bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright 2001 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
  29 #include <ctype.h>
  30
  31 struct sec_merge_sec_info;
  32
  33 /* An entry in the section merge hash table.  */
  34
  35 struct sec_merge_hash_entry
  36 {
  37   struct bfd_hash_entry root;
  38   /* Length of this entry.  */
  39   unsigned int len;
  40   /* Start of this string needs to be aligned to
  41      alignment octets (not 1 << align).  */
  42   unsigned int alignment;
  43   union {
  44     /* Index within the merged section.  */
  45     bfd_size_type index;
  46     /* Entity size (if present in suffix hash tables).  */
  47     unsigned int entsize;
  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   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   PTR *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;
  96   /* Original section content.  */
  97   unsigned char contents[1];
  98 };
  99
 100 static struct bfd_hash_entry *sec_merge_hash_newfunc
 101   PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
 102 static struct sec_merge_hash_entry *sec_merge_hash_lookup
 103   PARAMS ((struct sec_merge_hash *, const char *, unsigned int, boolean));
 104 static struct sec_merge_hash *sec_merge_init
 105   PARAMS ((unsigned int, boolean));
 106 static struct sec_merge_hash_entry *sec_merge_add
 107   PARAMS ((struct sec_merge_hash *, const char *, unsigned int,
 108            struct sec_merge_sec_info *));
 109 static boolean sec_merge_emit
 110   PARAMS ((bfd *, struct sec_merge_hash_entry *));
 111
 112 /* Routine to create an entry in a section merge hashtab.  */
 113
 114 static struct bfd_hash_entry *
 115 sec_merge_hash_newfunc (entry, table, string)
 116      struct bfd_hash_entry *entry;
 117      struct bfd_hash_table *table;
 118      const char *string;
 119 {
 120   struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 121
 122   /* Allocate the structure if it has not already been allocated by a
 123      subclass.  */
 124   if (ret == (struct sec_merge_hash_entry *) NULL)
 125     ret = ((struct sec_merge_hash_entry *)
 126            bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
 127   if (ret == (struct sec_merge_hash_entry *) NULL)
 128     return NULL;
 129
 130   /* Call the allocation method of the superclass.  */
 131   ret = ((struct sec_merge_hash_entry *)
 132          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 133
 134   if (ret)
 135     {
 136       /* Initialize the local fields.  */
 137       ret->u.suffix = NULL;
 138       ret->alignment = 0;
 139       ret->secinfo = NULL;
 140       ret->next = NULL;
 141     }
 142
 143   return (struct bfd_hash_entry *)ret;
 144 }
 145
 146 /* Look up an entry in a section merge hash table.  */
 147
 148 static struct sec_merge_hash_entry *
 149 sec_merge_hash_lookup (table, string, alignment, create)
 150      struct sec_merge_hash *table;
 151      const char *string;
 152      unsigned int alignment;
 153      boolean create;
 154 {
 155   register const unsigned char *s;
 156   register unsigned long hash;
 157   register unsigned int c;
 158   struct sec_merge_hash_entry *hashp;
 159   unsigned int len, i;
 160   unsigned int index;
 161
 162   hash = 0;
 163   len = 0;
 164   s = (const unsigned char *) string;
 165   if (table->strings)
 166     {
 167       if (table->entsize == 1)
 168         {
 169           while ((c = *s++) != '\0')
 170             {
 171               hash += c + (c << 17);
 172               hash ^= hash >> 2;
 173               ++len;
 174             }
 175           hash += len + (len << 17);
 176         }
 177       else
 178         {
 179           for (;;)
 180             {
 181               for (i = 0; i < table->entsize; ++i)
 182                 if (s[i] != '\0')
 183                   break;
 184               if (i == table->entsize)
 185                 break;
 186               for (i = 0; i < table->entsize; ++i)
