bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007
   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 = bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
 112   if (entry == NULL)
 113     return NULL;
 114
 115   /* Call the allocation method of the superclass.  */
 116   entry = bfd_hash_newfunc (entry, table, string);
 117
 118   if (entry != NULL)
 119     {
 120       /* Initialize the local fields.  */
 121       struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 122
 123       ret->u.suffix = NULL;
 124       ret->alignment = 0;
 125       ret->secinfo = NULL;
 126       ret->next = NULL;
 127     }
 128
 129   return entry;
 130 }
 131
 132 /* Look up an entry in a section merge hash table.  */
 133
 134 static struct sec_merge_hash_entry *
 135 sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
 136                        unsigned int alignment, bfd_boolean create)
 137 {
 138   register const unsigned char *s;
 139   register unsigned long hash;
 140   register unsigned int c;
 141   struct sec_merge_hash_entry *hashp;
 142   unsigned int len, i;
 143   unsigned int index;
 144
 145   hash = 0;
 146   len = 0;
 147   s = (const unsigned char *) string;
 148   if (table->strings)
 149     {
 150       if (table->entsize == 1)
 151         {
 152           while ((c = *s++) != '\0')
 153             {
 154               hash += c + (c << 17);
 155               hash ^= hash >> 2;
 156               ++len;
 157             }
 158           hash += len + (len << 17);
 159         }
 160       else
 161         {
 162           for (;;)
 163             {
 164               for (i = 0; i < table->entsize; ++i)
 165                 if (s[i] != '\0')
 166                   break;
 167               if (i == table->entsize)
 168                 break;
 169               for (i = 0; i < table->entsize; ++i)
 170                 {
 171                   c = *s++;
 172                   hash += c + (c << 17);
 173                   hash ^= hash >> 2;
 174                 }
 175               ++len;
 176             }
 177           hash += len + (len << 17);
 178           len *= table->entsize;
 179         }
 180       hash ^= hash >> 2;
 181       len += table->entsize;
 182     }
 183   else
 184     {
 185       for (i = 0; i < table->entsize; ++i)
 186         {
 187           c = *s++;
 188           hash += c + (c << 17);
 189           hash ^= hash >> 2;
 190         }
 191       len = table->entsize;
 192     }
 193
 194   index = hash % table->table.size;
 195   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 196        hashp != NULL;
 197        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 198     {
 199       if (hashp->root.hash == hash
 200           && len == hashp->len
 201           && memcmp (hashp->root.string, string, len) == 0)
 202         {
 203           /* If the string we found does not have at least the required
 204              alignment, we need to insert another copy.  */
 205           if (hashp->alignment < alignment)
 206             {
 207               if (create)
 208                 {
 209                   /*  Mark the less aligned copy as deleted.  */
 210                   hashp->len = 0;
 211                   hashp->alignment = 0;
 212                 }
 213               break;
 214             }
 215           return hashp;
 216         }
 217     }
 218
 219   if (! create)
 220     return NULL;
 221
 222   hashp = ((struct sec_merge_hash_entry *)
 223            sec_merge_hash_newfunc (NULL, &table->table, string));
 224   if (hashp == NULL)
 225     return NULL;
 226   hashp->root.string = string;
 227   hashp->root.hash = hash;
 228   hashp->len = len;
 229   hashp->alignment = alignment;
 230   hashp->root.next = table->table.table[index];
 231   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 232
 233   return hashp;
 234 }
 235
 236 /* Create a new hash table.  */
 237
 238 static struct sec_merge_hash *
 239 sec_merge_init (unsigned int entsize, bfd_boolean strings)
 240 {
 241   struct sec_merge_hash *table;
 242
 243   table = bfd_malloc (sizeof (struct sec_merge_hash));
 244   if (table == NULL)
 245     return NULL;
 246
 247   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
 248                                sizeof (struct sec_merge_hash_entry), 16699))
 249     {
 250       free (table);
 251       return NULL;
 252     }
 253
 254   table->size = 0;
 255   table->first = NULL;
