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                        const unsigned char *sec_end,
 137                        unsigned int alignment, bfd_boolean create)
 138 {
 139   register const unsigned char *s;
 140   register unsigned long hash;
 141   register 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               if (sec_end && s >= sec_end)
 159                 return NULL;
 160             }
 161           hash += len + (len << 17);
 162         }
 163       else
 164         {
 165           for (;;)
 166             {
 167               if (sec_end && s + table->entsize > sec_end)
 168                 return NULL;
 169               for (i = 0; i < table->entsize; ++i)
 170                 if (s[i] != '\0')
 171                   break;
 172               if (i == table->entsize)
 173                 break;
 174               for (i = 0; i < table->entsize; ++i)
 175                 {
 176                   c = *s++;
 177                   hash += c + (c << 17);
 178                   hash ^= hash >> 2;
 179                 }
 180               ++len;
 181             }
 182           hash += len + (len << 17);
 183           len *= table->entsize;
 184         }
 185       hash ^= hash >> 2;
 186       len += table->entsize;
 187     }
 188   else
 189     {
 190       for (i = 0; i < table->entsize; ++i)
 191         {
 192           c = *s++;
 193           hash += c + (c << 17);
 194           hash ^= hash >> 2;
 195         }
 196       len = table->entsize;
 197     }
 198
 199   index = hash % table->table.size;
 200   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 201        hashp != NULL;
 202        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 203     {
 204       if (hashp->root.hash == hash
 205           && len == hashp->len
 206           && memcmp (hashp->root.string, string, len) == 0)
 207         {
 208           /* If the string we found does not have at least the required
 209              alignment, we need to insert another copy.  */
 210           if (hashp->alignment < alignment)
 211             {
 212               if (create)
 213                 {
 214                   /*  Mark the less aligned copy as deleted.  */
 215                   hashp->len = 0;
 216                   hashp->alignment = 0;
 217                 }
 218               break;
 219             }
 220           return hashp;
 221         }
 222     }
 223
 224   if (! create)
 225     return NULL;
 226
 227   hashp = ((struct sec_merge_hash_entry *)
 228            bfd_hash_insert (&table->table, string, hash));
 229   if (hashp == NULL)
 230     return NULL;
 231   hashp->len = len;
 232   hashp->alignment = alignment;
 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,
 273                                  secinfo->contents + secinfo->sec->size,
 274                                  alignment, TRUE);
 275   if (entry == NULL)
 276     return NULL;
 277
 278   if (entry->secinfo == NULL)
 279     {
 280       tab->size++;
 281       entry->secinfo = secinfo;
 282       if (tab->first == NULL)
 283         tab->first = entry;
 284       else
 285         tab->last->next = entry;
 286       tab->last = entry;
 287     }
 288
 289   return entry;
 290 }
 291
 292 static bfd_boolean
 293 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
 294 {
 295   struct sec_merge_sec_info *secinfo = entry->secinfo;
 296   asection *sec = secinfo->sec;
 297   char *pad = NULL;
 298   bfd_size_type off = 0;
 299   int alignment_power = sec->output_section->alignment_power;
 300
 301   if (alignment_power)
 302     {
 303       pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 304       if (pad == NULL)
 305         return FALSE;
 306     }
 307
 308   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 309     {
 310       const char *str;
 311       bfd_size_type len;
 312
 313       len = -off & (entry->alignment - 1);
 314       if (len != 0)
 315         {
 316           if (bfd_bwrite (pad, len, abfd) != len)
 317             goto err;
 318           off += len;
 319         }
 320
 321       str = entry->root.string;
 322       len = entry->len;
 323
 324       if (bfd_bwrite (str, len, abfd) != len)
 325         goto err;
 326
 327       off += len;
 328     }
 329
 330   /* Trailing alignment needed?  */
 331   off = sec->size - off;
 332   if (off != 0
 333       && bfd_bwrite (pad, off, abfd) != off)
 334     goto err;
 335
 336   if (pad != NULL)
 337     free (pad);
 338   return TRUE;
 339
 340  err:
 341   if (pad != NULL)
 342     free (pad);
 343   return FALSE;
 344 }
 345
 346 /* Register a SEC_MERGE section as a candidate for merging.
