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 struct sec_merge_sec_info;
  30
  31 /* An entry in the section merge hash table.  */
  32
  33 struct sec_merge_hash_entry
  34 {
  35   struct bfd_hash_entry root;
  36   /* Length of this entry.  */
  37   unsigned int len;
  38   /* Start of this string needs to be aligned to
  39      alignment octets (not 1 << align).  */
  40   unsigned int alignment;
  41   union {
  42     /* Index within the merged section.  */
  43     bfd_size_type index;
  44     /* Entity size (if present in suffix hash tables).  */
  45     unsigned int entsize;
  46     /* Entry this is a suffix of (if alignment is 0).  */
  47     struct sec_merge_hash_entry *suffix;
  48   } u;
  49   /* Which section is it in.  */
  50   struct sec_merge_sec_info *secinfo;
  51   /* Next entity in the hash table.  */
  52   struct sec_merge_hash_entry *next;
  53 };
  54
  55 /* The section merge hash table.  */
  56
  57 struct sec_merge_hash
  58 {
  59   struct bfd_hash_table table;
  60   /* Next available index.  */
  61   bfd_size_type size;
  62   /* First entity in the SEC_MERGE sections of this type.  */
  63   struct sec_merge_hash_entry *first;
  64   /* Last entity in the SEC_MERGE sections of this type.  */
  65   struct sec_merge_hash_entry *last;
  66   /* Entity size.  */
  67   unsigned int entsize;
  68   /* Are entries fixed size or zero terminated strings?  */
  69   boolean strings;
  70 };
  71
  72 struct sec_merge_info
  73 {
  74   /* Chain of sec_merge_infos.  */
  75   struct sec_merge_info *next;
  76   /* Chain of sec_merge_sec_infos.  */
  77   struct sec_merge_sec_info *chain;
  78   /* A hash table used to hold section content.  */
  79   struct sec_merge_hash *htab;
  80 };
  81
  82 struct sec_merge_sec_info
  83 {
  84   /* Chain of sec_merge_sec_infos.  */
  85   struct sec_merge_sec_info *next;
  86   /* The corresponding section.  */
  87   asection *sec;
  88   /* Pointer to merge_info pointing to us.  */
  89   PTR *psecinfo;
  90   /* A hash table used to hold section content.  */
  91   struct sec_merge_hash *htab;
  92   /* First string in this section.  */
  93   struct sec_merge_hash_entry *first;
  94   /* Original section content.  */
  95   unsigned char contents[1];
  96 };
  97
  98 static struct bfd_hash_entry *sec_merge_hash_newfunc
  99   PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
 100 static struct sec_merge_hash_entry *sec_merge_hash_lookup
 101   PARAMS ((struct sec_merge_hash *, const char *, unsigned int, boolean));
 102 static struct sec_merge_hash *sec_merge_init
 103   PARAMS ((unsigned int, boolean));
 104 static struct sec_merge_hash_entry *sec_merge_add
 105   PARAMS ((struct sec_merge_hash *, const char *, unsigned int,
 106            struct sec_merge_sec_info *));
 107 static boolean sec_merge_emit
 108   PARAMS ((bfd *, struct sec_merge_hash_entry *));
 109 static int cmplengthentry PARAMS ((const PTR, const PTR));
 110 static int last4_eq PARAMS ((const PTR, const PTR));
 111 static int last_eq PARAMS ((const PTR, const PTR));
 112 static boolean record_section
 113   PARAMS ((struct sec_merge_info *, struct sec_merge_sec_info *));
 114 static void merge_strings PARAMS ((struct sec_merge_info *));
 115
 116 /* Routine to create an entry in a section merge hashtab.  */
 117
 118 static struct bfd_hash_entry *
 119 sec_merge_hash_newfunc (entry, table, string)
 120      struct bfd_hash_entry *entry;
 121      struct bfd_hash_table *table;
 122      const char *string;
 123 {
 124   struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
 125
 126   /* Allocate the structure if it has not already been allocated by a
 127      subclass.  */
 128   if (ret == (struct sec_merge_hash_entry *) NULL)
 129     ret = ((struct sec_merge_hash_entry *)
 130            bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
 131   if (ret == (struct sec_merge_hash_entry *) NULL)
 132     return NULL;
 133
 134   /* Call the allocation method of the superclass.  */
 135   ret = ((struct sec_merge_hash_entry *)
 136          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 137
 138   if (ret)
 139     {
 140       /* Initialize the local fields.  */
 141       ret->u.suffix = NULL;
 142       ret->alignment = 0;
 143       ret->secinfo = NULL;