 256   table->last = NULL;
 257   table->entsize = entsize;
 258   table->strings = strings;
 259
 260   return table;
 261 }
 262
 263 /* Get the index of an entity in a hash table, adding it if it is not
 264    already present.  */
 265
 266 static struct sec_merge_hash_entry *
 267 sec_merge_add (struct sec_merge_hash *tab, const char *str,
 268                unsigned int alignment, struct sec_merge_sec_info *secinfo)
 269 {
 270   register struct sec_merge_hash_entry *entry;
 271
 272   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
 273   if (entry == NULL)
 274     return NULL;
 275
 276   if (entry->secinfo == NULL)
 277     {
 278       tab->size++;
 279       entry->secinfo = secinfo;
 280       if (tab->first == NULL)
 281         tab->first = entry;
 282       else
 283         tab->last->next = entry;
 284       tab->last = entry;
 285     }
 286
 287   return entry;
 288 }
 289
 290 static bfd_boolean
 291 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
 292 {
 293   struct sec_merge_sec_info *secinfo = entry->secinfo;
 294   asection *sec = secinfo->sec;
 295   char *pad = NULL;
 296   bfd_size_type off = 0;
 297   int alignment_power = sec->output_section->alignment_power;
 298
 299   if (alignment_power)
 300     {
 301       pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 302       if (pad == NULL)
 303         return FALSE;
 304     }
 305
 306   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 307     {
 308       const char *str;
 309       bfd_size_type len;
 310
 311       len = -off & (entry->alignment - 1);
 312       if (len != 0)
 313         {
 314           if (bfd_bwrite (pad, len, abfd) != len)
 315             goto err;
 316           off += len;
 317         }
 318
 319       str = entry->root.string;
 320       len = entry->len;
 321
 322       if (bfd_bwrite (str, len, abfd) != len)
 323         goto err;
 324
 325       off += len;
 326     }
 327
 328   /* Trailing alignment needed?  */
 329   off = sec->size - off;
 330   if (off != 0
 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 = bfd_alloc (abfd, sizeof (struct sec_merge_info));
 399       if (sinfo == NULL)
 400         goto error_return;
 401       sinfo->next = (struct sec_merge_info *) *psinfo;
 402       sinfo->chain = NULL;
 403       *psinfo = sinfo;
 404       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 405       if (sinfo->htab == NULL)
 406         goto error_return;
 407     }
 408
 409   /* Read the section from abfd.  */
 410
 411   amt = sizeof (struct sec_merge_sec_info) + sec->size - 1;
 412   *psecinfo = bfd_alloc (abfd, amt);
 413   if (*psecinfo == NULL)
 414     goto error_return;
 415
 416   secinfo = (struct sec_merge_sec_info *) *psecinfo;
 417   if (sinfo->chain)
 418     {
 419       secinfo->next = sinfo->chain->next;
 420       sinfo->chain->next = secinfo;
 421     }
 422   else
 423     secinfo->next = secinfo;
 424   sinfo->chain = secinfo;
 425   secinfo->sec = sec;
 426   secinfo->psecinfo = psecinfo;
 427   secinfo->htab = sinfo->htab;
 428   secinfo->first_str = NULL;
 429
 430   sec->rawsize = sec->size;
 431   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 432                                   0, sec->size))
 433     goto error_return;
 434
 435   return TRUE;
 436
 437  error_return:
 438   *psecinfo = NULL;
 439   return FALSE;
 440 }
 441
 442 /* Record one section into the hash table.  */
 443 static bfd_boolean
 444 record_section (struct sec_merge_info *sinfo,
 445                 struct sec_merge_sec_info *secinfo)
 446 {
 447   asection *sec = secinfo->sec;
 448   struct sec_merge_hash_entry *entry;
 449   bfd_boolean nul;
 450   unsigned char *p, *end;
 451   bfd_vma mask, eltalign;
 452   unsigned int align, i;
 453
 454   align = sec->alignment_power;
 455   end = secinfo->contents + sec->size;
 456   nul = FALSE;
 457   mask = ((bfd_vma) 1 << align) - 1;
 458   if (sec->flags & SEC_STRINGS)
 459     {
 460       for (p = secinfo->contents; p < end; )
 461         {
 462           eltalign = p - secinfo->contents;
 463           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 464           if (!eltalign || eltalign > mask)
 465             eltalign = mask + 1;
 466           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 467                                  secinfo);
 468           if (! entry)
 469             goto error_return;
 470           p += entry->len;
