bfd/elf-attrs.c

   1 /* ELF attributes support (based on ARM EABI attributes).
   2    Copyright (C) 2005-2021 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
  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 bool
  43 is_default_attr (obj_attribute *attr)
  44 {
  45   if (ATTR_TYPE_HAS_ERROR (attr->type))
  46     return true;
  47   if (ATTR_TYPE_HAS_INT_VAL (attr->type) && attr->i != 0)
  48     return false;
  49   if (ATTR_TYPE_HAS_STR_VAL (attr->type) && attr->s && *attr->s)
  50     return false;
  51   if (ATTR_TYPE_HAS_NO_DEFAULT (attr->type))
  52     return false;
  53
  54   return true;
  55 }
  56
  57 /* Return the size of a single attribute.  */
  58 static bfd_vma
  59 obj_attr_size (unsigned int tag, obj_attribute *attr)
  60 {
  61   bfd_vma size;
  62
  63   if (is_default_attr (attr))
  64     return 0;
  65
  66   size = uleb128_size (tag);
  67   if (ATTR_TYPE_HAS_INT_VAL (attr->type))
  68     size += uleb128_size (attr->i);
  69   if (ATTR_TYPE_HAS_STR_VAL (attr->type))
  70     size += strlen ((char *)attr->s) + 1;
  71   return size;
  72 }
  73
  74 /* Return the vendor name for a given object attributes section.  */
  75 static const char *
  76 vendor_obj_attr_name (bfd *abfd, int vendor)
  77 {
  78   return (vendor == OBJ_ATTR_PROC
  79           ? get_elf_backend_data (abfd)->obj_attrs_vendor
  80           : "gnu");
  81 }
  82
  83 /* Return the size of the object attributes section for VENDOR
  84    (OBJ_ATTR_PROC or OBJ_ATTR_GNU), or 0 if there are no attributes
  85    for that vendor to record and the vendor is OBJ_ATTR_GNU.  */
  86 static bfd_vma
  87 vendor_obj_attr_size (bfd *abfd, int vendor)
  88 {
  89   bfd_vma size;
  90   obj_attribute *attr;
  91   obj_attribute_list *list;
  92   int i;
  93   const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
  94
  95   if (!vendor_name)
  96     return 0;
  97
  98   attr = elf_known_obj_attributes (abfd)[vendor];
  99   size = 0;
 100   for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
 101     size += obj_attr_size (i, &attr[i]);
 102
 103   for (list = elf_other_obj_attributes (abfd)[vendor];
 104        list;
 105        list = list->next)
 106     size += obj_attr_size (list->tag, &list->attr);
 107
 108   /* <size> <vendor_name> NUL 0x1 <size> */
 109   return (size
 110           ? size + 10 + strlen (vendor_name)
 111           : 0);
 112 }
 113
 114 /* Return the size of the object attributes section.  */
 115 bfd_vma
 116 bfd_elf_obj_attr_size (bfd *abfd)
 117 {
 118   bfd_vma size;
 119
 120   size = vendor_obj_attr_size (abfd, OBJ_ATTR_PROC);
 121   size += vendor_obj_attr_size (abfd, OBJ_ATTR_GNU);
 122
 123   /* 'A' <sections for each vendor> */
 124   return (size ? size + 1 : 0);
 125 }
 126
 127 /* Write VAL in uleb128 format to P, returning a pointer to the
 128    following byte.  */
 129 static bfd_byte *
 130 write_uleb128 (bfd_byte *p, unsigned int val)
 131 {
 132   bfd_byte c;
 133   do
 134     {
 135       c = val & 0x7f;
 136       val >>= 7;
 137       if (val)
 138         c |= 0x80;
 139       *(p++) = c;
 140     }
 141   while (val);
 142   return p;
 143 }
 144
 145 /* Write attribute ATTR to butter P, and return a pointer to the following
 146    byte.  */
 147 static bfd_byte *
 148 write_obj_attribute (bfd_byte *p, unsigned int tag, obj_attribute *attr)
 149 {
 150   /* Suppress default entries.  */
 151   if (is_default_attr (attr))
 152     return p;
 153
 154   p = write_uleb128 (p, tag);
 155   if (ATTR_TYPE_HAS_INT_VAL (attr->type))
 156     p = write_uleb128 (p, attr->i);
 157   if (ATTR_TYPE_HAS_STR_VAL (attr->type))
 158     {
 159       int len;
 160
 161       len = strlen (attr->s) + 1;
 162       memcpy (p, attr->s, len);
 163       p += len;
 164     }
 165
 166   return p;
 167 }
 168
 169 /* Write the contents of the object attributes section (length SIZE)
 170    for VENDOR to CONTENTS.  */
 171 static void
 172 vendor_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size,