 347    This function is called for all non-dynamic SEC_MERGE input sections.  */
 348
 349 bfd_boolean
 350 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 351                         void **psecinfo)
 352 {
 353   struct sec_merge_info *sinfo;
 354   struct sec_merge_sec_info *secinfo;
 355   unsigned int align;
 356   bfd_size_type amt;
 357
 358   if ((abfd->flags & DYNAMIC) != 0
 359       || (sec->flags & SEC_MERGE) == 0)
 360     abort ();
 361
 362   if (sec->size == 0
 363       || (sec->flags & SEC_EXCLUDE) != 0
 364       || sec->entsize == 0)
 365     return TRUE;
 366
 367   if ((sec->flags & SEC_RELOC) != 0)
 368     {
 369       /* We aren't prepared to handle relocations in merged sections.  */
 370       return TRUE;
 371     }
 372
 373   align = sec->alignment_power;
 374   if ((sec->entsize < (unsigned) 1 << align
 375        && ((sec->entsize & (sec->entsize - 1))
 376            || !(sec->flags & SEC_STRINGS)))
 377       || (sec->entsize > (unsigned) 1 << align
 378           && (sec->entsize & (((unsigned) 1 << align) - 1))))
 379     {
 380       /* Sanity check.  If string character size is smaller than
 381          alignment, then we require character size to be a power
 382          of 2, otherwise character size must be integer multiple
 383          of alignment.  For non-string constants, alignment must
 384          be smaller than or equal to entity size and entity size
 385          must be integer multiple of alignment.  */
 386       return TRUE;
 387     }
 388
 389   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 390     if ((secinfo = sinfo->chain)
 391         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 392         && secinfo->sec->entsize == sec->entsize
 393         && secinfo->sec->alignment_power == sec->alignment_power
 394         && secinfo->sec->output_section == sec->output_section)
 395       break;
 396
 397   if (sinfo == NULL)
 398     {
 399       /* Initialize the information we need to keep track of.  */
 400       sinfo = bfd_alloc (abfd, sizeof (struct sec_merge_info));
 401       if (sinfo == NULL)
 402         goto error_return;
 403       sinfo->next = (struct sec_merge_info *) *psinfo;
 404       sinfo->chain = NULL;
 405       *psinfo = sinfo;
 406       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 407       if (sinfo->htab == NULL)
 408         goto error_return;
 409     }
 410
 411   /* Read the section from abfd.  */
 412
 413   amt = sizeof (struct sec_merge_sec_info) + sec->size - 1;
 414   *psecinfo = bfd_alloc (abfd, amt);
 415   if (*psecinfo == NULL)
 416     goto error_return;
 417
 418   secinfo = (struct sec_merge_sec_info *) *psecinfo;
 419   if (sinfo->chain)
 420     {
 421       secinfo->next = sinfo->chain->next;
 422       sinfo->chain->next = secinfo;
 423     }
 424   else
 425     secinfo->next = secinfo;
 426   sinfo->chain = secinfo;
 427   secinfo->sec = sec;
 428   secinfo->psecinfo = psecinfo;
 429   secinfo->htab = sinfo->htab;
 430   secinfo->first_str = NULL;
 431
 432   sec->rawsize = sec->size;
 433   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 434                                   0, sec->size))
 435     goto error_return;
 436
 437   return TRUE;
 438
 439  error_return:
 440   *psecinfo = NULL;
 441   return FALSE;
 442 }
 443
 444 /* Record one section into the hash table.  */
 445 static bfd_boolean
 446 record_section (bfd *abfd,
 447                 struct sec_merge_info *sinfo,
 448                 struct sec_merge_sec_info *secinfo)
 449 {
 450   asection *sec = secinfo->sec;
 451   struct sec_merge_hash_entry *entry;
 452   bfd_boolean nul;
 453   unsigned char *p, *end;
 454   bfd_vma mask, eltalign;
 455   unsigned int align, i;
 456
 457   align = sec->alignment_power;
 458   end = secinfo->contents + sec->size;
 459   nul = FALSE;
 460   mask = ((bfd_vma) 1 << align) - 1;
 461   if (sec->flags & SEC_STRINGS)
 462     {
 463       for (p = secinfo->contents; p < end; )
 464         {
 465           eltalign = p - secinfo->contents;
 466           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 467           if (!eltalign || eltalign > mask)
 468             eltalign = mask + 1;
 469           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 470                                  secinfo);
 471           if (! entry)
 472             goto error_return;
 473           p += entry->len;
 474           if (sec->entsize == 1)
 475             {
 476               while (p < end && *p == 0)
