bfd/merge.c

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