bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright (C) 2001-2014 Free Software Foundation, Inc.
   3    Written by Jakub Jelinek <jakub@redhat.com>.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22
  23 /* This file contains support for merging duplicate entities within sections,
  24    as used in ELF SHF_MERGE.  */
  25
  26 #include "sysdep.h"
  27 #include "bfd.h"
  28 #include "libbfd.h"
  29 #include "hashtab.h"
  30 #include "libiberty.h"
  31
  32 struct sec_merge_sec_info;
  33
  34 /* An entry in the section merge hash table.  */
  35
  36 struct sec_merge_hash_entry
  37 {
  38   struct bfd_hash_entry root;
  39   /* Length of this entry.  This includes the zero terminator.  */
  40   unsigned int len;
  41   /* Start of this string needs to be aligned to
  42      alignment octets (not 1 << align).  */
  43   unsigned int alignment;
  44   union
  45   {
  46     /* Index within the merged section.  */
  47     bfd_size_type index;
  48     /* Entry this is a suffix of (if alignment is 0).  */
  49     struct sec_merge_hash_entry *suffix;
  50   } u;
  51   /* Which section is it in.  */
  52   struct sec_merge_sec_info *secinfo;
  53   /* Next entity in the hash table.  */
  54   struct sec_merge_hash_entry *next;
  55 };
  56
  57 /* The section merge hash table.  */
  58
  59 struct sec_merge_hash
  60 {
  61   struct bfd_hash_table table;
  62   /* Next available index.  */
  63   bfd_size_type size;
  64   /* First entity in the SEC_MERGE sections of this type.  */
  65   struct sec_merge_hash_entry *first;
  66   /* Last entity in the SEC_MERGE sections of this type.  */
  67   struct sec_merge_hash_entry *last;
  68   /* Entity size.  */
  69   unsigned int entsize;
  70   /* Are entries fixed size or zero terminated strings?  */
  71   bfd_boolean strings;
  72 };
  73
  74 struct sec_merge_info
  75 {
  76   /* Chain of sec_merge_infos.  */
  77   struct sec_merge_info *next;
  78   /* Chain of sec_merge_sec_infos.  */
  79   struct sec_merge_sec_info *chain;
  80   /* A hash table used to hold section content.  */
  81   struct sec_merge_hash *htab;
  82 };
  83
  84 struct sec_merge_sec_info
  85 {
  86   /* Chain of sec_merge_sec_infos.  */
  87   struct sec_merge_sec_info *next;
  88   /* The corresponding section.  */
  89   asection *sec;
  90   /* Pointer to merge_info pointing to us.  */
  91   void **psecinfo;
  92   /* A hash table used to hold section content.  */
  93   struct sec_merge_hash *htab;
  94   /* First string in this section.  */
  95   struct sec_merge_hash_entry *first_str;
  96   /* Original section content.  */
  97   unsigned char contents[1];
  98 };
  99
 100
 101 /* Routine to create an entry in a section merge hashtab.  */
 102
 103 static struct bfd_hash_entry *
 104 sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
 105                         struct bfd_hash_table *table, const char *string)
 106 {
 107   /* Allocate the structure if it has not already been allocated by a
 108      subclass.  */
 109   if (entry == NULL)
 110     entry = (struct bfd_hash_entry *)
 111         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   const unsigned char *s;
 139   unsigned long hash;
 140   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            bfd_hash_insert (&table->table, string, hash));
 224   if (hashp == NULL)
 225     return NULL;
 226   hashp->len = len;
 227   hashp->alignment = alignment;
 228   return hashp;
 229 }
 230
 231 /* Create a new hash table.  */
 232
 233 static struct sec_merge_hash *
 234 sec_merge_init (unsigned int entsize, bfd_boolean strings)
 235 {
 236   struct sec_merge_hash *table;
 237
 238   table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));
 239   if (table == NULL)
 240     return NULL;
 241
 242   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
 243                                sizeof (struct sec_merge_hash_entry), 16699))
 244     {
 245       free (table);
 246       return NULL;
 247     }
 248
 249   table->size = 0;
 250   table->first = NULL;
 251   table->last = NULL;
 252   table->entsize = entsize;
 253   table->strings = strings;
 254
 255   return table;
 256 }
 257
 258 /* Get the index of an entity in a hash table, adding it if it is not
 259    already present.  */
 260
 261 static struct sec_merge_hash_entry *
 262 sec_merge_add (struct sec_merge_hash *tab, const char *str,
 263                unsigned int alignment, struct sec_merge_sec_info *secinfo)
 264 {
 265   struct sec_merge_hash_entry *entry;
 266