 477                 {
 478                   if (!nul && !((p - secinfo->contents) & mask))
 479                     {
 480                       nul = TRUE;
 481                       entry = sec_merge_add (sinfo->htab, "",
 482                                              (unsigned) mask + 1, secinfo);
 483                       if (! entry)
 484                         goto error_return;
 485                     }
 486                   p++;
 487                 }
 488             }
 489           else
 490             {
 491               while (p < end)
 492                 {
 493                   for (i = 0; i < sec->entsize; i++)
 494                     if (p[i] != '\0')
 495                       break;
 496                   if (i != sec->entsize)
 497                     break;
 498                   if (!nul && !((p - secinfo->contents) & mask))
 499                     {
 500                       nul = TRUE;
 501                       entry = sec_merge_add (sinfo->htab, (char *) p,
 502                                              (unsigned) mask + 1, secinfo);
 503                       if (! entry)
 504                         goto error_return;
 505                     }
 506                   p += sec->entsize;
 507                 }
 508             }
 509         }
 510     }
 511   else
 512     {
 513       for (p = secinfo->contents; p < end; p += sec->entsize)
 514         {
 515           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 516           if (! entry)
 517             goto error_return;
 518         }
 519     }
 520
 521   return TRUE;
 522
 523 error_return:
 524   if (bfd_get_error () != bfd_error_no_memory)
 525     (*_bfd_error_handler)
 526       (_("%B: unterminated string in section `%A' marked for merging"),
 527        abfd, sec);
 528   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 529     *secinfo->psecinfo = NULL;
 530   return FALSE;
 531 }
 532
 533 static int
 534 strrevcmp (const void *a, const void *b)
 535 {
 536   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 537   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 538   unsigned int lenA = A->len;
 539   unsigned int lenB = B->len;
 540   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 541   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 542   int l = lenA < lenB ? lenA : lenB;
 543
 544   while (l)
 545     {
 546       if (*s != *t)
 547         return (int) *s - (int) *t;
 548       s--;
 549       t--;
 550       l--;
 551     }
 552   return lenA - lenB;
 553 }
 554
 555 /* Like strrevcmp, but for the case where all strings have the same
 556    alignment > entsize.  */
 557
 558 static int
 559 strrevcmp_align (const void *a, const void *b)
 560 {
 561   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 562   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 563   unsigned int lenA = A->len;
 564   unsigned int lenB = B->len;
 565   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 566   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 567   int l = lenA < lenB ? lenA : lenB;
 568   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 569
 570   if (tail_align != 0)
 571     return tail_align;
 572
 573   while (l)
 574     {
 575       if (*s != *t)
 576         return (int) *s - (int) *t;
 577       s--;
 578       t--;
 579       l--;
 580     }
 581   return lenA - lenB;
 582 }
 583
 584 static inline int
 585 is_suffix (const struct sec_merge_hash_entry *A,
 586            const struct sec_merge_hash_entry *B)
 587 {
 588   if (A->len <= B->len)
 589     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 590        not to be equal by the hash table.  */
 591     return 0;
 592
 593   return memcmp (A->root.string + (A->len - B->len),
 594                  B->root.string, B->len) == 0;
 595 }
 596
 597 /* This is a helper function for _bfd_merge_sections.  It attempts to
 598    merge strings matching suffixes of longer strings.  */
 599 static void
 600 merge_strings (struct sec_merge_info *sinfo)
 601 {
 602   struct sec_merge_hash_entry **array, **a, *e;
 603   struct sec_merge_sec_info *secinfo;
 604   bfd_size_type size, amt;
 605   unsigned int alignment = 0;
 606
 607   /* Now sort the strings */
 608   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 609   array = bfd_malloc (amt);
 610   if (array == NULL)
 611     goto alloc_failure;
 612
 613   for (e = sinfo->htab->first, a = array; e; e = e->next)
 614     if (e->alignment)