 144       ret->next = NULL;
 145     }
 146
 147   return (struct bfd_hash_entry *)ret;
 148 }
 149
 150 /* Look up an entry in a section merge hash table.  */
 151
 152 static struct sec_merge_hash_entry *
 153 sec_merge_hash_lookup (table, string, alignment, create)
 154      struct sec_merge_hash *table;
 155      const char *string;
 156      unsigned int alignment;
 157      boolean create;
 158 {
 159   register const unsigned char *s;
 160   register unsigned long hash;
 161   register unsigned int c;
 162   struct sec_merge_hash_entry *hashp;
 163   unsigned int len, i;
 164   unsigned int index;
 165
 166   hash = 0;
 167   len = 0;
 168   s = (const unsigned char *) string;
 169   if (table->strings)
 170     {
 171       if (table->entsize == 1)
 172         {
 173           while ((c = *s++) != '\0')
 174             {
 175               hash += c + (c << 17);
 176               hash ^= hash >> 2;
 177               ++len;
 178             }
 179           hash += len + (len << 17);
 180         }
 181       else
 182         {
 183           for (;;)
 184             {
 185               for (i = 0; i < table->entsize; ++i)
 186                 if (s[i] != '\0')
 187                   break;
 188               if (i == table->entsize)
 189                 break;
 190               for (i = 0; i < table->entsize; ++i)
 191                 {
 192                   c = *s++;
 193                   hash += c + (c << 17);
 194                   hash ^= hash >> 2;
 195                 }
 196               ++len;
 197             }
 198           hash += len + (len << 17);
 199           len *= table->entsize;
 200         }
 201       hash ^= hash >> 2;
 202       len += table->entsize;
 203     }
 204   else
 205     {
 206       for (i = 0; i < table->entsize; ++i)
 207         {
 208           c = *s++;
 209           hash += c + (c << 17);
 210           hash ^= hash >> 2;
 211         }
 212       len = table->entsize;
 213     }
 214
 215   index = hash % table->table.size;
 216   for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
 217        hashp != (struct sec_merge_hash_entry *) NULL;
 218        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
 219     {
 220       if (hashp->root.hash == hash
 221           && len == hashp->len
 222           && memcmp (hashp->root.string, string, len) == 0)
 223         {
 224           /* If the string we found does not have at least the required
 225              alignment, we need to insert another copy.  */
 226           if (hashp->alignment < alignment)
 227             {
 228               /*  Mark the less aligned copy as deleted.  */
 229               hashp->len = 0;
 230               hashp->alignment = 0;
 231               break;
 232             }
 233           return hashp;
 234         }
 235     }
 236
 237   if (! create)
 238     return (struct sec_merge_hash_entry *) NULL;
 239
 240   hashp = (struct sec_merge_hash_entry *)
 241           sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
 242                                   (struct bfd_hash_table *) table, string);
 243   if (hashp == (struct sec_merge_hash_entry *) NULL)
 244     return (struct sec_merge_hash_entry *) NULL;
 245   hashp->root.string = string;
 246   hashp->root.hash = hash;
 247   hashp->len = len;
 248   hashp->alignment = alignment;
 249   hashp->root.next = table->table.table[index];
 250   table->table.table[index] = (struct bfd_hash_entry *) hashp;
 251
 252   return hashp;
 253 }
 254
 255 /* Create a new hash table.  */
 256
 257 static struct sec_merge_hash *
 258 sec_merge_init (entsize, strings)
 259      unsigned int entsize;
 260      boolean strings;
 261 {
 262   struct sec_merge_hash *table;
 263   bfd_size_type amt = sizeof (struct sec_merge_hash);
 264
 265   table = (struct sec_merge_hash *) bfd_malloc (amt);
 266   if (table == NULL)
 267     return NULL;
 268
 269   if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
 270     {
 271       free (table);
 272       return NULL;
 273     }
 274
 275   table->size = 0;
 276   table->first = NULL;
 277   table->last = NULL;
 278   table->entsize = entsize;
 279   table->strings = strings;
 280
 281   return table;
 282 }
 283
 284 /* Get the index of an entity in a hash table, adding it if it is not
