1/* rddbg.c -- Read debugging information into a generic form.
2   Copyright (C) 1995-2017 Free Software Foundation, Inc.
3   Written by Ian Lance Taylor <ian@cygnus.com>.
4
5   This file is part of GNU Binutils.
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, MA
20   02110-1301, USA.  */
21
22
23/* This file reads debugging information into a generic form.  This
24   file knows how to dig the debugging information out of an object
25   file.  */
26
27#include "sysdep.h"
28#include "bfd.h"
29#include "libiberty.h"
30#include "bucomm.h"
31#include "debug.h"
32#include "budbg.h"
33
34static bfd_boolean read_section_stabs_debugging_info
35  (bfd *, asymbol **, long, void *, bfd_boolean *);
36static bfd_boolean read_symbol_stabs_debugging_info
37  (bfd *, asymbol **, long, void *, bfd_boolean *);
38static bfd_boolean read_ieee_debugging_info (bfd *, void *, bfd_boolean *);
39static void save_stab (int, int, bfd_vma, const char *);
40static void stab_context (void);
41static void free_saved_stabs (void);
42
43/* Read debugging information from a BFD.  Returns a generic debugging
44   pointer.  */
45
46void *
47read_debugging_info (bfd *abfd, asymbol **syms, long symcount, bfd_boolean no_messages)
48{
49  void *dhandle;
50  bfd_boolean found;
51
52  dhandle = debug_init ();
53  if (dhandle == NULL)
54    return NULL;
55
56  if (! read_section_stabs_debugging_info (abfd, syms, symcount, dhandle,
57					   &found))
58    return NULL;
59
60  if (bfd_get_flavour (abfd) == bfd_target_aout_flavour)
61    {
62      if (! read_symbol_stabs_debugging_info (abfd, syms, symcount, dhandle,
63					      &found))
64	return NULL;
65    }
66
67  if (bfd_get_flavour (abfd) == bfd_target_ieee_flavour)
68    {
69      if (! read_ieee_debugging_info (abfd, dhandle, &found))
70	return NULL;
71    }
72
73  /* Try reading the COFF symbols if we didn't find any stabs in COFF
74     sections.  */
75  if (! found
76      && bfd_get_flavour (abfd) == bfd_target_coff_flavour
77      && symcount > 0)
78    {
79      if (! parse_coff (abfd, syms, symcount, dhandle))
80	return NULL;
81      found = TRUE;
82    }
83
84  if (! found)
85    {
86      if (! no_messages)
87	non_fatal (_("%s: no recognized debugging information"),
88		   bfd_get_filename (abfd));
89      return NULL;
90    }
91
92  return dhandle;
93}
94
95/* Read stabs in sections debugging information from a BFD.  */
96
97static bfd_boolean
98read_section_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
99				   void *dhandle, bfd_boolean *pfound)
100{
101  static struct
102    {
103      const char *secname;
104      const char *strsecname;
105    }
106  names[] =
107    {
108      { ".stab", ".stabstr" },
109      { "LC_SYMTAB.stabs", "LC_SYMTAB.stabstr" },
110      { "$GDB_SYMBOLS$", "$GDB_STRINGS$" }
111    };
112  unsigned int i;
113  void *shandle;
114
115  *pfound = FALSE;
116  shandle = NULL;
117
118  for (i = 0; i < sizeof names / sizeof names[0]; i++)
119    {
120      asection *sec, *strsec;
121
122      sec = bfd_get_section_by_name (abfd, names[i].secname);
123      strsec = bfd_get_section_by_name (abfd, names[i].strsecname);
124      if (sec != NULL && strsec != NULL)
125	{
126	  bfd_size_type stabsize, strsize;
127	  bfd_byte *stabs, *strings;
128	  bfd_byte *stab;
129	  bfd_size_type stroff, next_stroff;
130
131	  stabsize = bfd_section_size (abfd, sec);
132	  stabs = (bfd_byte *) xmalloc (stabsize);
133	  if (! bfd_get_section_contents (abfd, sec, stabs, 0, stabsize))
134	    {
135	      fprintf (stderr, "%s: %s: %s\n",
136		       bfd_get_filename (abfd), names[i].secname,
137		       bfd_errmsg (bfd_get_error ()));
138	      return FALSE;
139	    }
140
141	  strsize = bfd_section_size (abfd, strsec);
142	  strings = (bfd_byte *) xmalloc (strsize + 1);
143	  if (! bfd_get_section_contents (abfd, strsec, strings, 0, strsize))
144	    {
145	      fprintf (stderr, "%s: %s: %s\n",
146		       bfd_get_filename (abfd), names[i].strsecname,
147		       bfd_errmsg (bfd_get_error ()));
148	      return FALSE;
149	    }
150	  /* Zero terminate the strings table, just in case.  */
151	  strings [strsize] = 0;
152	  if (shandle == NULL)
153	    {
154	      shandle = start_stab (dhandle, abfd, TRUE, syms, symcount);
155	      if (shandle == NULL)
156		return FALSE;
157	    }
158
159	  *pfound = TRUE;
160
161	  stroff = 0;
162	  next_stroff = 0;
163	  /* PR 17512: file: 078-60391-0.001:0.1.  */
