bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   3    Free Software Foundation, Inc.
   4    Written by Jakub Jelinek <jakub@redhat.com>.
   5
   6    This file is part of BFD, the Binary File Descriptor library.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21    MA 02110-1301, USA.  */
  22
  23
  24 /* This file contains support for merging duplicate entities within sections,
  25    as used in ELF SHF_MERGE.  */
  26
  27 #include "sysdep.h"
  28 #include "bfd.h"
  29 #include "libbfd.h"
  30 #include "hashtab.h"
  31 #include "libiberty.h"
  32
  33 struct sec_merge_sec_info;
  34
  35 /* An entry in the section merge hash table.  */
  36
  37 struct sec_merge_hash_entry
  38 {
  39   struct bfd_hash_entry root;
  40   /* Length of this entry.  This includes the zero terminator.  */
  41   unsigned int len;
  42   /* Start of this string needs to be aligned to
  43      alignment octets (not 1 << align).  */
  44   unsigned int alignment;
  45   union
  46   {
  47     /* Index within the merged section.  */
  48     bfd_size_type index;
  49     /* Entry this is a suffix of (if alignment is 0).  */
  50     struct sec_merge_hash_entry *suffix;
  51   } u;
  52   /* Which section is it in.  */
  53   struct sec_merge_sec_info *secinfo;
  54   /* Next entity in the hash table.  */
  55   struct sec_merge_hash_entry *next;
  56 };
  57
  58 /* The section merge hash table.  */
  59
  60 struct sec_merge_hash
  61 {
  62   struct bfd_hash_table table;
  63   /* Next available index.  */
  64   bfd_size_type size;
  65   /* First entity in the SEC_MERGE sections of this type.  */
  66   struct sec_merge_hash_entry *first;
  67   /* Last entity in the SEC_MERGE sections of this type.  */
  68   struct sec_merge_hash_entry *last;
  69   /* Entity size.  */
  70   unsigned int entsize;
  71   /* Are entries fixed size or zero terminated strings?  */
  72   bfd_boolean strings;
  73 };
  74
  75 struct sec_merge_info
  76 {
  77   /* Chain of sec_merge_infos.  */
  78   struct sec_merge_info *next;
  79   /* Chain of sec_merge_sec_infos.  */
  80   struct sec_merge_sec_info *chain;
  81   /* A hash table used to hold section content.  */
  82   struct sec_merge_hash *htab;
  83 };
  84
  85 struct sec_merge_sec_info
  86 {
  87   /* Chain of sec_merge_sec_infos.  */
  88   struct sec_merge_sec_info *next;
  89   /* The corresponding section.  */
  90   asection *sec;
  91   /* Pointer to merge_info pointing to us.  */
  92   void **psecinfo;
  93   /* A hash table used to hold section content.  */
  94   struct sec_merge_hash *htab;
  95   /* First string in this section.  */
  96   struct sec_merge_hash_entry *first_str;
  97   /* Original section content.  */
  98   unsigned char contents[1];
  99 };
 100
 101
 102 /* Routine to create an entry in a section merge hashtab.  */
 103
 104 static struct bfd_hash_entry *
 105 sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
 106                         struct bfd_hash_table *table, const char *string)
 107 {
 108   /* Allocate the structure if it has not already been allocated by a
 109      subclass.  */
 110   if (entry == NULL)
 111     entry = (struct bfd_hash_entry *)
 112         bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
 113   if (entry == NULL)
 114     return NULL;
 115
 116   /* Call the allocation method of the superclass.  */
 117   entry = bfd_hash_newfunc (entry, table, string);
 118
 119   if (entry != NULL)
 120     {
 121       /* Initialize the local fields.  */
 122       struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 123
 124       ret->u.suffix = NULL;
 125       ret->alignment = 0;
 126       ret->secinfo = NULL;
 127       ret->next = NULL;
 128     }
 129
 130   return entry;
 131 }
 132
 133 /* Look up an entry in a section merge hash table.  */
 134
 135 static struct sec_merge_hash_entry *
 136 sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
 137                        unsigned int alignment, bfd_boolean create)
 138 {
 139   const unsigned char *s;
 140   unsigned long hash;
 141   unsigned int c;
 142   struct sec_merge_hash_entry *hashp;
 143   unsigned int len, i;
 144   unsigned int _index;
 145
 146   hash = 0;
 147   len = 0;
 148   s = (const unsigned char *) string;
 149   if (table->strings)
 150     {
 151       if (table->entsize == 1)
 152         {
 153           while ((c = *s++) != '\0')
 154             {
 155               hash += c + (c << 17);
 156               hash ^= hash >> 2;
 157               ++len;
 158             }
 159           hash += len + (len << 17);
 160         }
 161       else
 162         {
 163           for (;;)
 164             {
 165               for (i = 0; i < table->entsize; ++i)
 166                 if (s[i] != '\0')
 167                   break;
 168               if (i == table->entsize)
 169                 break;
 170               for (i = 0; i < table->entsize; ++i)
 171                 {
