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 static int cmplengthentry PARAMS ((const PTR, const PTR));
 112 static int last4_eq PARAMS ((const PTR, const PTR));
 113 static int last_eq PARAMS ((const PTR, const PTR));
 114 static boolean record_section
 115   PARAMS ((struct sec_merge_info *, struct sec_merge_sec_info *));
 116 static void merge_strings PARAMS ((struct sec_merge_info *));
 117
 118 /* Routine to create an entry in a section merge hashtab.  */
 119
 120 static struct bfd_hash_entry *
 121 sec_merge_hash_newfunc (entry, table, string)
 122      struct bfd_hash_entry *entry;
 123      struct bfd_hash_table *table;
 124      const char *string;
 125 {
 126   struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 127
 128   /* Allocate the structure if it has not already been allocated by a
 129      subclass.  */
 130   if (ret == (struct sec_merge_hash_entry *) NULL)
 131     ret = ((struct sec_merge_hash_entry *)
 132            bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
 133   if (ret == (struct sec_merge_hash_entry *) NULL)
 134     return NULL;
 135
 136   /* Call the allocation method of the superclass.  */
 137   ret = ((struct sec_merge_hash_entry *)
 138          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 139
 140   if (ret)
 141     {
 142       /* Initialize the local fields.  */
 143       ret->u.suffix = NULL;
 144       ret->alignment = 0;
 145       ret->secinfo = NULL;
 146       ret->next = NULL;
 147     }
 148
 149   return (struct bfd_hash_entry *)ret;
 150 }
 151
 152 /* Look up an entry in a section merge hash table.  */
 153
 154 static struct sec_merge_hash_entry *
 155 sec_merge_hash_lookup (table, string, alignment, create)
 156      struct sec_merge_hash *table;
 157      const char *string;
 158      unsigned int alignment;
 159      boolean create;
 160 {
 161   register const unsigned char *s;
 162   register unsigned long hash;
 163   register unsigned int c;
 164   struct sec_merge_hash_entry *hashp;
 165   unsigned int len, i;
 166   unsigned int index;
 167
 168   hash = 0;
 169   len = 0;
 170   s = (const unsigned char *) string;
 171   if (table->strings)
 172     {
 173       if (table->entsize == 1)
 174         {
 175           while ((c = *s++) != '\0')
 176             {
 177               hash += c + (c << 17);
 178               hash ^= hash >> 2;
 179               ++len;
 180             }
 181           hash += len + (len << 17);
 182         }
 183       else
 184         {
 185           for (;;)
 186             {
 187               for (i = 0; i < table->entsize; ++i)
 188                 if (s[i] != '\0')
 189                   break;
 190               if (i == table->entsize)
 191                 break;
 192               for (i = 0; i < table->entsize; ++i)
 193                 {
 194                   c = *s++;
 195                   hash += c + (c << 17);
 196                   hash ^= hash >> 2;
 197                 }
 198               ++len;
 199             }
 200           hash += len + (len << 17);
 201           len *= table->entsize;
 202         }
 203       hash ^= hash >> 2;
 204       len += table->entsize;
 205     }
 206   else
 207     {
 208       for (i = 0; i < table->entsize; ++i)
 209         {
 210           c = *s++;
 211           hash += c + (c << 17);
 212           hash ^= hash >> 2;
 213         }
 214       len = table->entsize;
 215     }
 216
 217   index = hash % table->table.size;
 218   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 219        hashp != (struct sec_merge_hash_entry *) NULL;
 220        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 221     {
 222       if (hashp->root.hash == hash
 223           && len == hashp->len
 224           && memcmp (hashp->root.string, string, len) == 0)
 225         {
 226           /* If the string we found does not have at least the required
 227              alignment, we need to insert another copy.  */
 228           if (hashp->alignment < alignment)
 229             {
 230               /*  Mark the less aligned copy as deleted.  */
 231               hashp->len = 0;
 232               hashp->alignment = 0;
 233               break;
 234             }
 235           return hashp;
 236         }
 237     }
 238
 239   if (! create)
 240     return (struct sec_merge_hash_entry *) NULL;
 241
 242   hashp = (struct sec_merge_hash_entry *)
 243           sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
 244                                   (struct bfd_hash_table *) table, string);