 285    already present.  */
 286
 287 static struct sec_merge_hash_entry *
 288 sec_merge_add (tab, str, alignment, secinfo)
 289      struct sec_merge_hash *tab;
 290      const char *str;
 291      unsigned int alignment;
 292      struct sec_merge_sec_info *secinfo;
 293 {
 294   register struct sec_merge_hash_entry *entry;
 295
 296   entry = sec_merge_hash_lookup (tab, str, alignment, true);
 297   if (entry == NULL)
 298     return NULL;
 299
 300   if (entry->secinfo == NULL)
 301     {
 302       tab->size++;
 303       entry->secinfo = secinfo;
 304       if (tab->first == NULL)
 305         tab->first = entry;
 306       else
 307         tab->last->next = entry;
 308       tab->last = entry;
 309     }
 310
 311   return entry;
 312 }
 313
 314 static boolean
 315 sec_merge_emit (abfd, entry)
 316      register bfd *abfd;
 317      struct sec_merge_hash_entry *entry;
 318 {
 319   struct sec_merge_sec_info *secinfo = entry->secinfo;
 320   asection *sec = secinfo->sec;
 321   char *pad = "";
 322   bfd_size_type off = 0;
 323   int alignment_power = bfd_get_section_alignment (abfd, sec->output_section);
 324
 325   if (alignment_power)
 326     pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
 327
 328   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
 329     {
 330       register const char *str;
 331       register size_t len;
 332
 333       len = off & (entry->alignment - 1);
 334       if (len)
 335         {
 336           len = entry->alignment - len;
 337           if (bfd_bwrite ((PTR) pad, (bfd_size_type) len, abfd) != len)
 338             break;
 339           off += len;
 340         }
 341
 342       str = entry->root.string;
 343       len = entry->len;
 344
 345       if (bfd_bwrite ((PTR) str, (bfd_size_type) len, abfd) != len)
 346         break;
 347
 348       off += len;
 349     }
 350
 351   if (alignment_power)
 352     free (pad);
 353
 354   return entry == NULL || entry->secinfo != secinfo;
 355 }
 356
 357 /* This function is called for each input file from the add_symbols
 358    pass of the linker.  */
 359
 360 boolean
 361 _bfd_merge_section (abfd, psinfo, sec, psecinfo)
 362      bfd *abfd;
 363      PTR *psinfo;
 364      asection *sec;
 365      PTR *psecinfo;
 366 {
 367   struct sec_merge_info *sinfo;
 368   struct sec_merge_sec_info *secinfo;
 369   unsigned int align;
 370   bfd_size_type amt;
 371
 372   if (sec->_raw_size == 0
 373       || (sec->flags & SEC_EXCLUDE)
 374       || (sec->flags & SEC_MERGE) == 0
 375       || sec->entsize == 0)
 376     return true;
 377
 378   if ((sec->flags & SEC_RELOC) != 0)
 379     {
 380       /* We aren't prepared to handle relocations in merged sections.  */
 381       return true;
 382     }
 383
 384   if (sec->output_section != NULL
 385       && bfd_is_abs_section (sec->output_section))
 386     {
 387       /* The section is being discarded from the link, so we should
 388          just ignore it.  */
 389       return true;
 390     }
 391
 392   align = bfd_get_section_alignment (sec->owner, sec);
 393   if ((sec->entsize < (unsigned int)(1 << align)
 394        && ((sec->entsize & (sec->entsize - 1))
 395            || !(sec->flags & SEC_STRINGS)))
 396       || (sec->entsize > (unsigned int)(1 << align)
 397           && (sec->entsize & ((1 << align) - 1))))
 398     {
 399       /* Sanity check.  If string character size is smaller than
 400          alignment, then we require character size to be a power
 401          of 2, otherwise character size must be integer multiple
 402          of alignment.  For non-string constants, alignment must
 403          be smaller than or equal to entity size and entity size
 404          must be integer multiple of alignment.  */
 405       return true;
 406     }
 407
 408   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
 409     if ((secinfo = sinfo->chain)
 410         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
 411         && secinfo->sec->entsize == sec->entsize
 412         && ! strcmp (secinfo->sec->name, sec->name))
 413       break;
 414
 415   if (sinfo == NULL)
 416     {
 417       /* Initialize the information we need to keep track of.  */
 418       sinfo = (struct sec_merge_info *)
 419               bfd_alloc (abfd, (bfd_size_type) sizeof (struct sec_merge_info));
