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           if (bfd_bwrite (pad, len, abfd) != len)
 311             goto err;
 312           off += len;
 313         }
 314
 315       str = entry->root.string;
 316       len = entry->len;
 317
 318       if (bfd_bwrite (str, len, abfd) != len)
 319         goto err;
 320
 321       off += len;
 322     }
 323
 324   /* Trailing alignment needed?  */
 325   off = sec->size - off;
 326   if (off != 0
 327       && bfd_bwrite (pad, off, abfd) != off)
 328     goto err;
 329
 330   if (pad != NULL)
 331     free (pad);
 332   return TRUE;
 333
 334  err:
 335   if (pad != NULL)
 336     free (pad);
 337   return FALSE;
 338 }
 339
 340 /* Register a SEC_MERGE section as a candidate for merging.
 341    This function is called for all non-dynamic SEC_MERGE input sections.  */
 342
 343 bfd_boolean
 344 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 345                         void **psecinfo)
 346 {
 347   struct sec_merge_info *sinfo;
 348   struct sec_merge_sec_info *secinfo;
 349   unsigned int align;
 350   bfd_size_type amt;
 351   bfd_byte *contents;
 352
 353   if ((abfd->flags & DYNAMIC) != 0
 354       || (sec->flags & SEC_MERGE) == 0)
 355     abort ();
 356
 357   if (sec->size == 0
 358       || (sec->flags & SEC_EXCLUDE) != 0
 359       || sec->entsize == 0)
 360     return TRUE;
 361
 362   if ((sec->flags & SEC_RELOC) != 0)
 363     {
 364       /* We aren't prepared to handle relocations in merged sections.  */
 365       return TRUE;
 366     }
 367
 368   align = sec->alignment_power;
 369   if ((sec->entsize < (unsigned) 1 << align
 370        && ((sec->entsize & (sec->entsize - 1))
 371            || !(sec->flags & SEC_STRINGS)))
 372       || (sec->entsize > (unsigned) 1 << align
 373           && (sec->entsize & (((unsigned) 1 << align) - 1))))
 374     {
 375       /* Sanity check.  If string character size is smaller than
 376          alignment, then we require character size to be a power
 377          of 2, otherwise character size must be integer multiple
 378          of alignment.  For non-string constants, alignment must
 379          be smaller than or equal to entity size and entity size
 380          must be integer multiple of alignment.  */
 381       return TRUE;
 382     }
 383
 384   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 385     if ((secinfo = sinfo->chain)
 386         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 387         && secinfo->sec->entsize == sec->entsize
 388         && secinfo->sec->alignment_power == sec->alignment_power
 389         && secinfo->sec->output_section == sec->output_section)
 390       break;
 391
 392   if (sinfo == NULL)
 393     {
 394       /* Initialize the information we need to keep track of.  */
 395       sinfo = (struct sec_merge_info *)
 396           bfd_alloc (abfd, sizeof (struct sec_merge_info));
 397       if (sinfo == NULL)
 398         goto error_return;
 399       sinfo->next = (struct sec_merge_info *) *psinfo;
 400       sinfo->chain = NULL;
 401       *psinfo = sinfo;
 402       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 403       if (sinfo->htab == NULL)
 404         goto error_return;
 405     }
 406
 407   /* Read the section from abfd.  */
 408
 409   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
 410   if (sec->flags & SEC_STRINGS)
 411     /* Some versions of gcc may emit a string without a zero terminator.
