bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright 2001, 2002, 2003, 2004, 2005 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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /* This file contains support for merging duplicate entities within sections,
  22    as used in ELF SHF_MERGE.  */
  23
  24 #include "bfd.h"
  25 #include "sysdep.h"
  26 #include "libbfd.h"
  27 #include "hashtab.h"
  28 #include "libiberty.h"
  29
  30 struct sec_merge_sec_info;
  31
  32 /* An entry in the section merge hash table.  */
  33
  34 struct sec_merge_hash_entry
  35 {
  36   struct bfd_hash_entry root;
  37   /* Length of this entry.  This includes the zero terminator.  */
  38   unsigned int len;
  39   /* Start of this string needs to be aligned to
  40      alignment octets (not 1 << align).  */
  41   unsigned int alignment;
  42   union
  43   {
  44     /* Index within the merged section.  */
  45     bfd_size_type index;
  46     /* Entry this is a suffix of (if alignment is 0).  */
  47     struct sec_merge_hash_entry *suffix;
  48   } u;
  49   /* Which section is it in.  */
  50   struct sec_merge_sec_info *secinfo;
  51   /* Next entity in the hash table.  */
  52   struct sec_merge_hash_entry *next;
  53 };
  54
  55 /* The section merge hash table.  */
  56
  57 struct sec_merge_hash
  58 {
  59   struct bfd_hash_table table;
  60   /* Next available index.  */
  61   bfd_size_type size;
  62   /* First entity in the SEC_MERGE sections of this type.  */
  63   struct sec_merge_hash_entry *first;
  64   /* Last entity in the SEC_MERGE sections of this type.  */
  65   struct sec_merge_hash_entry *last;
  66   /* Entity size.  */
  67   unsigned int entsize;
  68   /* Are entries fixed size or zero terminated strings?  */
  69   bfd_boolean strings;
  70 };
  71
  72 struct sec_merge_info
  73 {
  74   /* Chain of sec_merge_infos.  */
  75   struct sec_merge_info *next;
  76   /* Chain of sec_merge_sec_infos.  */
  77   struct sec_merge_sec_info *chain;
  78   /* A hash table used to hold section content.  */
  79   struct sec_merge_hash *htab;
  80 };
  81
  82 struct sec_merge_sec_info
  83 {
  84   /* Chain of sec_merge_sec_infos.  */
  85   struct sec_merge_sec_info *next;
  86   /* The corresponding section.  */
  87   asection *sec;
  88   /* Pointer to merge_info pointing to us.  */
  89   void **psecinfo;
  90   /* A hash table used to hold section content.  */
  91   struct sec_merge_hash *htab;
  92   /* First string in this section.  */
  93   struct sec_merge_hash_entry *first_str;
  94   /* Original section content.  */
  95   unsigned char contents[1];
  96 };
  97
  98
  99 /* Routine to create an entry in a section merge hashtab.  */
 100
 101 static struct bfd_hash_entry *
 102 sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
 103                         struct bfd_hash_table *table, const char *string)
 104 {
 105   /* Allocate the structure if it has not already been allocated by a
 106      subclass.  */
 107   if (entry == NULL)
 108     entry = bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
 109   if (entry == NULL)
 110     return NULL;
 111
 112   /* Call the allocation method of the superclass.  */
 113   entry = bfd_hash_newfunc (entry, table, string);
 114
 115   if (entry != NULL)
 116     {
 117       /* Initialize the local fields.  */
 118       struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 119
 120       ret->u.suffix = NULL;
 121       ret->alignment = 0;
 122       ret->secinfo = NULL;
 123       ret->next = NULL;
 124     }
 125
 126   return entry;
 127 }
 128
 129 /* Look up an entry in a section merge hash table.  */
 130
 131 static struct sec_merge_hash_entry *
 132 sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
 133                        unsigned int alignment, bfd_boolean create)
 134 {
 135   register const unsigned char *s;
 136   register unsigned long hash;
 137   register unsigned int c;
 138   struct sec_merge_hash_entry *hashp;
 139   unsigned int len, i;
 140   unsigned int index;
 141
 142   hash = 0;
 143   len = 0;
 144   s = (const unsigned char *) string;
 145   if (table->strings)
 146     {
 147       if (table->entsize == 1)
 148         {
 149           while ((c = *s++) != '\0')
 150             {
 151               hash += c + (c << 17);
 152               hash ^= hash >> 2;
 153               ++len;
 154             }
 155           hash += len + (len << 17);
 156         }
 157       else
 158         {
 159           for (;;)
 160             {
 161               for (i = 0; i < table->entsize; ++i)
 162                 if (s[i] != '\0')
 163                   break;
 164               if (i == table->entsize)
 165                 break;
 166               for (i = 0; i < table->entsize; ++i)
 167                 {
 168                   c = *s++;