164	  for (stab = stabs; stab <= (stabs + stabsize) - 12; stab += 12)
165	    {
166	      unsigned int strx;
167	      int type;
168	      int other ATTRIBUTE_UNUSED;
169	      int desc;
170	      bfd_vma value;
171
172	      /* This code presumes 32 bit values.  */
173
174	      strx = bfd_get_32 (abfd, stab);
175	      type = bfd_get_8 (abfd, stab + 4);
176	      other = bfd_get_8 (abfd, stab + 5);
177	      desc = bfd_get_16 (abfd, stab + 6);
178	      value = bfd_get_32 (abfd, stab + 8);
179
180	      if (type == 0)
181		{
182		  /* Special type 0 stabs indicate the offset to the
183		     next string table.  */
184		  stroff = next_stroff;
185		  next_stroff += value;
186		}
187	      else
188		{
189		  size_t len;
190		  char *f, *s;
191
192		  if (stroff + strx >= strsize)
193		    {
194		      fprintf (stderr, _("%s: %s: stab entry %ld is corrupt, strx = 0x%x, type = %d\n"),
195			       bfd_get_filename (abfd), names[i].secname,
196			       (long) (stab - stabs) / 12, strx, type);
197		      continue;
198		    }
199
200		  s = (char *) strings + stroff + strx;
201		  f = NULL;
202
203		  /* PR 17512: file: 002-87578-0.001:0.1.
204		     It is possible to craft a file where, without the 'strlen (s) > 0',
205		     an attempt to read the byte before 'strings' would occur.  */
206		  while ((len = strlen (s)) > 0
207			 && s[len  - 1] == '\\'
208			 && stab + 12 < stabs + stabsize)
209		    {
210		      char *p;
211
212		      stab += 12;
213		      p = s + len - 1;
214		      *p = '\0';
215		      strx = stroff + bfd_get_32 (abfd, stab);
216		      if (strx >= strsize)
217			{
218			  fprintf (stderr, _("%s: %s: stab entry %ld is corrupt\n"),
219				   bfd_get_filename (abfd), names[i].secname,
220				   (long) (stab - stabs) / 12);
221			  break;
222			}
223		      else
224			s = concat (s, (char *) strings + strx,
225				    (const char *) NULL);
226
227		      /* We have to restore the backslash, because, if
228			 the linker is hashing stabs strings, we may
229			 see the same string more than once.  */
230		      *p = '\\';
231
232		      if (f != NULL)
233			free (f);
234		      f = s;
235		    }
236
237		  save_stab (type, desc, value, s);
238
239		  if (! parse_stab (dhandle, shandle, type, desc, value, s))
240		    {
241		      stab_context ();
242		      free_saved_stabs ();
243		      return FALSE;
244		    }
245
246		  /* Don't free f, since I think the stabs code
247		     expects strings to hang around.  This should be
248		     straightened out.  FIXME.  */
249		}
250	    }
251
252	  free_saved_stabs ();
253	  free (stabs);
254
255	  /* Don't free strings, since I think the stabs code expects
256	     the strings to hang around.  This should be straightened
257	     out.  FIXME.  */
258	}
259    }
260
261  if (shandle != NULL)
262    {
263      if (! finish_stab (dhandle, shandle))
264	return FALSE;
265    }
266
267  return TRUE;
268}
269
270/* Read stabs in the symbol table.  */
271
272static bfd_boolean
273read_symbol_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
274				  void *dhandle, bfd_boolean *pfound)
275{
276  void *shandle;
277  asymbol **ps, **symend;
278
279  shandle = NULL;
280  symend = syms + symcount;
281  for (ps = syms; ps < symend; ps++)
282    {
283      symbol_info i;
284
285      bfd_get_symbol_info (abfd, *ps, &i);
286
287      if (i.type == '-')
288	{
289	  const char *s;
290	  char *f;
291
292	  if (shandle == NULL)
293	    {
294	      shandle = start_stab (dhandle, abfd, FALSE, syms, symcount);
295	      if (shandle == NULL)
296		return FALSE;
297	    }
298
299	  *pfound = TRUE;
300
301	  s = i.name;
302	  f = NULL;
303	  while (s[strlen (s) - 1] == '\\'
304		 && ps + 1 < symend)
305	    {
306	      char *sc, *n;
307
308	      ++ps;
309	      sc = xstrdup (s);
310	      sc[strlen (sc) - 1] = '\0';
311	      n = concat (sc, bfd_asymbol_name (*ps), (const char *) NULL);
312	      free (sc);
313	      if (f != NULL)
314		free (f);
315	      f = n;
316	      s = n;
317	    }
318
319	  save_stab (i.stab_type, i.stab_desc, i.value, s);
320
321	  if (! parse_stab (dhandle, shandle, i.stab_type, i.stab_desc,
322			    i.value, s))
323	    {
324	      stab_context ();
325	      free_saved_stabs ();
326	      return FALSE;
327	    }
328
329	  /* Don't free f, since I think the stabs code expects
330	     strings to hang around.  This should be straightened out.