 615       {
 616         *a++ = e;
 617         /* Adjust the length to not include the zero terminator.  */
 618         e->len -= sinfo->htab->entsize;
 619         if (alignment != e->alignment)
 620           {
 621             if (alignment == 0)
 622               alignment = e->alignment;
 623             else
 624               alignment = (unsigned) -1;
 625           }
 626       }
 627
 628   sinfo->htab->size = a - array;
 629   if (sinfo->htab->size != 0)
 630     {
 631       qsort (array, (size_t) sinfo->htab->size,
 632              sizeof (struct sec_merge_hash_entry *),
 633              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 634               ? strrevcmp_align : strrevcmp));
 635
 636       /* Loop over the sorted array and merge suffixes */
 637       e = *--a;
 638       e->len += sinfo->htab->entsize;
 639       while (--a >= array)
 640         {
 641           struct sec_merge_hash_entry *cmp = *a;
 642
 643           cmp->len += sinfo->htab->entsize;
 644           if (e->alignment >= cmp->alignment
 645               && !((e->len - cmp->len) & (cmp->alignment - 1))
 646               && is_suffix (e, cmp))
 647             {
 648               cmp->u.suffix = e;
 649               cmp->alignment = 0;
 650             }
 651           else
 652             e = cmp;
 653         }
 654     }
 655
 656 alloc_failure:
 657   if (array)
 658     free (array);
 659
 660   /* Now assign positions to the strings we want to keep.  */
 661   size = 0;
 662   secinfo = sinfo->htab->first->secinfo;
 663   for (e = sinfo->htab->first; e; e = e->next)
 664     {
 665       if (e->secinfo != secinfo)
 666         {
 667           secinfo->sec->size = size;
 668           secinfo = e->secinfo;
 669         }
 670       if (e->alignment)
 671         {
 672           if (e->secinfo->first_str == NULL)
 673             {
 674               e->secinfo->first_str = e;
 675               size = 0;
 676             }
 677           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 678           e->u.index = size;
 679           size += e->len;
 680         }
 681     }
 682   secinfo->sec->size = size;
 683   if (secinfo->sec->alignment_power != 0)
 684     {
 685       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 686       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 687     }
 688
 689   /* And now adjust the rest, removing them from the chain (but not hashtable)
 690      at the same time.  */
 691   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 692     if (e->alignment)
 693       a = &e->next;
 694     else
 695       {
 696         *a = e->next;
 697         if (e->len)
 698           {
 699             e->secinfo = e->u.suffix->secinfo;
 700             e->alignment = e->u.suffix->alignment;
 701             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 702           }
 703       }
 704 }
 705
 706 /* This function is called once after all SEC_MERGE sections are registered
 707    with _bfd_merge_section.  */
 708
 709 bfd_boolean
 710 _bfd_merge_sections (bfd *abfd,
 711                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
 712                      void *xsinfo,
 713                      void (*remove_hook) (bfd *, asection *))
 714 {
 715   struct sec_merge_info *sinfo;
 716
 717   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 718     {
 719       struct sec_merge_sec_info * secinfo;
 720
 721       if (! sinfo->chain)
 722         continue;
 723
 724       /* Move sinfo->chain to head of the chain, terminate it.  */
 725       secinfo = sinfo->chain;
 726       sinfo->chain = secinfo->next;
 727       secinfo->next = NULL;
 728
 729       /* Record the sections into the hash table.  */
 730       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 731         if (secinfo->sec->flags & SEC_EXCLUDE)
 732           {
 733             *secinfo->psecinfo = NULL;
 734             if (remove_hook)
 735               (*remove_hook) (abfd, secinfo->sec);
 736           }
 737         else if (! record_section (abfd, sinfo, secinfo))
 738           break;
 739
 740       if (secinfo)
 741         continue;
 742
 743       if (sinfo->htab->first == NULL)
 744         continue;
 745
 746       if (sinfo->htab->strings)
 747         merge_strings (sinfo);
 748       else
 749         {
 750           struct sec_merge_hash_entry *e;
 751           bfd_size_type size = 0;
 752
 753           /* Things are much simpler for non-strings.