 245   if (hashp == (struct sec_merge_hash_entry *) NULL)
 246     return (struct sec_merge_hash_entry *) NULL;
 247   hashp->root.string = string;
 248   hashp->root.hash = hash;
 249   hashp->len = len;
 250   hashp->alignment = alignment;
 251   hashp->root.next = table->table.table[index];
 252   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 253
 254   return hashp;
 255 }
 256
 257 /* Create a new hash table.  */
 258
 259 static struct sec_merge_hash *
 260 sec_merge_init (entsize, strings)
 261      unsigned int entsize;
 262      boolean strings;
 263 {
 264   struct sec_merge_hash *table;
 265   bfd_size_type amt = sizeof (struct sec_merge_hash);
 266
 267   table = (struct sec_merge_hash *) bfd_malloc (amt);
 268   if (table == NULL)
 269     return NULL;
 270
 271   if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
 272     {
 273       free (table);
 274       return NULL;
 275     }
 276
 277   table->size = 0;
 278   table->first = NULL;
 279   table->last = NULL;
 280   table->entsize = entsize;
 281   table->strings = strings;
 282
 283   return table;
 284 }
 285
 286 /* Get the index of an entity in a hash table, adding it if it is not
 287    already present.  */
 288
 289 static struct sec_merge_hash_entry *
 290 sec_merge_add (tab, str, alignment, secinfo)
 291      struct sec_merge_hash *tab;
 292      const char *str;
 293      unsigned int alignment;
 294      struct sec_merge_sec_info *secinfo;
 295 {
 296   register struct sec_merge_hash_entry *entry;
 297
 298   entry = sec_merge_hash_lookup (tab, str, alignment, true);
 299   if (entry == NULL)
 300     return NULL;
 301
 302   if (entry->secinfo == NULL)
 303     {
 304       tab->size++;
 305       entry->secinfo = secinfo;
 306       if (tab->first == NULL)
 307         tab->first = entry;
 308       else
 309         tab->last->next = entry;
 310       tab->last = entry;
 311     }
 312
 313   return entry;
 314 }
 315
 316 static boolean
 317 sec_merge_emit (abfd, entry)
 318      register bfd *abfd;
 319      struct sec_merge_hash_entry *entry;
 320 {
 321   struct sec_merge_sec_info *secinfo = entry->secinfo;
 322   asection *sec = secinfo->sec;
 323   char *pad = "";
 324   bfd_size_type off = 0;
 325   int alignment_power = bfd_get_section_alignment (abfd, sec->output_section);
 326
 327   if (alignment_power)
 328     pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 329
 330   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 331     {
 332       register const char *str;
 333       register size_t len;
 334
 335       len = off & (entry->alignment - 1);
 336       if (len)
 337         {
 338           len = entry->alignment - len;
 339           if (bfd_bwrite ((PTR) pad, (bfd_size_type) len, abfd) != len)
 340             break;
 341           off += len;
 342         }
 343
 344       str = entry->root.string;
 345       len = entry->len;
 346
 347       if (bfd_bwrite ((PTR) str, (bfd_size_type) len, abfd) != len)
 348         break;
 349
 350       off += len;
 351     }
 352
 353   if (alignment_power)
 354     free (pad);
 355
 356   return entry == NULL || entry->secinfo != secinfo;
 357 }
 358
 359 /* This function is called for each input file from the add_symbols
 360    pass of the linker.  */
 361
 362 boolean
 363 _bfd_merge_section (abfd, psinfo, sec, psecinfo)
 364      bfd *abfd;
 365      PTR *psinfo;
 366      asection *sec;
 367      PTR *psecinfo;
 368 {
 369   struct sec_merge_info *sinfo;
 370   struct sec_merge_sec_info *secinfo;
 371   unsigned int align;
 372   bfd_size_type amt;
 373
 374   if (sec->_raw_size == 0
 375       || (sec->flags & SEC_EXCLUDE)
 376       || (sec->flags & SEC_MERGE) == 0
 377       || sec->entsize == 0)
 378     return true;
 379
 380   if ((sec->flags & SEC_RELOC) != 0)
 381     {
 382       /* We aren't prepared to handle relocations in merged sections.  */
 383       return true;
 384     }
 385
 386   if (sec->output_section != NULL
 387       && bfd_is_abs_section (sec->output_section))
 388     {
 389       /* The section is being discarded from the link, so we should
 390          just ignore it.  */
 391       return true;
 392     }
 393
 394   align = bfd_get_section_alignment (sec->owner, sec);
 395   if ((sec->entsize < (unsigned int)(1 << align)
 396        && ((sec->entsize & (sec->entsize - 1))
 397            || !(sec->flags & SEC_STRINGS)))
 398       || (sec->entsize > (unsigned int)(1 << align)
 399           && (sec->entsize & ((1 << align) - 1))))
 400     {