 169                   hash += c + (c << 17);
 170                   hash ^= hash >> 2;
 171                 }
 172               ++len;
 173             }
 174           hash += len + (len << 17);
 175           len *= table->entsize;
 176         }
 177       hash ^= hash >> 2;
 178       len += table->entsize;
 179     }
 180   else
 181     {
 182       for (i = 0; i < table->entsize; ++i)
 183         {
 184           c = *s++;
 185           hash += c + (c << 17);
 186           hash ^= hash >> 2;
 187         }
 188       len = table->entsize;
 189     }
 190
 191   index = hash % table->table.size;
 192   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 193        hashp != NULL;
 194        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 195     {
 196       if (hashp->root.hash == hash
 197           && len == hashp->len
 198           && memcmp (hashp->root.string, string, len) == 0)
 199         {
 200           /* If the string we found does not have at least the required
 201              alignment, we need to insert another copy.  */
 202           if (hashp->alignment < alignment)
 203             {
 204               if (create)
 205                 {
 206                   /*  Mark the less aligned copy as deleted.  */
 207                   hashp->len = 0;
 208                   hashp->alignment = 0;
 209                 }
 210               break;
 211             }
 212           return hashp;
 213         }
 214     }
 215
 216   if (! create)
 217     return NULL;
 218
 219   hashp = ((struct sec_merge_hash_entry *)
 220            sec_merge_hash_newfunc (NULL, &table->table, string));
 221   if (hashp == NULL)
 222     return NULL;
 223   hashp->root.string = string;
 224   hashp->root.hash = hash;
 225   hashp->len = len;
 226   hashp->alignment = alignment;
 227   hashp->root.next = table->table.table[index];
 228   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 229
 230   return hashp;
 231 }
 232
 233 /* Create a new hash table.  */
 234
 235 static struct sec_merge_hash *
 236 sec_merge_init (unsigned int entsize, bfd_boolean strings)
 237 {
 238   struct sec_merge_hash *table;
 239
 240   table = bfd_malloc (sizeof (struct sec_merge_hash));
 241   if (table == NULL)
 242     return NULL;
 243
 244   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
 245                                16699))
 246     {
 247       free (table);
 248       return NULL;
 249     }
 250
 251   table->size = 0;
 252   table->first = NULL;
 253   table->last = NULL;
 254   table->entsize = entsize;
 255   table->strings = strings;
 256
 257   return table;
 258 }
 259
 260 /* Get the index of an entity in a hash table, adding it if it is not
 261    already present.  */
 262
 263 static struct sec_merge_hash_entry *
 264 sec_merge_add (struct sec_merge_hash *tab, const char *str,
 265                unsigned int alignment, struct sec_merge_sec_info *secinfo)
 266 {
 267   register struct sec_merge_hash_entry *entry;
 268
 269   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
 270   if (entry == NULL)
 271     return NULL;
 272
 273   if (entry->secinfo == NULL)
 274     {
 275       tab->size++;
 276       entry->secinfo = secinfo;
 277       if (tab->first == NULL)
 278         tab->first = entry;
 279       else
 280         tab->last->next = entry;
 281       tab->last = entry;
 282     }
 283
 284   return entry;
 285 }
 286
 287 static bfd_boolean
 288 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
 289 {
 290   struct sec_merge_sec_info *secinfo = entry->secinfo;
 291   asection *sec = secinfo->sec;
 292   char *pad = NULL;
 293   bfd_size_type off = 0;
 294   int alignment_power = sec->output_section->alignment_power;
 295
 296   if (alignment_power)
 297     {
 298       pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 299       if (pad == NULL)
 300         return FALSE;
 301     }
 302
 303   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 304     {
 305       const char *str;
 306       bfd_size_type len;
 307
 308       len = -off & (entry->alignment - 1);
 309       if (len != 0)
 310         {
 311           if (bfd_bwrite (pad, len, abfd) != len)
 312             goto err;
 313           off += len;
 314         }
 315
 316       str = entry->root.string;
 317       len = entry->len;
 318
 319       if (bfd_bwrite (str, len, abfd) != len)
 320         goto err;
 321
 322       off += len;
 323     }
 324
 325   /* Trailing alignment needed?  */
 326   off = sec->size - off;
 327   if (off != 0
 328       && bfd_bwrite (pad, off, abfd) != off)
 329     goto err;
 330
 331   if (pad != NULL)
 332     free (pad);
 333   return TRUE;
 334
 335  err:
 336   if (pad != NULL)
 337     free (pad);
 338   return FALSE;
 339 }
 340
 341 /* Register a SEC_MERGE section as a candidate for merging.
