xref: /netbsd/external/gpl3/binutils/dist/bfd/merge.c (revision f22f0ef4)
1 /* SEC_MERGE support.
2    Copyright (C) 2001-2022 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 <limits.h>
28 #include "bfd.h"
29 #include "elf-bfd.h"
30 #include "libbfd.h"
31 #include "hashtab.h"
32 #include "libiberty.h"
33 
34 struct sec_merge_sec_info;
35 
36 /* An entry in the section merge hash table.  */
37 
38 struct sec_merge_hash_entry
39 {
40   struct bfd_hash_entry root;
41   /* Length of this entry.  This includes the zero terminator.  */
42   unsigned int len;
43   /* Start of this string needs to be aligned to
44      alignment octets (not 1 << align).  */
45   unsigned int alignment;
46   union
47   {
48     /* Index within the merged section.  */
49     bfd_size_type index;
50     /* Entry this is a suffix of (if alignment is 0).  */
51     struct sec_merge_hash_entry *suffix;
52   } u;
53   /* Which section is it in.  */
54   struct sec_merge_sec_info *secinfo;
55   /* Next entity in the hash table.  */
56   struct sec_merge_hash_entry *next;
57 };
58 
59 /* The section merge hash table.  */
60 
61 struct sec_merge_hash
62 {
63   struct bfd_hash_table table;
64   /* Next available index.  */
65   bfd_size_type size;
66   /* First entity in the SEC_MERGE sections of this type.  */
67   struct sec_merge_hash_entry *first;
68   /* Last entity in the SEC_MERGE sections of this type.  */
69   struct sec_merge_hash_entry *last;
70   /* Entity size.  */
71   unsigned int entsize;
72   /* Are entries fixed size or zero terminated strings?  */
73   bool strings;
74 };
75 
76 struct sec_merge_info
77 {
78   /* Chain of sec_merge_infos.  */
79   struct sec_merge_info *next;
80   /* Chain of sec_merge_sec_infos.  */
81   struct sec_merge_sec_info *chain;
82   /* A hash table used to hold section content.  */
83   struct sec_merge_hash *htab;
84 };
85 
86 struct sec_merge_sec_info
87 {
88   /* Chain of sec_merge_sec_infos.  */
89   struct sec_merge_sec_info *next;
90   /* The corresponding section.  */
91   asection *sec;
92   /* Pointer to merge_info pointing to us.  */
93   void **psecinfo;
94   /* A hash table used to hold section content.  */
95   struct sec_merge_hash *htab;
96   /* First string in this section.  */
97   struct sec_merge_hash_entry *first_str;
98   /* Original section content.  */
99   unsigned char contents[1];
100 };
101 
102 
103 /* Routine to create an entry in a section merge hashtab.  */
104 
105 static struct bfd_hash_entry *
sec_merge_hash_newfunc(struct bfd_hash_entry * entry,struct bfd_hash_table * table,const char * string)106 sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
107 			struct bfd_hash_table *table, const char *string)
108 {
109   /* Allocate the structure if it has not already been allocated by a
110      subclass.  */
111   if (entry == NULL)
112     entry = (struct bfd_hash_entry *)
113 	bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
114   if (entry == NULL)
115     return NULL;
116 
117   /* Call the allocation method of the superclass.  */
118   entry = bfd_hash_newfunc (entry, table, string);
119 
120   if (entry != NULL)
121     {
122       /* Initialize the local fields.  */
123       struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
124 
125       ret->u.suffix = NULL;
126       ret->alignment = 0;
127       ret->secinfo = NULL;
128       ret->next = NULL;
129     }
130 
131   return entry;
132 }
133 
134 /* Look up an entry in a section merge hash table.  */
135 
136 static struct sec_merge_hash_entry *
sec_merge_hash_lookup(struct sec_merge_hash * table,const char * string,unsigned int alignment,bool create)137 sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
138 		       unsigned int alignment, bool create)
139 {
140   const unsigned char *s;
141   unsigned long hash;
142   unsigned int c;
143   struct sec_merge_hash_entry *hashp;
144   unsigned int len, i;
145   unsigned int _index;
146 
147   hash = 0;
148   len = 0;
149   s = (const unsigned char *) string;
150   if (table->strings)
151     {
152       if (table->entsize == 1)
153 	{
154 	  while ((c = *s++) != '\0')
155 	    {
156 	      hash += c + (c << 17);
157 	      hash ^= hash >> 2;
158 	      ++len;