 172                   c = *s++;
 173                   hash += c + (c << 17);
 174                   hash ^= hash >> 2;
 175                 }
 176               ++len;
 177             }
 178           hash += len + (len << 17);
 179           len *= table->entsize;
 180         }
 181       hash ^= hash >> 2;
 182       len += table->entsize;
 183     }
 184   else
 185     {
 186       for (i = 0; i < table->entsize; ++i)
 187         {
 188           c = *s++;
 189           hash += c + (c << 17);
 190           hash ^= hash >> 2;
 191         }
 192       len = table->entsize;
 193     }
 194
 195   _index = hash % table->table.size;
 196   for (hashp = (struct sec_merge_hash_entry *) table->table.table[_index];
 197        hashp != NULL;
 198        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 199     {
 200       if (hashp->root.hash == hash
 201           && len == hashp->len
 202           && memcmp (hashp->root.string, string, len) == 0)
 203         {
 204           /* If the string we found does not have at least the required
 205              alignment, we need to insert another copy.  */
 206           if (hashp->alignment < alignment)
 207             {
 208               if (create)
 209                 {
 210                   /*  Mark the less aligned copy as deleted.  */
 211                   hashp->len = 0;
 212                   hashp->alignment = 0;
 213                 }
 214               break;
 215             }
 216           return hashp;
 217         }
 218     }
 219
 220   if (! create)
 221     return NULL;
 222
 223   hashp = ((struct sec_merge_hash_entry *)
 224            bfd_hash_insert (&table->table, string, hash));
 225   if (hashp == NULL)
 226     return NULL;
 227   hashp->len = len;
 228   hashp->alignment = alignment;
 229   return hashp;
 230 }
 231
 232 /* Create a new hash table.  */
 233
 234 static struct sec_merge_hash *
 235 sec_merge_init (unsigned int entsize, bfd_boolean strings)
 236 {
 237   struct sec_merge_hash *table;
 238
 239   table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));
 240   if (table == NULL)
 241     return NULL;
 242
 243   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
 244                                sizeof (struct sec_merge_hash_entry), 16699))
 245     {
 246       free (table);
 247       return NULL;
 248     }
 249
 250   table->size = 0;
 251   table->first = NULL;
 252   table->last = NULL;
 253   table->entsize = entsize;
 254   table->strings = strings;
 255
 256   return table;
 257 }
 258
 259 /* Get the index of an entity in a hash table, adding it if it is not
 260    already present.  */
 261
 262 static struct sec_merge_hash_entry *
 263 sec_merge_add (struct sec_merge_hash *tab, const char *str,
 264                unsigned int alignment, struct sec_merge_sec_info *secinfo)
 265 {
 266   struct sec_merge_hash_entry *entry;
 267
 268   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
 269   if (entry == NULL)
 270     return NULL;
 271
 272   if (entry->secinfo == NULL)
 273     {
 274       tab->size++;
 275       entry->secinfo = secinfo;
 276       if (tab->first == NULL)
 277         tab->first = entry;
 278       else
 279         tab->last->next = entry;
 280       tab->last = entry;
 281     }
 282
 283   return entry;
 284 }
 285
 286 static bfd_boolean
 287 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
 288 {
 289   struct sec_merge_sec_info *secinfo = entry->secinfo;
 290   asection *sec = secinfo->sec;
 291   char *pad = NULL;
 292   bfd_size_type off = 0;
 293   int alignment_power = sec->output_section->alignment_power;
 294
 295   if (alignment_power)
 296     {
 297       pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 298       if (pad == NULL)
 299         return FALSE;
 300     }
 301
 302   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 303     {
 304       const char *str;
 305       bfd_size_type len;
 306
 307       len = -off & (entry->alignment - 1);
 308       if (len != 0)
 309         {
 310           /* We should never have an entry with an alignment
 311              greater than the section's alignment.  */
 312           BFD_ASSERT (len <= (bfd_size_type) (1 << alignment_power));
 313           if (bfd_bwrite (pad, len, abfd) != len)
 314             goto err;
 315           off += len;
 316         }
 317
 318       str = entry->root.string;
 319       len = entry->len;
 320
 321       if (bfd_bwrite (str, len, abfd) != len)
 322         goto err;
 323
 324       off += len;
 325     }
 326
 327   /* Trailing alignment needed?  */
 328   off = sec->size - off;
 329   if (off != 0
 330       && alignment_power
 331       && bfd_bwrite (pad, off, abfd) != off)
 332     goto err;
 333
 334   if (pad != NULL)
 335     free (pad);
 336   return TRUE;
 337
 338  err:
 339   if (pad != NULL)
 340     free (pad);
 341   return FALSE;
 342 }
 343
 344 /* Register a SEC_MERGE section as a candidate for merging.