 187                 {
 188                   c = *s++;
 189                   hash += c + (c << 17);
 190                   hash ^= hash >> 2;
 191                 }
 192               ++len;
 193             }
 194           hash += len + (len << 17);
 195           len *= table->entsize;
 196         }
 197       hash ^= hash >> 2;
 198       len += table->entsize;
 199     }
 200   else
 201     {
 202       for (i = 0; i < table->entsize; ++i)
 203         {
 204           c = *s++;
 205           hash += c + (c << 17);
 206           hash ^= hash >> 2;
 207         }
 208       len = table->entsize;
 209     }
 210
 211   index = hash % table->table.size;
 212   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 213        hashp != (struct sec_merge_hash_entry *) NULL;
 214        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 215     {
 216       if (hashp->root.hash == hash
 217           && len == hashp->len
 218           && memcmp (hashp->root.string, string, len) == 0)
 219         {
 220           /* If the string we found does not have at least the required
 221              alignment, we need to insert another copy.  */
 222           if (hashp->alignment < alignment)
 223             {
 224               /*  Mark the less aligned copy as deleted.  */
 225               hashp->len = 0;
 226               hashp->alignment = 0;
 227               break;
 228             }
 229           return hashp;
 230         }
 231     }
 232
 233   if (! create)
 234     return (struct sec_merge_hash_entry *) NULL;
 235
 236   hashp = (struct sec_merge_hash_entry *)
 237           sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
 238                                   (struct bfd_hash_table *) table, string);
 239   if (hashp == (struct sec_merge_hash_entry *) NULL)
 240     return (struct sec_merge_hash_entry *) NULL;
 241   hashp->root.string = string;
 242   hashp->root.hash = hash;
 243   hashp->len = len;
 244   hashp->alignment = alignment;
 245   hashp->root.next = table->table.table[index];
 246   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 247
 248   return hashp;
 249 }
 250
 251 /* Create a new hash table.  */
 252
 253 static struct sec_merge_hash *
 254 sec_merge_init (entsize, strings)
 255      unsigned int entsize;
 256      boolean strings;
 257 {
 258   struct sec_merge_hash *table;
 259
 260   table = ((struct sec_merge_hash *)
 261            bfd_malloc (sizeof (struct sec_merge_hash)));
 262   if (table == NULL)
 263     return NULL;
 264
 265   if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
 266     {
 267       free (table);
 268       return NULL;
 269     }
 270
 271   table->size = 0;
 272   table->first = NULL;
 273   table->last = NULL;
 274   table->entsize = entsize;
 275   table->strings = strings;
 276
 277   return table;
 278 }
 279
 280 /* Get the index of an entity in a hash table, adding it if it is not
 281    already present.  */
 282
 283 static struct sec_merge_hash_entry *
 284 sec_merge_add (tab, str, alignment, secinfo)
 285      struct sec_merge_hash *tab;
 286      const char *str;
 287      unsigned int alignment;
 288      struct sec_merge_sec_info *secinfo;
 289 {
 290   register struct sec_merge_hash_entry *entry;
 291
 292   entry = sec_merge_hash_lookup (tab, str, alignment, true);
 293   if (entry == NULL)
 294     return NULL;
 295
 296   if (entry->secinfo == NULL)
 297     {
 298       tab->size++;
 299       entry->secinfo = secinfo;
 300       if (tab->first == NULL)
 301         tab->first = entry;
 302       else
 303         tab->last->next = entry;
 304       tab->last = entry;
 305     }
 306
 307   return entry;
 308 }
 309
 310 static boolean
 311 sec_merge_emit (abfd, entry)
 312      register bfd *abfd;
 313      struct sec_merge_hash_entry *entry;
 314 {
 315   struct sec_merge_sec_info *secinfo = entry->secinfo;
 316   asection *sec = secinfo->sec;
 317   char *pad = "";