159 	    }
160 	  hash += len + (len << 17);
161 	}
162       else
163 	{
164 	  for (;;)
165 	    {
166 	      for (i = 0; i < table->entsize; ++i)
167 		if (s[i] != '\0')
168 		  break;
169 	      if (i == table->entsize)
170 		break;
171 	      for (i = 0; i < table->entsize; ++i)
172 		{
173 		  c = *s++;
174 		  hash += c + (c << 17);
175 		  hash ^= hash >> 2;
176 		}
177 	      ++len;
178 	    }
179 	  hash += len + (len << 17);
180 	  len *= table->entsize;
181 	}
182       hash ^= hash >> 2;
183       len += table->entsize;
184     }
185   else
186     {
187       for (i = 0; i < table->entsize; ++i)
188 	{
189 	  c = *s++;
190 	  hash += c + (c << 17);
191 	  hash ^= hash >> 2;
192 	}
193       len = table->entsize;
194     }
195 
196   _index = hash % table->table.size;
197   for (hashp = (struct sec_merge_hash_entry *) table->table.table[_index];
198        hashp != NULL;
199        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
200     {
201       if (hashp->root.hash == hash
202 	  && len == hashp->len
203 	  && memcmp (hashp->root.string, string, len) == 0)
204 	{
205 	  /* If the string we found does not have at least the required
206 	     alignment, we need to insert another copy.  */
207 	  if (hashp->alignment < alignment)
208 	    {
209 	      if (create)
210 		{
211 		  /*  Mark the less aligned copy as deleted.  */
212 		  hashp->len = 0;
213 		  hashp->alignment = 0;
214 		}
215 	      break;
216 	    }
217 	  return hashp;
218 	}
219     }
220 
221   if (! create)
222     return NULL;
223 
224   hashp = ((struct sec_merge_hash_entry *)
225 	   bfd_hash_insert (&table->table, string, hash));
226   if (hashp == NULL)
227     return NULL;
228   hashp->len = len;
229   hashp->alignment = alignment;
230   return hashp;
231 }
232 
233 /* Create a new hash table.  */
234 
235 static struct sec_merge_hash *
sec_merge_init(unsigned int entsize,bool strings)236 sec_merge_init (unsigned int entsize, bool strings)
237 {
238   struct sec_merge_hash *table;
239 
240   table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));
241   if (table == NULL)
242     return NULL;
243 
244   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
245 			       sizeof (struct sec_merge_hash_entry), 16699))
246     {
247       free (table);
248       return NULL;
249     }
250 
251   table->size = 0;
252   table->first = NULL;
253   table->last = NULL;
254   table->entsize = entsize;
255   table->strings = strings;
256 
257   return table;
258 }
259 
260 /* Get the index of an entity in a hash table, adding it if it is not
261    already present.  */
262 
263 static struct sec_merge_hash_entry *
sec_merge_add(struct sec_merge_hash * tab,const char * str,unsigned int alignment,struct sec_merge_sec_info * secinfo)264 sec_merge_add (struct sec_merge_hash *tab, const char *str,
265 	       unsigned int alignment, struct sec_merge_sec_info *secinfo)
266 {
267   struct sec_merge_hash_entry *entry;
268 
269   entry = sec_merge_hash_lookup (tab, str, alignment, true);
270   if (entry == NULL)
271     return NULL;
272 
273   if (entry->secinfo == NULL)
274     {
275       tab->size++;
276       entry->secinfo = secinfo;
277       if (tab->first == NULL)
278 	tab->first = entry;
279       else
280 	tab->last->next = entry;
281       tab->last = entry;
282     }
283 
284   return entry;
285 }
286 
287 static bool
sec_merge_emit(bfd * abfd,struct sec_merge_hash_entry * entry,unsigned char * contents,file_ptr offset)288 sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry,
289 		unsigned char *contents, file_ptr offset)
290 {
291   struct sec_merge_sec_info *secinfo = entry->secinfo;
292   asection *sec = secinfo->sec;
293   char *pad = NULL;
294   bfd_size_type off = 0;
295   unsigned int opb = bfd_octets_per_byte (abfd, sec);
296   int alignment_power = sec->output_section->alignment_power * opb;
297   bfd_size_type pad_len;  /* Octets.  */
298 
299   /* FIXME: If alignment_power is 0 then really we should scan the
300      entry list for the largest required alignment and use that.  */
301   pad_len = alignment_power ? ((bfd_size_type) 1 << alignment_power) : 16;
302 
303   pad = (char *) bfd_zmalloc (pad_len);
