1/* rddbg.c -- Read debugging information into a generic form.
2   Copyright (C) 1995-2020 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 void save_stab (int, int, bfd_vma, const char *);
39static void stab_context (void);
40static void free_saved_stabs (void);
41
42/* Read debugging information from a BFD.  Returns a generic debugging
43   pointer.  */
44
45void *
46read_debugging_info (bfd *abfd, asymbol **syms, long symcount, bfd_boolean no_messages)
47{
48  void *dhandle;
49  bfd_boolean found;
50
51  dhandle = debug_init ();
52  if (dhandle == NULL)
53    return NULL;
54
55  if (! read_section_stabs_debugging_info (abfd, syms, symcount, dhandle,
56					   &found))
57    return NULL;
58
59  if (bfd_get_flavour (abfd) == bfd_target_aout_flavour)
60    {
61      if (! read_symbol_stabs_debugging_info (abfd, syms, symcount, dhandle,
62					      &found))
63	return NULL;
64    }
65
66  /* Try reading the COFF symbols if we didn't find any stabs in COFF
67     sections.  */
68  if (! found
69      && bfd_get_flavour (abfd) == bfd_target_coff_flavour
70      && symcount > 0)
71    {
72      if (! parse_coff (abfd, syms, symcount, dhandle))
73	return NULL;
74      found = TRUE;
75    }
76
77  if (! found)
78    {
79      if (! no_messages)
80	non_fatal (_("%s: no recognized debugging information"),
81		   bfd_get_filename (abfd));
82      return NULL;
83    }
84
85  return dhandle;
86}
87
88/* Read stabs in sections debugging information from a BFD.  */
89
90static bfd_boolean
91read_section_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
92				   void *dhandle, bfd_boolean *pfound)
93{
94  static struct
95    {
96      const char *secname;
97      const char *strsecname;
98    }
99  names[] =
100    {
101      { ".stab", ".stabstr" },
102      { "LC_SYMTAB.stabs", "LC_SYMTAB.stabstr" },
103      { "$GDB_SYMBOLS$", "$GDB_STRINGS$" }
104    };
105  unsigned int i;
106  void *shandle;
107
108  *pfound = FALSE;
109  shandle = NULL;
110
111  for (i = 0; i < sizeof names / sizeof names[0]; i++)
112    {
113      asection *sec, *strsec;
114
115      sec = bfd_get_section_by_name (abfd, names[i].secname);
116      strsec = bfd_get_section_by_name (abfd, names[i].strsecname);
117      if (sec != NULL && strsec != NULL)
118	{
119	  bfd_size_type stabsize, strsize;
120	  bfd_byte *stabs, *strings;
121	  bfd_byte *stab;
122	  bfd_size_type stroff, next_stroff;
123
124	  stabsize = bfd_section_size (sec);
125	  stabs = (bfd_byte *) xmalloc (stabsize);
126	  if (! bfd_get_section_contents (abfd, sec, stabs, 0, stabsize))
127	    {
128	      fprintf (stderr, "%s: %s: %s\n",
129		       bfd_get_filename (abfd), names[i].secname,
130		       bfd_errmsg (bfd_get_error ()));
131	      free (shandle);
132	      free (stabs);
133	      return FALSE;
134	    }
135
136	  strsize = bfd_section_size (strsec);
137	  strings = (bfd_byte *) xmalloc (strsize + 1);
138	  if (! bfd_get_section_contents (abfd, strsec, strings, 0, strsize))
139	    {
140	      fprintf (stderr, "%s: %s: %s\n",
141		       bfd_get_filename (abfd), names[i].strsecname,
142		       bfd_errmsg (bfd_get_error ()));
143	      free (shandle);
144	      free (strings);
145	      free (stabs);
146	      return FALSE;
147	    }
148	  /* Zero terminate the strings table, just in case.  */
149	  strings [strsize] = 0;
150	  if (shandle == NULL)
151	    {
152	      shandle = start_stab (dhandle, abfd, TRUE, syms, symcount);
153	      if (shandle == NULL)
154		{
155		  free (strings);
156		  free (stabs);