331	     FIXME.  */
332	}
333    }
334
335  free_saved_stabs ();
336
337  if (shandle != NULL)
338    {
339      if (! finish_stab (dhandle, shandle))
340	return FALSE;
341    }
342
343  return TRUE;
344}
345
346/* Read IEEE debugging information.  */
347
348static bfd_boolean
349read_ieee_debugging_info (bfd *abfd, void *dhandle, bfd_boolean *pfound)
350{
351  asection *dsec;
352  bfd_size_type size;
353  bfd_byte *contents;
354
355  /* The BFD backend puts the debugging information into a section
356     named .debug.  */
357
358  dsec = bfd_get_section_by_name (abfd, ".debug");
359  if (dsec == NULL)
360    return TRUE;
361
362  size = bfd_section_size (abfd, dsec);
363  contents = (bfd_byte *) xmalloc (size);
364  if (! bfd_get_section_contents (abfd, dsec, contents, 0, size))
365    return FALSE;
366
367  if (! parse_ieee (dhandle, abfd, contents, size))
368    return FALSE;
369
370  free (contents);
371
372  *pfound = TRUE;
373
374  return TRUE;
375}
376
377/* Record stabs strings, so that we can give some context for errors.  */
378
379#define SAVE_STABS_COUNT (16)
380
381struct saved_stab
382{
383  int type;
384  int desc;
385  bfd_vma value;
386  char *string;
387};
388
389static struct saved_stab saved_stabs[SAVE_STABS_COUNT];
390static int saved_stabs_index;
391
392/* Save a stabs string.  */
393
394static void
395save_stab (int type, int desc, bfd_vma value, const char *string)
396{
397  if (saved_stabs[saved_stabs_index].string != NULL)
398    free (saved_stabs[saved_stabs_index].string);
399  saved_stabs[saved_stabs_index].type = type;
400  saved_stabs[saved_stabs_index].desc = desc;
401  saved_stabs[saved_stabs_index].value = value;
402  saved_stabs[saved_stabs_index].string = xstrdup (string);
403  saved_stabs_index = (saved_stabs_index + 1) % SAVE_STABS_COUNT;
404}
405
406/* Provide context for an error.  */
407
408static void
409stab_context (void)
410{
411  int i;
412
413  fprintf (stderr, _("Last stabs entries before error:\n"));
414  fprintf (stderr, "n_type n_desc n_value  string\n");
415
416  i = saved_stabs_index;
417  do
418    {
419      struct saved_stab *stabp;
420
421      stabp = saved_stabs + i;
422      if (stabp->string != NULL)
423	{
424	  const char *s;
425
426	  s = bfd_get_stab_name (stabp->type);
427	  if (s != NULL)
428	    fprintf (stderr, "%-6s", s);
429	  else if (stabp->type == 0)
430	    fprintf (stderr, "HdrSym");
431	  else
432	    fprintf (stderr, "%-6d", stabp->type);
433	  fprintf (stderr, " %-6d ", stabp->desc);
434	  fprintf_vma (stderr, stabp->value);
435	  if (stabp->type != 0)
436	    fprintf (stderr, " %s", stabp->string);
437	  fprintf (stderr, "\n");
438	}
439      i = (i + 1) % SAVE_STABS_COUNT;
440    }
441  while (i != saved_stabs_index);
442}
443
444/* Free the saved stab strings.  */
445
446static void
447free_saved_stabs (void)
448{
449  int i;
450
451  for (i = 0; i < SAVE_STABS_COUNT; i++)
452    {
453      if (saved_stabs[i].string != NULL)
454	{
455	  free (saved_stabs[i].string);
456	  saved_stabs[i].string = NULL;
457	}
458    }
459
460  saved_stabs_index = 0;
461}
462