 342    This function is called for all non-dynamic SEC_MERGE input sections.  */
 343
 344 bfd_boolean
 345 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 346                         void **psecinfo)
 347 {
 348   struct sec_merge_info *sinfo;
 349   struct sec_merge_sec_info *secinfo;
 350   unsigned int align;
 351   bfd_size_type amt;
 352
 353   if ((abfd->flags & DYNAMIC) != 0
 354       || (sec->flags & SEC_MERGE) == 0)
 355     abort ();
 356
 357   if (sec->size == 0
 358       || (sec->flags & SEC_EXCLUDE) != 0
 359       || sec->entsize == 0)
 360     return TRUE;
 361
 362   if ((sec->flags & SEC_RELOC) != 0)
 363     {
 364       /* We aren't prepared to handle relocations in merged sections.  */
 365       return TRUE;
 366     }
 367
 368   align = sec->alignment_power;
 369   if ((sec->entsize < (unsigned) 1 << align
 370        && ((sec->entsize & (sec->entsize - 1))
 371            || !(sec->flags & SEC_STRINGS)))
 372       || (sec->entsize > (unsigned) 1 << align
 373           && (sec->entsize & (((unsigned) 1 << align) - 1))))
 374     {
 375       /* Sanity check.  If string character size is smaller than
 376          alignment, then we require character size to be a power
 377          of 2, otherwise character size must be integer multiple
 378          of alignment.  For non-string constants, alignment must
 379          be smaller than or equal to entity size and entity size
 380          must be integer multiple of alignment.  */
 381       return TRUE;
 382     }
 383
 384   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 385     if ((secinfo = sinfo->chain)
 386         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 387         && secinfo->sec->entsize == sec->entsize
 388         && secinfo->sec->alignment_power == sec->alignment_power
 389         && secinfo->sec->output_section == sec->output_section)
 390       break;
 391
 392   if (sinfo == NULL)
 393     {
 394       /* Initialize the information we need to keep track of.  */
 395       sinfo = 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) + sec->size - 1;
 409   *psecinfo = bfd_alloc (abfd, amt);
 410   if (*psecinfo == NULL)
 411     goto error_return;
 412
 413   secinfo = (struct sec_merge_sec_info *) *psecinfo;
 414   if (sinfo->chain)
 415     {
 416       secinfo->next = sinfo->chain->next;
 417       sinfo->chain->next = secinfo;
 418     }
 419   else
 420     secinfo->next = secinfo;
 421   sinfo->chain = secinfo;
 422   secinfo->sec = sec;
 423   secinfo->psecinfo = psecinfo;
 424   secinfo->htab = sinfo->htab;
 425   secinfo->first_str = NULL;
 426
 427   sec->rawsize = sec->size;
 428   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 429                                   0, sec->size))
 430     goto error_return;
 431
 432   return TRUE;
 433
 434  error_return:
 435   *psecinfo = NULL;
 436   return FALSE;
 437 }
 438
 439 /* Record one section into the hash table.  */
 440 static bfd_boolean
 441 record_section (struct sec_merge_info *sinfo,
 442                 struct sec_merge_sec_info *secinfo)
 443 {
 444   asection *sec = secinfo->sec;
 445   struct sec_merge_hash_entry *entry;
 446   bfd_boolean nul;
 447   unsigned char *p, *end;
 448   bfd_vma mask, eltalign;
 449   unsigned int align, i;
 450
 451   align = sec->alignment_power;
 452   end = secinfo->contents + sec->size;
 453   nul = FALSE;
 454   mask = ((bfd_vma) 1 << align) - 1;
 455   if (sec->flags & SEC_STRINGS)
 456     {
 457       for (p = secinfo->contents; p < end; )
 458         {
 459           eltalign = p - secinfo->contents;
 460           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 461           if (!eltalign || eltalign > mask)
 462             eltalign = mask + 1;
 463           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
 464                                  secinfo);
 465           if (! entry)
 466             goto error_return;
 467           p += entry->len;
 468           if (sec->entsize == 1)
 469             {
 470               while (p < end && *p == 0)
 471                 {
 472                   if (!nul && !((p - secinfo->contents) & mask))
 473                     {
 474                       nul = TRUE;
 475                       entry = sec_merge_add (sinfo->htab, "",
