1/* SEC_MERGE support.
2   Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
3   Free Software Foundation, Inc.
4   Written by Jakub Jelinek <jakub@redhat.com>.
5
6   This file is part of BFD, the Binary File Descriptor library.
7
8   This program is free software; you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation; either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program; if not, write to the Free Software
20   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21   MA 02110-1301, USA.  */
22
23
24/* This file contains support for merging duplicate entities within sections,
25   as used in ELF SHF_MERGE.  */
26
27#include "sysdep.h"
28#include "bfd.h"
29#include "libbfd.h"
30#include "hashtab.h"
31#include "libiberty.h"
32
33struct sec_merge_sec_info;
34
35/* An entry in the section merge hash table.  */
36
37struct sec_merge_hash_entry
38{
39  struct bfd_hash_entry root;
40  /* Length of this entry.  This includes the zero terminator.  */
41  unsigned int len;
42  /* Start of this string needs to be aligned to
43     alignment octets (not 1 << align).  */
44  unsigned int alignment;
45  union
46  {
47    /* Index within the merged section.  */
48    bfd_size_type index;
49    /* Entry this is a suffix of (if alignment is 0).  */
50    struct sec_merge_hash_entry *suffix;
51  } u;
52  /* Which section is it in.  */
53  struct sec_merge_sec_info *secinfo;
54  /* Next entity in the hash table.  */
55  struct sec_merge_hash_entry *next;
56};
57
58/* The section merge hash table.  */
59
60struct sec_merge_hash
61{
62  struct bfd_hash_table table;
63  /* Next available index.  */
64  bfd_size_type size;
65  /* First entity in the SEC_MERGE sections of this type.  */
66  struct sec_merge_hash_entry *first;
67  /* Last entity in the SEC_MERGE sections of this type.  */
68  struct sec_merge_hash_entry *last;
69  /* Entity size.  */
70  unsigned int entsize;
71  /* Are entries fixed size or zero terminated strings?  */
72  bfd_boolean strings;
73};
74
75struct sec_merge_info
76{
77  /* Chain of sec_merge_infos.  */
78  struct sec_merge_info *next;
79  /* Chain of sec_merge_sec_infos.  */
80  struct sec_merge_sec_info *chain;
81  /* A hash table used to hold section content.  */
82  struct sec_merge_hash *htab;
83};
84
85struct sec_merge_sec_info
86{
87  /* Chain of sec_merge_sec_infos.  */
88  struct sec_merge_sec_info *next;
89  /* The corresponding section.  */
90  asection *sec;
91  /* Pointer to merge_info pointing to us.  */
92  void **psecinfo;
93  /* A hash table used to hold section content.  */
94  struct sec_merge_hash *htab;
95  /* First string in this section.  */
96  struct sec_merge_hash_entry *first_str;
97  /* Original section content.  */
98  unsigned char contents[1];
99};
100
101
102/* Routine to create an entry in a section merge hashtab.  */
103
104static struct bfd_hash_entry *
105sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
106			struct bfd_hash_table *table, const char *string)
107{
108  /* Allocate the structure if it has not already been allocated by a
109     subclass.  */
110  if (entry == NULL)
111    entry = (struct bfd_hash_entry *)
112        bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
113  if (entry == NULL)
114    return NULL;
115
116  /* Call the allocation method of the superclass.  */
117  entry = bfd_hash_newfunc (entry, table, string);
118
119  if (entry != NULL)
120    {
121      /* Initialize the local fields.  */
122      struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
123
124      ret->u.suffix = NULL;
125      ret->alignment = 0;
126      ret->secinfo = NULL;
127      ret->next = NULL;
128    }
129
130  return entry;
131}
132
133/* Look up an entry in a section merge hash table.  */
134
135static struct sec_merge_hash_entry *
136sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
137		       unsigned int alignment, bfd_boolean create)
138{
139  const unsigned char *s;
140  unsigned long hash;
141  unsigned int c;
142  struct sec_merge_hash_entry *hashp;
143  unsigned int len, i;
144  unsigned int _index;
145
146  hash = 0;
147  len = 0;
148  s = (const unsigned char *) string;
149  if (table->strings)
150    {
151      if (table->entsize == 1)
152	{
153	  while ((c = *s++) != '\0')
154	    {
155	      hash += c + (c << 17);
156	      hash ^= hash >> 2;
157	      ++len;