157		  return FALSE;
158		}
159	    }
160
161	  *pfound = TRUE;
162
163	  stroff = 0;
164	  next_stroff = 0;
165	  /* PR 17512: file: 078-60391-0.001:0.1.  */
166	  for (stab = stabs; stab <= (stabs + stabsize) - 12; stab += 12)
167	    {
168	      unsigned int strx;
169	      int type;
170	      int other ATTRIBUTE_UNUSED;
171	      int desc;
172	      bfd_vma value;
173
174	      /* This code presumes 32 bit values.  */
175
176	      strx = bfd_get_32 (abfd, stab);
177	      type = bfd_get_8 (abfd, stab + 4);
178	      other = bfd_get_8 (abfd, stab + 5);
179	      desc = bfd_get_16 (abfd, stab + 6);
180	      value = bfd_get_32 (abfd, stab + 8);
181
182	      if (type == 0)
183		{
184		  /* Special type 0 stabs indicate the offset to the
185		     next string table.  */
186		  stroff = next_stroff;
187		  next_stroff += value;
188		}
189	      else
190		{
191		  size_t len;
192		  char *f, *s;
193
194		  if (stroff + strx >= strsize)
195		    {
196		      fprintf (stderr, _("%s: %s: stab entry %ld is corrupt, strx = 0x%x, type = %d\n"),
197			       bfd_get_filename (abfd), names[i].secname,
198			       (long) (stab - stabs) / 12, strx, type);
199		      continue;
200		    }
201
202		  s = (char *) strings + stroff + strx;
203		  f = NULL;
204
205		  /* PR 17512: file: 002-87578-0.001:0.1.
206		     It is possible to craft a file where, without the 'strlen (s) > 0',
207		     an attempt to read the byte before 'strings' would occur.  */
208		  while ((len = strlen (s)) > 0
209			 && s[len  - 1] == '\\'
210			 && stab + 12 < stabs + stabsize)
211		    {
212		      char *p;
213
214		      stab += 12;
215		      p = s + len - 1;
216		      *p = '\0';
217		      strx = stroff + bfd_get_32 (abfd, stab);
218		      if (strx >= strsize)
219			{
220			  fprintf (stderr, _("%s: %s: stab entry %ld is corrupt\n"),
221				   bfd_get_filename (abfd), names[i].secname,
222				   (long) (stab - stabs) / 12);
223			  break;
224			}
225
226		      s = concat (s, (char *) strings + strx,
227				  (const char *) NULL);
228
229		      /* We have to restore the backslash, because, if
230			 the linker is hashing stabs strings, we may
231			 see the same string more than once.  */
232		      *p = '\\';
233
234		      free (f);
235		      f = s;
236		    }
237
238		  save_stab (type, desc, value, s);
239
240		  if (! parse_stab (dhandle, shandle, type, desc, value, s))
241		    {
242		      stab_context ();
243		      free_saved_stabs ();
244		      free (f);
245		      free (shandle);
246		      free (stabs);
247		      free (strings);
248		      return FALSE;
249		    }
250
251		  /* Don't free f, since I think the stabs code
252		     expects strings to hang around.  This should be
253		     straightened out.  FIXME.  */
254		}
255	    }
256
257	  free_saved_stabs ();
258	  free (stabs);
259
260	  /* Don't free strings, since I think the stabs code expects
261	     the strings to hang around.  This should be straightened
262	     out.  FIXME.  */
263	}
264    }
265
266  if (shandle != NULL)
267    {
268      if (! finish_stab (dhandle, shandle))
269	return FALSE;
270    }
271
272  return TRUE;
273}
274
275/* Read stabs in the symbol table.  */
276
277static bfd_boolean
278read_symbol_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
279				  void *dhandle, bfd_boolean *pfound)
280{
281  void *shandle;
282  asymbol **ps, **symend;
283
284  shandle = NULL;
285  symend = syms + symcount;
286  for (ps = syms; ps < symend; ps++)
287    {
288      symbol_info i;
289