 345    This function is called for all non-dynamic SEC_MERGE input sections.  */
 346
 347 bfd_boolean
 348 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 349                         void **psecinfo)
 350 {
 351   struct sec_merge_info *sinfo;
 352   struct sec_merge_sec_info *secinfo;
 353   unsigned int align;
 354   bfd_size_type amt;
 355
 356   if ((abfd->flags & DYNAMIC) != 0
 357       || (sec->flags & SEC_MERGE) == 0)
 358     abort ();
 359
 360   if (sec->size == 0
 361       || (sec->flags & SEC_EXCLUDE) != 0
 362       || sec->entsize == 0)
 363     return TRUE;
 364
 365   if ((sec->flags & SEC_RELOC) != 0)
 366     {
 367       /* We aren't prepared to handle relocations in merged sections.  */
 368       return TRUE;
 369     }
 370
 371   align = sec->alignment_power;
 372   if ((sec->entsize < (unsigned) 1 << align
 373        && ((sec->entsize & (sec->entsize - 1))
 374            || !(sec->flags & SEC_STRINGS)))
 375       || (sec->entsize > (unsigned) 1 << align
 376           && (sec->entsize & (((unsigned) 1 << align) - 1))))
 377     {
 378       /* Sanity check.  If string character size is smaller than
 379          alignment, then we require character size to be a power
 380          of 2, otherwise character size must be integer multiple
 381          of alignment.  For non-string constants, alignment must
 382          be smaller than or equal to entity size and entity size
 383          must be integer multiple of alignment.  */
 384       return TRUE;
 385     }
 386
 387   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 388     if ((secinfo = sinfo->chain)
 389         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 390         && secinfo->sec->entsize == sec->entsize
 391         && secinfo->sec->alignment_power == sec->alignment_power
 392         && secinfo->sec->output_section == sec->output_section)
 393       break;
 394
 395   if (sinfo == NULL)
 396     {
 397       /* Initialize the information we need to keep track of.  */
 398       sinfo = (struct sec_merge_info *)
 399           bfd_alloc (abfd, sizeof (struct sec_merge_info));
 400       if (sinfo == NULL)
 401         goto error_return;
 402       sinfo->next = (struct sec_merge_info *) *psinfo;
 403       sinfo->chain = NULL;
 404       *psinfo = sinfo;
 405       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 406       if (sinfo->htab == NULL)
 407         goto error_return;
 408     }
 409
 410   /* Read the section from abfd.  */
 411
 412   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
 413   if (sec->flags & SEC_STRINGS)
 414     /* Some versions of gcc may emit a string without a zero terminator.