158	    }
159	  hash += len + (len << 17);
160	}
161      else
162	{
163	  for (;;)
164	    {
165	      for (i = 0; i < table->entsize; ++i)
166		if (s[i] != '\0')
167		  break;
168	      if (i == table->entsize)
169		break;
170	      for (i = 0; i < table->entsize; ++i)
171		{
172		  c = *s++;
173		  hash += c + (c << 17);
174		  hash ^= hash >> 2;
175		}
176	      ++len;
177	    }
178	  hash += len + (len << 17);
179	  len *= table->entsize;
180	}
181      hash ^= hash >> 2;
182      len += table->entsize;
183    }
184  else
185    {
186      for (i = 0; i < table->entsize; ++i)
187	{
188	  c = *s++;
189	  hash += c + (c << 17);
190	  hash ^= hash >> 2;
191	}
192      len = table->entsize;
193    }
194
195  _index = hash % table->table.size;
196  for (hashp = (struct sec_merge_hash_entry *) table->table.table[_index];
197       hashp != NULL;
198       hashp = (struct sec_merge_hash_entry *) hashp->root.next)
199    {
200      if (hashp->root.hash == hash
201	  && len == hashp->len
202	  && memcmp (hashp->root.string, string, len) == 0)
203	{
204	  /* If the string we found does not have at least the required
205	     alignment, we need to insert another copy.  */
206	  if (hashp->alignment < alignment)
207	    {
208	      if (create)
209		{
210		  /*  Mark the less aligned copy as deleted.  */
211		  hashp->len = 0;
212		  hashp->alignment = 0;
213		}
214	      break;
215	    }
216	  return hashp;
217	}
218    }
219
220  if (! create)
221    return NULL;
222
223  hashp = ((struct sec_merge_hash_entry *)
224	   bfd_hash_insert (&table->table, string, hash));
225  if (hashp == NULL)
226    return NULL;
227  hashp->len = len;
228  hashp->alignment = alignment;
229  return hashp;
230}
231
232/* Create a new hash table.  */
233
234static struct sec_merge_hash *
235sec_merge_init (unsigned int entsize, bfd_boolean strings)
236{
237  struct sec_merge_hash *table;
238
239  table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));
240  if (table == NULL)
241    return NULL;
242
243  if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
244			       sizeof (struct sec_merge_hash_entry), 16699))
245    {
246      free (table);
247      return NULL;
248    }
249
250  table->size = 0;
251  table->first = NULL;
252  table->last = NULL;
253  table->entsize = entsize;
254  table->strings = strings;
255
256  return table;
257}
258
259/* Get the index of an entity in a hash table, adding it if it is not
260   already present.  */
261
262static struct sec_merge_hash_entry *
263sec_merge_add (struct sec_merge_hash *tab, const char *str,
264	       unsigned int alignment, struct sec_merge_sec_info *secinfo)
265{
266  struct sec_merge_hash_entry *entry;
267
268  entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
269  if (entry == NULL)
270    return NULL;
271
272  if (entry->secinfo == NULL)
273    {
274      tab->size++;
275      entry->secinfo = secinfo;
276      if (tab->first == NULL)
277	tab->first = entry;
278      else
279	tab->last->next = entry;
280      tab->last = entry;
281    }
282
283  return entry;
284}
285
286static bfd_boolean
287sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
288{
289  struct sec_merge_sec_info *secinfo = entry->secinfo;
290  asection *sec = secinfo->sec;
291  char *pad = NULL;
292  bfd_size_type off = 0;
293  int alignment_power = sec->output_section->alignment_power;
294
295  if (alignment_power)
296    {
297      pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
298      if (pad == NULL)
299	return FALSE;
300    }
301
302  for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
303    {
304      const char *str;
305      bfd_size_type len;
306
307      len = -off & (entry->alignment - 1);
308      if (len != 0)
309	{
310	  if (bfd_bwrite (pad, len, abfd) != len)
311	    goto err;
312	  off += len;
313	}
314
315      str = entry->root.string;
316      len = entry->len;
317
318      if (bfd_bwrite (str, len, abfd) != len)
319	goto err;
320
321      off += len;
322    }
323
324  /* Trailing alignment needed?  */
325  off = sec->size - off;
326  if (off != 0
327      && bfd_bwrite (pad, off, abfd) != off)
328    goto err;
329
330  if (pad != NULL)
331    free (pad);
332  return TRUE;
333
334 err:
335  if (pad != NULL)
336    free (pad);
337  return FALSE;
338}
339
340/* Register a SEC_MERGE section as a candidate for merging.