 318   bfd_size_type off = 0;
 319   int alignment_power = bfd_get_section_alignment (abfd, sec->output_section);
 320
 321   if (alignment_power)
 322     pad = bfd_zmalloc (1 << alignment_power);
 323
 324   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 325     {
 326       register const char *str;
 327       register size_t len;
 328
 329       len = off & (entry->alignment - 1);
 330       if (len)
 331         {
 332           len = entry->alignment - len;
 333           if (bfd_write ((PTR) pad, 1, len, abfd) != len)
 334             break;
 335           off += len;
 336         }
 337
 338       str = entry->root.string;
 339       len = entry->len;
 340
 341       if (bfd_write ((PTR) str, 1, len, abfd) != len)
 342         break;
 343
 344       off += len;
 345     }
 346
 347   if (alignment_power)
 348     free (pad);
 349
 350   return entry == NULL || entry->secinfo != secinfo;
 351 }
 352
 353 /* This function is called for each input file from the add_symbols
 354    pass of the linker.  */
 355
 356 boolean
 357 _bfd_merge_section (abfd, psinfo, sec, psecinfo)
 358      bfd *abfd;
 359      PTR *psinfo;
 360      asection *sec;
 361      PTR *psecinfo;
 362 {
 363   struct sec_merge_info *sinfo;
 364   struct sec_merge_sec_info *secinfo;
 365   unsigned int align;
 366
 367   if (sec->_raw_size == 0
 368       || (sec->flags & SEC_EXCLUDE)
 369       || (sec->flags & SEC_MERGE) == 0
 370       || sec->entsize == 0)
 371     return true;
 372
 373   if ((sec->flags & SEC_RELOC) != 0)
 374     {
 375       /* We aren't prepared to handle relocations in merged sections.  */
 376       return true;
 377     }
 378
 379   if (sec->output_section != NULL
 380       && bfd_is_abs_section (sec->output_section))
 381     {
 382       /* The section is being discarded from the link, so we should
 383          just ignore it.  */
 384       return true;
 385     }
 386
 387   align = bfd_get_section_alignment (sec->owner, sec);
 388   if ((sec->entsize < (unsigned int)(1 << align)
 389        && ((sec->entsize & (sec->entsize - 1))
 390            || !(sec->flags & SEC_STRINGS)))
 391       || (sec->entsize > (unsigned int)(1 << align)
 392           && (sec->entsize & ((1 << align) - 1))))
 393     {
 394       /* Sanity check.  If string character size is smaller than
 395          alignment, then we require character size to be a power
 396          of 2, otherwise character size must be integer multiple
 397          of alignment.  For non-string constants, alignment must
 398          be smaller than or equal to entity size and entity size
 399          must be integer multiple of alignment.  */
 400       return true;
 401     }
 402
 403   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 404     if ((secinfo = sinfo->chain)
 405         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 406         && secinfo->sec->entsize == sec->entsize
 407         && ! strcmp (secinfo->sec->name, sec->name))
 408       break;
 409
 410   if (sinfo == NULL)
 411     {
 412       /* Initialize the information we need to keep track of.  */
 413       sinfo = (struct sec_merge_info *)
 414               bfd_alloc (abfd, sizeof (struct sec_merge_info));
 415       if (sinfo == NULL)
 416         goto error_return;
 417       sinfo->next = (struct sec_merge_info *) *psinfo;
 418       sinfo->chain = NULL;
 419       *psinfo = (PTR) sinfo;
 420       sinfo->htab =
 421         sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 422       if (sinfo->htab == NULL)
 423         goto error_return;
 424     }
 425
 426   /* Read the section from abfd.  */
 427
 428   *psecinfo = bfd_alloc (abfd, sizeof (struct sec_merge_sec_info)
 429                                + sec->_raw_size - 1);
 430   if (*psecinfo == NULL)
 431     goto error_return;
 432
 433   secinfo = (struct sec_merge_sec_info *)*psecinfo;
 434   if (sinfo->chain)
 435     {
 436       secinfo->next = sinfo->chain->next;
