bfd/merge.c

   1 /* SEC_MERGE support.
   2    Copyright 2001, 2002 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.  */
  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     /* 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 (boolean) (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   align = bfd_get_section_alignment (sec->owner, sec);
 387   if ((sec->entsize < (unsigned int)(1 << align)
 388        && ((sec->entsize & (sec->entsize - 1))
 389            || !(sec->flags & SEC_STRINGS)))
 390       || (sec->entsize > (unsigned int)(1 << align)
 391           && (sec->entsize & ((1 << align) - 1))))
 392     {
 393       /* Sanity check.  If string character size is smaller than
 394          alignment, then we require character size to be a power
 395          of 2, otherwise character size must be integer multiple
 396          of alignment.  For non-string constants, alignment must
 397          be smaller than or equal to entity size and entity size
 398          must be integer multiple of alignment.  */
 399       return true;
 400     }
 401
 402   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 403     if ((secinfo = sinfo->chain)
 404         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 405         && secinfo->sec->entsize == sec->entsize
 406         && ! strcmp (secinfo->sec->name, sec->name))
 407       break;
 408
 409   if (sinfo == NULL)
 410     {
 411       /* Initialize the information we need to keep track of.  */
 412       amt = sizeof (struct sec_merge_info);
 413       sinfo = (struct sec_merge_info *) bfd_alloc (abfd, amt);
 414       if (sinfo == NULL)
 415         goto error_return;
 416       sinfo->next = (struct sec_merge_info *) *psinfo;
 417       sinfo->chain = NULL;
 418       *psinfo = (PTR) sinfo;
 419       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 420       if (sinfo->htab == NULL)
 421         goto error_return;
 422     }
 423
 424   /* Read the section from abfd.  */
 425
 426   amt = sizeof (struct sec_merge_sec_info) + sec->_raw_size - 1;
 427   *psecinfo = bfd_alloc (abfd, amt);
 428   if (*psecinfo == NULL)
 429     goto error_return;
 430
 431   secinfo = (struct sec_merge_sec_info *)*psecinfo;
 432   if (sinfo->chain)
 433     {
 434       secinfo->next = sinfo->chain->next;
 435       sinfo->chain->next = secinfo;
 436     }
 437   else
 438     secinfo->next = secinfo;
 439   sinfo->chain = secinfo;
 440   secinfo->sec = sec;
 441   secinfo->psecinfo = psecinfo;
 442   secinfo->htab = sinfo->htab;
 443   secinfo->first = NULL;
 444
 445   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 446                                   (bfd_vma) 0, sec->_raw_size))
 447     goto error_return;
 448
 449   return true;
 450
 451  error_return:
 452   *psecinfo = NULL;
 453   return false;
 454 }
 455
 456 /* Compare two sec_merge_hash_entry structures.  This is called via qsort.  */
 457
 458 static int
 459 cmplengthentry (a, b)
 460      const PTR a;
 461      const PTR b;
 462 {
 463   struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
 464   struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
 465
 466   if (A->len < B->len)
 467     return 1;
 468   else if (A->len > B->len)
 469     return -1;
 470
 471   return memcmp (A->root.string, B->root.string, A->len);
 472 }
 473
 474 static int
 475 last4_eq (a, b)
 476      const PTR a;
 477      const PTR b;
 478 {
 479   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 480   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 481
 482   if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
 483               B->root.string + B->len - 5 * A->u.entsize,
 484               4 * A->u.entsize) != 0)
 485     /* This was a hashtable collision.  */
 486     return 0;
 487
 488   if (A->len <= B->len)
 489     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 490        not to be equal by the hash table.  */
 491     return 0;
 492
 493   if (A->alignment < B->alignment
 494       || ((A->len - B->len) & (B->alignment - 1)))
 495     /* The suffix is not sufficiently aligned.  */
 496     return 0;
 497
 498   return memcmp (A->root.string + (A->len - B->len),
 499                  B->root.string, B->len - 5 * A->u.entsize) == 0;
 500 }
 501
 502 static int
 503 last_eq (a, b)
 504      const PTR a;
 505      const PTR 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, (unsigned) 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, "",