304   if (pad == NULL)
305     return false;
306 
307   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
308     {
309       const char *str;
310       bfd_size_type len;
311 
312       len = -off & (entry->alignment - 1);
313       if (len != 0)
314 	{
315 	  BFD_ASSERT (len <= pad_len);
316 	  if (contents)
317 	    {
318 	      memcpy (contents + offset, pad, len);
319 	      offset += len;
320 	    }
321 	  else if (bfd_bwrite (pad, len, abfd) != len)
322 	    goto err;
323 	  off += len;
324 	}
325 
326       str = entry->root.string;
327       len = entry->len;
328 
329       if (contents)
330 	{
331 	  memcpy (contents + offset, str, len);
332 	  offset += len;
333 	}
334       else if (bfd_bwrite (str, len, abfd) != len)
335 	goto err;
336 
337       off += len;
338     }
339 
340   /* Trailing alignment needed?  */
341   off = sec->size - off;
342   if (off != 0)
343     {
344       BFD_ASSERT (off <= pad_len);
345       if (contents)
346 	memcpy (contents + offset, pad, off);
347       else if (bfd_bwrite (pad, off, abfd) != off)
348 	goto err;
349     }
350 
351   free (pad);
352   return true;
353 
354  err:
355   free (pad);
356   return false;
357 }
358 
359 /* Register a SEC_MERGE section as a candidate for merging.
360    This function is called for all non-dynamic SEC_MERGE input sections.  */
361 
362 bool
_bfd_add_merge_section(bfd * abfd,void ** psinfo,asection * sec,void ** psecinfo)363 _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
364 			void **psecinfo)
365 {
366   struct sec_merge_info *sinfo;
367   struct sec_merge_sec_info *secinfo;
368   unsigned int alignment_power;  /* Octets.  */
369   unsigned int align;            /* Octets.  */
370   bfd_size_type amt;
371   bfd_byte *contents;
372   unsigned int opb = bfd_octets_per_byte (abfd, sec);
373 
374   if ((abfd->flags & DYNAMIC) != 0
375       || (sec->flags & SEC_MERGE) == 0)
376     abort ();
377 
378   if (sec->size == 0
379       || (sec->flags & SEC_EXCLUDE) != 0
380       || sec->entsize == 0)
381     return true;
382 
383   if (sec->size % sec->entsize != 0)
384     return true;
385 
386   if ((sec->flags & SEC_RELOC) != 0)
387     {
388       /* We aren't prepared to handle relocations in merged sections.  */
389       return true;
390     }
391 
392 #ifndef CHAR_BIT
393 #define CHAR_BIT 8
394 #endif
395   alignment_power = sec->alignment_power * opb;
396   if (alignment_power >= sizeof (align) * CHAR_BIT)
397     return true;
398 
399   align = 1u << alignment_power;
400   if ((sec->entsize < align
401        && ((sec->entsize & (sec->entsize - 1))
402 	   || !(sec->flags & SEC_STRINGS)))
403       || (sec->entsize > align
404 	  && (sec->entsize & (align - 1))))
405     {
406       /* Sanity check.  If string character size is smaller than
407 	 alignment, then we require character size to be a power
408 	 of 2, otherwise character size must be integer multiple
409 	 of alignment.  For non-string constants, alignment must
410 	 be smaller than or equal to entity size and entity size
411 	 must be integer multiple of alignment.  */
412       return true;
413     }
414 
415   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
416     if ((secinfo = sinfo->chain)
417 	&& ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
418 	&& secinfo->sec->entsize == sec->entsize
419 	&& secinfo->sec->alignment_power == sec->alignment_power
420 	&& secinfo->sec->output_section == sec->output_section)
421       break;
422 
423   if (sinfo == NULL)
424     {
425       /* Initialize the information we need to keep track of.  */
426       sinfo = (struct sec_merge_info *)
427 	  bfd_alloc (abfd, sizeof (struct sec_merge_info));
428       if (sinfo == NULL)
429 	goto error_return;
430       sinfo->next = (struct sec_merge_info *) *psinfo;
431       sinfo->chain = NULL;
432       *psinfo = sinfo;
433       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
434       if (sinfo->htab == NULL)
435 	goto error_return;
436     }
437 
438   /* Read the section from abfd.  */
439 
440   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
441   if (sec->flags & SEC_STRINGS)
442     /* Some versions of gcc may emit a string without a zero terminator.