290      bfd_get_symbol_info (abfd, *ps, &i);
291
292      if (i.type == '-')
293	{
294	  const char *s;
295	  char *f;
296
297	  if (shandle == NULL)
298	    {
299	      shandle = start_stab (dhandle, abfd, FALSE, syms, symcount);
300	      if (shandle == NULL)
301		return FALSE;
302	    }
303
304	  *pfound = TRUE;
305
306	  s = i.name;
307	  if (s == NULL || strlen (s) < 1)
308	    return FALSE;
309	  f = NULL;
310
311	  while (strlen (s) > 0
312		 && s[strlen (s) - 1] == '\\'
313		 && ps + 1 < symend)
314	    {
315	      char *sc, *n;
316
317	      ++ps;
318	      sc = xstrdup (s);
319	      sc[strlen (sc) - 1] = '\0';
320	      n = concat (sc, bfd_asymbol_name (*ps), (const char *) NULL);
321	      free (sc);
322	      if (f != NULL)
323		free (f);
324	      f = n;
325	      s = n;
326	    }
327
328	  save_stab (i.stab_type, i.stab_desc, i.value, s);
329
330	  if (! parse_stab (dhandle, shandle, i.stab_type, i.stab_desc,
331			    i.value, s))
332	    {
333	      stab_context ();
334	      free_saved_stabs ();
335	      return FALSE;
336	    }
337
338	  /* Don't free f, since I think the stabs code expects
339	     strings to hang around.  This should be straightened out.
340	     FIXME.  */
341	}
342    }
343
344  free_saved_stabs ();
345
346  if (shandle != NULL)
347    {
348      if (! finish_stab (dhandle, shandle))
349	return FALSE;
350    }
351
352  return TRUE;
353}
354
355/* Record stabs strings, so that we can give some context for errors.  */
356
357#define SAVE_STABS_COUNT (16)
358
359struct saved_stab
360{
361  int type;
362  int desc;
363  bfd_vma value;
364  char *string;
365};
366
367static struct saved_stab saved_stabs[SAVE_STABS_COUNT];
368static int saved_stabs_index;
369
370/* Save a stabs string.  */
371
372static void
373save_stab (int type, int desc, bfd_vma value, const char *string)
374{
375  if (saved_stabs[saved_stabs_index].string != NULL)
376    free (saved_stabs[saved_stabs_index].string);
377  saved_stabs[saved_stabs_index].type = type;
378  saved_stabs[saved_stabs_index].desc = desc;
379  saved_stabs[saved_stabs_index].value = value;
380  saved_stabs[saved_stabs_index].string = xstrdup (string);
381  saved_stabs_index = (saved_stabs_index + 1) % SAVE_STABS_COUNT;
382}
383
384/* Provide context for an error.  */
385
386static void
387stab_context (void)
388{
389  int i;
390
391  fprintf (stderr, _("Last stabs entries before error:\n"));
392  fprintf (stderr, "n_type n_desc n_value  string\n");
393
394  i = saved_stabs_index;
395  do
396    {
397      struct saved_stab *stabp;
398
399      stabp = saved_stabs + i;
400      if (stabp->string != NULL)
401	{
402	  const char *s;
403
404	  s = bfd_get_stab_name (stabp->type);
405	  if (s != NULL)
406	    fprintf (stderr, "%-6s", s);
407	  else if (stabp->type == 0)
408	    fprintf (stderr, "HdrSym");
409	  else
410	    fprintf (stderr, "%-6d", stabp->type);
411	  fprintf (stderr, " %-6d ", stabp->desc);
412	  fprintf_vma (stderr, stabp->value);
413	  if (stabp->type != 0)
414	    fprintf (stderr, " %s", stabp->string);
415	  fprintf (stderr, "\n");
416	}
417      i = (i + 1) % SAVE_STABS_COUNT;
418    }
419  while (i != saved_stabs_index);
420}
421
422/* Free the saved stab strings.  */
423
424static void
425free_saved_stabs (void)
426{
427  int i;
428
429  for (i = 0; i < SAVE_STABS_COUNT; i++)
430    {
431      if (saved_stabs[i].string != NULL)
432	{
433	  free (saved_stabs[i].string);
434	  saved_stabs[i].string = NULL;
435	}
436    }
437
438  saved_stabs_index = 0;
439}
440