 437       sinfo->chain->next = secinfo;
 438     }
 439   else
 440     secinfo->next = secinfo;
 441   sinfo->chain = secinfo;
 442   secinfo->sec = sec;
 443   secinfo->psecinfo = psecinfo;
 444   secinfo->htab = sinfo->htab;
 445   secinfo->first = NULL;
 446
 447   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents, 0,
 448                                   sec->_raw_size))
 449     goto error_return;
 450
 451   return true;
 452
 453  error_return:
 454   *psecinfo = NULL;
 455   return false;
 456 }
 457
 458 /* Compare two sec_merge_hash_entry structures.  This is called via qsort.  */
 459
 460 static int
 461 cmplengthentry (a, b)
 462      const PTR a;
 463      const PTR b;
 464 {
 465   struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
 466   struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
 467
 468   if (A->len < B->len)
 469     return 1;
 470   else if (A->len > B->len)
 471     return -1;
 472
 473   return memcmp (A->root.string, B->root.string, A->len);
 474 }
 475
 476 static int
 477 last4_eq (a, b)
 478      const void *a, *b;
 479 {
 480   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 481   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 482
 483   if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
 484               B->root.string + B->len - 5 * A->u.entsize,
 485               4 * A->u.entsize) != 0)
 486     /* This was a hashtable collision.  */
 487     return 0;
 488
 489   if (A->len <= B->len)
 490     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 491        not to be equal by the hash table.  */
 492     return 0;
 493
 494   if (A->alignment < B->alignment
 495       || ((A->len - B->len) & (B->alignment - 1)))
 496     /* The suffix is not sufficiently aligned.  */
 497     return 0;
 498
 499   return memcmp (A->root.string + (A->len - B->len),
 500                  B->root.string, B->len - 5 * A->u.entsize) == 0;
 501 }
 502
 503 static int
 504 last_eq (a, b)
 505      const void *a, *b;
 506 {
 507   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 508   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 509
 510   if (B->len >= 5 * A->u.entsize)
 511     /* Longer strings are just pushed into the hash table,
 512        they'll be used when looking up for very short strings.  */
 513     return 0;
 514
 515   if (memcmp (A->root.string + A->len - 2 * A->u.entsize,
 516               B->root.string + B->len - 2 * A->u.entsize,
 517               A->u.entsize) != 0)
 518     /* This was a hashtable collision.  */
 519     return 0;
 520
 521   if (A->len <= B->len)
 522     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 523        not to be equal by the hash table.  */
 524     return 0;
 525
 526   if (A->alignment < B->alignment
 527       || ((A->len - B->len) & (B->alignment - 1)))
 528     /* The suffix is not sufficiently aligned.  */
 529     return 0;
 530
 531   return memcmp (A->root.string + (A->len - B->len),
 532                  B->root.string, B->len - 2 * A->u.entsize) == 0;
 533 }
 534
 535 /* Record one section into the hash table.  */
 536 static boolean
 537 record_section (sinfo, secinfo)
 538      struct sec_merge_info *sinfo;
 539      struct sec_merge_sec_info *secinfo;
 540 {
 541   asection *sec = secinfo->sec;
 542   struct sec_merge_hash_entry *entry;
 543   boolean nul;
 544   unsigned char *p, *end;
 545   bfd_vma mask, eltalign;
 546   unsigned int align, i;
 547
 548   align = bfd_get_section_alignment (sec->owner, sec);
 549   end = secinfo->contents + sec->_raw_size;
 550   nul = false;
 551   mask = ((bfd_vma)1 << align) - 1;
 552   if (sec->flags & SEC_STRINGS)
 553     {
 554       for (p = secinfo->contents; p < end;)
 555         {
 556           eltalign = p - secinfo->contents;
 557           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 558           if (!eltalign || eltalign > mask)
 559             eltalign = mask + 1;
