1/* SEC_MERGE support.
2   Copyright (C) 2001-2017 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 3 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., 51 Franklin Street - Fifth Floor, Boston,
20   MA 02110-1301, USA.  */
21
22
23/* This file contains support for merging duplicate entities within sections,
24   as used in ELF SHF_MERGE.  */
25
26#include "sysdep.h"
27#include "bfd.h"
28#include "elf-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		unsigned char *contents, file_ptr offset)
289{
290  struct sec_merge_sec_info *secinfo = entry->secinfo;
291  asection *sec = secinfo->sec;
292  char *pad = NULL;
293  bfd_size_type off = 0;
294  int alignment_power = sec->output_section->alignment_power;
295
296  if (alignment_power)
297    {
298      pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
299      if (pad == NULL)
300	return FALSE;
301    }
302
303  for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
304    {
305      const char *str;
306      bfd_size_type len;
307
308      len = -off & (entry->alignment - 1);
309      if (len != 0)
310	{
311	  if (contents)
312	    {
313	      memcpy (contents + offset, pad, len);
314	      offset += len;
315	    }
316	  else if (bfd_bwrite (pad, len, abfd) != len)
317	    goto err;
318	  off += len;
319	}
320
321      str = entry->root.string;
322      len = entry->len;
323
324      if (contents)
325	{
326	  memcpy (contents + offset, str, len);
327	  offset += len;
328	}
329      else if (bfd_bwrite (str, len, abfd) != len)
330	goto err;
331
332      off += len;
333    }
334
335  /* Trailing alignment needed?  */
336  off = sec->size - off;
337  if (off != 0)
338    {
339      if (contents)
340	memcpy (contents + offset, pad, off);
341      else if (bfd_bwrite (pad, off, abfd) != off)
342	goto err;
343    }
344
345  if (pad != NULL)
346    free (pad);
347  return TRUE;
348
349 err:
350  if (pad != NULL)
351    free (pad);
352  return FALSE;
353}
354
355/* Register a SEC_MERGE section as a candidate for merging.
356   This function is called for all non-dynamic SEC_MERGE input sections.  */
357
358bfd_boolean
359_bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
360			void **psecinfo)
361{
362  struct sec_merge_info *sinfo;
363  struct sec_merge_sec_info *secinfo;
364  unsigned int align;
365  bfd_size_type amt;
366  bfd_byte *contents;
367
368  if ((abfd->flags & DYNAMIC) != 0
369      || (sec->flags & SEC_MERGE) == 0)
370    abort ();
371
372  if (sec->size == 0
373      || (sec->flags & SEC_EXCLUDE) != 0
374      || sec->entsize == 0)
375    return TRUE;
376
377  if ((sec->flags & SEC_RELOC) != 0)
378    {
379      /* We aren't prepared to handle relocations in merged sections.  */
380      return TRUE;
381    }
382
383  align = sec->alignment_power;
384  if ((sec->entsize < (unsigned) 1 << align
385       && ((sec->entsize & (sec->entsize - 1))
386	   || !(sec->flags & SEC_STRINGS)))
387      || (sec->entsize > (unsigned) 1 << align
388	  && (sec->entsize & (((unsigned) 1 << align) - 1))))
389    {
390      /* Sanity check.  If string character size is smaller than
391	 alignment, then we require character size to be a power
392	 of 2, otherwise character size must be integer multiple
393	 of alignment.  For non-string constants, alignment must
394	 be smaller than or equal to entity size and entity size
395	 must be integer multiple of alignment.  */
396      return TRUE;
397    }
398
399  for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
400    if ((secinfo = sinfo->chain)
401	&& ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
402	&& secinfo->sec->entsize == sec->entsize
403	&& secinfo->sec->alignment_power == sec->alignment_power
404	&& secinfo->sec->output_section == sec->output_section)
405      break;
406
407  if (sinfo == NULL)
408    {
409      /* Initialize the information we need to keep track of.  */
410      sinfo = (struct sec_merge_info *)
411          bfd_alloc (abfd, sizeof (struct sec_merge_info));
412      if (sinfo == NULL)
413	goto error_return;
414      sinfo->next = (struct sec_merge_info *) *psinfo;
415      sinfo->chain = NULL;
416      *psinfo = sinfo;
417      sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
418      if (sinfo->htab == NULL)
419	goto error_return;
420    }
421
422  /* Read the section from abfd.  */
423
424  amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
425  if (sec->flags & SEC_STRINGS)
426    /* Some versions of gcc may emit a string without a zero terminator.