341   This function is called for all non-dynamic SEC_MERGE input sections.  */
342
343bfd_boolean
344_bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
345			void **psecinfo)
346{
347  struct sec_merge_info *sinfo;
348  struct sec_merge_sec_info *secinfo;
349  unsigned int align;
350  bfd_size_type amt;
351  bfd_byte *contents;
352
353  if ((abfd->flags & DYNAMIC) != 0
354      || (sec->flags & SEC_MERGE) == 0)
355    abort ();
356
357  if (sec->size == 0
358      || (sec->flags & SEC_EXCLUDE) != 0
359      || sec->entsize == 0)
360    return TRUE;
361
362  if ((sec->flags & SEC_RELOC) != 0)
363    {
364      /* We aren't prepared to handle relocations in merged sections.  */
365      return TRUE;
366    }
367
368  align = sec->alignment_power;
369  if ((sec->entsize < (unsigned) 1 << align
370       && ((sec->entsize & (sec->entsize - 1))
371	   || !(sec->flags & SEC_STRINGS)))
372      || (sec->entsize > (unsigned) 1 << align
373	  && (sec->entsize & (((unsigned) 1 << align) - 1))))
374    {
375      /* Sanity check.  If string character size is smaller than
376	 alignment, then we require character size to be a power
377	 of 2, otherwise character size must be integer multiple
378	 of alignment.  For non-string constants, alignment must
379	 be smaller than or equal to entity size and entity size
380	 must be integer multiple of alignment.  */
381      return TRUE;
382    }
383
384  for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
385    if ((secinfo = sinfo->chain)
386	&& ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
387	&& secinfo->sec->entsize == sec->entsize
388	&& secinfo->sec->alignment_power == sec->alignment_power
389	&& secinfo->sec->output_section == sec->output_section)
390      break;
391
392  if (sinfo == NULL)
393    {
394      /* Initialize the information we need to keep track of.  */
395      sinfo = (struct sec_merge_info *)
396          bfd_alloc (abfd, sizeof (struct sec_merge_info));
397      if (sinfo == NULL)
398	goto error_return;
399      sinfo->next = (struct sec_merge_info *) *psinfo;
400      sinfo->chain = NULL;
401      *psinfo = sinfo;
402      sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
403      if (sinfo->htab == NULL)
404	goto error_return;
405    }
406
407  /* Read the section from abfd.  */
408
409  amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
410  if (sec->flags & SEC_STRINGS)
411    /* Some versions of gcc may emit a string without a zero terminator.