 401       /* Sanity check.  If string character size is smaller than
 402          alignment, then we require character size to be a power
 403          of 2, otherwise character size must be integer multiple
 404          of alignment.  For non-string constants, alignment must
 405          be smaller than or equal to entity size and entity size
 406          must be integer multiple of alignment.  */
 407       return true;
 408     }
 409
 410   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 411     if ((secinfo = sinfo->chain)
 412         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 413         && secinfo->sec->entsize == sec->entsize
 414         && ! strcmp (secinfo->sec->name, sec->name))
 415       break;
 416
 417   if (sinfo == NULL)
 418     {
 419       /* Initialize the information we need to keep track of.  */
 420       sinfo = (struct sec_merge_info *)
 421               bfd_alloc (abfd, (bfd_size_type) sizeof (struct sec_merge_info));
 422       if (sinfo == NULL)
 423         goto error_return;
 424       sinfo->next = (struct sec_merge_info *) *psinfo;
 425       sinfo->chain = NULL;
 426       *psinfo = (PTR) sinfo;
 427       sinfo->htab =
 428         sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 429       if (sinfo->htab == NULL)
 430         goto error_return;
 431     }
 432
 433   /* Read the section from abfd.  */
 434
 435   amt = sizeof (struct sec_merge_sec_info) + sec->_raw_size - 1;
 436   *psecinfo = bfd_alloc (abfd, amt);
 437   if (*psecinfo == NULL)
 438     goto error_return;
 439
 440   secinfo = (struct sec_merge_sec_info *)*psecinfo;
 441   if (sinfo->chain)
 442     {
 443       secinfo->next = sinfo->chain->next;
 444       sinfo->chain->next = secinfo;
 445     }
 446   else
 447     secinfo->next = secinfo;
 448   sinfo->chain = secinfo;
 449   secinfo->sec = sec;
 450   secinfo->psecinfo = psecinfo;
 451   secinfo->htab = sinfo->htab;
 452   secinfo->first = NULL;
 453
 454   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 455                                   (bfd_vma) 0, sec->_raw_size))
 456     goto error_return;
 457
 458   return true;
 459
 460  error_return:
 461   *psecinfo = NULL;
 462   return false;
 463 }
 464
 465 /* Compare two sec_merge_hash_entry structures.  This is called via qsort.  */
 466
 467 static int
 468 cmplengthentry (a, b)
 469      const PTR a;
 470      const PTR b;
 471 {
 472   struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
 473   struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
 474
 475   if (A->len < B->len)
 476     return 1;
 477   else if (A->len > B->len)
 478     return -1;
 479
 480   return memcmp (A->root.string, B->root.string, A->len);
 481 }
 482
 483 static int
 484 last4_eq (a, b)
 485      const PTR a;
 486      const PTR b;
 487 {
 488   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 489   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 490
 491   if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
 492               B->root.string + B->len - 5 * A->u.entsize,
 493               4 * A->u.entsize) != 0)
 494     /* This was a hashtable collision.  */
 495     return 0;
 496
 497   if (A->len <= B->len)
 498     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 499        not to be equal by the hash table.  */
 500     return 0;
 501
 502   if (A->alignment < B->alignment
 503       || ((A->len - B->len) & (B->alignment - 1)))
 504     /* The suffix is not sufficiently aligned.  */
 505     return 0;
 506
 507   return memcmp (A->root.string + (A->len - B->len),
 508                  B->root.string, B->len - 5 * A->u.entsize) == 0;
 509 }
 510
 511 static int
 512 last_eq (a, b)
 513      const PTR a;
 514      const PTR b;
 515 {
 516   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 517   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 518
 519   if (B->len >= 5 * A->u.entsize)
 520     /* Longer strings are just pushed into the hash table,
 521        they'll be used when looking up for very short strings.  */
 522     return 0;
 523
 524   if (memcmp (A->root.string + A->len - 2 * A->u.entsize,
 525               B->root.string + B->len - 2 * A->u.entsize,
 526               A->u.entsize) != 0)
 527     /* This was a hashtable collision.  */
 528     return 0;
 529
 530   if (A->len <= B->len)
 531     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 532        not to be equal by the hash table.  */
 533     return 0;
 534
 535   if (A->alignment < B->alignment
 536       || ((A->len - B->len) & (B->alignment - 1)))