 572                                              (unsigned) mask + 1, 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,
 592                                              (unsigned) mask + 1, 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, amt;
 629
 630   /* Now sort the strings by length, longest first.  */
 631   array = NULL;
 632   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 633   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 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, (size_t) sinfo->htab->size,
 644          sizeof (struct sec_merge_hash_entry *), cmplengthentry);
 645
 646   last4tab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
 647                                 NULL, last4_eq, NULL, calloc, free);
 648   lasttab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
 649                                NULL, last_eq, NULL, calloc, free);
 650   if (lasttab == NULL || last4tab == NULL)
 651     goto alloc_failure;
 652
 653   /* Now insert the strings into hash tables (strings with last 4 characters
 654      and strings with last character equal), look for longer strings which
 655      we're suffix of.  */
 656   for (a = array, end = array + sinfo->htab->size; a < end; a++)
 657     {
 658       register hashval_t hash;
 659       unsigned int c;
 660       unsigned int i;
 661       const unsigned char *s;
 662       PTR *p;
 663
 664       e = *a;
 665       e->u.entsize = sinfo->htab->entsize;
 666       if (e->len <= e->u.entsize)
 667         break;
 668       if (e->len > 4 * e->u.entsize)
 669         {
 670           s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
 671           hash = 0;
 672           for (i = 0; i < 4 * e->u.entsize; i++)
 673             {
 674               c = *--s;
 675               hash += c + (c << 17);
 676               hash ^= hash >> 2;
 677             }
 678           p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
 679           if (p == NULL)
 680             goto alloc_failure;
 681           if (*p)
 682             {
 683               struct sec_merge_hash_entry *ent;
 684
 685               ent = (struct sec_merge_hash_entry *) *p;
 686               e->u.suffix = ent;
 687               e->alignment = 0;
 688               continue;
 689             }
 690           else
 691             *p = (PTR) e;
 692         }
 693       s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
 694       hash = 0;
 695       for (i = 0; i < e->u.entsize; i++)
 696         {
 697           c = *--s;
 698           hash += c + (c << 17);
 699           hash ^= hash >> 2;
 700         }
 701       p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
 702       if (p == NULL)
 703         goto alloc_failure;
 704       if (*p)
 705         {
 706           struct sec_merge_hash_entry *ent;
 707
 708           ent = (struct sec_merge_hash_entry *) *p;
 709           e->u.suffix = ent;
 710           e->alignment = 0;
 711         }
 712       else
 713         *p = (PTR) e;
 714     }
 715
 716 alloc_failure:
 717   if (array)
 718     free (array);
 719   if (lasttab)
 720     htab_delete (lasttab);
 721   if (last4tab)
 722     htab_delete (last4tab);
 723
 724   /* Now assign positions to the strings we want to keep.  */
 725   size = 0;
 726   secinfo = sinfo->htab->first->secinfo;
 727   for (e = sinfo->htab->first; e; e = e->next)
 728     {
 729       if (e->secinfo != secinfo)
 730         {
 731           secinfo->sec->_cooked_size = size;
 732           secinfo = e->secinfo;
 733         }
 734       if (e->alignment)
 735         {
 736           if (e->secinfo->first == NULL)
 737             {
 738               e->secinfo->first = e;
 739               size = 0;
 740             }
 741           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 742           e->u.index = size;
 743           size += e->len;
 744         }
 745     }
 746   secinfo->sec->_cooked_size = size;
 747
 748   /* And now adjust the rest, removing them from the chain (but not hashtable)
 749      at the same time.  */
 750   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 751     if (e->alignment)
 752       a = &e->next;
 753     else
 754       {
 755         *a = e->next;
 756         if (e->len)
 757           {
 758             e->secinfo = e->u.suffix->secinfo;
 759             e->alignment = e->u.suffix->alignment;
