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   bfd_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, bfd_boolean));
 104 static struct sec_merge_hash *sec_merge_init
 105   PARAMS ((unsigned int, bfd_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 bfd_boolean sec_merge_emit
 110   PARAMS ((bfd *, struct sec_merge_hash_entry *));
 111 static int cmplengthentry
 112   PARAMS ((const PTR, const PTR));
 113 static int last4_eq
 114   PARAMS ((const PTR, const PTR));
 115 static int last_eq
 116   PARAMS ((const PTR, const PTR));
 117 static bfd_boolean record_section
 118   PARAMS ((struct sec_merge_info *, struct sec_merge_sec_info *));
 119 static void merge_strings
 120   PARAMS ((struct sec_merge_info *));
 121
 122 /* Routine to create an entry in a section merge hashtab.  */
 123
 124 static struct bfd_hash_entry *
 125 sec_merge_hash_newfunc (entry, table, string)
 126      struct bfd_hash_entry *entry;
 127      struct bfd_hash_table *table;
 128      const char *string;
 129 {
 130   struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 131
 132   /* Allocate the structure if it has not already been allocated by a
 133      subclass.  */
 134   if (ret == (struct sec_merge_hash_entry *) NULL)
 135     ret = ((struct sec_merge_hash_entry *)
 136            bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
 137   if (ret == (struct sec_merge_hash_entry *) NULL)
 138     return NULL;
 139
 140   /* Call the allocation method of the superclass.  */
 141   ret = ((struct sec_merge_hash_entry *)
 142          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 143
 144   if (ret)
 145     {
 146       /* Initialize the local fields.  */
 147       ret->u.suffix = NULL;
 148       ret->alignment = 0;
 149       ret->secinfo = NULL;
 150       ret->next = NULL;
 151     }
 152
 153   return (struct bfd_hash_entry *) ret;
 154 }
 155
 156 /* Look up an entry in a section merge hash table.  */
 157
 158 static struct sec_merge_hash_entry *
 159 sec_merge_hash_lookup (table, string, alignment, create)
 160      struct sec_merge_hash *table;
 161      const char *string;
 162      unsigned int alignment;
 163      bfd_boolean create;
 164 {
 165   register const unsigned char *s;
 166   register unsigned long hash;
 167   register unsigned int c;
 168   struct sec_merge_hash_entry *hashp;
 169   unsigned int len, i;
 170   unsigned int index;
 171
 172   hash = 0;
 173   len = 0;
 174   s = (const unsigned char *) string;
 175   if (table->strings)
 176     {
 177       if (table->entsize == 1)
 178         {
 179           while ((c = *s++) != '\0')
 180             {
 181               hash += c + (c << 17);
 182               hash ^= hash >> 2;
 183               ++len;
 184             }
 185           hash += len + (len << 17);
 186         }
 187       else
 188         {
 189           for (;;)
 190             {
 191               for (i = 0; i < table->entsize; ++i)
 192                 if (s[i] != '\0')
 193                   break;
 194               if (i == table->entsize)
 195                 break;
 196               for (i = 0; i < table->entsize; ++i)
 197                 {
 198                   c = *s++;
 199                   hash += c + (c << 17);
 200                   hash ^= hash >> 2;
 201                 }
 202               ++len;
 203             }
 204           hash += len + (len << 17);
 205           len *= table->entsize;
 206         }
 207       hash ^= hash >> 2;
 208       len += table->entsize;
 209     }
 210   else
 211     {
 212       for (i = 0; i < table->entsize; ++i)
 213         {
 214           c = *s++;
 215           hash += c + (c << 17);
 216           hash ^= hash >> 2;
 217         }
 218       len = table->entsize;
 219     }
 220
 221   index = hash % table->table.size;
 222   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 223        hashp != (struct sec_merge_hash_entry *) NULL;
 224        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 225     {
 226       if (hashp->root.hash == hash
 227           && len == hashp->len
 228           && memcmp (hashp->root.string, string, len) == 0)
 229         {
 230           /* If the string we found does not have at least the required
 231              alignment, we need to insert another copy.  */
 232           if (hashp->alignment < alignment)
 233             {
 234               /*  Mark the less aligned copy as deleted.  */
 235               hashp->len = 0;
 236               hashp->alignment = 0;
 237               break;
 238             }
 239           return hashp;
 240         }
 241     }
 242
 243   if (! create)