 415        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
 416        Allocate space for an extra zero.  */
 417     amt += sec->entsize;
 418   *psecinfo = bfd_alloc (abfd, amt);
 419   if (*psecinfo == NULL)
 420     goto error_return;
 421
 422   secinfo = (struct sec_merge_sec_info *) *psecinfo;
 423   if (sinfo->chain)
 424     {
 425       secinfo->next = sinfo->chain->next;
 426       sinfo->chain->next = secinfo;
 427     }
 428   else
 429     secinfo->next = secinfo;
 430   sinfo->chain = secinfo;
 431   secinfo->sec = sec;
 432   secinfo->psecinfo = psecinfo;
 433   secinfo->htab = sinfo->htab;
 434   secinfo->first_str = NULL;
 435
 436   sec->rawsize = sec->size;
 437   if (sec->flags & SEC_STRINGS)
 438     memset (secinfo->contents + sec->size, 0, sec->entsize);
 439   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 440                                   0, sec->size))
 441     goto error_return;
 442
 443   return TRUE;
 444
 445  error_return:
 446   *psecinfo = NULL;
 447   return FALSE;
 448 }
 449
 450 /* Record one section into the hash table.  */
 451 static bfd_boolean
 452 record_section (struct sec_merge_info *sinfo,
 453                 struct sec_merge_sec_info *secinfo)
 454 {
 455   asection *sec = secinfo->sec;
 456   struct sec_merge_hash_entry *entry;
 457   bfd_boolean nul;
 458   unsigned char *p, *end;
 459   bfd_vma mask, eltalign;
 460   unsigned int align, i;
 461
 462   align = sec->alignment_power;
 463   end = secinfo->contents + sec->size;
 464   nul = FALSE;
 465   mask = ((bfd_vma) 1 << align) - 1;
 466   if (sec->flags & SEC_STRINGS)
 467     {
 468       for (p = secinfo->contents; p < end; )
 469         {
 470           eltalign = p - secinfo->contents;
 471           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 472           if (!eltalign || eltalign > mask)
 473             eltalign = mask + 1;
 474           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 475                                  secinfo);
 476           if (! entry)
 477             goto error_return;
 478           p += entry->len;
 479           if (sec->entsize == 1)
 480             {
 481               while (p < end && *p == 0)
 482                 {
 483                   if (!nul && !((p - secinfo->contents) & mask))
 484                     {
 485                       nul = TRUE;
 486                       entry = sec_merge_add (sinfo->htab, "",
 487                                              (unsigned) mask + 1, secinfo);
 488                       if (! entry)
 489                         goto error_return;
 490                     }
 491                   p++;
 492                 }
 493             }
 494           else
 495             {
 496               while (p < end)
 497                 {
 498                   for (i = 0; i < sec->entsize; i++)
 499                     if (p[i] != '\0')
 500                       break;
 501                   if (i != sec->entsize)
 502                     break;
 503                   if (!nul && !((p - secinfo->contents) & mask))
 504                     {
 505                       nul = TRUE;
 506                       entry = sec_merge_add (sinfo->htab, (char *) p,
 507                                              (unsigned) mask + 1, secinfo);
 508                       if (! entry)
 509                         goto error_return;
 510                     }
 511                   p += sec->entsize;
 512                 }
 513             }
 514         }
 515     }
 516   else
 517     {
 518       for (p = secinfo->contents; p < end; p += sec->entsize)
 519         {
 520           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 521           if (! entry)
 522             goto error_return;
 523         }
 524     }
 525
 526   return TRUE;
 527
 528 error_return:
 529   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 530     *secinfo->psecinfo = NULL;
 531   return FALSE;
 532 }
 533
 534 static int
 535 strrevcmp (const void *a, const void *b)
 536 {
 537   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 538   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 539   unsigned int lenA = A->len;
 540   unsigned int lenB = B->len;
 541   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 542   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 543   int l = lenA < lenB ? lenA : lenB;
 544
 545   while (l)
 546     {
 547       if (*s != *t)
 548         return (int) *s - (int) *t;
 549       s--;
 550       t--;
 551       l--;
 552     }
 553   return lenA - lenB;
 554 }
 555
 556 /* Like strrevcmp, but for the case where all strings have the same
 557    alignment > entsize.  */
 558
 559 static int
 560 strrevcmp_align (const void *a, const void *b)
 561 {
 562   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 563   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 564   unsigned int lenA = A->len;
 565   unsigned int lenB = B->len;
 566   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 567   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 568   int l = lenA < lenB ? lenA : lenB;
 569   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 570
 571   if (tail_align != 0)
 572     return tail_align;
 573
 574   while (l)
 575     {
 576       if (*s != *t)
 577         return (int) *s - (int) *t;
 578       s--;
 579       t--;
 580       l--;
 581     }
 582   return lenA - lenB;
 583 }
 584
 585 static inline int
 586 is_suffix (const struct sec_merge_hash_entry *A,