412       See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
413       Allocate space for an extra zero.  */
414    amt += sec->entsize;
415  *psecinfo = bfd_alloc (abfd, amt);
416  if (*psecinfo == NULL)
417    goto error_return;
418
419  secinfo = (struct sec_merge_sec_info *) *psecinfo;
420  if (sinfo->chain)
421    {
422      secinfo->next = sinfo->chain->next;
423      sinfo->chain->next = secinfo;
424    }
425  else
426    secinfo->next = secinfo;
427  sinfo->chain = secinfo;
428  secinfo->sec = sec;
429  secinfo->psecinfo = psecinfo;
430  secinfo->htab = sinfo->htab;
431  secinfo->first_str = NULL;
432
433  sec->rawsize = sec->size;
434  if (sec->flags & SEC_STRINGS)
435    memset (secinfo->contents + sec->size, 0, sec->entsize);
436  contents = secinfo->contents;
437  if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
438    goto error_return;
439
440  return TRUE;
441
442 error_return:
443  *psecinfo = NULL;
444  return FALSE;
445}
446
447/* Record one section into the hash table.  */
448static bfd_boolean
449record_section (struct sec_merge_info *sinfo,
450		struct sec_merge_sec_info *secinfo)
451{
452  asection *sec = secinfo->sec;
453  struct sec_merge_hash_entry *entry;
454  bfd_boolean nul;
455  unsigned char *p, *end;
456  bfd_vma mask, eltalign;
457  unsigned int align, i;
458
459  align = sec->alignment_power;
460  end = secinfo->contents + sec->size;
461  nul = FALSE;
462  mask = ((bfd_vma) 1 << align) - 1;
463  if (sec->flags & SEC_STRINGS)
464    {
465      for (p = secinfo->contents; p < end; )
466	{
467	  eltalign = p - secinfo->contents;
468	  eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
469	  if (!eltalign || eltalign > mask)
470	    eltalign = mask + 1;
471	  entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
472				 secinfo);
473	  if (! entry)
474	    goto error_return;
475	  p += entry->len;
476	  if (sec->entsize == 1)
477	    {
478	      while (p < end && *p == 0)
479		{
480		  if (!nul && !((p - secinfo->contents) & mask))
481		    {
482		      nul = TRUE;
483		      entry = sec_merge_add (sinfo->htab, "",
484					     (unsigned) mask + 1, secinfo);
485		      if (! entry)
486			goto error_return;
487		    }
488		  p++;
489		}
490	    }
491	  else
492	    {
493	      while (p < end)
494		{
495		  for (i = 0; i < sec->entsize; i++)
496		    if (p[i] != '\0')
497		      break;
498		  if (i != sec->entsize)
499		    break;
500		  if (!nul && !((p - secinfo->contents) & mask))
501		    {
502		      nul = TRUE;
503		      entry = sec_merge_add (sinfo->htab, (char *) p,
504					     (unsigned) mask + 1, secinfo);
505		      if (! entry)
506			goto error_return;
507		    }
508		  p += sec->entsize;
509		}
510	    }
511	}
512    }
513  else
514    {
515      for (p = secinfo->contents; p < end; p += sec->entsize)
516	{
517	  entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
518	  if (! entry)
519	    goto error_return;
520	}
521    }
522
523  return TRUE;
524
525error_return:
526  for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
527    *secinfo->psecinfo = NULL;
528  return FALSE;
529}
530
531static int
532strrevcmp (const void *a, const void *b)
533{
534  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
535  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
536  unsigned int lenA = A->len;
537  unsigned int lenB = B->len;
538  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
539  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
540  int l = lenA < lenB ? lenA : lenB;
541
542  while (l)
543    {
544      if (*s != *t)
545	return (int) *s - (int) *t;
546      s--;
547      t--;
548      l--;
549    }
550  return lenA - lenB;
551}
552
553/* Like strrevcmp, but for the case where all strings have the same
554   alignment > entsize.  */
555
556static int
557strrevcmp_align (const void *a, const void *b)
558{
559  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
560  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
561  unsigned int lenA = A->len;
562  unsigned int lenB = B->len;
563  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
564  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
565  int l = lenA < lenB ? lenA : lenB;
566  int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
567
568  if (tail_align != 0)
569    return tail_align;
570
571  while (l)
572    {
573      if (*s != *t)
574	return (int) *s - (int) *t;
575      s--;
576      t--;
577      l--;
578    }
579  return lenA - lenB;
580}
581
582static inline int
583is_suffix (const struct sec_merge_hash_entry *A,
584	   const struct sec_merge_hash_entry *B)
585{
586  if (A->len <= B->len)