 537     /* The suffix is not sufficiently aligned.  */
 538     return 0;
 539
 540   return memcmp (A->root.string + (A->len - B->len),
 541                  B->root.string, B->len - 2 * A->u.entsize) == 0;
 542 }
 543
 544 /* Record one section into the hash table.  */
 545 static boolean
 546 record_section (sinfo, secinfo)
 547      struct sec_merge_info *sinfo;
 548      struct sec_merge_sec_info *secinfo;
 549 {
 550   asection *sec = secinfo->sec;
 551   struct sec_merge_hash_entry *entry;
 552   boolean nul;
 553   unsigned char *p, *end;
 554   bfd_vma mask, eltalign;
 555   unsigned int align, i;
 556
 557   align = bfd_get_section_alignment (sec->owner, sec);
 558   end = secinfo->contents + sec->_raw_size;
 559   nul = false;
 560   mask = ((bfd_vma) 1 << align) - 1;
 561   if (sec->flags & SEC_STRINGS)
 562     {
 563       for (p = secinfo->contents; p < end; )
 564         {
 565           eltalign = p - secinfo->contents;
 566           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 567           if (!eltalign || eltalign > mask)
 568             eltalign = mask + 1;
 569           entry = sec_merge_add (sinfo->htab, p, (unsigned) eltalign, secinfo);
 570           if (! entry)
 571             goto error_return;
 572           p += entry->len;
 573           if (sec->entsize == 1)
 574             {
 575               while (p < end && *p == 0)
 576                 {
 577                   if (!nul && !((p - secinfo->contents) & mask))
 578                     {
 579                       nul = true;
 580                       entry = sec_merge_add (sinfo->htab, "",
 581                                              (unsigned) mask + 1, secinfo);
 582                       if (! entry)
 583                         goto error_return;
 584                     }
 585                   p++;
 586                 }
 587             }
 588           else
 589             {
 590               while (p < end)
 591                 {
 592                   for (i = 0; i < sec->entsize; i++)
 593                     if (p[i] != '\0')
 594                       break;
 595                   if (i != sec->entsize)
 596                     break;
 597                   if (!nul && !((p - secinfo->contents) & mask))
 598                     {
 599                       nul = true;
 600                       entry = sec_merge_add (sinfo->htab, p,
 601                                              (unsigned) mask + 1, secinfo);
 602                       if (! entry)
 603                         goto error_return;
 604                     }
 605                   p += sec->entsize;
 606                 }
 607             }
 608         }
 609     }
 610   else
 611     {
 612       for (p = secinfo->contents; p < end; p += sec->entsize)
 613         {
 614           entry = sec_merge_add (sinfo->htab, p, 1, secinfo);
 615           if (! entry)
 616             goto error_return;
 617         }
 618     }
 619
 620   return true;
 621
 622 error_return:
 623   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 624     *secinfo->psecinfo = NULL;
 625   return false;
 626 }
 627
 628 /* This is a helper function for _bfd_merge_sections.  It attempts to
 629    merge strings matching suffixes of longer strings.  */
 630 static void
 631 merge_strings (sinfo)
 632      struct sec_merge_info *sinfo;
 633 {
 634   struct sec_merge_hash_entry **array, **a, **end, *e;
 635   struct sec_merge_sec_info *secinfo;
 636   htab_t lasttab = NULL, last4tab = NULL;
 637   bfd_size_type size, amt;
 638
 639   /* Now sort the strings by length, longest first.  */
 640   array = NULL;
 641   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 642   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 643   if (array == NULL)
 644     goto alloc_failure;
 645
 646   for (e = sinfo->htab->first, a = array; e; e = e->next)
 647     if (e->alignment)
 648       *a++ = e;
 649
 650   sinfo->htab->size = a - array;
 651
 652   qsort (array, (size_t) sinfo->htab->size,
 653          sizeof (struct sec_merge_hash_entry *), cmplengthentry);
 654
 655   last4tab = htab_create ((size_t) sinfo->htab->size * 4, NULL, last4_eq, NULL);
 656   lasttab = htab_create ((size_t) sinfo->htab->size * 4, NULL, last_eq, NULL);
 657   if (lasttab == NULL || last4tab == NULL)
 658     goto alloc_failure;
 659
 660   /* Now insert the strings into hash tables (strings with last 4 characters
 661      and strings with last character equal), look for longer strings which
 662      we're suffix of.  */