 267   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
 268   if (entry == NULL)
 269     return NULL;
 270
 271   if (entry->secinfo == NULL)
 272     {
 273       tab->size++;
 274       entry->secinfo = secinfo;
 275       if (tab->first == NULL)
 276         tab->first = entry;
 277       else
 278         tab->last->next = entry;
 279       tab->last = entry;
 280     }
 281
 282   return entry;
 283 }
 284
 285 static bfd_boolean
 286 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
 287 {
 288   struct sec_merge_sec_info *secinfo = entry->secinfo;
 289   asection *sec = secinfo->sec;
 290   char *pad = NULL;
 291   bfd_size_type off = 0;
 292   int alignment_power = sec->output_section->alignment_power;
 293
 294   if (alignment_power)
 295     {
 296       pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 297       if (pad == NULL)
 298         return FALSE;
 299     }
 300
 301   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 302     {
 303       const char *str;
 304       bfd_size_type len;
 305
 306       len = -off & (entry->alignment - 1);
 307       if (len != 0)
 308         {
 309           if (bfd_bwrite (pad, len, abfd) != len)
 310             goto err;
 311           off += len;
 312         }
 313
 314       str = entry->root.string;
 315       len = entry->len;
 316
 317       if (bfd_bwrite (str, len, abfd) != len)
 318         goto err;
 319
 320       off += len;
 321     }
 322
 323   /* Trailing alignment needed?  */
 324   off = sec->size - off;
 325   if (off != 0
 326       && bfd_bwrite (pad, off, abfd) != off)
 327     goto err;
 328
 329   if (pad != NULL)
 330     free (pad);
 331   return TRUE;
 332
 333  err:
 334   if (pad != NULL)
 335     free (pad);
 336   return FALSE;
 337 }
 338
 339 /* Register a SEC_MERGE section as a candidate for merging.
 340    This function is called for all non-dynamic SEC_MERGE input sections.  */
 341
 342 bfd_boolean
 343 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 344                         void **psecinfo)
 345 {
 346   struct sec_merge_info *sinfo;
 347   struct sec_merge_sec_info *secinfo;
 348   unsigned int align;
 349   bfd_size_type amt;
 350   bfd_byte *contents;
 351
 352   if ((abfd->flags & DYNAMIC) != 0
 353       || (sec->flags & SEC_MERGE) == 0)
 354     abort ();
 355
 356   if (sec->size == 0
 357       || (sec->flags & SEC_EXCLUDE) != 0
 358       || sec->entsize == 0)
 359     return TRUE;
 360
 361   if ((sec->flags & SEC_RELOC) != 0)
 362     {
 363       /* We aren't prepared to handle relocations in merged sections.  */
 364       return TRUE;
 365     }
 366
 367   align = sec->alignment_power;
 368   if ((sec->entsize < (unsigned) 1 << align
 369        && ((sec->entsize & (sec->entsize - 1))
 370            || !(sec->flags & SEC_STRINGS)))
 371       || (sec->entsize > (unsigned) 1 << align
 372           && (sec->entsize & (((unsigned) 1 << align) - 1))))
 373     {
 374       /* Sanity check.  If string character size is smaller than
 375          alignment, then we require character size to be a power
 376          of 2, otherwise character size must be integer multiple
 377          of alignment.  For non-string constants, alignment must
 378          be smaller than or equal to entity size and entity size
 379          must be integer multiple of alignment.  */
 380       return TRUE;
 381     }
 382
 383   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 384     if ((secinfo = sinfo->chain)
 385         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 386         && secinfo->sec->entsize == sec->entsize
 387         && secinfo->sec->alignment_power == sec->alignment_power
 388         && secinfo->sec->output_section == sec->output_section)
 389       break;
 390
 391   if (sinfo == NULL)
 392     {
 393       /* Initialize the information we need to keep track of.  */
 394       sinfo = (struct sec_merge_info *)
 395           bfd_alloc (abfd, sizeof (struct sec_merge_info));
 396       if (sinfo == NULL)
 397         goto error_return;
 398       sinfo->next = (struct sec_merge_info *) *psinfo;
 399       sinfo->chain = NULL;
 400       *psinfo = sinfo;
 401       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 402       if (sinfo->htab == NULL)
 403         goto error_return;
 404     }
 405
 406   /* Read the section from abfd.  */
 407
 408   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
 409   if (sec->flags & SEC_STRINGS)
 410     /* Some versions of gcc may emit a string without a zero terminator.