587    /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
588       not to be equal by the hash table.  */
589    return 0;
590
591  return memcmp (A->root.string + (A->len - B->len),
592		 B->root.string, B->len) == 0;
593}
594
595/* This is a helper function for _bfd_merge_sections.  It attempts to
596   merge strings matching suffixes of longer strings.  */
597static void
598merge_strings (struct sec_merge_info *sinfo)
599{
600  struct sec_merge_hash_entry **array, **a, *e;
601  struct sec_merge_sec_info *secinfo;
602  bfd_size_type size, amt;
603  unsigned int alignment = 0;
604
605  /* Now sort the strings */
606  amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
607  array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
608  if (array == NULL)
609    goto alloc_failure;
610
611  for (e = sinfo->htab->first, a = array; e; e = e->next)
612    if (e->alignment)
613      {
614	*a++ = e;
615	/* Adjust the length to not include the zero terminator.  */
616	e->len -= sinfo->htab->entsize;
617	if (alignment != e->alignment)
618	  {
619	    if (alignment == 0)
620	      alignment = e->alignment;
621	    else
622	      alignment = (unsigned) -1;
623	  }
624      }
625
626  sinfo->htab->size = a - array;
627  if (sinfo->htab->size != 0)
628    {
629      qsort (array, (size_t) sinfo->htab->size,
630	     sizeof (struct sec_merge_hash_entry *),
631	     (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
632	      ? strrevcmp_align : strrevcmp));
633
634      /* Loop over the sorted array and merge suffixes */
635      e = *--a;
636      e->len += sinfo->htab->entsize;
637      while (--a >= array)
638	{
639	  struct sec_merge_hash_entry *cmp = *a;
640
641	  cmp->len += sinfo->htab->entsize;
642	  if (e->alignment >= cmp->alignment
643	      && !((e->len - cmp->len) & (cmp->alignment - 1))
644	      && is_suffix (e, cmp))
645	    {
646	      cmp->u.suffix = e;
647	      cmp->alignment = 0;
648	    }
649	  else
650	    e = cmp;
651	}
652    }
653
654alloc_failure:
655  if (array)
656    free (array);
657
658  /* Now assign positions to the strings we want to keep.  */
659  size = 0;
660  secinfo = sinfo->htab->first->secinfo;
661  for (e = sinfo->htab->first; e; e = e->next)
662    {
663      if (e->secinfo != secinfo)
664	{
665	  secinfo->sec->size = size;
666	  secinfo = e->secinfo;
667	}
668      if (e->alignment)
669	{
670	  if (e->secinfo->first_str == NULL)
671	    {
672	      e->secinfo->first_str = e;
673	      size = 0;
674	    }
675	  size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
676	  e->u.index = size;
677	  size += e->len;
678	}
679    }
680  secinfo->sec->size = size;
681  if (secinfo->sec->alignment_power != 0)
682    {
683      bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
684      secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
685    }
686
687  /* And now adjust the rest, removing them from the chain (but not hashtable)
688     at the same time.  */
689  for (a = &sinfo->htab->first, e = *a; e; e = e->next)
690    if (e->alignment)
691      a = &e->next;
692    else
693      {
694	*a = e->next;
695	if (e->len)
696	  {
697	    e->secinfo = e->u.suffix->secinfo;
698	    e->alignment = e->u.suffix->alignment;
699	    e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
700	  }
701      }
702}
703
704/* This function is called once after all SEC_MERGE sections are registered
705   with _bfd_merge_section.  */
706
707bfd_boolean
708_bfd_merge_sections (bfd *abfd,
709		     struct bfd_link_info *info ATTRIBUTE_UNUSED,
710		     void *xsinfo,
711		     void (*remove_hook) (bfd *, asection *))
712{
713  struct sec_merge_info *sinfo;
714
715  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
716    {
717      struct sec_merge_sec_info * secinfo;
718
719      if (! sinfo->chain)
720	continue;
721
722      /* Move sinfo->chain to head of the chain, terminate it.  */
723      secinfo = sinfo->chain;
724      sinfo->chain = secinfo->next;
725      secinfo->next = NULL;
726
727      /* Record the sections into the hash table.  */
728      for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
729	if (secinfo->sec->flags & SEC_EXCLUDE)
730	  {
731	    *secinfo->psecinfo = NULL;
732	    if (remove_hook)
733	      (*remove_hook) (abfd, secinfo->sec);
734	  }
735	else if (! record_section (sinfo, secinfo))
736	  break;
737
738      if (secinfo)
739	continue;
740
741      if (sinfo->htab->first == NULL)
742	continue;
743
744      if (sinfo->htab->strings)
745	merge_strings (sinfo);
746      else
747	{
748	  struct sec_merge_hash_entry *e;
749	  bfd_size_type size = 0;
750
751	  /* Things are much simpler for non-strings.