 412        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
 413        Allocate space for an extra zero.  */
 414     amt += sec->entsize;
 415   *psecinfo = bfd_alloc (abfd, amt);
 416   if (*psecinfo == NULL)
 417     goto error_return;
 418
 419   secinfo = (struct sec_merge_sec_info *) *psecinfo;
 420   if (sinfo->chain)
 421     {
 422       secinfo->next = sinfo->chain->next;
 423       sinfo->chain->next = secinfo;
 424     }
 425   else
 426     secinfo->next = secinfo;
 427   sinfo->chain = secinfo;
 428   secinfo->sec = sec;
 429   secinfo->psecinfo = psecinfo;
 430   secinfo->htab = sinfo->htab;
 431   secinfo->first_str = NULL;
 432
 433   sec->rawsize = sec->size;
 434   if (sec->flags & SEC_STRINGS)
 435     memset (secinfo->contents + sec->size, 0, sec->entsize);
 436   contents = secinfo->contents;
 437   if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
 438     goto error_return;
 439
 440   return TRUE;
 441
 442  error_return:
 443   *psecinfo = NULL;
 444   return FALSE;
 445 }
 446
 447 /* Record one section into the hash table.  */
 448 static bfd_boolean
 449 record_section (struct sec_merge_info *sinfo,
 450                 struct sec_merge_sec_info *secinfo)
 451 {
 452   asection *sec = secinfo->sec;
 453   struct sec_merge_hash_entry *entry;
 454   bfd_boolean nul;
 455   unsigned char *p, *end;
 456   bfd_vma mask, eltalign;
 457   unsigned int align, i;
 458
 459   align = sec->alignment_power;
 460   end = secinfo->contents + sec->size;
 461   nul = FALSE;
 462   mask = ((bfd_vma) 1 << align) - 1;
 463   if (sec->flags & SEC_STRINGS)
 464     {
 465       for (p = secinfo->contents; p < end; )
 466         {
 467           eltalign = p - secinfo->contents;
 468           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 469           if (!eltalign || eltalign > mask)
 470             eltalign = mask + 1;
 471           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 472                                  secinfo);
 473           if (! entry)
 474             goto error_return;
 475           p += entry->len;
 476           if (sec->entsize == 1)
 477             {
 478               while (p < end && *p == 0)
 479                 {
 480                   if (!nul && !((p - secinfo->contents) & mask))
 481                     {
 482                       nul = TRUE;
 483                       entry = sec_merge_add (sinfo->htab, "",
 484                                              (unsigned) mask + 1, secinfo);
 485                       if (! entry)
 486                         goto error_return;
 487                     }
 488                   p++;
 489                 }
 490             }
 491           else
 492             {
 493               while (p < end)
 494                 {
 495                   for (i = 0; i < sec->entsize; i++)
 496                     if (p[i] != '\0')
 497                       break;
 498                   if (i != sec->entsize)
 499                     break;
 500                   if (!nul && !((p - secinfo->contents) & mask))
 501                     {
 502                       nul = TRUE;
 503                       entry = sec_merge_add (sinfo->htab, (char *) p,
 504                                              (unsigned) mask + 1, secinfo);
 505                       if (! entry)
 506                         goto error_return;
 507                     }
 508                   p += sec->entsize;
 509                 }
 510             }
 511         }
 512     }
 513   else
 514     {
 515       for (p = secinfo->contents; p < end; p += sec->entsize)
 516         {
 517           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 518           if (! entry)
 519             goto error_return;
 520         }
 521     }
 522
 523   return TRUE;
 524
 525 error_return:
 526   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 527     *secinfo->psecinfo = NULL;
 528   return FALSE;
 529 }
 530
 531 static int
 532 strrevcmp (const void *a, const void *b)
 533 {
 534   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 535   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 536   unsigned int lenA = A->len;
 537   unsigned int lenB = B->len;
 538   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 539   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 540   int l = lenA < lenB ? lenA : lenB;
 541
 542   while (l)
 543     {
 544       if (*s != *t)
 545         return (int) *s - (int) *t;
 546       s--;
 547       t--;
 548       l--;
 549     }
 550   return lenA - lenB;
 551 }
 552
 553 /* Like strrevcmp, but for the case where all strings have the same
 554    alignment > entsize.  */
 555
 556 static int
 557 strrevcmp_align (const void *a, const void *b)
 558 {
 559   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 560   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 561   unsigned int lenA = A->len;
 562   unsigned int lenB = B->len;
 563   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 564   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 565   int l = lenA < lenB ? lenA : lenB;
 566   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 567
 568   if (tail_align != 0)
 569     return tail_align;
 570
 571   while (l)
 572     {
 573       if (*s != *t)
 574         return (int) *s - (int) *t;
 575       s--;
 576       t--;
 577       l--;
 578     }
 579   return lenA - lenB;
 580 }
 581
 582 static inline int
 583 is_suffix (const struct sec_merge_hash_entry *A,