443        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
444        Allocate space for an extra zero.  */
445     amt += sec->entsize;
446   *psecinfo = bfd_alloc (abfd, amt);
447   if (*psecinfo == NULL)
448     goto error_return;
449 
450   secinfo = (struct sec_merge_sec_info *) *psecinfo;
451   if (sinfo->chain)
452     {
453       secinfo->next = sinfo->chain->next;
454       sinfo->chain->next = secinfo;
455     }
456   else
457     secinfo->next = secinfo;
458   sinfo->chain = secinfo;
459   secinfo->sec = sec;
460   secinfo->psecinfo = psecinfo;
461   secinfo->htab = sinfo->htab;
462   secinfo->first_str = NULL;
463 
464   sec->rawsize = sec->size;
465   if (sec->flags & SEC_STRINGS)
466     memset (secinfo->contents + sec->size, 0, sec->entsize);
467   contents = secinfo->contents;
468   if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
469     goto error_return;
470 
471   return true;
472 
473  error_return:
474   *psecinfo = NULL;
475   return false;
476 }
477 
478 /* Record one section into the hash table.  */
479 static bool
record_section(struct sec_merge_info * sinfo,struct sec_merge_sec_info * secinfo)480 record_section (struct sec_merge_info *sinfo,
481 		struct sec_merge_sec_info *secinfo)
482 {
483   asection *sec = secinfo->sec;
484   struct sec_merge_hash_entry *entry;
485   bool nul;
486   unsigned char *p, *end;
487   bfd_vma mask, eltalign;
488   unsigned int align, i;
489 
490   align = sec->alignment_power;
491   end = secinfo->contents + sec->size;
492   nul = false;
493   mask = ((bfd_vma) 1 << align) - 1;
494   if (sec->flags & SEC_STRINGS)
495     {
496       for (p = secinfo->contents; p < end; )
497 	{
498 	  eltalign = p - secinfo->contents;
499 	  eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
500 	  if (!eltalign || eltalign > mask)
501 	    eltalign = mask + 1;
502 	  entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
503 				 secinfo);
504 	  if (! entry)
505 	    goto error_return;
506 	  p += entry->len;
507 	  if (sec->entsize == 1)
508 	    {
509 	      while (p < end && *p == 0)
510 		{
511 		  if (!nul && !((p - secinfo->contents) & mask))
512 		    {
513 		      nul = true;
514 		      entry = sec_merge_add (sinfo->htab, "",
515 					     (unsigned) mask + 1, secinfo);
516 		      if (! entry)
517 			goto error_return;
518 		    }
519 		  p++;
520 		}
521 	    }
522 	  else
523 	    {
524 	      while (p < end)
525 		{
526 		  for (i = 0; i < sec->entsize; i++)
527 		    if (p[i] != '\0')
528 		      break;
529 		  if (i != sec->entsize)
530 		    break;
531 		  if (!nul && !((p - secinfo->contents) & mask))
532 		    {
533 		      nul = true;
534 		      entry = sec_merge_add (sinfo->htab, (char *) p,
535 					     (unsigned) mask + 1, secinfo);
536 		      if (! entry)
537 			goto error_return;
538 		    }
539 		  p += sec->entsize;
540 		}
541 	    }
542 	}
543     }
544   else
545     {
546       for (p = secinfo->contents; p < end; p += sec->entsize)
547 	{
548 	  entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
549 	  if (! entry)
550 	    goto error_return;
551 	}
552     }
553 
554   return true;
555 
556  error_return:
557   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
558     *secinfo->psecinfo = NULL;
559   return false;
560 }
561 
562 /* qsort comparison function.  Won't ever return zero as all entries
563    differ, so there is no issue with qsort stability here.  */
564 
565 static int