 420       if (sinfo == NULL)
 421         goto error_return;
 422       sinfo->next = (struct sec_merge_info *) *psinfo;
 423       sinfo->chain = NULL;
 424       *psinfo = (PTR) sinfo;
 425       sinfo->htab =
 426         sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
 427       if (sinfo->htab == NULL)
 428         goto error_return;
 429     }
 430
 431   /* Read the section from abfd.  */
 432
 433   amt = sizeof (struct sec_merge_sec_info) + sec->_raw_size - 1;
 434   *psecinfo = bfd_alloc (abfd, amt);
 435   if (*psecinfo == NULL)
 436     goto error_return;
 437
 438   secinfo = (struct sec_merge_sec_info *)*psecinfo;
 439   if (sinfo->chain)
 440     {
 441       secinfo->next = sinfo->chain->next;
 442       sinfo->chain->next = secinfo;
 443     }
 444   else
 445     secinfo->next = secinfo;
 446   sinfo->chain = secinfo;
 447   secinfo->sec = sec;
 448   secinfo->psecinfo = psecinfo;
 449   secinfo->htab = sinfo->htab;
 450   secinfo->first = NULL;
 451
 452   if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
 453                                   (bfd_vma) 0, sec->_raw_size))
 454     goto error_return;
 455
 456   return true;
 457
 458  error_return:
 459   *psecinfo = NULL;
 460   return false;
 461 }
 462
 463 /* Compare two sec_merge_hash_entry structures.  This is called via qsort.  */
 464
 465 static int
 466 cmplengthentry (a, b)
 467      const PTR a;
 468      const PTR b;
 469 {
 470   struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
 471   struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
 472
 473   if (A->len < B->len)
 474     return 1;
 475   else if (A->len > B->len)
 476     return -1;
 477
 478   return memcmp (A->root.string, B->root.string, A->len);
 479 }
 480
 481 static int
 482 last4_eq (a, b)
 483      const PTR a;
 484      const PTR b;
 485 {
 486   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 487   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 488
 489   if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
 490               B->root.string + B->len - 5 * A->u.entsize,
 491               4 * A->u.entsize) != 0)
 492     /* This was a hashtable collision.  */
 493     return 0;
 494
 495   if (A->len <= B->len)
 496     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 497        not to be equal by the hash table.  */
 498     return 0;
 499
 500   if (A->alignment < B->alignment
 501       || ((A->len - B->len) & (B->alignment - 1)))
 502     /* The suffix is not sufficiently aligned.  */
 503     return 0;
 504
 505   return memcmp (A->root.string + (A->len - B->len),
 506                  B->root.string, B->len - 5 * A->u.entsize) == 0;
 507 }
 508
 509 static int
 510 last_eq (a, b)
 511      const PTR a;
 512      const PTR b;
 513 {
 514   struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
 515   struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
 516
 517   if (B->len >= 5 * A->u.entsize)
 518     /* Longer strings are just pushed into the hash table,
 519        they'll be used when looking up for very short strings.  */
 520     return 0;
 521
 522   if (memcmp (A->root.string + A->len - 2 * A->u.entsize,
 523               B->root.string + B->len - 2 * A->u.entsize,
 524               A->u.entsize) != 0)
 525     /* This was a hashtable collision.  */
 526     return 0;
 527
 528   if (A->len <= B->len)
 529     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
 530        not to be equal by the hash table.  */
 531     return 0;
 532
 533   if (A->alignment < B->alignment
 534       || ((A->len - B->len) & (B->alignment - 1)))
 535     /* The suffix is not sufficiently aligned.  */
 536     return 0;
 537
 538   return memcmp (A->root.string + (A->len - B->len),
 539                  B->root.string, B->len - 2 * A->u.entsize) == 0;
 540 }
 541
 542 /* Record one section into the hash table.  */
 543 static boolean
 544 record_section (sinfo, secinfo)
 545      struct sec_merge_info *sinfo;
 546      struct sec_merge_sec_info *secinfo;
 547 {
 548   asection *sec = secinfo->sec;
 549   struct sec_merge_hash_entry *entry;
 550   boolean nul;
 551   unsigned char *p, *end;
 552   bfd_vma mask, eltalign;
 553   unsigned int align, i;
 554
 555   align = bfd_get_section_alignment (sec->owner, sec);