 244     return (struct sec_merge_hash_entry *) NULL;
 245
 246   hashp = (struct sec_merge_hash_entry *)
 247           sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
 248                                   (struct bfd_hash_table *) table, string);
 249   if (hashp == (struct sec_merge_hash_entry *) NULL)
 250     return (struct sec_merge_hash_entry *) NULL;
 251   hashp->root.string = string;
 252   hashp->root.hash = hash;
 253   hashp->len = len;
 254   hashp->alignment = alignment;
 255   hashp->root.next = table->table.table[index];
 256   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 257
 258   return hashp;
 259 }
 260
 261 /* Create a new hash table.  */
 262
 263 static struct sec_merge_hash *
 264 sec_merge_init (entsize, strings)
 265      unsigned int entsize;
 266      bfd_boolean strings;
 267 {
 268   struct sec_merge_hash *table;
 269   bfd_size_type amt = sizeof (struct sec_merge_hash);
 270
 271   table = (struct sec_merge_hash *) bfd_malloc (amt);
 272   if (table == NULL)
 273     return NULL;
 274
 275   if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
 276     {
 277       free (table);
 278       return NULL;
 279     }
 280
 281   table->size = 0;
 282   table->first = NULL;
 283   table->last = NULL;
 284   table->entsize = entsize;
 285   table->strings = strings;
 286
 287   return table;
 288 }
 289
 290 /* Get the index of an entity in a hash table, adding it if it is not
 291    already present.  */
 292
 293 static struct sec_merge_hash_entry *
 294 sec_merge_add (tab, str, alignment, secinfo)
 295      struct sec_merge_hash *tab;
 296      const char *str;
 297      unsigned int alignment;
 298      struct sec_merge_sec_info *secinfo;
 299 {
 300   register struct sec_merge_hash_entry *entry;
 301
 302   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
 303   if (entry == NULL)
 304     return NULL;
 305
 306   if (entry->secinfo == NULL)
 307     {
 308       tab->size++;
 309       entry->secinfo = secinfo;
 310       if (tab->first == NULL)
 311         tab->first = entry;
 312       else
 313         tab->last->next = entry;
 314       tab->last = entry;
 315     }
 316
 317   return entry;
 318 }
 319
 320 static bfd_boolean
 321 sec_merge_emit (abfd, entry)
 322      register bfd *abfd;
 323      struct sec_merge_hash_entry *entry;
 324 {
 325   struct sec_merge_sec_info *secinfo = entry->secinfo;
 326   asection *sec = secinfo->sec;
 327   char *pad = "";
 328   bfd_size_type off = 0;
 329   int alignment_power = bfd_get_section_alignment (abfd, sec->output_section);
 330
 331   if (alignment_power)
 332     pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 333
 334   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 335     {
 336       register const char *str;
 337       register size_t len;
 338
 339       len = off & (entry->alignment - 1);
 340       if (len)
 341         {
 342           len = entry->alignment - len;
 343           if (bfd_bwrite ((PTR) pad, (bfd_size_type) len, abfd) != len)
 344             break;
 345           off += len;
 346         }
 347
 348       str = entry->root.string;
 349       len = entry->len;
 350
 351       if (bfd_bwrite ((PTR) str, (bfd_size_type) len, abfd) != len)
 352         break;
 353
 354       off += len;
 355     }
 356
 357   if (alignment_power)
 358     free (pad);
 359
 360   return entry == NULL || entry->secinfo != secinfo;
 361 }
 362
 363 /* This function is called for each input file from the add_symbols
 364    pass of the linker.  */
 365
 366 bfd_boolean
 367 _bfd_merge_section (abfd, psinfo, sec, psecinfo)
 368      bfd *abfd;
 369      PTR *psinfo;
 370      asection *sec;
 371      PTR *psecinfo;
 372 {
 373   struct sec_merge_info *sinfo;
 374   struct sec_merge_sec_info *secinfo;
 375   unsigned int align;
 376   bfd_size_type amt;
 377
 378   if (sec->_raw_size == 0
 379       || (sec->flags & SEC_EXCLUDE)
 380       || (sec->flags & SEC_MERGE) == 0
 381       || sec->entsize == 0)
 382     return TRUE;
 383
 384   if ((sec->flags & SEC_RELOC) != 0)
 385     {
 386       /* We aren't prepared to handle relocations in merged sections.  */
 387       return TRUE;
 388     }
 389
 390   align = bfd_get_section_alignment (sec->owner, sec);
 391   if ((sec->entsize < (unsigned int)(1 << align)
 392        && ((sec->entsize & (sec->entsize - 1))
 393            || !(sec->flags & SEC_STRINGS)))
 394       || (sec->entsize > (unsigned int)(1 << align)
 395           && (sec->entsize & ((1 << align) - 1))))
 396     {
 397       /* Sanity check.  If string character size is smaller than
 398          alignment, then we require character size to be a power