427       See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
428       Allocate space for an extra zero.  */
429    amt += sec->entsize;
430  *psecinfo = bfd_alloc (abfd, amt);
431  if (*psecinfo == NULL)
432    goto error_return;
433
434  secinfo = (struct sec_merge_sec_info *) *psecinfo;
435  if (sinfo->chain)
436    {
437      secinfo->next = sinfo->chain->next;
438      sinfo->chain->next = secinfo;
439    }
440  else
441    secinfo->next = secinfo;
442  sinfo->chain = secinfo;
443  secinfo->sec = sec;
444  secinfo->psecinfo = psecinfo;
445  secinfo->htab = sinfo->htab;
446  secinfo->first_str = NULL;
447
448  sec->rawsize = sec->size;
449  if (sec->flags & SEC_STRINGS)
450    memset (secinfo->contents + sec->size, 0, sec->entsize);
451  contents = secinfo->contents;
452  if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
453    goto error_return;
454
455  return TRUE;
456
457 error_return:
458  *psecinfo = NULL;
459  return FALSE;
460}
461
462/* Record one section into the hash table.  */
463static bfd_boolean
464record_section (struct sec_merge_info *sinfo,
465		struct sec_merge_sec_info *secinfo)
466{
467  asection *sec = secinfo->sec;
468  struct sec_merge_hash_entry *entry;
469  bfd_boolean nul;
470  unsigned char *p, *end;
471  bfd_vma mask, eltalign;
472  unsigned int align, i;
473
474  align = sec->alignment_power;
475  end = secinfo->contents + sec->size;
476  nul = FALSE;
477  mask = ((bfd_vma) 1 << align) - 1;
478  if (sec->flags & SEC_STRINGS)
479    {
480      for (p = secinfo->contents; p < end; )
481	{
482	  eltalign = p - secinfo->contents;
483	  eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
484	  if (!eltalign || eltalign > mask)
485	    eltalign = mask + 1;
486	  entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
487				 secinfo);
488	  if (! entry)
489	    goto error_return;
490	  p += entry->len;
491	  if (sec->entsize == 1)
492	    {
493	      while (p < end && *p == 0)
494		{
495		  if (!nul && !((p - secinfo->contents) & mask))
496		    {
497		      nul = TRUE;
498		      entry = sec_merge_add (sinfo->htab, "",
499					     (unsigned) mask + 1, secinfo);
500		      if (! entry)
501			goto error_return;
502		    }
503		  p++;
504		}
505	    }
506	  else
507	    {
508	      while (p < end)
509		{
510		  for (i = 0; i < sec->entsize; i++)
511		    if (p[i] != '\0')
512		      break;
513		  if (i != sec->entsize)
514		    break;
515		  if (!nul && !((p - secinfo->contents) & mask))
516		    {
517		      nul = TRUE;
518		      entry = sec_merge_add (sinfo->htab, (char *) p,
519					     (unsigned) mask + 1, secinfo);
520		      if (! entry)
521			goto error_return;
522		    }
523		  p += sec->entsize;
524		}
525	    }
526	}
527    }
528  else
529    {
530      for (p = secinfo->contents; p < end; p += sec->entsize)
531	{
532	  entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
533	  if (! entry)
534	    goto error_return;
535	}
536    }
537
538  return TRUE;
539
540error_return:
541  for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
542    *secinfo->psecinfo = NULL;
543  return FALSE;
544}
545
546static int
547strrevcmp (const void *a, const void *b)
548{
549  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
550  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
551  unsigned int lenA = A->len;
552  unsigned int lenB = B->len;
553  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
554  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
555  int l = lenA < lenB ? lenA : lenB;
556
557  while (l)
558    {
559      if (*s != *t)
560	return (int) *s - (int) *t;
561      s--;
562      t--;
563      l--;
564    }
565  return lenA - lenB;
566}
567
568/* Like strrevcmp, but for the case where all strings have the same
569   alignment > entsize.  */
570
571static int
572strrevcmp_align (const void *a, const void *b)
573{
574  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
575  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
576  unsigned int lenA = A->len;
577  unsigned int lenB = B->len;
578  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
579  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
580  int l = lenA < lenB ? lenA : lenB;
581  int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
582
583  if (tail_align != 0)
584    return tail_align;
585
586  while (l)
587    {
588      if (*s != *t)
589	return (int) *s - (int) *t;
590      s--;
591      t--;
592      l--;
593    }
594  return lenA - lenB;
595}
596
597static inline int
598is_suffix (const struct sec_merge_hash_entry *A,
599	   const struct sec_merge_hash_entry *B)
600{
601  if (A->len <= B->len)