 471           if (sec->entsize == 1)
 472             {
 473               while (p < end && *p == 0)
 474                 {
 475                   if (!nul && !((p - secinfo->contents) & mask))
 476                     {
 477                       nul = TRUE;
 478                       entry = sec_merge_add (sinfo->htab, "",
 479                                              (unsigned) mask + 1, secinfo);
 480                       if (! entry)
 481                         goto error_return;
 482                     }
 483                   p++;
 484                 }
 485             }
 486           else
 487             {
 488               while (p < end)
 489                 {
 490                   for (i = 0; i < sec->entsize; i++)
 491                     if (p[i] != '\0')
 492                       break;
 493                   if (i != sec->entsize)
 494                     break;
 495                   if (!nul && !((p - secinfo->contents) & mask))
 496                     {
 497                       nul = TRUE;
 498                       entry = sec_merge_add (sinfo->htab, (char *) p,
 499                                              (unsigned) mask + 1, secinfo);
 500                       if (! entry)
 501                         goto error_return;
 502                     }
 503                   p += sec->entsize;
 504                 }
 505             }
 506         }
 507     }
 508   else
 509     {
 510       for (p = secinfo->contents; p < end; p += sec->entsize)
 511         {
 512           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 513           if (! entry)
 514             goto error_return;
 515         }
 516     }
 517
 518   return TRUE;
 519
 520 error_return:
 521   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 522     *secinfo->psecinfo = NULL;
 523   return FALSE;
 524 }
 525
 526 static int
 527 strrevcmp (const void *a, const void *b)
 528 {
 529   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 530   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 531   unsigned int lenA = A->len;
 532   unsigned int lenB = B->len;
 533   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 534   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 535   int l = lenA < lenB ? lenA : lenB;
 536
 537   while (l)
 538     {
 539       if (*s != *t)
 540         return (int) *s - (int) *t;
 541       s--;
 542       t--;
 543       l--;
 544     }
 545   return lenA - lenB;
 546 }
 547
 548 /* Like strrevcmp, but for the case where all strings have the same
 549    alignment > entsize.  */
 550
 551 static int
 552 strrevcmp_align (const void *a, const void *b)
 553 {
 554   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 555   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 556   unsigned int lenA = A->len;
 557   unsigned int lenB = B->len;
 558   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 559   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 560   int l = lenA < lenB ? lenA : lenB;
 561   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 562
 563   if (tail_align != 0)
 564     return tail_align;
 565
 566   while (l)
 567     {
 568       if (*s != *t)
 569         return (int) *s - (int) *t;
 570       s--;
 571       t--;
 572       l--;
 573     }
 574   return lenA - lenB;
 575 }
 576
 577 static inline int
 578 is_suffix (const struct sec_merge_hash_entry *A,
 579            const struct sec_merge_hash_entry *B)
 580 {
 581   if (A->len <= B->len)
 582     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 583        not to be equal by the hash table.  */
 584     return 0;
 585
 586   return memcmp (A->root.string + (A->len - B->len),
 587                  B->root.string, B->len) == 0;
 588 }
 589
 590 /* This is a helper function for _bfd_merge_sections.  It attempts to
 591    merge strings matching suffixes of longer strings.  */
 592 static void
 593 merge_strings (struct sec_merge_info *sinfo)
 594 {
 595   struct sec_merge_hash_entry **array, **a, *e;
 596   struct sec_merge_sec_info *secinfo;
 597   bfd_size_type size, amt;
 598   unsigned int alignment = 0;
 599
 600   /* Now sort the strings */
 601   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 602   array = bfd_malloc (amt);
 603   if (array == NULL)
 604     goto alloc_failure;
 605
 606   for (e = sinfo->htab->first, a = array; e; e = e->next)
 607     if (e->alignment)
 608       {
 609         *a++ = e;