 556   end = secinfo->contents + sec->_raw_size;
 557   nul = false;
 558   mask = ((bfd_vma) 1 << align) - 1;
 559   if (sec->flags & SEC_STRINGS)
 560     {
 561       for (p = secinfo->contents; p < end; )
 562         {
 563           eltalign = p - secinfo->contents;
 564           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
 565           if (!eltalign || eltalign > mask)
 566             eltalign = mask + 1;
 567           entry = sec_merge_add (sinfo->htab, p, (unsigned) eltalign, secinfo);
 568           if (! entry)
 569             goto error_return;
 570           p += entry->len;
 571           if (sec->entsize == 1)
 572             {
 573               while (p < end && *p == 0)
 574                 {
 575                   if (!nul && !((p - secinfo->contents) & mask))
 576                     {
 577                       nul = true;
 578                       entry = sec_merge_add (sinfo->htab, "",
 579                                              (unsigned) mask + 1, secinfo);
 580                       if (! entry)
 581                         goto error_return;
 582                     }
 583                   p++;
 584                 }
 585             }
 586           else
 587             {
 588               while (p < end)
 589                 {
 590                   for (i = 0; i < sec->entsize; i++)
 591                     if (p[i] != '\0')
 592                       break;
 593                   if (i != sec->entsize)
 594                     break;
 595                   if (!nul && !((p - secinfo->contents) & mask))
 596                     {
 597                       nul = true;
 598                       entry = sec_merge_add (sinfo->htab, p,
 599                                              (unsigned) mask + 1, secinfo);
 600                       if (! entry)
 601                         goto error_return;
 602                     }
 603                   p += sec->entsize;
 604                 }
 605             }
 606         }
 607     }
 608   else
 609     {
 610       for (p = secinfo->contents; p < end; p += sec->entsize)
 611         {
 612           entry = sec_merge_add (sinfo->htab, p, 1, secinfo);
 613           if (! entry)
 614             goto error_return;
 615         }
 616     }
 617
 618   return true;
 619
 620 error_return:
 621   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 622     *secinfo->psecinfo = NULL;
 623   return false;
 624 }
 625
 626 /* This is a helper function for _bfd_merge_sections.  It attempts to
 627    merge strings matching suffixes of longer strings.  */
 628 static void
 629 merge_strings (sinfo)
 630      struct sec_merge_info *sinfo;
 631 {
 632   struct sec_merge_hash_entry **array, **a, **end, *e;
 633   struct sec_merge_sec_info *secinfo;
 634   htab_t lasttab = NULL, last4tab = NULL;
 635   bfd_size_type size, amt;
 636
 637   /* Now sort the strings by length, longest first.  */
 638   array = NULL;
 639   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
 640   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
 641   if (array == NULL)
 642     goto alloc_failure;
 643
 644   for (e = sinfo->htab->first, a = array; e; e = e->next)
 645     if (e->alignment)
 646       *a++ = e;
 647
 648   sinfo->htab->size = a - array;
 649
 650   qsort (array, (size_t) sinfo->htab->size,
 651          sizeof (struct sec_merge_hash_entry *), cmplengthentry);
 652
 653   last4tab = htab_create ((size_t) sinfo->htab->size * 4, NULL, last4_eq, NULL);
 654   lasttab = htab_create ((size_t) sinfo->htab->size * 4, NULL, last_eq, NULL);
 655   if (lasttab == NULL || last4tab == NULL)
 656     goto alloc_failure;
 657
 658   /* Now insert the strings into hash tables (strings with last 4 characters
 659      and strings with last character equal), look for longer strings which
 660      we're suffix of.  */
 661   for (a = array, end = array + sinfo->htab->size; a < end; a++)
 662     {
 663       register hashval_t hash;
 664       unsigned int c;
 665       unsigned int i;
 666       const unsigned char *s;
 667       PTR *p;
 668
 669       e = *a;
 670       e->u.entsize = sinfo->htab->entsize;
 671       if (e->len <= e->u.entsize)
 672         break;
 673       if (e->len > 4 * e->u.entsize)
 674         {
 675           s = e->root.string + e->len - e->u.entsize;