 560           entry = sec_merge_add (sinfo->htab, p, eltalign, secinfo);
 561           if (! entry)
 562             goto error_return;
 563           p += entry->len;
 564           if (sec->entsize == 1)
 565             {
 566               while (p < end && *p == 0)
 567                 {
 568                   if (!nul && !((p - secinfo->contents) & mask))
 569                     {
 570                       nul = true;
 571                       entry = sec_merge_add (sinfo->htab, "", mask + 1,
 572                                              secinfo);
 573                       if (! entry)
 574                         goto error_return;
 575                     }
 576                   p++;
 577                 }
 578             }
 579           else
 580             {
 581               while (p < end)
 582                 {
 583                   for (i = 0; i < sec->entsize; i++)
 584                     if (p[i] != '\0')
 585                       break;
 586                   if (i != sec->entsize)
 587                     break;
 588                   if (!nul && !((p - secinfo->contents) & mask))
 589                     {
 590                       nul = true;
 591                       entry = sec_merge_add (sinfo->htab, p, mask + 1,
 592                                              secinfo);
 593                       if (! entry)
 594                         goto error_return;
 595                     }
 596                   p += sec->entsize;
 597                 }
 598             }
 599         }
 600     }
 601   else
 602     {
 603       for (p = secinfo->contents; p < end; p += sec->entsize)
 604         {
 605           entry = sec_merge_add (sinfo->htab, p, 1, secinfo);
 606           if (! entry)
 607             goto error_return;
 608         }
 609     }
 610
 611   return true;
 612
 613 error_return:
 614   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 615     *secinfo->psecinfo = NULL;
 616   return false;
 617 }
 618
 619 /* This is a helper function for _bfd_merge_sections.  It attempts to
 620    merge strings matching suffixes of longer strings.  */
 621 static void
 622 merge_strings (sinfo)
 623      struct sec_merge_info *sinfo;
 624 {
 625   struct sec_merge_hash_entry **array, **a, **end, *e;
 626   struct sec_merge_sec_info *secinfo;
 627   htab_t lasttab = NULL, last4tab = NULL;
 628   bfd_size_type size;
 629
 630   /* Now sort the strings by length, longest first.  */
 631   array = (struct sec_merge_hash_entry **)
 632           malloc (sinfo->htab->size
 633                   * sizeof (struct sec_merge_hash_entry *));
 634   if (array == NULL)
 635     goto alloc_failure;
 636
 637   for (e = sinfo->htab->first, a = array; e; e = e->next)
 638     if (e->alignment)
 639       *a++ = e;
 640
 641   sinfo->htab->size = a - array;
 642
 643   qsort (array, sinfo->htab->size, sizeof (struct sec_merge_hash_entry *),
 644          cmplengthentry);
 645
 646   last4tab = htab_create (sinfo->htab->size * 4, NULL, last4_eq, NULL);
 647   lasttab = htab_create (sinfo->htab->size * 4, NULL, last_eq, NULL);
 648   if (lasttab == NULL || last4tab == NULL)
 649     goto alloc_failure;
 650
 651   /* Now insert the strings into hash tables (strings with last 4 characters
 652      and strings with last character equal), look for longer strings which
 653      we're suffix of.  */
 654   for (a = array, end = array + sinfo->htab->size; a < end; a++)
 655     {
 656       register hashval_t hash;
 657       unsigned int c;
 658       unsigned int i;
 659       const unsigned char *s;
 660       PTR *p;
 661
 662       e = *a;
 663       e->u.entsize = sinfo->htab->entsize;
 664       if (e->len <= e->u.entsize)
 665         break;
 666       if (e->len > 4 * e->u.entsize)
 667         {
 668           s = e->root.string + e->len - e->u.entsize;
 669           hash = 0;
 670           for (i = 0; i < 4 * e->u.entsize; i++)
 671             {
 672               c = *--s;
