aboutsummaryrefslogtreecommitdiff
path: root/ld/ldsym.c
blob: ed8a246a53c3c01fe9e61fa788f84ca88b1abc55 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
/* All symbol handling for the linker
   Copyright (C) 1991 Free Software Foundation, Inc.
   Written by Steve Chamberlain steve@cygnus.com

This file is part of GLD, the Gnu Linker.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
   We keep a hash table of global symbols. Each entry in a hash table
   is called an ldsym_type. Each has three chains; a pointer to a
   chain of definitions for the symbol (hopefully one long), a pointer
   to a chain of references to the symbol, and a pointer to a chain of
   common symbols. Each pointer points into the canonical symbol table
   provided by bfd, each one of which points to an asymbol. During
   linkage, the linker uses the udata field to point to the next entry
   in a canonical table....


   ld_sym
			|          |
   +----------+		+----------+
   | defs     |      a canonical symbol table
   +----------+         +----------+
   | refs     | ----->  | one entry|  -----> asymbol
   +----------+		+----------+	   |   	     |
   | coms     |		|          |	   +---------+
   +----------+		+----------+	   | udata   |-----> another canonical
					   +---------+		symbol



   It is very simple to make all the symbol pointers point to the same
   definition - just run down the chain and make the asymbols pointers
   within the canonical table point to the asymbol attacthed to the
   definition of the symbol.

*/

#include "bfd.h"
#include "sysdep.h"

#include "ld.h"
#include "ldsym.h"
#include "ldmisc.h"
#include "ldlang.h"
/* IMPORT */
extern int symbol_truncate;
extern bfd *output_bfd;
extern strip_symbols_type strip_symbols;
extern discard_locals_type discard_locals;
/* Head and tail of global symbol table chronological list */

ldsym_type *symbol_head = (ldsym_type *) NULL;
ldsym_type **symbol_tail_ptr = &symbol_head;
CONST char *keepsyms_file;
int kept_syms;

extern ld_config_type config;

struct obstack global_sym_obstack;
#define obstack_chunk_alloc ldmalloc
#define obstack_chunk_free  free

/*
  incremented for each symbol in the ldsym_type table
  no matter what flavour it is
*/
unsigned int global_symbol_count;

/* IMPORTS */

/* LOCALS */
#define	TABSIZE	1009
static ldsym_type *global_symbol_hash_table[TABSIZE];

/* Compute the hash code for symbol name KEY.  */
static
#ifdef __GNUC__
  __inline
#endif

int
hash_string (key)
     CONST char *key;
{
  register CONST char *cp;
  register int k;
  register int l = 0;
  cp = key;
  k = 0;
  while (*cp && l < symbol_truncate)
    {
      k = (((k << 1) + (k >> 14)) ^ (*cp++)) & 0x3fff;
      l++;
    }
  return k;
}

static
#ifdef __GNUC__
  __inline
#endif
  ldsym_type *
search (key, hashval)
     CONST char *key;
     int hashval;
{
  ldsym_type *bp;
  for (bp = global_symbol_hash_table[hashval]; bp; bp = bp->link)
    if (!strncmp (key, bp->name, symbol_truncate))
      {
	if (bp->flags & SYM_INDIRECT)
	  {
	    /* Use the symbol we're aliased to instead */
	    return (ldsym_type *) (bp->sdefs_chain);
	  }
	return bp;
      }
  return 0;
}


/* Get the symbol table entry for the global symbol named KEY.
   Create one if there is none.  */
ldsym_type *
ldsym_get (key)
     CONST char *key;
{
  register int hashval;
  register ldsym_type *bp;

  /* Determine the proper bucket.  */

  hashval = hash_string (key) % TABSIZE;

  /* Search the bucket.  */
  bp = search (key, hashval);
  if (bp)
    {
      return bp;
    }

  /* Nothing was found; create a new symbol table entry.  */

  bp = (ldsym_type *) obstack_alloc (&global_sym_obstack, (bfd_size_type) (sizeof (ldsym_type)));
  bp->srefs_chain = (asymbol **) NULL;
  bp->sdefs_chain = (asymbol **) NULL;
  bp->scoms_chain = (asymbol **) NULL;
  bp->name = obstack_copy (&global_sym_obstack, key, strlen (key) + 1);
  bp->flags = 0;
  /* Add the entry to the bucket.  */

  bp->link = global_symbol_hash_table[hashval];
  global_symbol_hash_table[hashval] = bp;

