bfd/elf-attrs.c

   1 /* ELF attributes support (based on ARM EABI attributes).
   2    Copyright 2005, 2006, 2007
   3    Free Software Foundation, 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 2 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, 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 bfd_boolean
  43 is_default_attr (obj_attribute *attr)
  44 {
  45   if ((attr->type & 1) && attr->i != 0)
  46     return FALSE;
  47   if ((attr->type & 2) && attr->s && *attr->s)
  48     return FALSE;
  49
  50   return TRUE;
  51 }
  52
  53 /* Return the size of a single attribute.  */
  54 static bfd_vma
  55 obj_attr_size (int tag, obj_attribute *attr)
  56 {
  57   bfd_vma size;
  58
  59   if (is_default_attr (attr))
  60     return 0;
  61
  62   size = uleb128_size (tag);
  63   if (attr->type & 1)
  64     size += uleb128_size (attr->i);
  65   if (attr->type & 2)
  66     size += strlen ((char *)attr->s) + 1;
  67   return size;
  68 }
  69
  70 /* Return the vendor name for a given object attributes section.  */
  71 static const char *
  72 vendor_obj_attr_name (bfd *abfd, int vendor)
  73 {
  74   return (vendor == OBJ_ATTR_PROC
  75           ? get_elf_backend_data (abfd)->obj_attrs_vendor
  76           : "gnu");
  77 }
  78
  79 /* Return the size of the object attributes section for VENDOR
  80    (OBJ_ATTR_PROC or OBJ_ATTR_GNU), or 0 if there are no attributes
  81    for that vendor to record and the vendor is OBJ_ATTR_GNU.  */
  82 static bfd_vma
  83 vendor_obj_attr_size (bfd *abfd, int vendor)
  84 {
  85   bfd_vma size;
  86   obj_attribute *attr;
  87   obj_attribute_list *list;
  88   int i;
  89   const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
  90
  91   if (!vendor_name)
  92     return 0;
  93
  94   attr = elf_known_obj_attributes (abfd)[vendor];
  95   size = 0;
  96   for (i = 4; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
  97     size += obj_attr_size (i, &attr[i]);
  98
  99   for (list = elf_other_obj_attributes (abfd)[vendor];
 100        list;
 101        list = list->next)
 102     size += obj_attr_size (list->tag, &list->attr);
 103
 104   /* <size> <vendor_name> NUL 0x1 <size> */
 105   return ((size || vendor == OBJ_ATTR_PROC)
 106           ? size + 10 + strlen (vendor_name)
 107           : 0);
 108 }
 109
 110 /* Return the size of the object attributes section.  */
 111 bfd_vma
 112 bfd_elf_obj_attr_size (bfd *abfd)
 113 {
 114   bfd_vma size;
 115
 116   size = vendor_obj_attr_size (abfd, OBJ_ATTR_PROC);
 117   size += vendor_obj_attr_size (abfd, OBJ_ATTR_GNU);
 118
 119   /* 'A' <sections for each vendor> */
 120   return (size ? size + 1 : 0);
 121 }
 122
 123 /* Write VAL in uleb128 format to P, returning a pointer to the
 124    following byte.  */
 125 static bfd_byte *
 126 write_uleb128 (bfd_byte *p, unsigned int val)
 127 {
 128   bfd_byte c;
 129   do
 130     {
 131       c = val & 0x7f;
 132       val >>= 7;
 133       if (val)
 134         c |= 0x80;
 135       *(p++) = c;
 136     }
 137   while (val);
 138   return p;
 139 }
 140
 141 /* Write attribute ATTR to butter P, and return a pointer to the following
 142    byte.  */
 143 static bfd_byte *
 144 write_obj_attribute (bfd_byte *p, int tag, obj_attribute *attr)
 145 {
 146   /* Suppress default entries.  */
 147   if (is_default_attr (attr))
 148     return p;
 149
 150   p = write_uleb128 (p, tag);
 151   if (attr->type & 1)
 152     p = write_uleb128 (p, attr->i);
 153   if (attr->type & 2)
 154     {
 155       int len;
 156
 157       len = strlen (attr->s) + 1;
 158       memcpy (p, attr->s, len);
 159       p += len;
 160     }
 161
 162   return p;
 163 }
 164
 165 /* Write the contents of the object attributes section (length SIZE)
 166    for VENDOR to CONTENTS.  */
 167 static void
 168 vendor_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size,
 169                               int vendor)
 170 {
 171   bfd_byte *p;