 173                               int vendor)
 174 {
 175   bfd_byte *p;
 176   obj_attribute *attr;
 177   obj_attribute_list *list;
 178   int i;
 179   const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
 180   size_t vendor_length = strlen (vendor_name) + 1;
 181
 182   p = contents;
 183   bfd_put_32 (abfd, size, p);
 184   p += 4;
 185   memcpy (p, vendor_name, vendor_length);
 186   p += vendor_length;
 187   *(p++) = Tag_File;
 188   bfd_put_32 (abfd, size - 4 - vendor_length, p);
 189   p += 4;
 190
 191   attr = elf_known_obj_attributes (abfd)[vendor];
 192   for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
 193     {
 194       unsigned int tag = i;
 195       if (get_elf_backend_data (abfd)->obj_attrs_order)
 196         tag = get_elf_backend_data (abfd)->obj_attrs_order (i);
 197       p = write_obj_attribute (p, tag, &attr[tag]);
 198     }
 199
 200   for (list = elf_other_obj_attributes (abfd)[vendor];
 201        list;
 202        list = list->next)
 203     p = write_obj_attribute (p, list->tag, &list->attr);
 204 }
 205
 206 /* Write the contents of the object attributes section to CONTENTS.  */
 207 void
 208 bfd_elf_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size)
 209 {
 210   bfd_byte *p;
 211   int vendor;
 212   bfd_vma my_size;
 213
 214   p = contents;
 215   *(p++) = 'A';
 216   my_size = 1;
 217   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 218     {
 219       bfd_vma vendor_size = vendor_obj_attr_size (abfd, vendor);
 220       if (vendor_size)
 221         vendor_set_obj_attr_contents (abfd, p, vendor_size, vendor);
 222       p += vendor_size;
 223       my_size += vendor_size;
 224     }
 225
 226   if (size != my_size)
 227     abort ();
 228 }
 229
 230 /* Allocate/find an object attribute.  */
 231 static obj_attribute *
 232 elf_new_obj_attr (bfd *abfd, int vendor, unsigned int tag)
 233 {
 234   obj_attribute *attr;
 235   obj_attribute_list *list;
 236   obj_attribute_list *p;
 237   obj_attribute_list **lastp;
 238
 239
 240   if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
 241     {
 242       /* Known tags are preallocated.  */
 243       attr = &elf_known_obj_attributes (abfd)[vendor][tag];
 244     }
 245   else
 246     {
 247       /* Create a new tag.  */
 248       list = (obj_attribute_list *)
 249         bfd_alloc (abfd, sizeof (obj_attribute_list));
 250       memset (list, 0, sizeof (obj_attribute_list));
 251       list->tag = tag;
 252       /* Keep the tag list in order.  */
 253       lastp = &elf_other_obj_attributes (abfd)[vendor];
 254       for (p = *lastp; p; p = p->next)
 255         {
 256           if (tag < p->tag)
 257             break;
 258           lastp = &p->next;
 259         }
 260       list->next = *lastp;
 261       *lastp = list;
 262       attr = &list->attr;
 263     }
 264
 265   return attr;
 266 }
 267
 268 /* Return the value of an integer object attribute.  */
 269 int
 270 bfd_elf_get_obj_attr_int (bfd *abfd, int vendor, unsigned int tag)
 271 {
 272   obj_attribute_list *p;
 273
 274   if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
 275     {
 276       /* Known tags are preallocated.  */
 277       return elf_known_obj_attributes (abfd)[vendor][tag].i;
 278     }
 279   else
 280     {
 281       for (p = elf_other_obj_attributes (abfd)[vendor];
 282            p;
 283            p = p->next)
 284         {
 285           if (tag == p->tag)
 286             return p->attr.i;
 287           if (tag < p->tag)
 288             break;
 289         }
 290       return 0;
 291     }
 292 }
 293
 294 /* Add an integer object attribute.  */
 295 void
 296 bfd_elf_add_obj_attr_int (bfd *abfd, int vendor, unsigned int tag, unsigned int i)
 297 {
 298   obj_attribute *attr;
 299
 300   attr = elf_new_obj_attr (abfd, vendor, tag);
 301   attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
 302   attr->i = i;
 303 }
 304
 305 /* Duplicate an object attribute string value.  */
 306 static char *