  /* Keep the chronological list up to date too */
  *symbol_tail_ptr = bp;
  symbol_tail_ptr = &bp->next;
  bp->next = 0;
  global_symbol_count++;

  return bp;
}

/* Like `ldsym_get' but return 0 if the symbol is not already known.  */

ldsym_type *
ldsym_get_soft (key)
     CONST char *key;
{
  register int hashval;
  /* Determine which bucket.  */

  hashval = hash_string (key) % TABSIZE;

  /* Search the bucket.  */
  return search (key, hashval);
}

static asymbol **
process_keepsyms (table, size)
     asymbol **table;
     int size;
{
  struct obstack obstack;
  char *start_of_obstack;
  FILE *ks_file = 0;
  asymbol **out = table;
  asymbol **end = table + size;
  asymbol **sym;

  if (!keepsyms_file || size == 0)
    return end;
  obstack_init (&obstack);
  obstack_alloc (&obstack, 1);
  obstack_finish (&obstack);
  start_of_obstack = obstack_alloc (&obstack, 1);
  ks_file = fopen (keepsyms_file, "r");
  if (!ks_file)
    {
      info_msg ("%X%P: cannot open keep-symbols file `%s'\n", keepsyms_file);
      goto egress;
    }
  errno = 0;

#define KEEP(S) \
  do { asymbol **p = (S), *tmp = *out; *out = *p; *p = tmp; out++; } while (0)

  while (!feof (ks_file) && !ferror (ks_file))
    {
      int c;
      char *ptr;
      int found = 0;

      obstack_free (&obstack, start_of_obstack);
      do
	{
	  c = getc (ks_file);
	  if (c == '\n')
	    c = 0;
	  obstack_1grow (&obstack, c);
	}
      while (c > 0);
      if (c == EOF)
	{
	  if (!feof (ks_file))
	    /* error occurred */
	    {
	      info_msg ("%X%P: error reading keep-symbols file `%s': %E\n",
		    keepsyms_file);
	      out = end;
	      goto egress;
	    }
	  if (obstack_next_free (&obstack) != obstack_base (&obstack) + 1)
	    /* eof in middle of symbol */
	    {
	      info_msg ("%X%P: eof reached mid-line while reading keep-symbols file `%s'\n",
		    keepsyms_file);
	      out = end;
	      goto egress;
	    }
	  /* All okay -- no incomplete lines, EOF reached.  */
	  break;
	}
      ptr = obstack_next_free (&obstack) - 2;
      /* discard trailing trash */
      while (*ptr == ' '
	     || *ptr == '\t')
	*ptr-- = 0;
      ptr = obstack_base (&obstack);
      for (sym = out; sym < end; sym++)
	if (!strncmp ((*sym)->name, ptr, symbol_truncate))
	  {
	    KEEP (sym);
	    found = 1;
	  }
      if (!found)
	info_msg ("%P: symbol `%s' (requested to be kept) not found\n", ptr);
    }
  /* It'd be slightly faster to move this pass above the previous one,
     but that'd mean any symbols preserved in this pass would generate
     warnings if they were also listed in the keepsyms file.  */
  for (sym = out; sym < end; sym++)
    {
      asymbol *s = *sym;
      if (s->section == &bfd_und_section
	  || bfd_is_com_section (s->section)
	  || s->flags & BSF_KEEP_G)
	KEEP (sym);
    }
egress:
  obstack_free (&obstack, start_of_obstack);
  if (ks_file)
    fclose (ks_file);
  return out;
}

static void
list_file_locals (entry)
     lang_input_statement_type *entry;
{
  asymbol **q;
  fprintf (config.map_file, "\nLocal symbols of ");
  minfo ("%I", entry);
  fprintf (config.map_file, ":\n\n");
  if (entry->asymbols)
    {
      for (q = entry->asymbols; *q; q++)
	{
	  asymbol *p = *q;
	  /* If this is a definition,
	   update it if necessary by this file's start address.  */
	  if (p->flags & BSF_LOCAL)
	    info_msg ("  %V %s\n", p->value, p->name);
	}
    }
}


static void
print_file_stuff (f)
     lang_input_statement_type * f;
{
  fprintf (config.map_file, "  %s\n", f->filename);
  if (f->just_syms_flag)
    {
      fprintf (config.map_file, " symbols only\n");
    }
  else
    {
      asection *s;
      if (true)
	{
	  for (s = f->the_bfd->sections;
	       s != (asection *) NULL;
	       s = s->next)
	    {
	      print_address (s->output_offset);
	      if (s->reloc_done)
		{
		  fprintf (config.map_file, " %08x 2**%2ud %s\n",
			   (unsigned) bfd_get_section_size_after_reloc (s),
			   s->alignment_power, s->name);
		}