 411        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
 412        Allocate space for an extra zero.  */
 413     amt += sec->entsize;
 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 (sec->flags & SEC_STRINGS)
 434     memset (secinfo->contents + sec->size, 0, sec->entsize);
 435   contents = secinfo->contents;
 436   if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
 437     goto error_return;
 438
 439   return TRUE;
 440
 441  error_return:
 442   *psecinfo = NULL;
 443   return FALSE;
 444 }
 445
 446 /* Record one section into the hash table.  */
 447 static bfd_boolean
 448 record_section (struct sec_merge_info *sinfo,
 449                 struct sec_merge_sec_info *secinfo)
 450 {
 451   asection *sec = secinfo->sec;
 452   struct sec_merge_hash_entry *entry;
 453   bfd_boolean nul;
 454   unsigned char *p, *end;
 455   bfd_vma mask, eltalign;
 456   unsigned int align, i;
 457
 458   align = sec->alignment_power;
 459   end = secinfo->contents + sec->size;
 460   nul = FALSE;
 461   mask = ((bfd_vma) 1 << align) - 1;
 462   if (sec->flags & SEC_STRINGS)
 463     {
 464       for (p = secinfo->contents; p < end; )
 465         {
 466           eltalign = p - secinfo->contents;
 467           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 468           if (!eltalign || eltalign > mask)
 469             eltalign = mask + 1;
 470           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 471                                  secinfo);
 472           if (! entry)
 473             goto error_return;
 474           p += entry->len;
 475           if (sec->entsize == 1)
 476             {
 477               while (p < end && *p == 0)
 478                 {
 479                   if (!nul && !((p - secinfo->contents) & mask))
 480                     {
 481                       nul = TRUE;
 482                       entry = sec_merge_add (sinfo->htab, "",
 483                                              (unsigned) mask + 1, secinfo);
 484                       if (! entry)
 485                         goto error_return;
 486                     }
 487                   p++;
 488                 }
 489             }
 490           else
 491             {
 492               while (p < end)
 493                 {
 494                   for (i = 0; i < sec->entsize; i++)
 495                     if (p[i] != '\0')
 496                       break;
 497                   if (i != sec->entsize)
 498                     break;
 499                   if (!nul && !((p - secinfo->contents) & mask))
 500                     {
 501                       nul = TRUE;
 502                       entry = sec_merge_add (sinfo->htab, (char *) p,
 503                                              (unsigned) mask + 1, secinfo);
 504                       if (! entry)
 505                         goto error_return;
 506                     }
 507                   p += sec->entsize;
 508                 }
 509             }
 510         }
 511     }
 512   else
 513     {
 514       for (p = secinfo->contents; p < end; p += sec->entsize)
 515         {
 516           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 517           if (! entry)
 518             goto error_return;
 519         }
 520     }
 521
 522   return TRUE;
 523
 524 error_return:
 525   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 526     *secinfo->psecinfo = NULL;
 527   return FALSE;
 528 }
 529
 530 static int
 531 strrevcmp (const void *a, const void *b)
 532 {
 533   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 534   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 535   unsigned int lenA = A->len;
 536   unsigned int lenB = B->len;
 537   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 538   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 539   int l = lenA < lenB ? lenA : lenB;
 540
 541   while (l)
 542     {
 543       if (*s != *t)
 544         return (int) *s - (int) *t;
 545       s--;
 546       t--;
 547       l--;
 548     }
 549   return lenA - lenB;
 550 }
 551
 552 /* Like strrevcmp, but for the case where all strings have the same
 553    alignment > entsize.  */
 554
 555 static int
 556 strrevcmp_align (const void *a, const void *b)
 557 {
 558   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 559   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 560   unsigned int lenA = A->len;
 561   unsigned int lenB = B->len;
 562   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 563   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 564   int l = lenA < lenB ? lenA : lenB;
 565   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 566
 567   if (tail_align != 0)
 568     return tail_align;
 569
 570   while (l)
 571     {
 572       if (*s != *t)
 573         return (int) *s - (int) *t;
 574       s--;
 575       t--;
 576       l--;
 577     }
 578   return lenA - lenB;
 579 }
 580
 581 static inline int
 582 is_suffix (const struct sec_merge_hash_entry *A,
 583            const struct sec_merge_hash_entry *B)
 584 {
 585   if (A->len <= B->len)
 586     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 587        not to be equal by the hash table.  */
 588     return 0;
 589
 590   return memcmp (A->root.string + (A->len - B->len),