 760             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 761           }
 762       }
 763 }
 764
 765 /* This function is called once after all SEC_MERGE sections are registered
 766    with _bfd_merge_section.  */
 767
 768 boolean
 769 _bfd_merge_sections (abfd, xsinfo, remove_hook)
 770      bfd *abfd ATTRIBUTE_UNUSED;
 771      PTR xsinfo;
 772      void (*remove_hook) PARAMS((bfd *, asection *));
 773 {
 774   struct sec_merge_info *sinfo;
 775
 776   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 777     {
 778       struct sec_merge_sec_info * secinfo;
 779
 780       if (! sinfo->chain)
 781         continue;
 782
 783       /* Move sinfo->chain to head of the chain, terminate it.  */
 784       secinfo = sinfo->chain;
 785       sinfo->chain = secinfo->next;
 786       secinfo->next = NULL;
 787
 788       /* Record the sections into the hash table.  */
 789       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 790         if (secinfo->sec->flags & SEC_EXCLUDE)
 791           {
 792             *secinfo->psecinfo = NULL;
 793             if (remove_hook)
 794               (*remove_hook) (abfd, secinfo->sec);
 795           }
 796         else if (! record_section (sinfo, secinfo))
 797           break;
 798
 799       if (secinfo)
 800         continue;
 801
 802       if (sinfo->htab->first == NULL)
 803         continue;
 804
 805       if (sinfo->htab->strings)
 806         merge_strings (sinfo);
 807       else
 808         {
 809           struct sec_merge_hash_entry *e;
 810           bfd_size_type size = 0;
 811
 812           /* Things are much simpler for non-strings.
 813              Just assign them slots in the section.  */
 814           secinfo = NULL;
 815           for (e = sinfo->htab->first; e; e = e->next)
 816             {
 817               if (e->secinfo->first == NULL)
 818                 {
 819                   if (secinfo)
 820                     secinfo->sec->_cooked_size = size;
 821                   e->secinfo->first = e;
 822                   size = 0;
 823                 }
 824               size = (size + e->alignment - 1)
 825                      & ~((bfd_vma) e->alignment - 1);
 826               e->u.index = size;
 827               size += e->len;
 828               secinfo = e->secinfo;
 829             }
 830           secinfo->sec->_cooked_size = size;
 831         }
 832
 833         /* Finally shrink all input sections which have not made it into
 834            the hash table at all.  */
 835         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 836           if (secinfo->first == NULL)
 837             secinfo->sec->_cooked_size = 0;
 838     }
 839
 840   return true;
 841 }
 842
 843 /* Write out the merged section.  */
 844
 845 boolean
 846 _bfd_write_merged_section (output_bfd, sec, psecinfo)
 847      bfd *output_bfd;
 848      asection *sec;
 849      PTR psecinfo;
 850 {
 851   struct sec_merge_sec_info *secinfo;
 852   file_ptr pos;
 853
 854   secinfo = (struct sec_merge_sec_info *) psecinfo;
 855
 856   if (!secinfo->first)
 857     return true;
 858
 859   pos = sec->output_section->filepos + sec->output_offset;
 860   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 861     return false;
 862
 863   if (! sec_merge_emit (output_bfd, secinfo->first))
 864     return false;
 865
 866   return true;
 867 }
 868
 869 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 870    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 871    section and writes the new section back into *PSEC.  */
 872
 873 bfd_vma
 874 _bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
 875      bfd *output_bfd ATTRIBUTE_UNUSED;
 876      asection **psec;
 877      PTR psecinfo;
 878      bfd_vma offset, addend;
 879 {
 880   struct sec_merge_sec_info *secinfo;
 881   struct sec_merge_hash_entry *entry;
 882   unsigned char *p;
 883   asection *sec = *psec;
 884
 885   secinfo = (struct sec_merge_sec_info *) psecinfo;
 886
 887   if (offset + addend >= sec->_raw_size)
 888     {
 889       if (offset + addend > sec->_raw_size)
 890         {
 891           (*_bfd_error_handler)
 892             (_("%s: access beyond end of merged section (%ld + %ld)"),
 893              bfd_get_filename (sec->owner), (long) offset, (long) addend);
 894         }
 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 >= secinfo->contents && *p)
 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 }