	      else
		{
		  fprintf (config.map_file, " %08x 2**%2ud %s\n",
			   (unsigned) bfd_get_section_size_before_reloc (s),
			   s->alignment_power, s->name);
		}
	    }
	}
      else
	{
	  for (s = f->the_bfd->sections;
	       s != (asection *) NULL;
	       s = s->next)
	    {
	      fprintf (config.map_file, "%s ", s->name);
	      print_address (s->output_offset);
	      fprintf (config.map_file, "(%x)", (unsigned) bfd_get_section_size_after_reloc (s));
	    }
	  fprintf (config.map_file, "hex \n");
	}
    }
  fprintf (config.map_file, "\n");
}

void
ldsym_print_symbol_table ()
{
  fprintf (config.map_file, "**FILES**\n\n");

  lang_for_each_file (print_file_stuff);

  fprintf (config.map_file, "**GLOBAL SYMBOLS**\n\n");
  fprintf (config.map_file, "offset    section    offset   symbol\n");
  {
    register ldsym_type *sp;

    for (sp = symbol_head; sp; sp = sp->next)
      {
	if (sp->flags & SYM_INDIRECT)
	  {
	    fprintf (config.map_file, "indirect %s to %s\n",
		     sp->name, (((ldsym_type *) (sp->sdefs_chain))->name));
	  }
	else
	  {
	    if (sp->sdefs_chain)
	      {
		asymbol *defsym = *(sp->sdefs_chain);
		asection *defsec = bfd_get_section (defsym);
		print_address (defsym->value);
		if (defsec)
		  {
		    fprintf (config.map_file, "  %-10s",
			     bfd_section_name (output_bfd,
					       defsec));
		    print_space ();
		    print_address (defsym->value + defsec->vma);

		  }
		else
		  {
		    fprintf (config.map_file, "         .......");
		  }

	      }


	    if (sp->scoms_chain)
	      {
		fprintf (config.map_file, "common               ");
		print_address ((*(sp->scoms_chain))->value);
		fprintf (config.map_file, " %s ", sp->name);
	      }
	    else if (sp->sdefs_chain)
	      {
		fprintf (config.map_file, " %s ", sp->name);
	      }
	    else
	      {
		fprintf (config.map_file, "undefined                     ");
		fprintf (config.map_file, "%s ", sp->name);

	      }
	  }
	print_nl ();

      }
  }
}

extern lang_output_section_statement_type *create_object_symbols;
extern char lprefix;
static asymbol **
write_file_locals (output_buffer)
     asymbol **output_buffer;
{
  LANG_FOR_EACH_INPUT_STATEMENT (entry)
  {
    /* Run trough the symbols and work out what to do with them */
    unsigned int i;

    /* Add one for the filename symbol if needed */
    if (create_object_symbols
	!= (lang_output_section_statement_type *) NULL)
      {
	asection *s;
	for (s = entry->the_bfd->sections;
	     s != (asection *) NULL;
	     s = s->next)
	  {
	    if (s->output_section == create_object_symbols->bfd_section)
	      {
		/* Add symbol to this section */
		asymbol *newsym =
		(asymbol *) bfd_make_empty_symbol (entry->the_bfd);
		newsym->name = entry->local_sym_name;
		/* The symbol belongs to the output file's text section */

		/* The value is the start of this section in the output file*/
		newsym->value = 0;
		/* FIXME: Usurping BSF_KEEP_G flag, since it's defined as
		   "used by the linker" and I can't find any other code that
		   uses it.  Should be a cleaner way of doing this (like an
		   "application flags" field in the symbol structure?).  */
		newsym->flags = BSF_LOCAL | BSF_KEEP_G;
		newsym->section = s;
		*output_buffer++ = newsym;
		break;
	      }
	  }
      }
    for (i = 0; i < entry->symbol_count; i++)
      {
	asymbol *p = entry->asymbols[i];
	/* FIXME, temporary hack, since not all of ld knows about the new abs section convention */