 399          of 2, otherwise character size must be integer multiple
 400          of alignment.  For non-string constants, alignment must
 401          be smaller than or equal to entity size and entity size
 402          must be integer multiple of alignment.  */
 403       return TRUE;
 404     }
 405
 406   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 407     if ((secinfo = sinfo->chain)
 408         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 409         && secinfo->sec->entsize == sec->entsize
 410         && ! strcmp (secinfo->sec->name, sec->name))
 411       break;
 412
 413   if (sinfo == NULL)
 414     {
 415       /* Initialize the information we need to keep track of.  */
 416       amt = sizeof (struct sec_merge_info);
 417       sinfo = (struct sec_merge_info *) bfd_alloc (abfd, amt);
 418       if (sinfo == NULL)
 419         goto error_return;
 420       sinfo->next = (struct sec_merge_info *) *psinfo;
 421       sinfo->chain = NULL;
 422       *psinfo = (PTR) sinfo;
 423       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 424       if (sinfo->htab == NULL)
 425         goto error_return;
 426     }
 427
 428   /* Read the section from abfd.  */
 429
 430   amt = sizeof (struct sec_merge_sec_info) + sec->_raw_size - 1;
 431   *psecinfo = bfd_alloc (abfd, amt);
 432   if (*psecinfo == NULL)
 433     goto error_return;
 434
 435   secinfo = (struct sec_merge_sec_info *)*psecinfo;
 436   if (sinfo->chain)
 437     {
 438       secinfo->next = sinfo->chain->next;
 439       sinfo->chain->next = secinfo;
 440     }
 441   else
 442     secinfo->next = secinfo;
 443   sinfo->chain = secinfo;
 444   secinfo->sec = sec;
 445   secinfo->psecinfo = psecinfo;
 446   secinfo->htab = sinfo->htab;
 447   secinfo->first = NULL;
 448
 449   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 450                                   (bfd_vma) 0, sec->_raw_size))
 451     goto error_return;
 452
 453   return TRUE;
 454
 455  error_return:
 456   *psecinfo = NULL;
 457   return FALSE;
 458 }
 459
 460 /* Compare two sec_merge_hash_entry structures.  This is called via qsort.  */
 461
 462 static int
 463 cmplengthentry (a, b)
 464      const PTR a;
 465      const PTR b;
 466 {
 467   struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
 468   struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
 469
 470   if (A->len < B->len)
 471     return 1;
 472   else if (A->len > B->len)
 473     return -1;
 474
 475   return memcmp (A->root.string, B->root.string, A->len);
 476 }
 477
 478 static int
 479 last4_eq (a, b)
 480      const PTR a;
 481      const PTR b;
 482 {
 483   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 484   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 485
 486   if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
 487               B->root.string + B->len - 5 * A->u.entsize,
 488               4 * A->u.entsize) != 0)
 489     /* This was a hashtable collision.  */
 490     return 0;
 491
 492   if (A->len <= B->len)
 493     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 494        not to be equal by the hash table.  */
 495     return 0;
 496
 497   if (A->alignment < B->alignment
 498       || ((A->len - B->len) & (B->alignment - 1)))
 499     /* The suffix is not sufficiently aligned.  */
 500     return 0;
 501
 502   return memcmp (A->root.string + (A->len - B->len),
 503                  B->root.string, B->len - 5 * A->u.entsize) == 0;
 504 }
 505
 506 static int
 507 last_eq (a, b)
 508      const PTR a;
 509      const PTR b;
 510 {
 511   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 512   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 513
 514   if (B->len >= 5 * A->u.entsize)
 515     /* Longer strings are just pushed into the hash table,
 516        they'll be used when looking up for very short strings.  */
 517     return 0;
 518
 519   if (memcmp (A->root.string + A->len - 2 * A->u.entsize,
 520               B->root.string + B->len - 2 * A->u.entsize,
 521               A->u.entsize) != 0)
 522     /* This was a hashtable collision.  */
 523     return 0;
 524
 525   if (A->len <= B->len)
 526     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 527        not to be equal by the hash table.  */
 528     return 0;
 529
 530   if (A->alignment < B->alignment
 531       || ((A->len - B->len) & (B->alignment - 1)))
 532     /* The suffix is not sufficiently aligned.  */
 533     return 0;
 534
 535   return memcmp (A->root.string + (A->len - B->len),
 536                  B->root.string, B->len - 2 * A->u.entsize) == 0;
 537 }
 538