 754              Just assign them slots in the section.  */
 755           secinfo = NULL;
 756           for (e = sinfo->htab->first; e; e = e->next)
 757             {
 758               if (e->secinfo->first_str == NULL)
 759                 {
 760                   if (secinfo)
 761                     secinfo->sec->size = size;
 762                   e->secinfo->first_str = e;
 763                   size = 0;
 764                 }
 765               size = (size + e->alignment - 1)
 766                      & ~((bfd_vma) e->alignment - 1);
 767               e->u.index = size;
 768               size += e->len;
 769               secinfo = e->secinfo;
 770             }
 771           secinfo->sec->size = size;
 772         }
 773
 774         /* Finally remove all input sections which have not made it into
 775            the hash table at all.  */
 776         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 777           if (secinfo->first_str == NULL)
 778             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
 779     }
 780
 781   return TRUE;
 782 }
 783
 784 /* Write out the merged section.  */
 785
 786 bfd_boolean
 787 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 788 {
 789   struct sec_merge_sec_info *secinfo;
 790   file_ptr pos;
 791
 792   secinfo = (struct sec_merge_sec_info *) psecinfo;
 793
 794   if (!secinfo)
 795     return FALSE;
 796
 797   if (secinfo->first_str == NULL)
 798     return TRUE;
 799
 800   pos = sec->output_section->filepos + sec->output_offset;
 801   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 802     return FALSE;
 803
 804   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 805     return FALSE;
 806
 807   return TRUE;
 808 }
 809
 810 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 811    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 812    section and writes the new section back into *PSEC.  */
 813
 814 bfd_vma
 815 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 816                             void *psecinfo, bfd_vma offset)
 817 {
 818   struct sec_merge_sec_info *secinfo;
 819   struct sec_merge_hash_entry *entry;
 820   unsigned char *p;
 821   asection *sec = *psec;
 822
 823   secinfo = (struct sec_merge_sec_info *) psecinfo;
 824
 825   if (!secinfo)
 826     return 0;
 827
 828   if (offset >= sec->rawsize)
 829     {
 830       if (offset > sec->rawsize)
 831         {
 832           (*_bfd_error_handler)
 833             (_("%s: access beyond end of merged section (%ld)"),
 834              bfd_get_filename (sec->owner), (long) offset);
 835         }
 836       return secinfo->first_str ? sec->size : 0;
 837     }
 838
 839   if (secinfo->htab->strings)
 840     {
 841       if (sec->entsize == 1)
 842         {
 843           p = secinfo->contents + offset - 1;
 844           while (p >= secinfo->contents && *p)
 845             --p;
 846           ++p;
 847         }
 848       else
 849         {
 850           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 851           p -= sec->entsize;
 852           while (p >= secinfo->contents)
 853             {
 854               unsigned int i;
 855
 856               for (i = 0; i < sec->entsize; ++i)
 857                 if (p[i] != '\0')
 858                   break;
 859               if (i == sec->entsize)
 860                 break;
 861               p -= sec->entsize;
 862             }
 863           p += sec->entsize;
 864         }
 865     }
 866   else
 867     {
 868       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 869     }
 870   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, NULL, 0, FALSE);
 871   if (!entry)
 872     {
 873       if (! secinfo->htab->strings)
 874         abort ();
 875       /* This should only happen if somebody points into the padding
 876          after a NUL character but before next entity.  */
 877       if (*p)
 878         abort ();
 879       if (! secinfo->htab->first)
 880         abort ();
 881       entry = secinfo->htab->first;
 882       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 883            - entry->len);
 884     }
 885
 886   *psec = entry->secinfo->sec;
 887   return entry->u.index + (secinfo->contents + offset - p);
 888 }