 591                  B->root.string, B->len) == 0;
 592 }
 593
 594 /* This is a helper function for _bfd_merge_sections.  It attempts to
 595    merge strings matching suffixes of longer strings.  */
 596 static void
 597 merge_strings (struct sec_merge_info *sinfo)
 598 {
 599   struct sec_merge_hash_entry **array, **a, *e;
 600   struct sec_merge_sec_info *secinfo;
 601   bfd_size_type size, amt;
 602   unsigned int alignment = 0;
 603
 604   /* Now sort the strings */
 605   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 606   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 607   if (array == NULL)
 608     goto alloc_failure;
 609
 610   for (e = sinfo->htab->first, a = array; e; e = e->next)
 611     if (e->alignment)
 612       {
 613         *a++ = e;
 614         /* Adjust the length to not include the zero terminator.  */
 615         e->len -= sinfo->htab->entsize;
 616         if (alignment != e->alignment)
 617           {
 618             if (alignment == 0)
 619               alignment = e->alignment;
 620             else
 621               alignment = (unsigned) -1;
 622           }
 623       }
 624
 625   sinfo->htab->size = a - array;
 626   if (sinfo->htab->size != 0)
 627     {
 628       qsort (array, (size_t) sinfo->htab->size,
 629              sizeof (struct sec_merge_hash_entry *),
 630              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 631               ? strrevcmp_align : strrevcmp));
 632
 633       /* Loop over the sorted array and merge suffixes */
 634       e = *--a;
 635       e->len += sinfo->htab->entsize;
 636       while (--a >= array)
 637         {
 638           struct sec_merge_hash_entry *cmp = *a;
 639
 640           cmp->len += sinfo->htab->entsize;
 641           if (e->alignment >= cmp->alignment
 642               && !((e->len - cmp->len) & (cmp->alignment - 1))
 643               && is_suffix (e, cmp))
 644             {
 645               cmp->u.suffix = e;
 646               cmp->alignment = 0;
 647             }
 648           else
 649             e = cmp;
 650         }
 651     }
 652
 653 alloc_failure:
 654   if (array)
 655     free (array);
 656
 657   /* Now assign positions to the strings we want to keep.  */
 658   size = 0;
 659   secinfo = sinfo->htab->first->secinfo;
 660   for (e = sinfo->htab->first; e; e = e->next)
 661     {
 662       if (e->secinfo != secinfo)
 663         {
 664           secinfo->sec->size = size;
 665           secinfo = e->secinfo;
 666         }
 667       if (e->alignment)
 668         {
 669           if (e->secinfo->first_str == NULL)
 670             {
 671               e->secinfo->first_str = e;
 672               size = 0;
 673             }
 674           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 675           e->u.index = size;
 676           size += e->len;
 677         }
 678     }
 679   secinfo->sec->size = size;
 680   if (secinfo->sec->alignment_power != 0)
 681     {
 682       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 683       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 684     }
 685
 686   /* And now adjust the rest, removing them from the chain (but not hashtable)
 687      at the same time.  */
 688   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 689     if (e->alignment)
 690       a = &e->next;
 691     else
 692       {
 693         *a = e->next;
 694         if (e->len)
 695           {
 696             e->secinfo = e->u.suffix->secinfo;
 697             e->alignment = e->u.suffix->alignment;
 698             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 699           }
 700       }
 701 }
 702
 703 /* This function is called once after all SEC_MERGE sections are registered
 704    with _bfd_merge_section.  */
 705
 706 bfd_boolean
 707 _bfd_merge_sections (bfd *abfd,
 708                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
 709                      void *xsinfo,
 710                      void (*remove_hook) (bfd *, asection *))
 711 {
 712   struct sec_merge_info *sinfo;
 713
 714   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 715     {
 716       struct sec_merge_sec_info * secinfo;
 717
 718       if (! sinfo->chain)
 719         continue;
 720
 721       /* Move sinfo->chain to head of the chain, terminate it.  */
 722       secinfo = sinfo->chain;
 723       sinfo->chain = secinfo->next;
 724       secinfo->next = NULL;
 725
 726       /* Record the sections into the hash table.  */
 727       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 728         if (secinfo->sec->flags & SEC_EXCLUDE)
 729           {
 730             *secinfo->psecinfo = NULL;
 731             if (remove_hook)
 732               (*remove_hook) (abfd, secinfo->sec);
 733           }
 734         else if (! record_section (sinfo, secinfo))
 735           break;
 736
 737       if (secinfo)
 738         continue;
 739
 740       if (sinfo->htab->first == NULL)
 741         continue;
 742
 743       if (sinfo->htab->strings)
 744         merge_strings (sinfo);
 745       else
 746         {
 747           struct sec_merge_hash_entry *e;
 748           bfd_size_type size = 0;
 749
 750           /* Things are much simpler for non-strings.