 172   obj_attribute *attr;
 173   obj_attribute_list *list;
 174   int i;
 175   const char *vendor_name = vendor_obj_attr_name (abfd, vendor);
 176   size_t vendor_length = strlen (vendor_name) + 1;
 177
 178   p = contents;
 179   bfd_put_32 (abfd, size, p);
 180   p += 4;
 181   memcpy (p, vendor_name, vendor_length);
 182   p += vendor_length;
 183   *(p++) = Tag_File;
 184   bfd_put_32 (abfd, size - 4 - vendor_length, p);
 185   p += 4;
 186
 187   attr = elf_known_obj_attributes (abfd)[vendor];
 188   for (i = 4; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
 189     p = write_obj_attribute (p, i, &attr[i]);
 190
 191   for (list = elf_other_obj_attributes (abfd)[vendor];
 192        list;
 193        list = list->next)
 194     p = write_obj_attribute (p, list->tag, &list->attr);
 195 }
 196
 197 /* Write the contents of the object attributes section to CONTENTS.  */
 198 void
 199 bfd_elf_set_obj_attr_contents (bfd *abfd, bfd_byte *contents, bfd_vma size)
 200 {
 201   bfd_byte *p;
 202   int vendor;
 203   bfd_vma my_size;
 204
 205   p = contents;
 206   *(p++) = 'A';
 207   my_size = 1;
 208   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 209     {
 210       bfd_vma vendor_size = vendor_obj_attr_size (abfd, vendor);
 211       if (vendor_size)
 212         vendor_set_obj_attr_contents (abfd, p, vendor_size, vendor);
 213       p += vendor_size;
 214       my_size += vendor_size;
 215     }
 216
 217   if (size != my_size)
 218     abort ();
 219 }
 220
 221 /* Allocate/find an object attribute.  */
 222 static obj_attribute *
 223 elf_new_obj_attr (bfd *abfd, int vendor, int tag)
 224 {
 225   obj_attribute *attr;
 226   obj_attribute_list *list;
 227   obj_attribute_list *p;
 228   obj_attribute_list **lastp;
 229
 230
 231   if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
 232     {
 233       /* Knwon tags are preallocated.  */
 234       attr = &elf_known_obj_attributes (abfd)[vendor][tag];
 235     }
 236   else
 237     {
 238       /* Create a new tag.  */
 239       list = (obj_attribute_list *)
 240         bfd_alloc (abfd, sizeof (obj_attribute_list));
 241       memset (list, 0, sizeof (obj_attribute_list));
 242       list->tag = tag;
 243       /* Keep the tag list in order.  */
 244       lastp = &elf_other_obj_attributes (abfd)[vendor];
 245       for (p = *lastp; p; p = p->next)
 246         {
 247           if (tag < p->tag)
 248             break;
 249           lastp = &p->next;
 250         }
 251       list->next = *lastp;
 252       *lastp = list;
 253       attr = &list->attr;
 254     }
 255
 256   return attr;
 257 }
 258
 259 /* Return the value of an integer object attribute.  */
 260 int
 261 bfd_elf_get_obj_attr_int (bfd *abfd, int vendor, int tag)
 262 {
 263   obj_attribute_list *p;
 264
 265   if (tag < NUM_KNOWN_OBJ_ATTRIBUTES)
 266     {
 267       /* Knwon tags are preallocated.  */
 268       return elf_known_obj_attributes (abfd)[vendor][tag].i;
 269     }
 270   else
 271     {
 272       for (p = elf_other_obj_attributes (abfd)[vendor];
 273            p;
 274            p = p->next)
 275         {
 276           if (tag == p->tag)
 277             return p->attr.i;
 278           if (tag < p->tag)
 279             break;
 280         }
 281       return 0;
 282     }
 283 }
 284
 285 /* Add an integer object attribute.  */
 286 void
 287 bfd_elf_add_obj_attr_int (bfd *abfd, int vendor, int tag, unsigned int i)
 288 {
 289   obj_attribute *attr;
 290
 291   attr = elf_new_obj_attr (abfd, vendor, tag);
 292   attr->type = 1;
 293   attr->i = i;
 294 }
 295
 296 /* Duplicate an object attribute string value.  */
 297 char *
 298 _bfd_elf_attr_strdup (bfd *abfd, const char * s)
 299 {
 300   char * p;
 301   int len;
 302
 303   len = strlen (s) + 1;
 304   p = (char *) bfd_alloc (abfd, len);
 305   return memcpy (p, s, len);
 306 }
 307
 308 /* Add a string object attribute.  */
 309 void