 587            const struct sec_merge_hash_entry *B)
 588 {
 589   if (A->len <= B->len)
 590     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 591        not to be equal by the hash table.  */
 592     return 0;
 593
 594   return memcmp (A->root.string + (A->len - B->len),
 595                  B->root.string, B->len) == 0;
 596 }
 597
 598 /* This is a helper function for _bfd_merge_sections.  It attempts to
 599    merge strings matching suffixes of longer strings.  */
 600 static void
 601 merge_strings (struct sec_merge_info *sinfo)
 602 {
 603   struct sec_merge_hash_entry **array, **a, *e;
 604   struct sec_merge_sec_info *secinfo;
 605   bfd_size_type size, amt;
 606   unsigned int alignment = 0;
 607
 608   /* Now sort the strings */
 609   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 610   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 611   if (array == NULL)
 612     goto alloc_failure;
 613
 614   for (e = sinfo->htab->first, a = array; e; e = e->next)
 615     if (e->alignment)
 616       {
 617         *a++ = e;
 618         /* Adjust the length to not include the zero terminator.  */
 619         e->len -= sinfo->htab->entsize;
 620         if (alignment != e->alignment)
 621           {
 622             if (alignment == 0)
 623               alignment = e->alignment;
 624             else
 625               alignment = (unsigned) -1;
 626           }
 627       }
 628
 629   sinfo->htab->size = a - array;
 630   if (sinfo->htab->size != 0)
 631     {
 632       qsort (array, (size_t) sinfo->htab->size,
 633              sizeof (struct sec_merge_hash_entry *),
 634              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 635               ? strrevcmp_align : strrevcmp));
 636
 637       /* Loop over the sorted array and merge suffixes */
 638       e = *--a;
 639       e->len += sinfo->htab->entsize;
 640       while (--a >= array)
 641         {
 642           struct sec_merge_hash_entry *cmp = *a;
 643
 644           cmp->len += sinfo->htab->entsize;
 645           if (e->alignment >= cmp->alignment
 646               && !((e->len - cmp->len) & (cmp->alignment - 1))
 647               && is_suffix (e, cmp))
 648             {
 649               cmp->u.suffix = e;
 650               cmp->alignment = 0;
 651             }
 652           else
 653             e = cmp;
 654         }
 655     }
 656
 657 alloc_failure:
 658   if (array)
 659     free (array);
 660
 661   /* Now assign positions to the strings we want to keep.  */
 662   size = 0;
 663   secinfo = sinfo->htab->first->secinfo;
 664   for (e = sinfo->htab->first; e; e = e->next)
 665     {
 666       if (e->secinfo != secinfo)
 667         {
 668           secinfo->sec->size = size;
 669           secinfo = e->secinfo;
 670         }
 671       if (e->alignment)
 672         {
 673           if (e->secinfo->first_str == NULL)
 674             {
 675               e->secinfo->first_str = e;
 676               size = 0;
 677             }
 678           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 679           e->u.index = size;
 680           size += e->len;
 681         }
 682     }
 683   secinfo->sec->size = size;
 684   if (secinfo->sec->alignment_power != 0)
 685     {
 686       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 687       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 688     }
 689
 690   /* And now adjust the rest, removing them from the chain (but not hashtable)
 691      at the same time.  */
 692   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 693     if (e->alignment)
 694       a = &e->next;
 695     else
 696       {
 697         *a = e->next;
 698         if (e->len)
 699           {
 700             e->secinfo = e->u.suffix->secinfo;
 701             e->alignment = e->u.suffix->alignment;
 702             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 703           }
 704       }
 705 }
 706
 707 /* This function is called once after all SEC_MERGE sections are registered
 708    with _bfd_merge_section.  */
 709
 710 bfd_boolean
 711 _bfd_merge_sections (bfd *abfd,
 712                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
 713                      void *xsinfo,
 714                      void (*remove_hook) (bfd *, asection *))
 715 {
 716   struct sec_merge_info *sinfo;
 717
 718   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 719     {
 720       struct sec_merge_sec_info * secinfo;
 721
 722       if (! sinfo->chain)
 723         continue;
 724
 725       /* Move sinfo->chain to head of the chain, terminate it.  */
 726       secinfo = sinfo->chain;
 727       sinfo->chain = secinfo->next;
 728       secinfo->next = NULL;
 729
 730       /* Record the sections into the hash table.  */
 731       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 732         if (secinfo->sec->flags & SEC_EXCLUDE)
 733           {
 734             *secinfo->psecinfo = NULL;
 735             if (remove_hook)
 736               (*remove_hook) (abfd, secinfo->sec);
 737           }
 738         else if (! record_section (sinfo, secinfo))
 739           break;
 740
 741       if (secinfo)
 742         continue;
 743
 744       if (sinfo->htab->first == NULL)
 745         continue;
 746
 747       if (sinfo->htab->strings)
 748         merge_strings (sinfo);
 749       else
 750         {
 751           struct sec_merge_hash_entry *e;
 752           bfd_size_type size = 0;
 753
 754           /* Things are much simpler for non-strings.