 676           hash = 0;
 677           for (i = 0; i < 4 * e->u.entsize; i++)
 678             {
 679               c = *--s;
 680               hash += c + (c << 17);
 681               hash ^= hash >> 2;
 682             }
 683           p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
 684           if (p == NULL)
 685             goto alloc_failure;
 686           if (*p)
 687             {
 688               struct sec_merge_hash_entry *ent;
 689
 690               ent = (struct sec_merge_hash_entry *) *p;
 691               e->u.suffix = ent;
 692               e->alignment = 0;
 693               continue;
 694             }
 695           else
 696             *p = (PTR) e;
 697         }
 698       s = e->root.string + e->len - e->u.entsize;
 699       hash = 0;
 700       for (i = 0; i < e->u.entsize; i++)
 701         {
 702           c = *--s;
 703           hash += c + (c << 17);
 704           hash ^= hash >> 2;
 705         }
 706       p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
 707       if (p == NULL)
 708         goto alloc_failure;
 709       if (*p)
 710         {
 711           struct sec_merge_hash_entry *ent;
 712
 713           ent = (struct sec_merge_hash_entry *) *p;
 714           e->u.suffix = ent;
 715           e->alignment = 0;
 716         }
 717       else
 718         *p = (PTR) e;
 719     }
 720
 721 alloc_failure:
 722   if (array)
 723     free (array);
 724   if (lasttab)
 725     htab_delete (lasttab);
 726   if (last4tab)
 727     htab_delete (last4tab);
 728
 729   /* Now assign positions to the strings we want to keep.  */
 730   size = 0;
 731   secinfo = sinfo->htab->first->secinfo;
 732   for (e = sinfo->htab->first; e; e = e->next)
 733     {
 734       if (e->secinfo != secinfo)
 735         {
 736           secinfo->sec->_cooked_size = size;
 737           secinfo = e->secinfo;
 738         }
 739       if (e->alignment)
 740         {
 741           if (e->secinfo->first == NULL)
 742             {
 743               e->secinfo->first = e;
 744               size = 0;
 745             }
 746           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
 747           e->u.index = size;
 748           size += e->len;
 749         }
 750     }
 751   secinfo->sec->_cooked_size = size;
 752
 753   /* And now adjust the rest, removing them from the chain (but not hashtable)
 754      at the same time.  */
 755   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
 756     if (e->alignment)
 757       a = &e->next;
 758     else
 759       {
 760         *a = e->next;
 761         if (e->len)
 762           {
 763             e->secinfo = e->u.suffix->secinfo;
 764             e->alignment = e->u.suffix->alignment;
 765             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
 766           }
 767       }
 768 }
 769
 770 /* This function is called once after all SEC_MERGE sections are registered
 771    with _bfd_merge_section.  */
 772
 773 boolean
 774 _bfd_merge_sections (abfd, xsinfo, remove_hook)
 775      bfd *abfd ATTRIBUTE_UNUSED;
 776      PTR xsinfo;
 777      void (*remove_hook) PARAMS((bfd *, asection *));
 778 {
 779   struct sec_merge_info *sinfo;
 780
 781   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
 782     {
 783       struct sec_merge_sec_info * secinfo;
 784
 785       if (! sinfo->chain)
 786         continue;
 787
 788       /* Move sinfo->chain to head of the chain, terminate it.  */
 789       secinfo = sinfo->chain;
 790       sinfo->chain = secinfo->next;
 791       secinfo->next = NULL;
 792
 793       /* Record the sections into the hash table.  */
 794       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 795         if (secinfo->sec->flags & SEC_EXCLUDE)
 796           {
 797             *secinfo->psecinfo = NULL;
 798             if (remove_hook)
 799               (*remove_hook) (abfd, secinfo->sec);
 800           }
 801         else if (! record_section (sinfo, secinfo))
 802           break;
 803
 804       if (secinfo)
 805         continue;
 806
 807       if (sinfo->htab->strings)
 808         merge_strings (sinfo);
 809       else
 810         {
 811           struct sec_merge_hash_entry *e;
 812           bfd_size_type size = 0;
 813
 814           /* Things are much simpler for non-strings.
