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