 476                                              (unsigned) mask + 1, secinfo);
 477                       if (! entry)
 478                         goto error_return;
 479                     }
 480                   p++;
 481                 }
 482             }
 483           else
 484             {
 485               while (p < end)
 486                 {
 487                   for (i = 0; i < sec->entsize; i++)
 488                     if (p[i] != '\0')
 489                       break;
 490                   if (i != sec->entsize)
 491                     break;
 492                   if (!nul && !((p - secinfo->contents) & mask))
 493                     {
 494                       nul = TRUE;
 495                       entry = sec_merge_add (sinfo->htab, (char *) p,
 496                                              (unsigned) mask + 1, secinfo);
 497                       if (! entry)
 498                         goto error_return;
 499                     }
 500                   p += sec->entsize;
 501                 }
 502             }
 503         }
 504     }
 505   else
 506     {
 507       for (p = secinfo->contents; p < end; p += sec->entsize)
 508         {
 509           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
 510           if (! entry)
 511             goto error_return;
 512         }
 513     }
 514
 515   return TRUE;
 516
 517 error_return:
 518   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 519     *secinfo->psecinfo = NULL;
 520   return FALSE;
 521 }
 522
 523 static int
 524 strrevcmp (const void *a, const void *b)
 525 {
 526   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 527   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 528   unsigned int lenA = A->len;
 529   unsigned int lenB = B->len;
 530   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 531   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 532   int l = lenA < lenB ? lenA : lenB;
 533
 534   while (l)
 535     {
 536       if (*s != *t)
 537         return (int) *s - (int) *t;
 538       s--;
 539       t--;
 540       l--;
 541     }
 542   return lenA - lenB;
 543 }
 544
 545 /* Like strrevcmp, but for the case where all strings have the same
 546    alignment > entsize.  */
 547
 548 static int
 549 strrevcmp_align (const void *a, const void *b)
 550 {
 551   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
 552   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
 553   unsigned int lenA = A->len;
 554   unsigned int lenB = B->len;
 555   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
 556   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
 557   int l = lenA < lenB ? lenA : lenB;
 558   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
 559
 560   if (tail_align != 0)
 561     return tail_align;
 562
 563   while (l)
 564     {
 565       if (*s != *t)
 566         return (int) *s - (int) *t;
 567       s--;
 568       t--;
 569       l--;
 570     }
 571   return lenA - lenB;
 572 }
 573
 574 static inline int
 575 is_suffix (const struct sec_merge_hash_entry *A,
 576            const struct sec_merge_hash_entry *B)
 577 {
 578   if (A->len <= B->len)
 579     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 580        not to be equal by the hash table.  */
 581     return 0;
 582
 583   return memcmp (A->root.string + (A->len - B->len),
 584                  B->root.string, B->len) == 0;
 585 }
 586
 587 /* This is a helper function for _bfd_merge_sections.  It attempts to
 588    merge strings matching suffixes of longer strings.  */
 589 static void
 590 merge_strings (struct sec_merge_info *sinfo)
 591 {
 592   struct sec_merge_hash_entry **array, **a, *e;
 593   struct sec_merge_sec_info *secinfo;
 594   bfd_size_type size, amt;
 595   unsigned int alignment = 0;
 596
 597   /* Now sort the strings */
 598   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 599   array = bfd_malloc (amt);
 600   if (array == NULL)
 601     goto alloc_failure;
 602
 603   for (e = sinfo->htab->first, a = array; e; e = e->next)
 604     if (e->alignment)
 605       {
 606         *a++ = e;
 607         /* Adjust the length to not include the zero terminator.  */
 608         e->len -= sinfo->htab->entsize;