 673               hash += c + (c << 17);
 674               hash ^= hash >> 2;
 675             }
 676           p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
 677           if (p == NULL)
 678             goto alloc_failure;
 679           if (*p)
 680             {
 681               struct sec_merge_hash_entry *ent;
 682
 683               ent = (struct sec_merge_hash_entry *) *p;
 684               e->u.suffix = ent;
 685               e->alignment = 0;
 686               continue;
 687             }
 688           else
 689             *p = (PTR) e;
 690         }
 691       s = e->root.string + e->len - e->u.entsize;
 692       hash = 0;
 693       for (i = 0; i < e->u.entsize; i++)
 694         {
 695           c = *--s;
 696           hash += c + (c << 17);
 697           hash ^= hash >> 2;
 698         }
 699       p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
 700       if (p == NULL)
 701         goto alloc_failure;
 702       if (*p)
 703         {
 704           struct sec_merge_hash_entry *ent;
 705
 706           ent = (struct sec_merge_hash_entry *) *p;
 707           e->u.suffix = ent;
 708           e->alignment = 0;
 709         }
 710       else
 711         *p = (PTR) e;
 712     }
 713
 714 alloc_failure:
 715   if (array)
 716     free (array);
 717   if (lasttab)
 718     htab_delete (lasttab);
 719   if (last4tab)
 720     htab_delete (last4tab);
 721
 722   /* Now assign positions to the strings we want to keep.  */
 723   size = 0;
 724   secinfo = sinfo->htab->first->secinfo;
 725   for (e = sinfo->htab->first; e; e = e->next)
 726     {
 727       if (e->secinfo != secinfo)
 728         {
 729           secinfo->sec->_cooked_size = size;
 730           secinfo = e->secinfo;
 731         }
 732       if (e->alignment)
 733         {
 734           if (e->secinfo->first == NULL)
 735             {
 736               e->secinfo->first = e;
 737               size = 0;
 738             }
 739           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 740           e->u.index = size;
 741           size += e->len;
 742         }
 743     }
 744   secinfo->sec->_cooked_size = size;
 745
 746   /* And now adjust the rest, removing them from the chain (but not hashtable)
 747      at the same time.  */
 748   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 749     if (e->alignment)
 750       a = &e->next;
 751     else
 752       {
 753         *a = e->next;
 754         if (e->len)
 755           {
 756             e->secinfo = e->u.suffix->secinfo;
 757             e->alignment = e->u.suffix->alignment;
 758             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 759           }
 760       }
 761 }
 762
 763 /* This function is called once after all SEC_MERGE sections are registered
 764    with _bfd_merge_section.  */
 765
 766 boolean
 767 _bfd_merge_sections (abfd, xsinfo)
 768      bfd *abfd ATTRIBUTE_UNUSED;
 769      PTR xsinfo;
 770 {
 771   struct sec_merge_info *sinfo;
 772
 773   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 774     {
 775       struct sec_merge_sec_info * secinfo;
 776
 777       if (! sinfo->chain)
 778         continue;
 779
 780       /* Move sinfo->chain to head of the chain, terminate it.  */
 781       secinfo = sinfo->chain;
 782       sinfo->chain = secinfo->next;
 783       secinfo->next = NULL;
 784
 785       /* Record the sections into the hash table.  */
 786       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 787         if (secinfo->sec->flags & SEC_EXCLUDE)
 788           *secinfo->psecinfo = NULL;
 789         else if (! record_section (sinfo, secinfo))
 790           break;
 791
 792       if (secinfo)
 793         continue;
 794
 795       if (sinfo->htab->strings)
 796         merge_strings (sinfo);
 797       else
 798         {
 799           struct sec_merge_hash_entry *e;
 800           bfd_size_type size = 0;
 801
 802           /* Things are much simpler for non-strings.