 307 elf_attr_strdup (bfd *abfd, const char *s, const char *end)
 308 {
 309   char *p;
 310   size_t len;
 311
 312   if (end)
 313     len = strnlen (s, end - s);
 314   else
 315     len = strlen (s);
 316
 317   p = (char *) bfd_alloc (abfd, len + 1);
 318   if (p != NULL)
 319     {
 320       memcpy (p, s, len);
 321       p[len] = 0;
 322     }
 323   return p;
 324 }
 325
 326 char *
 327 _bfd_elf_attr_strdup (bfd *abfd, const char *s)
 328 {
 329   return elf_attr_strdup (abfd, s, NULL);
 330 }
 331
 332 /* Add a string object attribute.  */
 333 static void
 334 elf_add_obj_attr_string (bfd *abfd, int vendor, unsigned int tag,
 335                          const char *s, const char *end)
 336 {
 337   obj_attribute *attr;
 338
 339   attr = elf_new_obj_attr (abfd, vendor, tag);
 340   attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
 341   attr->s = elf_attr_strdup (abfd, s, end);
 342 }
 343
 344 void
 345 bfd_elf_add_obj_attr_string (bfd *abfd, int vendor, unsigned int tag,
 346                              const char *s)
 347 {
 348   elf_add_obj_attr_string (abfd, vendor, tag, s, NULL);
 349 }
 350
 351 /* Add a int+string object attribute.  */
 352 static void
 353 elf_add_obj_attr_int_string (bfd *abfd, int vendor, unsigned int tag,
 354                              unsigned int i, const char *s, const char *end)
 355 {
 356   obj_attribute *attr;
 357
 358   attr = elf_new_obj_attr (abfd, vendor, tag);
 359   attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
 360   attr->i = i;
 361   attr->s = elf_attr_strdup (abfd, s, end);
 362 }
 363
 364 void
 365 bfd_elf_add_obj_attr_int_string (bfd *abfd, int vendor, unsigned int tag,
 366                                  unsigned int i, const char *s)
 367 {
 368   elf_add_obj_attr_int_string (abfd, vendor, tag, i, s, NULL);
 369 }
 370
 371 /* Copy the object attributes from IBFD to OBFD.  */
 372 void
 373 _bfd_elf_copy_obj_attributes (bfd *ibfd, bfd *obfd)
 374 {
 375   obj_attribute *in_attr;
 376   obj_attribute *out_attr;
 377   obj_attribute_list *list;
 378   int i;
 379   int vendor;
 380
 381   if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
 382       || bfd_get_flavour (obfd) != bfd_target_elf_flavour)
 383     return;
 384
 385   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 386     {
 387       in_attr
 388         = &elf_known_obj_attributes (ibfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
 389       out_attr
 390         = &elf_known_obj_attributes (obfd)[vendor][LEAST_KNOWN_OBJ_ATTRIBUTE];
 391       for (i = LEAST_KNOWN_OBJ_ATTRIBUTE; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
 392         {
 393           out_attr->type = in_attr->type;
 394           out_attr->i = in_attr->i;
 395           if (in_attr->s && *in_attr->s)
 396             out_attr->s = _bfd_elf_attr_strdup (obfd, in_attr->s);
 397           in_attr++;
 398           out_attr++;
 399         }
 400
 401       for (list = elf_other_obj_attributes (ibfd)[vendor];
 402            list;
 403            list = list->next)
 404         {
 405           in_attr = &list->attr;
 406           switch (in_attr->type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
 407             {
 408             case ATTR_TYPE_FLAG_INT_VAL:
 409               bfd_elf_add_obj_attr_int (obfd, vendor, list->tag, in_attr->i);
 410               break;
 411             case ATTR_TYPE_FLAG_STR_VAL:
 412               bfd_elf_add_obj_attr_string (obfd, vendor, list->tag,
 413                                            in_attr->s);
 414               break;
 415             case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
 416               bfd_elf_add_obj_attr_int_string (obfd, vendor, list->tag,
 417                                                in_attr->i, in_attr->s);
 418               break;
 419             default:
 420               abort ();
 421             }
 422         }
 423     }
 424 }
 425
 426 /* Determine whether a GNU object attribute tag takes an integer, a