 584            const struct sec_merge_hash_entry *B)
 585 {
 586   if (A->len <= B->len)
 587     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 588        not to be equal by the hash table.  */
 589     return 0;
 590
 591   return memcmp (A->root.string + (A->len - B->len),
 592                  B->root.string, B->len) == 0;
 593 }
 594
 595 /* This is a helper function for _bfd_merge_sections.  It attempts to
 596    merge strings matching suffixes of longer strings.  */
 597 static void
 598 merge_strings (struct sec_merge_info *sinfo)
 599 {
 600   struct sec_merge_hash_entry **array, **a, *e;
 601   struct sec_merge_sec_info *secinfo;
 602   bfd_size_type size, amt;
 603   unsigned int alignment = 0;
 604
 605   /* Now sort the strings */
 606   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 607   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 608   if (array == NULL)
 609     goto alloc_failure;
 610
 611   for (e = sinfo->htab->first, a = array; e; e = e->next)
 612     if (e->alignment)
 613       {
 614         *a++ = e;
 615         /* Adjust the length to not include the zero terminator.  */
 616         e->len -= sinfo->htab->entsize;
 617         if (alignment != e->alignment)
 618           {
 619             if (alignment == 0)
 620               alignment = e->alignment;
 621             else
 622               alignment = (unsigned) -1;
 623           }
 624       }
 625
 626   sinfo->htab->size = a - array;
 627   if (sinfo->htab->size != 0)
 628     {
 629       qsort (array, (size_t) sinfo->htab->size,
 630              sizeof (struct sec_merge_hash_entry *),
 631              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 632               ? strrevcmp_align : strrevcmp));
 633
 634       /* Loop over the sorted array and merge suffixes */
 635       e = *--a;
 636       e->len += sinfo->htab->entsize;
 637       while (--a >= array)
 638         {
 639           struct sec_merge_hash_entry *cmp = *a;
 640
 641           cmp->len += sinfo->htab->entsize;
 642           if (e->alignment >= cmp->alignment
 643               && !((e->len - cmp->len) & (cmp->alignment - 1))
 644               && is_suffix (e, cmp))
 645             {
 646               cmp->u.suffix = e;
 647               cmp->alignment = 0;
 648             }
 649           else
 650             e = cmp;
 651         }
 652     }
 653
 654 alloc_failure:
 655   if (array)
 656     free (array);
 657
 658   /* Now assign positions to the strings we want to keep.  */
 659   size = 0;
 660   secinfo = sinfo->htab->first->secinfo;
 661   for (e = sinfo->htab->first; e; e = e->next)
 662     {
 663       if (e->secinfo != secinfo)
 664         {
 665           secinfo->sec->size = size;
 666           secinfo = e->secinfo;
 667         }
 668       if (e->alignment)
 669         {
 670           if (e->secinfo->first_str == NULL)
 671             {
 672               e->secinfo->first_str = e;
 673               size = 0;
 674             }
 675           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 676           e->u.index = size;
 677           size += e->len;
 678         }
 679     }
 680   secinfo->sec->size = size;
 681   if (secinfo->sec->alignment_power != 0)
 682     {
 683       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 684       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 685     }
 686
 687   /* And now adjust the rest, removing them from the chain (but not hashtable)
 688      at the same time.  */
 689   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 690     if (e->alignment)
 691       a = &e->next;
 692     else
 693       {
 694         *a = e->next;
 695         if (e->len)
 696           {
 697             e->secinfo = e->u.suffix->secinfo;
 698             e->alignment = e->u.suffix->alignment;
 699             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 700           }
 701       }
 702 }
 703
 704 /* This function is called once after all SEC_MERGE sections are registered
 705    with _bfd_merge_section.  */
 706
 707 bfd_boolean
 708 _bfd_merge_sections (bfd *abfd,
 709                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
 710                      void *xsinfo,
 711                      void (*remove_hook) (bfd *, asection *))
 712 {
 713   struct sec_merge_info *sinfo;
 714
 715   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 716     {
 717       struct sec_merge_sec_info * secinfo;
 718
 719       if (! sinfo->chain)
 720         continue;
 721
 722       /* Move sinfo->chain to head of the chain, terminate it.  */
 723       secinfo = sinfo->chain;
 724       sinfo->chain = secinfo->next;
 725       secinfo->next = NULL;
 726
 727       /* Record the sections into the hash table.  */
 728       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 729         if (secinfo->sec->flags & SEC_EXCLUDE)
 730           {
 731             *secinfo->psecinfo = NULL;
 732             if (remove_hook)
 733               (*remove_hook) (abfd, secinfo->sec);
 734           }
 735         else if (! record_section (sinfo, secinfo))
 736           break;
 737
 738       if (secinfo)
 739         continue;
 740
 741       if (sinfo->htab->first == NULL)
 742         continue;
 743
 744       if (sinfo->htab->strings)
 745         merge_strings (sinfo);
 746       else
 747         {
 748           struct sec_merge_hash_entry *e;
 749           bfd_size_type size = 0;
 750
 751           /* Things are much simpler for non-strings.