strrevcmp(const void * a,const void * b)566 strrevcmp (const void *a, const void *b)
567 {
568   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
569   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
570   unsigned int lenA = A->len;
571   unsigned int lenB = B->len;
572   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
573   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
574   int l = lenA < lenB ? lenA : lenB;
575 
576   while (l)
577     {
578       if (*s != *t)
579 	return (int) *s - (int) *t;
580       s--;
581       t--;
582       l--;
583     }
584   return lenA - lenB;
585 }
586 
587 /* Like strrevcmp, but for the case where all strings have the same
588    alignment > entsize.  */
589 
590 static int
strrevcmp_align(const void * a,const void * b)591 strrevcmp_align (const void *a, const void *b)
592 {
593   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
594   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
595   unsigned int lenA = A->len;
596   unsigned int lenB = B->len;
597   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
598   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
599   int l = lenA < lenB ? lenA : lenB;
600   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
601 
602   if (tail_align != 0)
603     return tail_align;
604 
605   while (l)
606     {
607       if (*s != *t)
608 	return (int) *s - (int) *t;
609       s--;
610       t--;
611       l--;
612     }
613   return lenA - lenB;
614 }
615 
616 static inline int
is_suffix(const struct sec_merge_hash_entry * A,const struct sec_merge_hash_entry * B)617 is_suffix (const struct sec_merge_hash_entry *A,
618 	   const struct sec_merge_hash_entry *B)
619 {
620   if (A->len <= B->len)
621     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
622        not to be equal by the hash table.  */
623     return 0;
624 
625   return memcmp (A->root.string + (A->len - B->len),
626 		 B->root.string, B->len) == 0;
627 }
628 
629 /* This is a helper function for _bfd_merge_sections.  It attempts to
630    merge strings matching suffixes of longer strings.  */
631 static struct sec_merge_sec_info *
merge_strings(struct sec_merge_info * sinfo)632 merge_strings (struct sec_merge_info *sinfo)
633 {
634   struct sec_merge_hash_entry **array, **a, *e;
635   struct sec_merge_sec_info *secinfo;
636   bfd_size_type size, amt;
637   unsigned int alignment = 0;
638 
639   /* Now sort the strings */
640   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
641   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
642   if (array == NULL)
643     return NULL;
644 
645   for (e = sinfo->htab->first, a = array; e; e = e->next)
646     if (e->alignment)
647       {
648 	*a++ = e;
649 	/* Adjust the length to not include the zero terminator.  */
650 	e->len -= sinfo->htab->entsize;
651 	if (alignment != e->alignment)
652 	  {
653 	    if (alignment == 0)
654 	      alignment = e->alignment;
655 	    else
656 	      alignment = (unsigned) -1;
657 	  }
658       }
659 
660   sinfo->htab->size = a - array;
661   if (sinfo->htab->size != 0)
662     {
663       qsort (array, (size_t) sinfo->htab->size,
664 	     sizeof (struct sec_merge_hash_entry *),
665 	     (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
666 	      ? strrevcmp_align : strrevcmp));
667 
668       /* Loop over the sorted array and merge suffixes */
669       e = *--a;
670       e->len += sinfo->htab->entsize;
671       while (--a >= array)