 755              Just assign them slots in the section.  */
 756           secinfo = NULL;
 757           for (e = sinfo->htab->first; e; e = e->next)
 758             {
 759               if (e->secinfo->first_str == NULL)
 760                 {
 761                   if (secinfo)
 762                     secinfo->sec->size = size;
 763                   e->secinfo->first_str = e;
 764                   size = 0;
 765                 }
 766               size = (size + e->alignment - 1)
 767                      & ~((bfd_vma) e->alignment - 1);
 768               e->u.index = size;
 769               size += e->len;
 770               secinfo = e->secinfo;
 771             }
 772           secinfo->sec->size = size;
 773         }
 774
 775         /* Finally remove all input sections which have not made it into
 776            the hash table at all.  */
 777         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 778           if (secinfo->first_str == NULL)
 779             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
 780     }
 781
 782   return TRUE;
 783 }
 784
 785 /* Write out the merged section.  */
 786
 787 bfd_boolean
 788 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 789 {
 790   struct sec_merge_sec_info *secinfo;
 791   file_ptr pos;
 792
 793   secinfo = (struct sec_merge_sec_info *) psecinfo;
 794
 795   if (!secinfo)
 796     return FALSE;
 797
 798   if (secinfo->first_str == NULL)
 799     return TRUE;
 800
 801   /* FIXME: octets_per_byte.  */
 802   pos = sec->output_section->filepos + sec->output_offset;
 803   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 804     return FALSE;
 805
 806   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 807     return FALSE;
 808
 809   return TRUE;
 810 }
 811
 812 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 813    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 814    section and writes the new section back into *PSEC.  */
 815
 816 bfd_vma
 817 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 818                             void *psecinfo, bfd_vma offset)
 819 {
 820   struct sec_merge_sec_info *secinfo;
 821   struct sec_merge_hash_entry *entry;
 822   unsigned char *p;
 823   asection *sec = *psec;
 824
 825   secinfo = (struct sec_merge_sec_info *) psecinfo;
 826
 827   if (!secinfo)
 828     return offset;
 829
 830   if (offset >= sec->rawsize)
 831     {
 832       if (offset > sec->rawsize)
 833         {
 834           (*_bfd_error_handler)
 835             (_("%s: access beyond end of merged section (%ld)"),
 836              bfd_get_filename (sec->owner), (long) offset);
 837         }
 838       return secinfo->first_str ? sec->size : 0;
 839     }
 840
 841   if (secinfo->htab->strings)
 842     {
 843       if (sec->entsize == 1)
 844         {
 845           p = secinfo->contents + offset - 1;
 846           while (p >= secinfo->contents && *p)
 847             --p;
 848           ++p;
 849         }
 850       else
 851         {
 852           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 853           p -= sec->entsize;
 854           while (p >= secinfo->contents)
 855             {
 856               unsigned int i;
 857
 858               for (i = 0; i < sec->entsize; ++i)
 859                 if (p[i] != '\0')
 860                   break;
 861               if (i == sec->entsize)
 862                 break;
 863               p -= sec->entsize;
 864             }
 865           p += sec->entsize;
 866         }
 867     }
 868   else
 869     {
 870       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 871     }
 872   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
 873   if (!entry)
 874     {
 875       if (! secinfo->htab->strings)
 876         abort ();
 877       /* This should only happen if somebody points into the padding
 878          after a NUL character but before next entity.  */
 879       if (*p)
 880         abort ();
 881       if (! secinfo->htab->first)
 882         abort ();
 883       entry = secinfo->htab->first;
 884       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 885            - entry->len);
 886     }
 887
 888   *psec = entry->secinfo->sec;
 889   return entry->u.index + (secinfo->contents + offset - p);
 890 }