 751              Just assign them slots in the section.  */
 752           secinfo = NULL;
 753           for (e = sinfo->htab->first; e; e = e->next)
 754             {
 755               if (e->secinfo->first_str == NULL)
 756                 {
 757                   if (secinfo)
 758                     secinfo->sec->size = size;
 759                   e->secinfo->first_str = e;
 760                   size = 0;
 761                 }
 762               size = (size + e->alignment - 1)
 763                      & ~((bfd_vma) e->alignment - 1);
 764               e->u.index = size;
 765               size += e->len;
 766               secinfo = e->secinfo;
 767             }
 768           secinfo->sec->size = size;
 769         }
 770
 771         /* Finally remove all input sections which have not made it into
 772            the hash table at all.  */
 773         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 774           if (secinfo->first_str == NULL)
 775             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
 776     }
 777
 778   return TRUE;
 779 }
 780
 781 /* Write out the merged section.  */
 782
 783 bfd_boolean
 784 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 785 {
 786   struct sec_merge_sec_info *secinfo;
 787   file_ptr pos;
 788
 789   secinfo = (struct sec_merge_sec_info *) psecinfo;
 790
 791   if (!secinfo)
 792     return FALSE;
 793
 794   if (secinfo->first_str == NULL)
 795     return TRUE;
 796
 797   /* FIXME: octets_per_byte.  */
 798   pos = sec->output_section->filepos + sec->output_offset;
 799   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 800     return FALSE;
 801
 802   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 803     return FALSE;
 804
 805   return TRUE;
 806 }
 807
 808 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 809    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 810    section and writes the new section back into *PSEC.  */
 811
 812 bfd_vma
 813 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 814                             void *psecinfo, bfd_vma offset)
 815 {
 816   struct sec_merge_sec_info *secinfo;
 817   struct sec_merge_hash_entry *entry;
 818   unsigned char *p;
 819   asection *sec = *psec;
 820
 821   secinfo = (struct sec_merge_sec_info *) psecinfo;
 822
 823   if (!secinfo)
 824     return offset;
 825
 826   if (offset >= sec->rawsize)
 827     {
 828       if (offset > sec->rawsize)
 829         {
 830           (*_bfd_error_handler)
 831             (_("%s: access beyond end of merged section (%ld)"),
 832              bfd_get_filename (sec->owner), (long) offset);
 833         }
 834       return secinfo->first_str ? sec->size : 0;
 835     }
 836
 837   if (secinfo->htab->strings)
 838     {
 839       if (sec->entsize == 1)
 840         {
 841           p = secinfo->contents + offset - 1;
 842           while (p >= secinfo->contents && *p)
 843             --p;
 844           ++p;
 845         }
 846       else
 847         {
 848           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 849           p -= sec->entsize;
 850           while (p >= secinfo->contents)
 851             {
 852               unsigned int i;
 853
 854               for (i = 0; i < sec->entsize; ++i)
 855                 if (p[i] != '\0')
 856                   break;
 857               if (i == sec->entsize)
 858                 break;
 859               p -= sec->entsize;
 860             }
 861           p += sec->entsize;
 862         }
 863     }
 864   else
 865     {
 866       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 867     }
 868   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
 869   if (!entry)
 870     {
 871       if (! secinfo->htab->strings)
 872         abort ();
 873       /* This should only happen if somebody points into the padding
 874          after a NUL character but before next entity.  */
 875       if (*p)
 876         abort ();
 877       if (! secinfo->htab->first)
 878         abort ();
 879       entry = secinfo->htab->first;
 880       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 881            - entry->len);
 882     }
 883
 884   *psec = entry->secinfo->sec;
 885   return entry->u.index + (secinfo->contents + offset - p);
 886 }
 887
 888 /* Tidy up when done.  */
 889
 890 void
 891 _bfd_merge_sections_free (void *xsinfo)
 892 {
 893   struct sec_merge_info *sinfo;
 894
 895   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 896     {
 897       bfd_hash_table_free (&sinfo->htab->table);
 898       free (sinfo->htab);
 899     }
 900 }