672 	{
673 	  struct sec_merge_hash_entry *cmp = *a;
674 
675 	  cmp->len += sinfo->htab->entsize;
676 	  if (e->alignment >= cmp->alignment
677 	      && !((e->len - cmp->len) & (cmp->alignment - 1))
678 	      && is_suffix (e, cmp))
679 	    {
680 	      cmp->u.suffix = e;
681 	      cmp->alignment = 0;
682 	    }
683 	  else
684 	    e = cmp;
685 	}
686     }
687 
688   free (array);
689 
690   /* Now assign positions to the strings we want to keep.  */
691   size = 0;
692   secinfo = sinfo->htab->first->secinfo;
693   for (e = sinfo->htab->first; e; e = e->next)
694     {
695       if (e->secinfo != secinfo)
696 	{
697 	  secinfo->sec->size = size;
698 	  secinfo = e->secinfo;
699 	}
700       if (e->alignment)
701 	{
702 	  if (e->secinfo->first_str == NULL)
703 	    {
704 	      e->secinfo->first_str = e;
705 	      size = 0;
706 	    }
707 	  size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
708 	  e->u.index = size;
709 	  size += e->len;
710 	}
711     }
712   secinfo->sec->size = size;
713 
714   /* And now adjust the rest, removing them from the chain (but not hashtable)
715      at the same time.  */
716   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
717     if (e->alignment)
718       a = &e->next;
719     else
720       {
721 	*a = e->next;
722 	if (e->len)
723 	  {
724 	    e->secinfo = e->u.suffix->secinfo;
725 	    e->alignment = e->u.suffix->alignment;
726 	    e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
727 	  }
728       }
729   return secinfo;
730 }
731 
732 /* This function is called once after all SEC_MERGE sections are registered
733    with _bfd_merge_section.  */
734 
735 bool
_bfd_merge_sections(bfd * abfd,struct bfd_link_info * info ATTRIBUTE_UNUSED,void * xsinfo,void (* remove_hook)(bfd *,asection *))736 _bfd_merge_sections (bfd *abfd,
737 		     struct bfd_link_info *info ATTRIBUTE_UNUSED,
738 		     void *xsinfo,
739 		     void (*remove_hook) (bfd *, asection *))
740 {
741   struct sec_merge_info *sinfo;
742 
743   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
744     {
745       struct sec_merge_sec_info *secinfo;
746       bfd_size_type align;  /* Bytes.  */
747 
748       if (! sinfo->chain)
749 	continue;
750 
751       /* Move sinfo->chain to head of the chain, terminate it.  */
752       secinfo = sinfo->chain;
753       sinfo->chain = secinfo->next;
754       secinfo->next = NULL;
755 
756       /* Record the sections into the hash table.  */
757       align = 1;
758       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
759 	if (secinfo->sec->flags & SEC_EXCLUDE)
760 	  {
761 	    *secinfo->psecinfo = NULL;
762 	    if (remove_hook)
763 	      (*remove_hook) (abfd, secinfo->sec);
764 	  }
765 	else
766 	  {
767 	    if (!record_section (sinfo, secinfo))
768 	      return false;
769 	    if (align)
770 	      {
771 		unsigned int opb = bfd_octets_per_byte (abfd, secinfo->sec);
772 
773 		align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
774 		if (((secinfo->sec->size / opb) & (align - 1)) != 0)
775 		  align = 0;
776 	      }
777 	  }
778 
779       if (sinfo->htab->first == NULL)
780 	continue;
781 
782       if (sinfo->htab->strings)
783 	{
784 	  secinfo = merge_strings (sinfo);
785 	  if (!secinfo)
786 	    return false;
787 	}
788       else
789 	{
790 	  struct sec_merge_hash_entry *e;
791 	  bfd_size_type size = 0;  /* Octets.  */
792 
793 	  /* Things are much simpler for non-strings.