 427    string or both.  */
 428 static int
 429 gnu_obj_attrs_arg_type (unsigned int tag)
 430 {
 431   /* Except for Tag_compatibility, for GNU attributes we follow the
 432      same rule ARM ones > 32 follow: odd-numbered tags take strings
 433      and even-numbered tags take integers.  In addition, tag & 2 is
 434      nonzero for architecture-independent tags and zero for
 435      architecture-dependent ones.  */
 436   if (tag == Tag_compatibility)
 437     return 3;
 438   else
 439     return (tag & 1) != 0 ? 2 : 1;
 440 }
 441
 442 /* Determine what arguments an attribute tag takes.  */
 443 int
 444 _bfd_elf_obj_attrs_arg_type (bfd *abfd, int vendor, unsigned int tag)
 445 {
 446   switch (vendor)
 447     {
 448     case OBJ_ATTR_PROC:
 449       return get_elf_backend_data (abfd)->obj_attrs_arg_type (tag);
 450       break;
 451     case OBJ_ATTR_GNU:
 452       return gnu_obj_attrs_arg_type (tag);
 453       break;
 454     default:
 455       abort ();
 456     }
 457 }
 458
 459 /* Parse an object attributes section.  */
 460 void
 461 _bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
 462 {
 463   bfd_byte *contents;
 464   bfd_byte *p;
 465   bfd_byte *p_end;
 466   const char *std_sec;
 467   ufile_ptr filesize;
 468
 469   /* PR 17512: file: 2844a11d.  */
 470   if (hdr->sh_size == 0)
 471     return;
 472
 473   filesize = bfd_get_file_size (abfd);
 474   if (filesize != 0 && hdr->sh_size > filesize)
 475     {
 476       /* xgettext:c-format */
 477       _bfd_error_handler (_("%pB: error: attribute section '%pA' too big: %#llx"),
 478                           abfd, hdr->bfd_section, (long long) hdr->sh_size);
 479       bfd_set_error (bfd_error_invalid_operation);
 480       return;
 481     }
 482
 483   contents = (bfd_byte *) bfd_malloc (hdr->sh_size);
 484   if (!contents)
 485     return;
 486   if (!bfd_get_section_contents (abfd, hdr->bfd_section, contents, 0,
 487                                  hdr->sh_size))
 488     {
 489       free (contents);
 490       return;
 491     }
 492   p = contents;
 493   p_end = p + hdr->sh_size;
 494   std_sec = get_elf_backend_data (abfd)->obj_attrs_vendor;
 495
 496   if (*p++ == 'A')
 497     {
 498       while (p_end - p >= 4)
 499         {
 500           size_t len = p_end - p;
 501           size_t namelen;
 502           size_t section_len;
 503           int vendor;
 504
 505           section_len = bfd_get_32 (abfd, p);
 506           p += 4;
 507           if (section_len == 0)
 508             break;
 509           if (section_len > len)
 510             section_len = len;
 511           if (section_len <= 4)
 512             {
 513               _bfd_error_handler
 514                 (_("%pB: error: attribute section length too small: %ld"),
 515                  abfd, (long) section_len);
 516               break;
 517             }
 518           section_len -= 4;
 519           namelen = strnlen ((char *) p, section_len) + 1;
 520           if (namelen >= section_len)
 521             break;
 522           if (std_sec && strcmp ((char *) p, std_sec) == 0)
 523             vendor = OBJ_ATTR_PROC;
 524           else if (strcmp ((char *) p, "gnu") == 0)
 525             vendor = OBJ_ATTR_GNU;
 526           else
 527             {
 528               /* Other vendor section.  Ignore it.  */
 529               p += section_len;
 530               continue;
 531             }
 532
 533           p += namelen;
 534           section_len -= namelen;
 535           while (section_len > 0)
 536             {
 537               unsigned int tag;
 538               unsigned int val;
 539               size_t subsection_len;
 540               bfd_byte *end, *orig_p;
 541
 542               orig_p = p;
 543               tag = _bfd_safe_read_leb128 (abfd, &p, false, p_end);
 544               if (p_end - p >= 4)
 545                 {
 546                   subsection_len = bfd_get_32 (abfd, p);
 547                   p += 4;
 548                 }