 539 /* Record one section into the hash table.  */
 540 static bfd_boolean
 541 record_section (sinfo, secinfo)
 542      struct sec_merge_info *sinfo;
 543      struct sec_merge_sec_info *secinfo;
 544 {
 545   asection *sec = secinfo->sec;
 546   struct sec_merge_hash_entry *entry;
 547   bfd_boolean nul;
 548   unsigned char *p, *end;
 549   bfd_vma mask, eltalign;
 550   unsigned int align, i;
 551
 552   align = bfd_get_section_alignment (sec->owner, sec);
 553   end = secinfo->contents + sec->_raw_size;
 554   nul = FALSE;
 555   mask = ((bfd_vma) 1 << align) - 1;
 556   if (sec->flags & SEC_STRINGS)
 557     {
 558       for (p = secinfo->contents; p < end; )
 559         {
 560           eltalign = p - secinfo->contents;
 561           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 562           if (!eltalign || eltalign > mask)
 563             eltalign = mask + 1;
 564           entry = sec_merge_add (sinfo->htab, p, (unsigned) eltalign, secinfo);
 565           if (! entry)
 566             goto error_return;
 567           p += entry->len;
 568           if (sec->entsize == 1)
 569             {
 570               while (p < end && *p == 0)
 571                 {
 572                   if (!nul && !((p - secinfo->contents) & mask))
 573                     {
 574                       nul = TRUE;
 575                       entry = sec_merge_add (sinfo->htab, "",
 576                                              (unsigned) mask + 1, secinfo);
 577                       if (! entry)
 578                         goto error_return;
 579                     }
 580                   p++;
 581                 }
 582             }
 583           else
 584             {
 585               while (p < end)
 586                 {
 587                   for (i = 0; i < sec->entsize; i++)
 588                     if (p[i] != '\0')
 589                       break;
 590                   if (i != sec->entsize)
 591                     break;
 592                   if (!nul && !((p - secinfo->contents) & mask))
 593                     {
 594                       nul = TRUE;
 595                       entry = sec_merge_add (sinfo->htab, p,
 596                                              (unsigned) mask + 1, secinfo);
 597                       if (! entry)
 598                         goto error_return;
 599                     }
 600                   p += sec->entsize;
 601                 }
 602             }
 603         }
 604     }
 605   else
 606     {
 607       for (p = secinfo->contents; p < end; p += sec->entsize)
 608         {
 609           entry = sec_merge_add (sinfo->htab, p, 1, secinfo);
 610           if (! entry)
 611             goto error_return;
 612         }
 613     }
 614
 615   return TRUE;
 616
 617 error_return:
 618   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 619     *secinfo->psecinfo = NULL;
 620   return FALSE;
 621 }
 622
 623 /* This is a helper function for _bfd_merge_sections.  It attempts to
 624    merge strings matching suffixes of longer strings.  */
 625 static void
 626 merge_strings (sinfo)
 627      struct sec_merge_info *sinfo;
 628 {
 629   struct sec_merge_hash_entry **array, **a, **end, *e;
 630   struct sec_merge_sec_info *secinfo;
 631   htab_t lasttab = NULL, last4tab = NULL;
 632   bfd_size_type size, amt;
 633
 634   /* Now sort the strings by length, longest first.  */
 635   array = NULL;
 636   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 637   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 638   if (array == NULL)
 639     goto alloc_failure;
 640
 641   for (e = sinfo->htab->first, a = array; e; e = e->next)
 642     if (e->alignment)
 643       *a++ = e;
 644
 645   sinfo->htab->size = a - array;
 646
 647   qsort (array, (size_t) sinfo->htab->size,
 648          sizeof (struct sec_merge_hash_entry *), cmplengthentry);
 649
 650   last4tab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
 651                                 NULL, last4_eq, NULL, calloc, free);
 652   lasttab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
 653                                NULL, last_eq, NULL, calloc, free);
 654   if (lasttab == NULL || last4tab == NULL)
 655     goto alloc_failure;
 656
 657   /* Now insert the strings into hash tables (strings with last 4 characters
 658      and strings with last character equal), look for longer strings which
 659      we're suffix of.  */
 660   for (a = array, end = array + sinfo->htab->size; a < end; a++)
 661     {
 662       register hashval_t hash;
 663       unsigned int c;
 664       unsigned int i;
 665       const unsigned char *s;