 663   for (a = array, end = array + sinfo->htab->size; a < end; a++)
 664     {
 665       register hashval_t hash;
 666       unsigned int c;
 667       unsigned int i;
 668       const unsigned char *s;
 669       PTR *p;
 670
 671       e = *a;
 672       e->u.entsize = sinfo->htab->entsize;
 673       if (e->len <= e->u.entsize)
 674         break;
 675       if (e->len > 4 * e->u.entsize)
 676         {
 677           s = e->root.string + e->len - e->u.entsize;
 678           hash = 0;
 679           for (i = 0; i < 4 * e->u.entsize; i++)
 680             {
 681               c = *--s;
 682               hash += c + (c << 17);
 683               hash ^= hash >> 2;
 684             }
 685           p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
 686           if (p == NULL)
 687             goto alloc_failure;
 688           if (*p)
 689             {
 690               struct sec_merge_hash_entry *ent;
 691
 692               ent = (struct sec_merge_hash_entry *) *p;
 693               e->u.suffix = ent;
 694               e->alignment = 0;
 695               continue;
 696             }
 697           else
 698             *p = (PTR) e;
 699         }
 700       s = e->root.string + e->len - e->u.entsize;
 701       hash = 0;
 702       for (i = 0; i < e->u.entsize; i++)
 703         {
 704           c = *--s;
 705           hash += c + (c << 17);
 706           hash ^= hash >> 2;
 707         }
 708       p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
 709       if (p == NULL)
 710         goto alloc_failure;
 711       if (*p)
 712         {
 713           struct sec_merge_hash_entry *ent;
 714
 715           ent = (struct sec_merge_hash_entry *) *p;
 716           e->u.suffix = ent;
 717           e->alignment = 0;
 718         }
 719       else
 720         *p = (PTR) e;
 721     }
 722
 723 alloc_failure:
 724   if (array)
 725     free (array);
 726   if (lasttab)
 727     htab_delete (lasttab);
 728   if (last4tab)
 729     htab_delete (last4tab);
 730
 731   /* Now assign positions to the strings we want to keep.  */
 732   size = 0;
 733   secinfo = sinfo->htab->first->secinfo;
 734   for (e = sinfo->htab->first; e; e = e->next)
 735     {
 736       if (e->secinfo != secinfo)
 737         {
 738           secinfo->sec->_cooked_size = size;
 739           secinfo = e->secinfo;
 740         }
 741       if (e->alignment)
 742         {
 743           if (e->secinfo->first == NULL)
 744             {
 745               e->secinfo->first = e;
 746               size = 0;
 747             }
 748           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 749           e->u.index = size;
 750           size += e->len;
 751         }
 752     }
 753   secinfo->sec->_cooked_size = size;
 754
 755   /* And now adjust the rest, removing them from the chain (but not hashtable)
 756      at the same time.  */
 757   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 758     if (e->alignment)
 759       a = &e->next;
 760     else
 761       {
 762         *a = e->next;
 763         if (e->len)
 764           {
 765             e->secinfo = e->u.suffix->secinfo;
 766             e->alignment = e->u.suffix->alignment;
 767             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 768           }
 769       }
 770 }
 771
 772 /* This function is called once after all SEC_MERGE sections are registered
 773    with _bfd_merge_section.  */
 774
 775 boolean
 776 _bfd_merge_sections (abfd, xsinfo)
 777      bfd *abfd ATTRIBUTE_UNUSED;
 778      PTR xsinfo;
 779 {
 780   struct sec_merge_info *sinfo;
 781
 782   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 783     {
 784       struct sec_merge_sec_info * secinfo;
 785
 786       if (! sinfo->chain)
 787         continue;
 788
 789       /* Move sinfo->chain to head of the chain, terminate it.  */
 790       secinfo = sinfo->chain;
 791       sinfo->chain = secinfo->next;
 792       secinfo->next = NULL;
 793
 794       /* Record the sections into the hash table.  */
 795       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 796         if (secinfo->sec->flags & SEC_EXCLUDE)
 797           *secinfo->psecinfo = NULL;
 798         else if (! record_section (sinfo, secinfo))
 799           break;
 800
 801       if (secinfo)
 802         continue;
 803
 804       if (sinfo->htab->strings)
 805         merge_strings (sinfo);
 806       else
 807         {
 808           struct sec_merge_hash_entry *e;
 809           bfd_size_type size = 0;
 810
 811           /* Things are much simpler for non-strings.