	if (p->section == 0)
	  p->section = &bfd_abs_section;
	if (flag_is_global (p->flags)
	    || flag_is_weak (p->flags))
	  {
	    /* If this symbol is marked as occurring now, rather than
	       at the end, output it now.  This is used for COFF C_EXT
	       FCN symbols.  FIXME: There must be a better way.  */
	    if (bfd_asymbol_bfd (p) == entry->the_bfd
		&& flag_is_not_at_end (p->flags))
	      {
		*(output_buffer++) = p;
		p->flags |= BSF_KEEP;
	      }
	  }
	else
	  {
	    if (p->section == &bfd_ind_section)
	      {
		/* Dont think about indirect symbols */
	      }
	    else if (flag_is_debugger (p->flags))
	      {
		/* Only keep the debugger symbols if no stripping required */
		if (strip_symbols == STRIP_NONE)
		  {
		    *output_buffer++ = p;
		  }
	      }
	    else if (p->section == &bfd_und_section
		     || bfd_is_com_section (p->section))
	      {
		/* These must be global.  */
	      }
	    else if (flag_is_ordinary_local (p->flags))
	      {
		if (discard_locals == DISCARD_ALL)
		  {
		  }
		else if (discard_locals == DISCARD_L &&
			 (p->name[0] == lprefix))
		  {
		  }
		else if (p->flags == BSF_WARNING)
		  {
		  }
		else
		  {
		    *output_buffer++ = p;
		  }
	      }
	    else if (p->flags & BSF_CONSTRUCTOR)
	      {
		if (strip_symbols != STRIP_ALL)
		  {
		    *output_buffer++ = p;
		  }
	      }
	    else
	      {
		FAIL ();
	      }
	  }
      }


  }
  return output_buffer;
}


static asymbol **
write_file_globals (symbol_table)
     asymbol **symbol_table;
{
  FOR_EACH_LDSYM (sp)
  {
    if (sp->flags & SYM_INDIRECT)
      {
	asymbol *bufp = (*(sp->srefs_chain));
	ldsym_type *aliased_to = (ldsym_type *) (sp->sdefs_chain);
	if (aliased_to->sdefs_chain)
	  {
	    asymbol *p = aliased_to->sdefs_chain[0];
	    bufp->value = p->value;
	    bufp->section = p->section;
	    bufp->flags = p->flags;
	  }
	else
	  {
	    bufp->value = 0;
	    bufp->flags = 0;
	    bufp->section = &bfd_und_section;
	  }
	*symbol_table++ = bufp;
      }
    else if ((sp->flags & SYM_INDIRECT) == 0 && sp->sdefs_chain != (asymbol **) NULL)
      {
	asymbol *bufp = (*(sp->sdefs_chain));

	if ((bufp->flags & BSF_KEEP) == 0)
	  {
	    ASSERT (bufp != (asymbol *) NULL);

	    bufp->name = sp->name;

	    if (sp->scoms_chain != (asymbol **) NULL)

	      {
		/*
		 defined as common but not allocated, this happens
		 only with -r and not -d, write out a common
		 definition
		 */
		bufp = *(sp->scoms_chain);
	      }
	    *symbol_table++ = bufp;
	  }
      }
    else if (sp->scoms_chain != (asymbol **) NULL)
      {
	/* This symbol is a common - just output */
	asymbol *bufp = (*(sp->scoms_chain));
	*symbol_table++ = bufp;
      }
    else if (sp->srefs_chain != (asymbol **) NULL)
      {
	/* This symbol is undefined but has a reference */
	asymbol *bufp = (*(sp->srefs_chain));
	*symbol_table++ = bufp;
      }
    else
      {
	/*
	   This symbol has neither defs nor refs, it must have come
	   from the command line, since noone has used it it has no
	   data attatched, so we'll ignore it
	   */
      }
  }
  return symbol_table;
}

void
ldsym_write ()
{
  if (keepsyms_file != 0
      && strip_symbols != STRIP_SOME)
    {
      info_msg ("%P: `-retain-symbols-file' overrides `-s' and `-S'\n");
      strip_symbols = STRIP_SOME;
    }
  if (strip_symbols != STRIP_ALL)
    {
      /* We know the maximum size of the symbol table -
       it's the size of all the global symbols ever seen +
       the size of all the symbols from all the files +
       the number of files (for the per file symbols)
       +1 (for the null at the end)
       */
      extern unsigned int total_files_seen;
      extern unsigned int total_symbols_seen;

      asymbol **symbol_table = (asymbol **)
      ldmalloc ((bfd_size_type) (global_symbol_count +
				 total_files_seen +
			      total_symbols_seen + 1) * sizeof (asymbol *));
      asymbol **tablep = write_file_locals (symbol_table);

      tablep = write_file_globals (tablep);
      tablep = process_keepsyms (symbol_table, tablep - symbol_table);

      *tablep = (asymbol *) NULL;
      bfd_set_symtab (output_bfd, symbol_table, (unsigned) (tablep - symbol_table));
    }
}

/*
return true if the supplied symbol name is not in the
linker symbol table
*/
boolean
ldsym_undefined (sym)
     CONST char *sym;
{
  ldsym_type *from_table = ldsym_get_soft (sym);
  if (from_table != (ldsym_type *) NULL)
    {
      if (from_table->sdefs_chain != (asymbol **) NULL)
	return false;
    }
  return true;
}

void
ldsym_init ()
{
  obstack_begin (&global_sym_obstack, 20000);
}