 752              Just assign them slots in the section.  */
 753           secinfo = NULL;
 754           for (e = sinfo->htab->first; e; e = e->next)
 755             {
 756               if (e->secinfo->first_str == NULL)
 757                 {
 758                   if (secinfo)
 759                     secinfo->sec->size = size;
 760                   e->secinfo->first_str = e;
 761                   size = 0;
 762                 }
 763               size = (size + e->alignment - 1)
 764                      & ~((bfd_vma) e->alignment - 1);
 765               e->u.index = size;
 766               size += e->len;
 767               secinfo = e->secinfo;
 768             }
 769           secinfo->sec->size = size;
 770         }
 771
 772         /* Finally remove all input sections which have not made it into
 773            the hash table at all.  */
 774         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 775           if (secinfo->first_str == NULL)
 776             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
 777     }
 778
 779   return TRUE;
 780 }
 781
 782 /* Write out the merged section.  */
 783
 784 bfd_boolean
 785 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 786 {
 787   struct sec_merge_sec_info *secinfo;
 788   file_ptr pos;
 789
 790   secinfo = (struct sec_merge_sec_info *) psecinfo;
 791
 792   if (!secinfo)
 793     return FALSE;
 794
 795   if (secinfo->first_str == NULL)
 796     return TRUE;
 797
 798   /* FIXME: octets_per_byte.  */
 799   pos = sec->output_section->filepos + sec->output_offset;
 800   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 801     return FALSE;
 802
 803   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 804     return FALSE;
 805
 806   return TRUE;
 807 }
 808
 809 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 810    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 811    section and writes the new section back into *PSEC.  */
 812
 813 bfd_vma
 814 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 815                             void *psecinfo, bfd_vma offset)
 816 {
 817   struct sec_merge_sec_info *secinfo;
 818   struct sec_merge_hash_entry *entry;
 819   unsigned char *p;
 820   asection *sec = *psec;
 821
 822   secinfo = (struct sec_merge_sec_info *) psecinfo;
 823
 824   if (!secinfo)
 825     return offset;
 826
 827   if (offset >= sec->rawsize)
 828     {
 829       if (offset > sec->rawsize)
 830         {
 831           (*_bfd_error_handler)
 832             (_("%s: access beyond end of merged section (%ld)"),
 833              bfd_get_filename (sec->owner), (long) offset);
 834         }
 835       return secinfo->first_str ? sec->size : 0;
 836     }
 837
 838   if (secinfo->htab->strings)
 839     {
 840       if (sec->entsize == 1)
 841         {
 842           p = secinfo->contents + offset - 1;
 843           while (p >= secinfo->contents && *p)
 844             --p;
 845           ++p;
 846         }
 847       else
 848         {
 849           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 850           p -= sec->entsize;
 851           while (p >= secinfo->contents)
 852             {
 853               unsigned int i;
 854
 855               for (i = 0; i < sec->entsize; ++i)
 856                 if (p[i] != '\0')
 857                   break;
 858               if (i == sec->entsize)
 859                 break;
 860               p -= sec->entsize;
 861             }
 862           p += sec->entsize;
 863         }
 864     }
 865   else
 866     {
 867       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 868     }
 869   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
 870   if (!entry)
 871     {
 872       if (! secinfo->htab->strings)
 873         abort ();
 874       /* This should only happen if somebody points into the padding
 875          after a NUL character but before next entity.  */
 876       if (*p)
 877         abort ();
 878       if (! secinfo->htab->first)
 879         abort ();
 880       entry = secinfo->htab->first;
 881       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 882            - entry->len);
 883     }
 884
 885   *psec = entry->secinfo->sec;
 886   return entry->u.index + (secinfo->contents + offset - p);
 887 }