602    /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
603       not to be equal by the hash table.  */
604    return 0;
605
606  return memcmp (A->root.string + (A->len - B->len),
607		 B->root.string, B->len) == 0;
608}
609
610/* This is a helper function for _bfd_merge_sections.  It attempts to
611   merge strings matching suffixes of longer strings.  */
612static void
613merge_strings (struct sec_merge_info *sinfo)
614{
615  struct sec_merge_hash_entry **array, **a, *e;
616  struct sec_merge_sec_info *secinfo;
617  bfd_size_type size, amt;
618  unsigned int alignment = 0;
619
620  /* Now sort the strings */
621  amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
622  array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
623  if (array == NULL)
624    goto alloc_failure;
625
626  for (e = sinfo->htab->first, a = array; e; e = e->next)
627    if (e->alignment)
628      {
629	*a++ = e;
630	/* Adjust the length to not include the zero terminator.  */
631	e->len -= sinfo->htab->entsize;
632	if (alignment != e->alignment)
633	  {
634	    if (alignment == 0)
635	      alignment = e->alignment;
636	    else
637	      alignment = (unsigned) -1;
638	  }
639      }
640
641  sinfo->htab->size = a - array;
642  if (sinfo->htab->size != 0)
643    {
644      qsort (array, (size_t) sinfo->htab->size,
645	     sizeof (struct sec_merge_hash_entry *),
646	     (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
647	      ? strrevcmp_align : strrevcmp));
648
649      /* Loop over the sorted array and merge suffixes */
650      e = *--a;
651      e->len += sinfo->htab->entsize;
652      while (--a >= array)
653	{
654	  struct sec_merge_hash_entry *cmp = *a;
655
656	  cmp->len += sinfo->htab->entsize;
657	  if (e->alignment >= cmp->alignment
658	      && !((e->len - cmp->len) & (cmp->alignment - 1))
659	      && is_suffix (e, cmp))
660	    {
661	      cmp->u.suffix = e;
662	      cmp->alignment = 0;
663	    }
664	  else
665	    e = cmp;
666	}
667    }
668
669alloc_failure:
670  if (array)
671    free (array);
672
673  /* Now assign positions to the strings we want to keep.  */
674  size = 0;
675  secinfo = sinfo->htab->first->secinfo;
676  for (e = sinfo->htab->first; e; e = e->next)
677    {
678      if (e->secinfo != secinfo)
679	{
680	  secinfo->sec->size = size;
681	  secinfo = e->secinfo;
682	}
683      if (e->alignment)
684	{
685	  if (e->secinfo->first_str == NULL)
686	    {
687	      e->secinfo->first_str = e;
688	      size = 0;
689	    }
690	  size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
691	  e->u.index = size;
692	  size += e->len;
693	}
694    }
695  secinfo->sec->size = size;
696  if (secinfo->sec->alignment_power != 0)
697    {
698      bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
699      secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
700    }
701
702  /* And now adjust the rest, removing them from the chain (but not hashtable)
703     at the same time.  */
704  for (a = &sinfo->htab->first, e = *a; e; e = e->next)
705    if (e->alignment)
706      a = &e->next;
707    else
708      {
709	*a = e->next;
710	if (e->len)
711	  {
712	    e->secinfo = e->u.suffix->secinfo;
713	    e->alignment = e->u.suffix->alignment;
714	    e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
715	  }
716      }
717}
718
719/* This function is called once after all SEC_MERGE sections are registered
720   with _bfd_merge_section.  */
721
722bfd_boolean
723_bfd_merge_sections (bfd *abfd,
724		     struct bfd_link_info *info ATTRIBUTE_UNUSED,
725		     void *xsinfo,
726		     void (*remove_hook) (bfd *, asection *))
727{
728  struct sec_merge_info *sinfo;
729
730  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
731    {
732      struct sec_merge_sec_info * secinfo;
733
734      if (! sinfo->chain)
735	continue;
736
737      /* Move sinfo->chain to head of the chain, terminate it.  */
738      secinfo = sinfo->chain;
739      sinfo->chain = secinfo->next;
740      secinfo->next = NULL;
741
742      /* Record the sections into the hash table.  */
743      for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
744	if (secinfo->sec->flags & SEC_EXCLUDE)
745	  {
746	    *secinfo->psecinfo = NULL;
747	    if (remove_hook)
748	      (*remove_hook) (abfd, secinfo->sec);
749	  }
750	else if (! record_section (sinfo, secinfo))
751	  break;
752
753      if (secinfo)
754	continue;
755
756      if (sinfo->htab->first == NULL)
757	continue;
758
759      if (sinfo->htab->strings)
760	merge_strings (sinfo);
761      else
762	{
763	  struct sec_merge_hash_entry *e;
764	  bfd_size_type size = 0;
765
766	  /* Things are much simpler for non-strings.