 610         /* Adjust the length to not include the zero terminator.  */
 611         e->len -= sinfo->htab->entsize;
 612         if (alignment != e->alignment)
 613           {
 614             if (alignment == 0)
 615               alignment = e->alignment;
 616             else
 617               alignment = (unsigned) -1;
 618           }
 619       }
 620
 621   sinfo->htab->size = a - array;
 622   if (sinfo->htab->size != 0)
 623     {
 624       qsort (array, (size_t) sinfo->htab->size,
 625              sizeof (struct sec_merge_hash_entry *),
 626              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 627               ? strrevcmp_align : strrevcmp));
 628
 629       /* Loop over the sorted array and merge suffixes */
 630       e = *--a;
 631       e->len += sinfo->htab->entsize;
 632       while (--a >= array)
 633         {
 634           struct sec_merge_hash_entry *cmp = *a;
 635
 636           cmp->len += sinfo->htab->entsize;
 637           if (e->alignment >= cmp->alignment
 638               && !((e->len - cmp->len) & (cmp->alignment - 1))
 639               && is_suffix (e, cmp))
 640             {
 641               cmp->u.suffix = e;
 642               cmp->alignment = 0;
 643             }
 644           else
 645             e = cmp;
 646         }
 647     }
 648
 649 alloc_failure:
 650   if (array)
 651     free (array);
 652
 653   /* Now assign positions to the strings we want to keep.  */
 654   size = 0;
 655   secinfo = sinfo->htab->first->secinfo;
 656   for (e = sinfo->htab->first; e; e = e->next)
 657     {
 658       if (e->secinfo != secinfo)
 659         {
 660           secinfo->sec->size = size;
 661           secinfo = e->secinfo;
 662         }
 663       if (e->alignment)
 664         {
 665           if (e->secinfo->first_str == NULL)
 666             {
 667               e->secinfo->first_str = e;
 668               size = 0;
 669             }
 670           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 671           e->u.index = size;
 672           size += e->len;
 673         }
 674     }
 675   secinfo->sec->size = size;
 676   if (secinfo->sec->alignment_power != 0)
 677     {
 678       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 679       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 680     }
 681
 682   /* And now adjust the rest, removing them from the chain (but not hashtable)
 683      at the same time.  */
 684   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 685     if (e->alignment)
 686       a = &e->next;
 687     else
 688       {
 689         *a = e->next;
 690         if (e->len)
 691           {
 692             e->secinfo = e->u.suffix->secinfo;
 693             e->alignment = e->u.suffix->alignment;
 694             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 695           }
 696       }
 697 }
 698
 699 /* This function is called once after all SEC_MERGE sections are registered
 700    with _bfd_merge_section.  */
 701
 702 bfd_boolean
 703 _bfd_merge_sections (bfd *abfd ATTRIBUTE_UNUSED,
 704                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
 705                      void *xsinfo,
 706                      void (*remove_hook) (bfd *, asection *))
 707 {
 708   struct sec_merge_info *sinfo;
 709
 710   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 711     {
 712       struct sec_merge_sec_info * secinfo;
 713
 714       if (! sinfo->chain)
 715         continue;
 716
 717       /* Move sinfo->chain to head of the chain, terminate it.  */
 718       secinfo = sinfo->chain;
 719       sinfo->chain = secinfo->next;
 720       secinfo->next = NULL;
 721
 722       /* Record the sections into the hash table.  */
 723       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 724         if (secinfo->sec->flags & SEC_EXCLUDE)
 725           {
 726             *secinfo->psecinfo = NULL;
 727             if (remove_hook)
 728               (*remove_hook) (abfd, secinfo->sec);
 729           }
 730         else if (! record_section (sinfo, secinfo))
 731           break;
 732
 733       if (secinfo)
 734         continue;
 735
 736       if (sinfo->htab->first == NULL)
 737         continue;
 738
 739       if (sinfo->htab->strings)
 740         merge_strings (sinfo);
 741       else
 742         {
 743           struct sec_merge_hash_entry *e;
 744           bfd_size_type size = 0;
 745
 746           /* Things are much simpler for non-strings.