 609         if (alignment != e->alignment)
 610           {
 611             if (alignment == 0)
 612               alignment = e->alignment;
 613             else
 614               alignment = (unsigned) -1;
 615           }
 616       }
 617
 618   sinfo->htab->size = a - array;
 619   if (sinfo->htab->size != 0)
 620     {
 621       qsort (array, (size_t) sinfo->htab->size,
 622              sizeof (struct sec_merge_hash_entry *),
 623              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
 624               ? strrevcmp_align : strrevcmp));
 625
 626       /* Loop over the sorted array and merge suffixes */
 627       e = *--a;
 628       e->len += sinfo->htab->entsize;
 629       while (--a >= array)
 630         {
 631           struct sec_merge_hash_entry *cmp = *a;
 632
 633           cmp->len += sinfo->htab->entsize;
 634           if (e->alignment >= cmp->alignment
 635               && !((e->len - cmp->len) & (cmp->alignment - 1))
 636               && is_suffix (e, cmp))
 637             {
 638               cmp->u.suffix = e;
 639               cmp->alignment = 0;
 640             }
 641           else
 642             e = cmp;
 643         }
 644     }
 645
 646 alloc_failure:
 647   if (array)
 648     free (array);
 649
 650   /* Now assign positions to the strings we want to keep.  */
 651   size = 0;
 652   secinfo = sinfo->htab->first->secinfo;
 653   for (e = sinfo->htab->first; e; e = e->next)
 654     {
 655       if (e->secinfo != secinfo)
 656         {
 657           secinfo->sec->size = size;
 658           secinfo = e->secinfo;
 659         }
 660       if (e->alignment)
 661         {
 662           if (e->secinfo->first_str == NULL)
 663             {
 664               e->secinfo->first_str = e;
 665               size = 0;
 666             }
 667           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 668           e->u.index = size;
 669           size += e->len;
 670         }
 671     }
 672   secinfo->sec->size = size;
 673   if (secinfo->sec->alignment_power != 0)
 674     {
 675       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
 676       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
 677     }
 678
 679   /* And now adjust the rest, removing them from the chain (but not hashtable)
 680      at the same time.  */
 681   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 682     if (e->alignment)
 683       a = &e->next;
 684     else
 685       {
 686         *a = e->next;
 687         if (e->len)
 688           {
 689             e->secinfo = e->u.suffix->secinfo;
 690             e->alignment = e->u.suffix->alignment;
 691             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 692           }
 693       }
 694 }
 695
 696 /* This function is called once after all SEC_MERGE sections are registered
 697    with _bfd_merge_section.  */
 698
 699 bfd_boolean
 700 _bfd_merge_sections (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_link_info *info,
 701                      void *xsinfo, void (*remove_hook) (bfd *, asection *))
 702 {
 703   struct sec_merge_info *sinfo;
 704
 705   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 706     {
 707       struct sec_merge_sec_info * secinfo;
 708
 709       if (! sinfo->chain)
 710         continue;
 711
 712       /* Move sinfo->chain to head of the chain, terminate it.  */
 713       secinfo = sinfo->chain;
 714       sinfo->chain = secinfo->next;
 715       secinfo->next = NULL;
 716
 717       /* Record the sections into the hash table.  */
 718       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 719         if (secinfo->sec->flags & SEC_EXCLUDE)
 720           {
 721             *secinfo->psecinfo = NULL;
 722             if (remove_hook)
 723               (*remove_hook) (abfd, secinfo->sec);
 724           }
 725         else if (! record_section (sinfo, secinfo))
 726           break;
 727
 728       if (secinfo)
 729         continue;
 730
 731       if (sinfo->htab->first == NULL)
 732         continue;
 733
 734       if (sinfo->htab->strings)
 735         merge_strings (sinfo);
 736       else
 737         {
 738           struct sec_merge_hash_entry *e;
 739           bfd_size_type size = 0;
 740
 741           /* Things are much simpler for non-strings.