 549               else
 550                 {
 551                   p = p_end;
 552                   break;
 553                 }
 554               if (subsection_len > section_len)
 555                 subsection_len = section_len;
 556               section_len -= subsection_len;
 557               end = orig_p + subsection_len;
 558               if (end < p)
 559                 break;
 560               switch (tag)
 561                 {
 562                 case Tag_File:
 563                   while (p < end)
 564                     {
 565                       int type;
 566
 567                       tag = _bfd_safe_read_leb128 (abfd, &p, false, end);
 568                       type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
 569                       switch (type & (ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL))
 570                         {
 571                         case ATTR_TYPE_FLAG_INT_VAL | ATTR_TYPE_FLAG_STR_VAL:
 572                           val = _bfd_safe_read_leb128 (abfd, &p, false, end);
 573                           elf_add_obj_attr_int_string (abfd, vendor, tag, val,
 574                                                        (char *) p,
 575                                                        (char *) end);
 576                           p += strnlen ((char *) p, end - p);
 577                           if (p < end)
 578                             p++;
 579                           break;
 580                         case ATTR_TYPE_FLAG_STR_VAL:
 581                           elf_add_obj_attr_string (abfd, vendor, tag,
 582                                                    (char *) p,
 583                                                    (char *) end);
 584                           p += strnlen ((char *) p, end - p);
 585                           if (p < end)
 586                             p++;
 587                           break;
 588                         case ATTR_TYPE_FLAG_INT_VAL:
 589                           val = _bfd_safe_read_leb128 (abfd, &p, false, end);
 590                           bfd_elf_add_obj_attr_int (abfd, vendor, tag, val);
 591                           break;
 592                         default:
 593                           abort ();
 594                         }
 595                     }
 596                   break;
 597                 case Tag_Section:
 598                 case Tag_Symbol:
 599                   /* Don't have anywhere convenient to attach these.
 600                      Fall through for now.  */
 601                 default:
 602                   /* Ignore things we don't know about.  */
 603                   p = end;
 604                   break;
 605                 }
 606             }
 607         }
 608     }
 609   free (contents);
 610 }
 611
 612 /* Merge common object attributes from IBFD into OBFD.  Raise an error
 613    if there are conflicting attributes.  Any processor-specific
 614    attributes have already been merged.  This must be called from the
 615    bfd_elfNN_bfd_merge_private_bfd_data hook for each individual
 616    target, along with any target-specific merging.  Because there are
 617    no common attributes other than Tag_compatibility at present, and
 618    non-"gnu" Tag_compatibility is not expected in "gnu" sections, this
 619    is not presently called for targets without their own
 620    attributes.  */
 621
 622 bool
 623 _bfd_elf_merge_object_attributes (bfd *ibfd, struct bfd_link_info *info)
 624 {
 625   bfd *obfd = info->output_bfd;
 626   obj_attribute *in_attr;
 627   obj_attribute *out_attr;
 628   int vendor;
 629
 630   /* The only common attribute is currently Tag_compatibility,
 631      accepted in both processor and "gnu" sections.  */
 632   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 633     {
 634       /* Handle Tag_compatibility.  The tags are only compatible if the flags
 635          are identical and, if the flags are '1', the strings are identical.