794 	     Just assign them slots in the section.  */
795 	  secinfo = NULL;
796 	  for (e = sinfo->htab->first; e; e = e->next)
797 	    {
798 	      if (e->secinfo->first_str == NULL)
799 		{
800 		  if (secinfo)
801 		    secinfo->sec->size = size;
802 		  e->secinfo->first_str = e;
803 		  size = 0;
804 		}
805 	      size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
806 	      e->u.index = size;
807 	      size += e->len;
808 	      secinfo = e->secinfo;
809 	    }
810 	  secinfo->sec->size = size;
811 	}
812 
813       /* If the input sections were padded according to their alignments,
814 	 then pad the output too.  */
815       if (align)
816 	secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
817 
818       /* Finally remove all input sections which have not made it into
819 	 the hash table at all.  */
820       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
821 	if (secinfo->first_str == NULL)
822 	  secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
823     }
824 
825   return true;
826 }
827 
828 /* Write out the merged section.  */
829 
830 bool
_bfd_write_merged_section(bfd * output_bfd,asection * sec,void * psecinfo)831 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
832 {
833   struct sec_merge_sec_info *secinfo;
834   file_ptr pos;
835   unsigned char *contents;
836   Elf_Internal_Shdr *hdr;
837 
838   secinfo = (struct sec_merge_sec_info *) psecinfo;
839 
840   if (!secinfo)
841     return false;
842 
843   if (secinfo->first_str == NULL)
844     return true;
845 
846   /* FIXME: octets_per_byte.  */
847   hdr = &elf_section_data (sec->output_section)->this_hdr;
848   if (hdr->sh_offset == (file_ptr) -1)
849     {
850       /* We must compress this section.  Write output to the
851 	 buffer.  */
852       contents = hdr->contents;
853       if ((sec->output_section->flags & SEC_ELF_COMPRESS) == 0
854 	  || contents == NULL)
855 	abort ();
856     }
857   else
858     {
859       contents = NULL;
860       pos = sec->output_section->filepos + sec->output_offset;
861       if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
862 	return false;
863     }
864 
865   if (! sec_merge_emit (output_bfd, secinfo->first_str, contents,
866 			sec->output_offset))
867     return false;
868 
869   return true;
870 }
871 
872 /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
873    *PSEC, this returns the new offset in the adjusted SEC_MERGE
874    section and writes the new section back into *PSEC.  */
875 
876 bfd_vma
_bfd_merged_section_offset(bfd * output_bfd ATTRIBUTE_UNUSED,asection ** psec,void * psecinfo,bfd_vma offset)877 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
878 			    void *psecinfo, bfd_vma offset)
879 {
880   struct sec_merge_sec_info *secinfo;
881   struct sec_merge_hash_entry *entry;
882   unsigned char *p;
883   asection *sec = *psec;
884 
885   secinfo = (struct sec_merge_sec_info *) psecinfo;
886 
887   if (!secinfo)
888     return offset;
889 
890   if (offset >= sec->rawsize)
891     {
892       if (offset > sec->rawsize)
893 	_bfd_error_handler
894 	  /* xgettext:c-format */
895 	  (_("%pB: access beyond end of merged section (%" PRId64 ")"),
896 	   sec->owner, (int64_t) offset);
897       return secinfo->first_str ? sec->size : 0;
898     }
899 
900   if (secinfo->htab->strings)
901     {
902       if (sec->entsize == 1)
903 	{
904 	  p = secinfo->contents + offset - 1;
905 	  while (p >= secinfo->contents && *p)
906 	    --p;
907 	  ++p;
908 	}
909       else
910 	{
911 	  p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
912 	  p -= sec->entsize;
913 	  while (p >= secinfo->contents)
914 	    {
915 	      unsigned int i;
916 
917 	      for (i = 0; i < sec->entsize; ++i)
918 		if (p[i] != '\0')
919 		  break;
920 	      if (i == sec->entsize)
921 		break;
922 	      p -= sec->entsize;
923 	    }
924 	  p += sec->entsize;
925 	}
926     }
927   else
928     {
929       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
930     }
931   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, false);
932   if (!entry)
933     {
934       if (! secinfo->htab->strings)
935 	abort ();
936       /* This should only happen if somebody points into the padding
937 	 after a NUL character but before next entity.  */
938       if (*p)
939 	abort ();
940       if (! secinfo->htab->first)
941 	abort ();
942       entry = secinfo->htab->first;
943       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
944 	   - entry->len);
945     }
946 
947   *psec = entry->secinfo->sec;
948   return entry->u.index + (secinfo->contents + offset - p);
949 }
950 
951 /* Tidy up when done.  */
952 
953 void
_bfd_merge_sections_free(void * xsinfo)954 _bfd_merge_sections_free (void *xsinfo)
955 {
956   struct sec_merge_info *sinfo;
957 
958   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
959     {
960       bfd_hash_table_free (&sinfo->htab->table);
961       free (sinfo->htab);
962     }
963 }
964