 803              Just assign them slots in the section.  */
 804           secinfo = NULL;
 805           for (e = sinfo->htab->first; e; e = e->next)
 806             {
 807               if (e->secinfo->first == NULL)
 808                 {
 809                   if (secinfo)
 810                     secinfo->sec->_cooked_size = size;
 811                   e->secinfo->first = e;
 812                   size = 0;
 813                 }
 814               size = (size + e->alignment - 1)
 815                      & ~((bfd_vma) e->alignment - 1);
 816               e->u.index = size;
 817               size += e->len;
 818               secinfo = e->secinfo;
 819             }
 820           secinfo->sec->_cooked_size = size;
 821         }
 822
 823         /* Finally shrink all input sections which have not made it into
 824            the hash table at all.  */
 825         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 826           if (secinfo->first == NULL)
 827             {
 828               secinfo->sec->_cooked_size = 0;
 829               secinfo->sec->flags |= SEC_EXCLUDE;
 830             }
 831     }
 832
 833   return true;
 834 }
 835
 836 /* Write out the merged section.  */
 837
 838 boolean
 839 _bfd_write_merged_section (output_bfd, sec, psecinfo)
 840      bfd *output_bfd;
 841      asection *sec;
 842      PTR psecinfo;
 843 {
 844   struct sec_merge_sec_info *secinfo;
 845
 846   secinfo = (struct sec_merge_sec_info *) psecinfo;
 847
 848   if (!secinfo->first)
 849     return true;
 850
 851   if (bfd_seek (output_bfd,
 852                 (sec->output_section->filepos + sec->output_offset),
 853                 SEEK_SET) != 0)
 854     return false;
 855
 856   if (! sec_merge_emit (output_bfd, secinfo->first))
 857     return false;
 858
 859   return true;
 860 }
 861
 862 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 863    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 864    section and writes the new section back into *PSEC.  */
 865
 866 bfd_vma
 867 _bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
 868      bfd *output_bfd ATTRIBUTE_UNUSED;
 869      asection **psec;
 870      PTR psecinfo;
 871      bfd_vma offset, addend;
 872 {
 873   struct sec_merge_sec_info *secinfo;
 874   struct sec_merge_hash_entry *entry;
 875   unsigned char *p;
 876   asection *sec = *psec;
 877
 878   secinfo = (struct sec_merge_sec_info *) psecinfo;
 879
 880   if (offset + addend >= sec->_raw_size)
 881     {
 882       if (offset + addend > sec->_raw_size)
 883         (*_bfd_error_handler) (_("%s: access beyond end of merged section (%ld + %ld)"),
 884                                bfd_get_filename (sec->owner), (long)offset,
 885                                (long) addend);
 886       return (secinfo->first ? sec->_cooked_size : 0);
 887     }
 888
 889   if (secinfo->htab->strings)
 890     {
 891       if (sec->entsize == 1)
 892         {
 893           p = secinfo->contents + offset + addend - 1;
 894           while (*p && p >= secinfo->contents)
 895             --p;
 896           ++p;
 897         }
 898       else
 899         {
 900           p = secinfo->contents
 901               + ((offset + addend) / sec->entsize) * sec->entsize;
 902           p -= sec->entsize;
 903           while (p >= secinfo->contents)
 904             {
 905               unsigned int i;
 906
 907               for (i = 0; i < sec->entsize; ++i)
 908                 if (p[i] != '\0')
 909                   break;
 910               if (i == sec->entsize)
 911                 break;
 912               p -= sec->entsize;
 913             }
 914           p += sec->entsize;
 915         }
 916     }
 917   else
 918     {
 919       p = secinfo->contents
 920           + ((offset + addend) / sec->entsize) * sec->entsize;
 921     }
 922   entry = sec_merge_hash_lookup (secinfo->htab, p, 0, false);
 923   if (!entry)
 924     {
 925       if (! secinfo->htab->strings)
 926         abort ();
 927       /* This should only happen if somebody points into the padding
 928          after a NUL character but before next entity.  */
 929       if (*p)
 930         abort ();
 931       if (! secinfo->htab->first)
 932         abort ();
 933       entry = secinfo->htab->first;
 934       p = secinfo->contents
 935           + ((offset + addend) / sec->entsize + 1) * sec->entsize
 936           - entry->len;
 937     }
 938
 939   *psec = entry->secinfo->sec;
 940   return entry->u.index + (secinfo->contents + offset - p);
 941 }