752	     Just assign them slots in the section.  */
753	  secinfo = NULL;
754	  for (e = sinfo->htab->first; e; e = e->next)
755	    {
756	      if (e->secinfo->first_str == NULL)
757		{
758		  if (secinfo)
759		    secinfo->sec->size = size;
760		  e->secinfo->first_str = e;
761		  size = 0;
762		}
763	      size = (size + e->alignment - 1)
764		     & ~((bfd_vma) e->alignment - 1);
765	      e->u.index = size;
766	      size += e->len;
767	      secinfo = e->secinfo;
768	    }
769	  secinfo->sec->size = size;
770	}
771
772	/* Finally remove all input sections which have not made it into
773	   the hash table at all.  */
774	for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
775	  if (secinfo->first_str == NULL)
776	    secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
777    }
778
779  return TRUE;
780}
781
782/* Write out the merged section.  */
783
784bfd_boolean
785_bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
786{
787  struct sec_merge_sec_info *secinfo;
788  file_ptr pos;
789
790  secinfo = (struct sec_merge_sec_info *) psecinfo;
791
792  if (!secinfo)
793    return FALSE;
794
795  if (secinfo->first_str == NULL)
796    return TRUE;
797
798  /* FIXME: octets_per_byte.  */
799  pos = sec->output_section->filepos + sec->output_offset;
800  if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
801    return FALSE;
802
803  if (! sec_merge_emit (output_bfd, secinfo->first_str))
804    return FALSE;
805
806  return TRUE;
807}
808
809/* Adjust an address in the SEC_MERGE section.  Given OFFSET within
810   *PSEC, this returns the new offset in the adjusted SEC_MERGE
811   section and writes the new section back into *PSEC.  */
812
813bfd_vma
814_bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
815			    void *psecinfo, bfd_vma offset)
816{
817  struct sec_merge_sec_info *secinfo;
818  struct sec_merge_hash_entry *entry;
819  unsigned char *p;
820  asection *sec = *psec;
821
822  secinfo = (struct sec_merge_sec_info *) psecinfo;
823
824  if (!secinfo)
825    return offset;
826
827  if (offset >= sec->rawsize)
828    {
829      if (offset > sec->rawsize)
830	{
831	  (*_bfd_error_handler)
832	    (_("%s: access beyond end of merged section (%ld)"),
833	     bfd_get_filename (sec->owner), (long) offset);
834	}
835      return secinfo->first_str ? sec->size : 0;
836    }
837
838  if (secinfo->htab->strings)
839    {
840      if (sec->entsize == 1)
841	{
842	  p = secinfo->contents + offset - 1;
843	  while (p >= secinfo->contents && *p)
844	    --p;
845	  ++p;
846	}
847      else
848	{
849	  p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
850	  p -= sec->entsize;
851	  while (p >= secinfo->contents)
852	    {
853	      unsigned int i;
854
855	      for (i = 0; i < sec->entsize; ++i)
856		if (p[i] != '\0')
857		  break;
858	      if (i == sec->entsize)
859		break;
860	      p -= sec->entsize;
861	    }
862	  p += sec->entsize;
863	}
864    }
865  else
866    {
867      p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
868    }
869  entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
870  if (!entry)
871    {
872      if (! secinfo->htab->strings)
873	abort ();
874      /* This should only happen if somebody points into the padding
875	 after a NUL character but before next entity.  */
876      if (*p)
877	abort ();
878      if (! secinfo->htab->first)
879	abort ();
880      entry = secinfo->htab->first;
881      p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
882	   - entry->len);
883    }
884
885  *psec = entry->secinfo->sec;
886  return entry->u.index + (secinfo->contents + offset - p);
887}
888