 636          If the flags are non-zero, then we can only use the string "gnu".  */
 637       in_attr = &elf_known_obj_attributes (ibfd)[vendor][Tag_compatibility];
 638       out_attr = &elf_known_obj_attributes (obfd)[vendor][Tag_compatibility];
 639
 640       if (in_attr->i > 0 && strcmp (in_attr->s, "gnu") != 0)
 641         {
 642           _bfd_error_handler
 643             /* xgettext:c-format */
 644                 (_("error: %pB: object has vendor-specific contents that "
 645                    "must be processed by the '%s' toolchain"),
 646                  ibfd, in_attr->s);
 647           return false;
 648         }
 649
 650       if (in_attr->i != out_attr->i
 651           || (in_attr->i != 0 && strcmp (in_attr->s, out_attr->s) != 0))
 652         {
 653           /* xgettext:c-format */
 654           _bfd_error_handler (_("error: %pB: object tag '%d, %s' is "
 655                                 "incompatible with tag '%d, %s'"),
 656                               ibfd,
 657                               in_attr->i, in_attr->s ? in_attr->s : "",
 658                               out_attr->i, out_attr->s ? out_attr->s : "");
 659           return false;
 660         }
 661     }
 662
 663   return true;
 664 }
 665
 666 /* Merge an unknown processor-specific attribute TAG, within the range
 667    of known attributes, from IBFD into OBFD; return TRUE if the link
 668    is OK, FALSE if it must fail.  */
 669
 670 bool
 671 _bfd_elf_merge_unknown_attribute_low (bfd *ibfd, bfd *obfd, int tag)
 672 {
 673   obj_attribute *in_attr;
 674   obj_attribute *out_attr;
 675   bfd *err_bfd = NULL;
 676   bool result = true;
 677
 678   in_attr = elf_known_obj_attributes_proc (ibfd);
 679   out_attr = elf_known_obj_attributes_proc (obfd);
 680
 681   if (out_attr[tag].i != 0 || out_attr[tag].s != NULL)
 682     err_bfd = obfd;
 683   else if (in_attr[tag].i != 0 || in_attr[tag].s != NULL)
 684     err_bfd = ibfd;
 685
 686   if (err_bfd != NULL)
 687     result
 688       = get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd, tag);
 689
 690   /* Only pass on attributes that match in both inputs.  */
 691   if (in_attr[tag].i != out_attr[tag].i
 692       || (in_attr[tag].s == NULL) != (out_attr[tag].s == NULL)
 693       || (in_attr[tag].s != NULL && out_attr[tag].s != NULL
 694           && strcmp (in_attr[tag].s, out_attr[tag].s) != 0))
 695     {
 696       out_attr[tag].i = 0;
 697       out_attr[tag].s = NULL;
 698     }
 699
 700   return result;
 701 }
 702
 703 /* Merge the lists of unknown processor-specific attributes, outside
 704    the known range, from IBFD into OBFD; return TRUE if the link is
 705    OK, FALSE if it must fail.  */
 706
 707 bool
 708 _bfd_elf_merge_unknown_attribute_list (bfd *ibfd, bfd *obfd)
 709 {
 710   obj_attribute_list *in_list;
 711   obj_attribute_list *out_list;
 712   obj_attribute_list **out_listp;
 713   bool result = true;
 714
 715   in_list = elf_other_obj_attributes_proc (ibfd);
 716   out_listp = &elf_other_obj_attributes_proc (obfd);
 717   out_list = *out_listp;
 718
 719   for (; in_list || out_list; )
 720     {
 721       bfd *err_bfd = NULL;
 722       unsigned int err_tag = 0;
 723
 724       /* The tags for each list are in numerical order.  */
 725       /* If the tags are equal, then merge.  */
 726       if (out_list && (!in_list || in_list->tag > out_list->tag))
 727         {
 728           /* This attribute only exists in obfd.  We can't merge, and we don't
 729              know what the tag means, so delete it.  */
 730           err_bfd = obfd;
 731           err_tag = out_list->tag;
 732           *out_listp = out_list->next;
 733           out_list = *out_listp;
 734         }
 735       else if (in_list && (!out_list || in_list->tag < out_list->tag))
 736         {
 737           /* This attribute only exists in ibfd. We can't merge, and we don't
 738              know what the tag means, so ignore it.  */
 739           err_bfd = ibfd;
 740           err_tag = in_list->tag;
 741           in_list = in_list->next;
 742         }
 743       else /* The tags are equal.  */
 744         {
 745           /* As present, all attributes in the list are unknown, and
 746              therefore can't be merged meaningfully.  */
 747           err_bfd = obfd;
 748           err_tag = out_list->tag;
 749
 750           /*  Only pass on attributes that match in both inputs.  */
 751           if (in_list->attr.i != out_list->attr.i
 752               || (in_list->attr.s == NULL) != (out_list->attr.s == NULL)
 753               || (in_list->attr.s && out_list->attr.s
 754                   && strcmp (in_list->attr.s, out_list->attr.s) != 0))
 755             {
 756               /* No match.  Delete the attribute.  */
 757               *out_listp = out_list->next;
 758               out_list = *out_listp;
 759             }
 760           else
 761             {
 762               /* Matched.  Keep the attribute and move to the next.  */
 763               out_list = out_list->next;
 764               in_list = in_list->next;
 765             }
 766         }
 767
 768       if (err_bfd)
 769         result = result
 770           && get_elf_backend_data (err_bfd)->obj_attrs_handle_unknown (err_bfd,
 771                                                                        err_tag);
 772     }
 773
 774   return result;
 775 }