 742              Just assign them slots in the section.  */
 743           secinfo = NULL;
 744           for (e = sinfo->htab->first; e; e = e->next)
 745             {
 746               if (e->secinfo->first_str == NULL)
 747                 {
 748                   if (secinfo)
 749                     secinfo->sec->size = size;
 750                   e->secinfo->first_str = e;
 751                   size = 0;
 752                 }
 753               size = (size + e->alignment - 1)
 754                      & ~((bfd_vma) e->alignment - 1);
 755               e->u.index = size;
 756               size += e->len;
 757               secinfo = e->secinfo;
 758             }
 759           secinfo->sec->size = size;
 760         }
 761
 762         /* Finally remove all input sections which have not made it into
 763            the hash table at all.  */
 764         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 765           if (secinfo->first_str == NULL)
 766             _bfd_strip_section_from_output (info, secinfo->sec);
 767     }
 768
 769   return TRUE;
 770 }
 771
 772 /* Write out the merged section.  */
 773
 774 bfd_boolean
 775 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
 776 {
 777   struct sec_merge_sec_info *secinfo;
 778   file_ptr pos;
 779
 780   secinfo = (struct sec_merge_sec_info *) psecinfo;
 781
 782   if (secinfo->first_str == NULL)
 783     return TRUE;
 784
 785   pos = sec->output_section->filepos + sec->output_offset;
 786   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 787     return FALSE;
 788
 789   if (! sec_merge_emit (output_bfd, secinfo->first_str))
 790     return FALSE;
 791
 792   return TRUE;
 793 }
 794
 795 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 796    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 797    section and writes the new section back into *PSEC.  */
 798
 799 bfd_vma
 800 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
 801                             void *psecinfo, bfd_vma offset)
 802 {
 803   struct sec_merge_sec_info *secinfo;
 804   struct sec_merge_hash_entry *entry;
 805   unsigned char *p;
 806   asection *sec = *psec;
 807
 808   secinfo = (struct sec_merge_sec_info *) psecinfo;
 809
 810   if (offset >= sec->rawsize)
 811     {
 812       if (offset > sec->rawsize)
 813         {
 814           (*_bfd_error_handler)
 815             (_("%s: access beyond end of merged section (%ld)"),
 816              bfd_get_filename (sec->owner), (long) offset);
 817         }
 818       return secinfo->first_str ? sec->size : 0;
 819     }
 820
 821   if (secinfo->htab->strings)
 822     {
 823       if (sec->entsize == 1)
 824         {
 825           p = secinfo->contents + offset - 1;
 826           while (p >= secinfo->contents && *p)
 827             --p;
 828           ++p;
 829         }
 830       else
 831         {
 832           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 833           p -= sec->entsize;
 834           while (p >= secinfo->contents)
 835             {
 836               unsigned int i;
 837
 838               for (i = 0; i < sec->entsize; ++i)
 839                 if (p[i] != '\0')
 840                   break;
 841               if (i == sec->entsize)
 842                 break;
 843               p -= sec->entsize;
 844             }
 845           p += sec->entsize;
 846         }
 847     }
 848   else
 849     {
 850       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
 851     }
 852   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
 853   if (!entry)
 854     {
 855       if (! secinfo->htab->strings)
 856         abort ();
 857       /* This should only happen if somebody points into the padding
 858          after a NUL character but before next entity.  */
 859       if (*p)
 860         abort ();
 861       if (! secinfo->htab->first)
 862         abort ();
 863       entry = secinfo->htab->first;
 864       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
 865            - entry->len);
 866     }
 867
 868   *psec = entry->secinfo->sec;
 869   return entry->u.index + (secinfo->contents + offset - p);
 870 }