 815              Just assign them slots in the section.  */
 816           secinfo = NULL;
 817           for (e = sinfo->htab->first; e; e = e->next)
 818             {
 819               if (e->secinfo->first == NULL)
 820                 {
 821                   if (secinfo)
 822                     secinfo->sec->_cooked_size = size;
 823                   e->secinfo->first = e;
 824                   size = 0;
 825                 }
 826               size = (size + e->alignment - 1)
 827                      & ~((bfd_vma) e->alignment - 1);
 828               e->u.index = size;
 829               size += e->len;
 830               secinfo = e->secinfo;
 831             }
 832           secinfo->sec->_cooked_size = size;
 833         }
 834
 835         /* Finally shrink all input sections which have not made it into
 836            the hash table at all.  */
 837         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
 838           if (secinfo->first == NULL)
 839             {
 840               secinfo->sec->_cooked_size = 0;
 841               secinfo->sec->flags |= SEC_EXCLUDE;
 842             }
 843     }
 844
 845   return true;
 846 }
 847
 848 /* Write out the merged section.  */
 849
 850 boolean
 851 _bfd_write_merged_section (output_bfd, sec, psecinfo)
 852      bfd *output_bfd;
 853      asection *sec;
 854      PTR psecinfo;
 855 {
 856   struct sec_merge_sec_info *secinfo;
 857   file_ptr pos;
 858
 859   secinfo = (struct sec_merge_sec_info *) psecinfo;
 860
 861   if (!secinfo->first)
 862     return true;
 863
 864   pos = sec->output_section->filepos + sec->output_offset;
 865   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
 866     return false;
 867
 868   if (! sec_merge_emit (output_bfd, secinfo->first))
 869     return false;
 870
 871   return true;
 872 }
 873
 874 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
 875    *PSEC, this returns the new offset in the adjusted SEC_MERGE
 876    section and writes the new section back into *PSEC.  */
 877
 878 bfd_vma
 879 _bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
 880      bfd *output_bfd ATTRIBUTE_UNUSED;
 881      asection **psec;
 882      PTR psecinfo;
 883      bfd_vma offset, addend;
 884 {
 885   struct sec_merge_sec_info *secinfo;
 886   struct sec_merge_hash_entry *entry;
 887   unsigned char *p;
 888   asection *sec = *psec;
 889
 890   secinfo = (struct sec_merge_sec_info *) psecinfo;
 891
 892   if (offset + addend >= sec->_raw_size)
 893     {
 894       if (offset + addend > sec->_raw_size)
 895         {
 896           (*_bfd_error_handler)
 897             (_("%s: access beyond end of merged section (%ld + %ld)"),
 898              bfd_get_filename (sec->owner), (long) offset, (long) addend);
 899         }
 900       return (secinfo->first ? sec->_cooked_size : 0);
 901     }
 902
 903   if (secinfo->htab->strings)
 904     {
 905       if (sec->entsize == 1)
 906         {
 907           p = secinfo->contents + offset + addend - 1;
 908           while (*p && p >= secinfo->contents)
 909             --p;
 910           ++p;
 911         }
 912       else
 913         {
 914           p = secinfo->contents
 915               + ((offset + addend) / sec->entsize) * sec->entsize;
 916           p -= sec->entsize;
 917           while (p >= secinfo->contents)
 918             {
 919               unsigned int i;
 920
 921               for (i = 0; i < sec->entsize; ++i)
 922                 if (p[i] != '\0')
 923                   break;
 924               if (i == sec->entsize)
 925                 break;
 926               p -= sec->entsize;
 927             }
 928           p += sec->entsize;
 929         }
 930     }
 931   else
 932     {
 933       p = secinfo->contents
 934           + ((offset + addend) / sec->entsize) * sec->entsize;
 935     }
 936   entry = sec_merge_hash_lookup (secinfo->htab, p, 0, false);
 937   if (!entry)
 938     {
 939       if (! secinfo->htab->strings)
 940         abort ();
 941       /* This should only happen if somebody points into the padding
 942          after a NUL character but before next entity.  */
 943       if (*p)
 944         abort ();
 945       if (! secinfo->htab->first)
 946         abort ();
 947       entry = secinfo->htab->first;
 948       p = secinfo->contents
 949           + ((offset + addend) / sec->entsize + 1) * sec->entsize
 950           - entry->len;
 951     }
 952
 953   *psec = entry->secinfo->sec;
 954   return entry->u.index + (secinfo->contents + offset - p);
 955 }