 310 bfd_elf_add_obj_attr_string (bfd *abfd, int vendor, int tag, const char *s)
 311 {
 312   obj_attribute *attr;
 313
 314   attr = elf_new_obj_attr (abfd, vendor, tag);
 315   attr->type = 2;
 316   attr->s = _bfd_elf_attr_strdup (abfd, s);
 317 }
 318
 319 /* Add a Tag_compatibility object attribute.  */
 320 void
 321 bfd_elf_add_obj_attr_compat (bfd *abfd, int vendor, unsigned int i,
 322                              const char *s)
 323 {
 324   obj_attribute_list *list;
 325   obj_attribute_list *p;
 326   obj_attribute_list **lastp;
 327
 328   list = (obj_attribute_list *)
 329     bfd_alloc (abfd, sizeof (obj_attribute_list));
 330   memset (list, 0, sizeof (obj_attribute_list));
 331   list->tag = Tag_compatibility;
 332   list->attr.type = 3;
 333   list->attr.i = i;
 334   list->attr.s = _bfd_elf_attr_strdup (abfd, s);
 335
 336   lastp = &elf_other_obj_attributes (abfd)[vendor];
 337   for (p = *lastp; p; p = p->next)
 338     {
 339       int cmp;
 340       if (p->tag != Tag_compatibility)
 341         break;
 342       cmp = strcmp(s, p->attr.s);
 343       if (cmp < 0 || (cmp == 0 && i < p->attr.i))
 344         break;
 345       lastp = &p->next;
 346     }
 347   list->next = *lastp;
 348   *lastp = list;
 349 }
 350
 351 /* Copy the object attributes from IBFD to OBFD.  */
 352 void
 353 _bfd_elf_copy_obj_attributes (bfd *ibfd, bfd *obfd)
 354 {
 355   obj_attribute *in_attr;
 356   obj_attribute *out_attr;
 357   obj_attribute_list *list;
 358   int i;
 359   int vendor;
 360
 361   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 362     {
 363       in_attr = &elf_known_obj_attributes (ibfd)[vendor][4];
 364       out_attr = &elf_known_obj_attributes (obfd)[vendor][4];
 365       for (i = 4; i < NUM_KNOWN_OBJ_ATTRIBUTES; i++)
 366         {
 367           out_attr->type = in_attr->type;
 368           out_attr->i = in_attr->i;
 369           if (in_attr->s && *in_attr->s)
 370             out_attr->s = _bfd_elf_attr_strdup (obfd, in_attr->s);
 371           in_attr++;
 372           out_attr++;
 373         }
 374
 375       for (list = elf_other_obj_attributes (ibfd)[vendor];
 376            list;
 377            list = list->next)
 378         {
 379           in_attr = &list->attr;
 380           switch (in_attr->type)
 381             {
 382             case 1:
 383               bfd_elf_add_obj_attr_int (obfd, vendor, list->tag, in_attr->i);
 384               break;
 385             case 2:
 386               bfd_elf_add_obj_attr_string (obfd, vendor, list->tag,
 387                                            in_attr->s);
 388               break;
 389             case 3:
 390               bfd_elf_add_obj_attr_compat (obfd, vendor, in_attr->i,
 391                                            in_attr->s);
 392               break;
 393             default:
 394               abort ();
 395             }
 396         }
 397     }
 398 }
 399
 400 /* Determine whether a GNU object attribute tag takes an integer, a
 401    string or both.  */
 402 static int
 403 gnu_obj_attrs_arg_type (int tag)
 404 {
 405   /* Except for Tag_compatibility, for GNU attributes we follow the
 406      same rule ARM ones > 32 follow: odd-numbered tags take strings
 407      and even-numbered tags take integers.  In addition, tag & 2 is
 408      nonzero for architecture-independent tags and zero for
 409      architecture-dependent ones.  */
 410   if (tag == Tag_compatibility)
 411     return 3;
 412   else
 413     return (tag & 1) != 0 ? 2 : 1;
 414 }
 415
 416 /* Determine what arguments an attribute tag takes.  */
 417 int
 418 _bfd_elf_obj_attrs_arg_type (bfd *abfd, int vendor, int tag)
 419 {
 420   switch (vendor)
 421     {
 422     case OBJ_ATTR_PROC:
 423       return get_elf_backend_data (abfd)->obj_attrs_arg_type (tag);
 424       break;
 425     case OBJ_ATTR_GNU:
 426       return gnu_obj_attrs_arg_type (tag);
 427       break;
 428     default:
 429       abort ();
 430     }
 431 }
 432
 433 /* Parse an object attributes section.  */
 434 void
 435 _bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
 436 {
 437   bfd_byte *contents;
 438   bfd_byte *p;
 439   bfd_vma len;
 440   const char *std_section;
 441
 442   contents = bfd_malloc (hdr->sh_size);
 443   if (!contents)
 444     return;
 445   if (!bfd_get_section_contents (abfd, hdr->bfd_section, contents, 0,
 446                                  hdr->sh_size))
 447     {
 448       free (contents);
 449       return;
 450     }
 451   p = contents;
 452   std_section = get_elf_backend_data (abfd)->obj_attrs_vendor;
 453   if (*(p++) == 'A')
 454     {
 455       len = hdr->sh_size - 1;
 456       while (len > 0)
 457         {
 458           int namelen;
 459           bfd_vma section_len;
 460           int vendor;
 461
 462           section_len = bfd_get_32 (abfd, p);
 463           p += 4;
 464           if (section_len > len)
 465             section_len = len;
 466           len -= section_len;
 467           namelen = strlen ((char *)p) + 1;
 468           section_len -= namelen + 4;
 469           if (std_section && strcmp ((char *)p, std_section) == 0)
 470             vendor = OBJ_ATTR_PROC;
 471           else if (strcmp ((char *)p, "gnu") == 0)
 472             vendor = OBJ_ATTR_GNU;
 473           else
 474             {
 475               /* Other vendor section.  Ignore it.  */
 476               p += namelen + section_len;
 477               continue;
 478             }
 479
 480           p += namelen;
 481           while (section_len > 0)
 482             {
 483               int tag;
 484               unsigned int n;
 485               unsigned int val;
 486               bfd_vma subsection_len;
 487               bfd_byte *end;
 488
 489               tag = read_unsigned_leb128 (abfd, p, &n);
 490               p += n;
 491               subsection_len = bfd_get_32 (abfd, p);
 492               p += 4;
 493               if (subsection_len > section_len)
 494                 subsection_len = section_len;
 495               section_len -= subsection_len;
 496               subsection_len -= n + 4;
 497               end = p + subsection_len;
 498               switch (tag)
 499                 {
 500                 case Tag_File:
 501                   while (p < end)
 502                     {
 503                       int type;
 504
 505                       tag = read_unsigned_leb128 (abfd, p, &n);
 506                       p += n;
 507                       type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
 508                       switch (type)
 509                         {
 510                         case 3:
 511                           val = read_unsigned_leb128 (abfd, p, &n);
 512                           p += n;
 513                           bfd_elf_add_obj_attr_compat (abfd, vendor, val,
 514                                                        (char *)p);
 515                           p += strlen ((char *)p) + 1;
 516                           break;
 517                         case 2:
 518                           bfd_elf_add_obj_attr_string (abfd, vendor, tag,
 519                                                        (char *)p);
 520                           p += strlen ((char *)p) + 1;
 521                           break;
 522                         case 1:
 523                           val = read_unsigned_leb128 (abfd, p, &n);
 524                           p += n;
 525                           bfd_elf_add_obj_attr_int (abfd, vendor, tag, val);
 526                           break;
 527                         default:
 528                           abort ();
 529                         }
 530                     }
 531                   break;
 532                 case Tag_Section:
 533                 case Tag_Symbol:
 534                   /* Don't have anywhere convenient to attach these.