767	     Just assign them slots in the section.  */
768	  secinfo = NULL;
769	  for (e = sinfo->htab->first; e; e = e->next)
770	    {
771	      if (e->secinfo->first_str == NULL)
772		{
773		  if (secinfo)
774		    secinfo->sec->size = size;
775		  e->secinfo->first_str = e;
776		  size = 0;
777		}
778	      size = (size + e->alignment - 1)
779		     & ~((bfd_vma) e->alignment - 1);
780	      e->u.index = size;
781	      size += e->len;
782	      secinfo = e->secinfo;
783	    }
784	  secinfo->sec->size = size;
785	}
786
787	/* Finally remove all input sections which have not made it into
788	   the hash table at all.  */
789	for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
790	  if (secinfo->first_str == NULL)
791	    secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
792    }
793
794  return TRUE;
795}
796
797/* Write out the merged section.  */
798
799bfd_boolean
800_bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
801{
802  struct sec_merge_sec_info *secinfo;
803  file_ptr pos;
804  unsigned char *contents;
805  Elf_Internal_Shdr *hdr;
806
807  secinfo = (struct sec_merge_sec_info *) psecinfo;
808
809  if (!secinfo)
810    return FALSE;
811
812  if (secinfo->first_str == NULL)
813    return TRUE;
814
815  /* FIXME: octets_per_byte.  */
816  hdr = &elf_section_data (sec->output_section)->this_hdr;
817  if (hdr->sh_offset == (file_ptr) -1)
818    {
819      /* We must compress this section.  Write output to the
820	 buffer.  */
821      contents = hdr->contents;
822      if ((sec->output_section->flags & SEC_ELF_COMPRESS) == 0
823	  || contents == NULL)
824	abort ();
825    }
826  else
827    {
828      contents = NULL;
829      pos = sec->output_section->filepos + sec->output_offset;
830      if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
831	return FALSE;
832    }
833
834  if (! sec_merge_emit (output_bfd, secinfo->first_str, contents,
835			sec->output_offset))
836    return FALSE;
837
838  return TRUE;
839}
840
841/* Adjust an address in the SEC_MERGE section.  Given OFFSET within
842   *PSEC, this returns the new offset in the adjusted SEC_MERGE
843   section and writes the new section back into *PSEC.  */
844
845bfd_vma
846_bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
847			    void *psecinfo, bfd_vma offset)
848{
849  struct sec_merge_sec_info *secinfo;
850  struct sec_merge_hash_entry *entry;
851  unsigned char *p;
852  asection *sec = *psec;
853
854  secinfo = (struct sec_merge_sec_info *) psecinfo;
855
856  if (!secinfo)
857    return offset;
858
859  if (offset >= sec->rawsize)
860    {
861      if (offset > sec->rawsize)
862	_bfd_error_handler
863	  /* xgettext:c-format */
864	  (_("%s: access beyond end of merged section (%ld)"),
865	   bfd_get_filename (sec->owner), (long) offset);
866      return secinfo->first_str ? sec->size : 0;
867    }
868
869  if (secinfo->htab->strings)
870    {
871      if (sec->entsize == 1)
872	{
873	  p = secinfo->contents + offset - 1;
874	  while (p >= secinfo->contents && *p)
875	    --p;
876	  ++p;
877	}
878      else
879	{
880	  p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
881	  p -= sec->entsize;
882	  while (p >= secinfo->contents)
883	    {
884	      unsigned int i;
885
886	      for (i = 0; i < sec->entsize; ++i)
887		if (p[i] != '\0')
888		  break;
889	      if (i == sec->entsize)
890		break;
891	      p -= sec->entsize;
892	    }
893	  p += sec->entsize;
894	}
895    }
896  else
897    {
898      p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
899    }
900  entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
901  if (!entry)
902    {
903      if (! secinfo->htab->strings)
904	abort ();
905      /* This should only happen if somebody points into the padding
906	 after a NUL character but before next entity.  */
907      if (*p)
908	abort ();
909      if (! secinfo->htab->first)
910	abort ();
911      entry = secinfo->htab->first;
912      p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
913	   - entry->len);
914    }
915
916  *psec = entry->secinfo->sec;
917  return entry->u.index + (secinfo->contents + offset - p);
918}
919
920/* Tidy up when done.  */
921
922void
923_bfd_merge_sections_free (void *xsinfo)
924{
925  struct sec_merge_info *sinfo;
926
927  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
928    {
929      bfd_hash_table_free (&sinfo->htab->table);
930      free (sinfo->htab);
931    }
932}
933