next;
692 out_list = *out_listp;
693 }
694 else
695 {
696 /* Matched. Keep the attribute and move to the next. */
697 out_list = out_list->next;
698 in_list = in_list->next;
699 }
700 }
701
702 if (err_bfd)
703 result = result
704 && get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd,
705 err_tag);
706 }
707
708 return result;
709 }
710