 666       PTR *p;
 667
 668       e = *a;
 669       e->u.entsize = sinfo->htab->entsize;
 670       if (e->len <= e->u.entsize)
 671         break;
 672       if (e->len > 4 * e->u.entsize)
 673         {
 674           s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
 675           hash = 0;
 676           for (i = 0; i < 4 * e->u.entsize; i++)
 677             {
 678               c = *--s;
 679               hash += c + (c << 17);
 680               hash ^= hash >> 2;
 681             }
 682           p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
 683           if (p == NULL)
 684             goto alloc_failure;
 685           if (*p)
 686             {
 687               struct sec_merge_hash_entry *ent;
 688
 689               ent = (struct sec_merge_hash_entry *) *p;
 690               e->u.suffix = ent;
 691               e->alignment = 0;
 692               continue;
 693             }
 694           else
 695             *p = (PTR) e;
 696         }
 697       s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
 698       hash = 0;
 699       for (i = 0; i < e->u.entsize; i++)
 700         {
 701           c = *--s;
 702           hash += c + (c << 17);
 703           hash ^= hash >> 2;
 704         }
 705       p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
 706       if (p == NULL)
 707         goto alloc_failure;
 708       if (*p)
 709         {
 710           struct sec_merge_hash_entry *ent;
 711
 712           ent = (struct sec_merge_hash_entry *) *p;
 713           e->u.suffix = ent;
 714           e->alignment = 0;
 715         }
 716       else
 717         *p = (PTR) e;
 718     }
 719
 720 alloc_failure:
 721   if (array)
 722     free (array);
 723   if (lasttab)
 724     htab_delete (lasttab);
 725   if (last4tab)
 726     htab_delete (last4tab);
 727
 728   /* Now assign positions to the strings we want to keep.  */
 729   size = 0;
 730   secinfo = sinfo->htab->first->secinfo;
 731   for (e = sinfo->htab->first; e; e = e->next)
 732     {
 733       if (e->secinfo != secinfo)
 734         {
 735           secinfo->sec->_cooked_size = size;
 736           secinfo = e->secinfo;
 737         }
 738       if (e->alignment)
 739         {
 740           if (e->secinfo->first == NULL)
 741             {
 742               e->secinfo->first = e;
 743               size = 0;
 744             }
 745           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 746           e->u.index = size;
 747           size += e->len;
 748         }
 749     }
 750   secinfo->sec->_cooked_size = size;
 751
 752   /* And now adjust the rest, removing them from the chain (but not hashtable)
 753      at the same time.  */
 754   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 755     if (e->alignment)
 756       a = &e->next;
 757     else
 758       {
 759         *a = e->next;
 760         if (e->len)
 761           {
 762             e->secinfo = e->u.suffix->secinfo;
 763             e->alignment = e->u.suffix->alignment;
 764             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 765           }
 766       }
 767 }
 768
 769 /* This function is called once after all SEC_MERGE sections are registered
 770    with _bfd_merge_section.  */
 771
 772 bfd_boolean
 773 _bfd_merge_sections (abfd, xsinfo, remove_hook)
 774      bfd *abfd ATTRIBUTE_UNUSED;
 775      PTR xsinfo;
 776      void (*remove_hook) PARAMS((bfd *, asection *));
 777 {
 778   struct sec_merge_info *sinfo;
 779
 780   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 781     {
 782       struct sec_merge_sec_info * secinfo;
 783
 784       if (! sinfo->chain)
 785         continue;
 786
 787       /* Move sinfo->chain to head of the chain, terminate it.  */
 788       secinfo = sinfo->chain;
 789       sinfo->chain = secinfo->next;
 790       secinfo->next = NULL;
 791
 792       /* Record the sections into the hash table.  */
 793       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 794         if (secinfo->sec->flags & SEC_EXCLUDE)
 795           {
 796             *secinfo->psecinfo = NULL;
 797             if (remove_hook)
 798               (*remove_hook) (abfd, secinfo->sec);
 799           }
 800         else if (! record_section (sinfo, secinfo))
 801           break;
 802
 803       if (secinfo)
 804         continue;
 805
 806       if (sinfo->htab->first == NULL)
 807         continue;
 808
 809       if (sinfo->htab->strings)
 810         merge_strings (sinfo);
 811       else
 812         {
 813           struct sec_merge_hash_entry *e;
 814           bfd_size_type size = 0;
 815
 816           /* Things are much simpler for non-strings.