 747              Just assign them slots in the section.  */
 748           secinfo = NULL;
 749           for (e = sinfo->htab->first; e; e = e->next)
 750             {
 751               if (e->secinfo->first_str == NULL)
 752                 {
 753                   if (secinfo)
 754                     secinfo->sec->size = size;
 755                   e->secinfo->first_str = e;
 756                   size = 0;
 757                 }
 758               size = (size + e->alignment - 1)
 759                      & ~((bfd_vma) e->alignment - 1);
 760               e->u.index = size;
 761               size += e->len;
 762               secinfo = e->secinfo;
 763             }
 764           secinfo->sec->size = size;
 765         }
 766
 767         /* Finally remove all input sections which have not made it into
 768            the hash table at all.  */
 769         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 770           if (secinfo->first_str == NULL)
 771             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
 772     }
 773
 774   return TRUE;
 775 }
 776
 777 /* Write out the merged section.  */
 778
 779 bfd_boolean
 780 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 781 {
 782   struct sec_merge_sec_info *secinfo;
 783   file_ptr pos;
 784
 785   secinfo = (struct sec_merge_sec_info *) psecinfo;
 786
 787   if (secinfo->first_str == NULL)
 788     return TRUE;
 789
 790   pos = sec->output_section->filepos + sec->output_offset;
 791   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 792     return FALSE;
 793
 794   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 795     return FALSE;
 796
 797   return TRUE;
 798 }
 799
 800 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 801    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 802    section and writes the new section back into *PSEC.  */
 803
 804 bfd_vma
 805 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 806                             void *psecinfo, bfd_vma offset)
 807 {
 808   struct sec_merge_sec_info *secinfo;
 809   struct sec_merge_hash_entry *entry;
 810   unsigned char *p;
 811   asection *sec = *psec;
 812
 813   secinfo = (struct sec_merge_sec_info *) psecinfo;
 814
 815   if (offset >= sec->rawsize)
 816     {
 817       if (offset > sec->rawsize)
 818         {
 819           (*_bfd_error_handler)
 820             (_("%s: access beyond end of merged section (%ld)"),
 821              bfd_get_filename (sec->owner), (long) offset);
 822         }
 823       return secinfo->first_str ? sec->size : 0;
 824     }
 825
 826   if (secinfo->htab->strings)
 827     {
 828       if (sec->entsize == 1)
 829         {
 830           p = secinfo->contents + offset - 1;
 831           while (p >= secinfo->contents && *p)
 832             --p;
 833           ++p;
 834         }
 835       else
 836         {
 837           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 838           p -= sec->entsize;
 839           while (p >= secinfo->contents)
 840             {
 841               unsigned int i;
 842
 843               for (i = 0; i < sec->entsize; ++i)
 844                 if (p[i] != '\0')
 845                   break;
 846               if (i == sec->entsize)
 847                 break;
 848               p -= sec->entsize;
 849             }
 850           p += sec->entsize;
 851         }
 852     }
 853   else
 854     {
 855       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 856     }
 857   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
 858   if (!entry)
 859     {
 860       if (! secinfo->htab->strings)
 861         abort ();
 862       /* This should only happen if somebody points into the padding
 863          after a NUL character but before next entity.  */
 864       if (*p)
 865         abort ();
 866       if (! secinfo->htab->first)
 867         abort ();
 868       entry = secinfo->htab->first;
 869       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 870            - entry->len);
 871     }
 872
 873   *psec = entry->secinfo->sec;
 874   return entry->u.index + (secinfo->contents + offset - p);
 875 }