 535                      Fall through for now.  */
 536                 default:
 537                   /* Ignore things we don't kow about.  */
 538                   p += subsection_len;
 539                   subsection_len = 0;
 540                   break;
 541                 }
 542             }
 543         }
 544     }
 545   free (contents);
 546 }
 547
 548 /* Merge common object attributes from IBFD into OBFD.  Raise an error
 549    if there are conflicting attributes.  Any processor-specific
 550    attributes have already been merged.  This must be called from the
 551    bfd_elfNN_bfd_merge_private_bfd_data hook for each individual
 552    target, along with any target-specific merging.  Because there are
 553    no common attributes other than Tag_compatibility at present, and
 554    non-"gnu" Tag_compatibility is not expected in "gnu" sections, this
 555    is not presently called for targets without their own
 556    attributes.  */
 557
 558 bfd_boolean
 559 _bfd_elf_merge_object_attributes (bfd *ibfd, bfd *obfd)
 560 {
 561   obj_attribute *in_attr;
 562   obj_attribute *out_attr;
 563   obj_attribute_list *in_list;
 564   obj_attribute_list *out_list;
 565   int vendor;
 566
 567   /* The only common attribute is currently Tag_compatibility,
 568      accepted in both processor and "gnu" sections.  */
 569   for (vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; vendor++)
 570     {
 571       in_list = elf_other_obj_attributes (ibfd)[vendor];
 572       out_list = elf_other_obj_attributes (ibfd)[vendor];
 573       while (in_list && in_list->tag == Tag_compatibility)
 574         {
 575           in_attr = &in_list->attr;
 576           if (in_attr->i == 0)
 577             continue;
 578           if (in_attr->i == 1 && strcmp (in_attr->s, "gnu") != 0)
 579             {
 580               _bfd_error_handler
 581                 (_("ERROR: %B: Must be processed by '%s' toolchain"),
 582                  ibfd, in_attr->s);
 583               return FALSE;
 584             }
 585           if (!out_list || out_list->tag != Tag_compatibility
 586               || strcmp (in_attr->s, out_list->attr.s) != 0)
 587             {
 588               /* Add this compatibility tag to the output.  */
 589               bfd_elf_add_proc_attr_compat (obfd, in_attr->i, in_attr->s);
 590               continue;
 591             }
 592           out_attr = &out_list->attr;
 593           /* Check all the input tags with the same identifier.  */
 594           for (;;)
 595             {
 596               if (out_list->tag != Tag_compatibility
 597                   || in_attr->i != out_attr->i
 598                   || strcmp (in_attr->s, out_attr->s) != 0)
 599                 {
 600                   _bfd_error_handler
 601                     (_("ERROR: %B: Incompatible object tag '%s':%d"),
 602                      ibfd, in_attr->s, in_attr->i);
 603                   return FALSE;
 604                 }
 605               in_list = in_list->next;
 606               if (in_list->tag != Tag_compatibility
 607                   || strcmp (in_attr->s, in_list->attr.s) != 0)
 608                 break;
 609               in_attr = &in_list->attr;
 610               out_list = out_list->next;
 611               if (out_list)
 612                 out_attr = &out_list->attr;
 613             }
 614
 615           /* Check the output doesn't have extra tags with this identifier.  */
 616           if (out_list && out_list->tag == Tag_compatibility
 617               && strcmp (in_attr->s, out_list->attr.s) == 0)
 618             {
 619               _bfd_error_handler
 620                 (_("ERROR: %B: Incompatible object tag '%s':%d"),
 621                  ibfd, in_attr->s, out_list->attr.i);
 622               return FALSE;
 623             }
 624         }
 625     }
 626
 627   return TRUE;
 628 }