 817              Just assign them slots in the section.  */
 818           secinfo = NULL;
 819           for (e = sinfo->htab->first; e; e = e->next)
 820             {
 821               if (e->secinfo->first == NULL)
 822                 {
 823                   if (secinfo)
 824                     secinfo->sec->_cooked_size = size;
 825                   e->secinfo->first = e;
 826                   size = 0;
 827                 }
 828               size = (size + e->alignment - 1)
 829                      & ~((bfd_vma) e->alignment - 1);
 830               e->u.index = size;
 831               size += e->len;
 832               secinfo = e->secinfo;
 833             }
 834           secinfo->sec->_cooked_size = size;
 835         }
 836
 837         /* Finally shrink all input sections which have not made it into
 838            the hash table at all.  */
 839         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 840           if (secinfo->first == NULL)
 841             secinfo->sec->_cooked_size = 0;
 842     }
 843
 844   return TRUE;
 845 }
 846
 847 /* Write out the merged section.  */
 848
 849 bfd_boolean
 850 _bfd_write_merged_section (output_bfd, sec, psecinfo)
 851      bfd *output_bfd;
 852      asection *sec;
 853      PTR psecinfo;
 854 {
 855   struct sec_merge_sec_info *secinfo;
 856   file_ptr pos;
 857
 858   secinfo = (struct sec_merge_sec_info *) psecinfo;
 859
 860   if (!secinfo->first)
 861     return TRUE;
 862
 863   pos = sec->output_section->filepos + sec->output_offset;
 864   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 865     return FALSE;
 866
 867   if (! sec_merge_emit (output_bfd, secinfo->first))
 868     return FALSE;
 869
 870   return TRUE;
 871 }
 872
 873 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 874    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 875    section and writes the new section back into *PSEC.  */
 876
 877 bfd_vma
 878 _bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
 879      bfd *output_bfd ATTRIBUTE_UNUSED;
 880      asection **psec;
 881      PTR psecinfo;
 882      bfd_vma offset, addend;
 883 {
 884   struct sec_merge_sec_info *secinfo;
 885   struct sec_merge_hash_entry *entry;
 886   unsigned char *p;
 887   asection *sec = *psec;
 888
 889   secinfo = (struct sec_merge_sec_info *) psecinfo;
 890
 891   if (offset + addend >= sec->_raw_size)
 892     {
 893       if (offset + addend > sec->_raw_size)
 894         {
 895           (*_bfd_error_handler)
 896             (_("%s: access beyond end of merged section (%ld + %ld)"),
 897              bfd_get_filename (sec->owner), (long) offset, (long) addend);
 898         }
 899       return (secinfo->first ? sec->_cooked_size : 0);
 900     }
 901
 902   if (secinfo->htab->strings)
 903     {
 904       if (sec->entsize == 1)
 905         {
 906           p = secinfo->contents + offset + addend - 1;
 907           while (p >= secinfo->contents && *p)
 908             --p;
 909           ++p;
 910         }
 911       else
 912         {
 913           p = secinfo->contents
 914               + ((offset + addend) / sec->entsize) * sec->entsize;
 915           p -= sec->entsize;
 916           while (p >= secinfo->contents)
 917             {
 918               unsigned int i;
 919
 920               for (i = 0; i < sec->entsize; ++i)
 921                 if (p[i] != '\0')
 922                   break;
 923               if (i == sec->entsize)
 924                 break;
 925               p -= sec->entsize;
 926             }
 927           p += sec->entsize;
 928         }
 929     }
 930   else
 931     {
 932       p = secinfo->contents
 933           + ((offset + addend) / sec->entsize) * sec->entsize;
 934     }
 935   entry = sec_merge_hash_lookup (secinfo->htab, p, 0, FALSE);
 936   if (!entry)
 937     {
 938       if (! secinfo->htab->strings)
 939         abort ();
 940       /* This should only happen if somebody points into the padding
 941          after a NUL character but before next entity.  */
 942       if (*p)
 943         abort ();
 944       if (! secinfo->htab->first)
 945         abort ();
 946       entry = secinfo->htab->first;
 947       p = secinfo->contents
 948           + ((offset + addend) / sec->entsize + 1) * sec->entsize
 949           - entry->len;
 950     }
 951
 952   *psec = entry->secinfo->sec;
 953   return entry->u.index + (secinfo->contents + offset - p);
 954 }