 812              Just assign them slots in the section.  */
 813           secinfo = NULL;
 814           for (e = sinfo->htab->first; e; e = e->next)
 815             {
 816               if (e->secinfo->first == NULL)
 817                 {
 818                   if (secinfo)
 819                     secinfo->sec->_cooked_size = size;
 820                   e->secinfo->first = e;
 821                   size = 0;
 822                 }
 823               size = (size + e->alignment - 1)
 824                      & ~((bfd_vma) e->alignment - 1);
 825               e->u.index = size;
 826               size += e->len;
 827               secinfo = e->secinfo;
 828             }
 829           secinfo->sec->_cooked_size = size;
 830         }
 831
 832         /* Finally shrink all input sections which have not made it into
 833            the hash table at all.  */
 834         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 835           if (secinfo->first == NULL)
 836             {
 837               secinfo->sec->_cooked_size = 0;
 838               secinfo->sec->flags |= SEC_EXCLUDE;
 839             }
 840     }
 841
 842   return true;
 843 }
 844
 845 /* Write out the merged section.  */
 846
 847 boolean
 848 _bfd_write_merged_section (output_bfd, sec, psecinfo)
 849      bfd *output_bfd;
 850      asection *sec;
 851      PTR psecinfo;
 852 {
 853   struct sec_merge_sec_info *secinfo;
 854   file_ptr pos;
 855
 856   secinfo = (struct sec_merge_sec_info *) psecinfo;
 857
 858   if (!secinfo->first)
 859     return true;
 860
 861   pos = sec->output_section->filepos + sec->output_offset;
 862   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 863     return false;
 864
 865   if (! sec_merge_emit (output_bfd, secinfo->first))
 866     return false;
 867
 868   return true;
 869 }
 870
 871 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 872    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 873    section and writes the new section back into *PSEC.  */
 874
 875 bfd_vma
 876 _bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
 877      bfd *output_bfd ATTRIBUTE_UNUSED;
 878      asection **psec;
 879      PTR psecinfo;
 880      bfd_vma offset, addend;
 881 {
 882   struct sec_merge_sec_info *secinfo;
 883   struct sec_merge_hash_entry *entry;
 884   unsigned char *p;
 885   asection *sec = *psec;
 886
 887   secinfo = (struct sec_merge_sec_info *) psecinfo;
 888
 889   if (offset + addend >= sec->_raw_size)
 890     {
 891       if (offset + addend > sec->_raw_size)
 892         (*_bfd_error_handler) (_("%s: access beyond end of merged section (%ld + %ld)"),
 893                                bfd_get_filename (sec->owner), (long)offset,
 894                                (long) addend);
 895       return (secinfo->first ? sec->_cooked_size : 0);
 896     }
 897
 898   if (secinfo->htab->strings)
 899     {
 900       if (sec->entsize == 1)
 901         {
 902           p = secinfo->contents + offset + addend - 1;
 903           while (*p && p >= secinfo->contents)
 904             --p;
 905           ++p;
 906         }
 907       else
 908         {
 909           p = secinfo->contents
 910               + ((offset + addend) / sec->entsize) * sec->entsize;
 911           p -= sec->entsize;
 912           while (p >= secinfo->contents)
 913             {
 914               unsigned int i;
 915
 916               for (i = 0; i < sec->entsize; ++i)
 917                 if (p[i] != '\0')
 918                   break;
 919               if (i == sec->entsize)
 920                 break;
 921               p -= sec->entsize;
 922             }
 923           p += sec->entsize;
 924         }
 925     }
 926   else
 927     {
 928       p = secinfo->contents
 929           + ((offset + addend) / sec->entsize) * sec->entsize;
 930     }
 931   entry = sec_merge_hash_lookup (secinfo->htab, p, 0, false);
 932   if (!entry)
 933     {
 934       if (! secinfo->htab->strings)
 935         abort ();
 936       /* This should only happen if somebody points into the padding
 937          after a NUL character but before next entity.  */
 938       if (*p)
 939         abort ();
 940       if (! secinfo->htab->first)
 941         abort ();
 942       entry = secinfo->htab->first;
 943       p = secinfo->contents
 944           + ((offset + addend) / sec->entsize + 1) * sec->entsize
 945           - entry->len;
 946     }
 947
 948   *psec = entry->secinfo->sec;
 949   return entry->u.index + (secinfo->contents + offset - p);
 950 }