binutils/rddbg.c

   1 /* rddbg.c -- Read debugging information into a generic form.
   2    Copyright (C) 1995-2022 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
  34 static bool read_section_stabs_debugging_info
  35   (bfd *, asymbol **, long, void *, bool *);
  36 static bool read_symbol_stabs_debugging_info
  37   (bfd *, asymbol **, long, void *, bool *);
  38 static void save_stab (int, int, bfd_vma, const char *);
  39 static void stab_context (void);
  40 static void free_saved_stabs (void);
  41
  42 /* Read debugging information from a BFD.  Returns a generic debugging
  43    pointer.  */
  44
  45 void *
  46 read_debugging_info (bfd *abfd, asymbol **syms, long symcount,
  47                      bool no_messages)
  48 {
  49   void *dhandle;
  50   bool 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     goto err_exit;
  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         goto err_exit;
  65     }
  66
  67   /* Try reading the COFF symbols if we didn't find any stabs in COFF
  68      sections.  */
  69   if (! found
  70       && bfd_get_flavour (abfd) == bfd_target_coff_flavour
  71       && symcount > 0)
  72     {
  73       if (! parse_coff (abfd, syms, symcount, dhandle))
  74         goto err_exit;
  75       found = true;
  76     }
  77
  78   if (! found)
  79     {
  80       if (! no_messages)
  81         non_fatal (_("%s: no recognized debugging information"),
  82                    bfd_get_filename (abfd));
  83     err_exit:
  84       free (dhandle);
  85       return NULL;
  86     }
  87
  88   return dhandle;
  89 }
  90
  91 /* Read stabs in sections debugging information from a BFD.  */
  92
  93 static bool
  94 read_section_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
  95                                    void *dhandle, bool *pfound)
  96 {
  97   static struct
  98     {
  99       const char *secname;
 100       const char *strsecname;
 101     }
 102   names[] =
 103     {
 104       { ".stab", ".stabstr" },
 105       { "LC_SYMTAB.stabs", "LC_SYMTAB.stabstr" },
 106       { "$GDB_SYMBOLS$", "$GDB_STRINGS$" }
 107     };
 108   unsigned int i;
 109   void *shandle;
 110
 111   *pfound = false;
 112   shandle = NULL;
 113
 114   for (i = 0; i < sizeof names / sizeof names[0]; i++)
 115     {
 116       asection *sec, *strsec;
 117
 118       sec = bfd_get_section_by_name (abfd, names[i].secname);
 119       strsec = bfd_get_section_by_name (abfd, names[i].strsecname);
 120       if (sec != NULL && strsec != NULL)
 121         {
 122           bfd_size_type stabsize, strsize;
 123           bfd_byte *stabs, *strings;
 124           bfd_byte *stab;
 125           bfd_size_type stroff, next_stroff;
 126
 127           stabsize = bfd_section_size (sec);
 128           stabs = (bfd_byte *) xmalloc (stabsize);
 129           if (! bfd_get_section_contents (abfd, sec, stabs, 0, stabsize))
 130             {
 131               fprintf (stderr, "%s: %s: %s\n",
 132                        bfd_get_filename (abfd), names[i].secname,
 133                        bfd_errmsg (bfd_get_error ()));
 134               free (shandle);
 135               free (stabs);
 136               return false;
 137             }
 138
 139           strsize = bfd_section_size (strsec);
 140           strings = (bfd_byte *) xmalloc (strsize + 1);
 141           if (! bfd_get_section_contents (abfd, strsec, strings, 0, strsize))
 142             {
 143               fprintf (stderr, "%s: %s: %s\n",
 144                        bfd_get_filename (abfd), names[i].strsecname,
 145                        bfd_errmsg (bfd_get_error ()));
 146               free (shandle);
 147               free (strings);
 148               free (stabs);
 149               return false;
 150             }
 151           /* Zero terminate the strings table, just in case.  */
 152           strings [strsize] = 0;
 153           if (shandle == NULL)
 154             {
 155               shandle = start_stab (dhandle, abfd, true, syms, symcount);
 156               if (shandle == NULL)
 157                 {
 158                   free (strings);
 159                   free (stabs);
 160                   return false;
 161                 }
 162             }
 163
 164           *pfound = true;
 165
 166           stroff = 0;
 167           next_stroff = 0;
 168           /* PR 17512: file: 078-60391-0.001:0.1.  */
 169           for (stab = stabs; stab <= (stabs + stabsize) - 12; stab += 12)
 170             {
 171               unsigned int strx;
 172               int type;
 173               int other ATTRIBUTE_UNUSED;
 174               int desc;
 175               bfd_vma value;
 176
 177               /* This code presumes 32 bit values.  */
 178
 179               strx = bfd_get_32 (abfd, stab);
 180               type = bfd_get_8 (abfd, stab + 4);
 181               other = bfd_get_8 (abfd, stab + 5);
 182               desc = bfd_get_16 (abfd, stab + 6);
 183               value = bfd_get_32 (abfd, stab + 8);
 184
 185               if (type == 0)
 186                 {
 187                   /* Special type 0 stabs indicate the offset to the
 188                      next string table.  */
 189                   stroff = next_stroff;
 190                   next_stroff += value;
 191                 }
 192               else
 193                 {
 194                   size_t len;
 195                   char *f, *s;
 196
 197                   if (stroff + strx >= strsize)
 198                     {
 199                       fprintf (stderr, _("%s: %s: stab entry %ld is corrupt, strx = 0x%x, type = %d\n"),
 200                                bfd_get_filename (abfd), names[i].secname,
 201                                (long) (stab - stabs) / 12, strx, type);
 202                       continue;
 203                     }
 204
 205                   s = (char *) strings + stroff + strx;
 206                   f = NULL;
 207
 208                   /* PR 17512: file: 002-87578-0.001:0.1.
 209                      It is possible to craft a file where, without the 'strlen (s) > 0',
 210                      an attempt to read the byte before 'strings' would occur.  */
 211                   while ((len = strlen (s)) > 0
 212                          && s[len  - 1] == '\\'
 213                          && stab + 16 <= stabs + stabsize)
 214                     {
 215                       char *p;
 216
 217                       stab += 12;
 218                       p = s + len - 1;
 219                       *p = '\0';
 220                       strx = stroff + bfd_get_32 (abfd, stab);
 221                       if (strx >= strsize)
 222                         {
 223                           fprintf (stderr, _("%s: %s: stab entry %ld is corrupt\n"),
 224                                    bfd_get_filename (abfd), names[i].secname,
 225                                    (long) (stab - stabs) / 12);
 226                           break;
 227                         }
 228
 229                       s = concat (s, (char *) strings + strx,
 230                                   (const char *) NULL);
 231
 232                       /* We have to restore the backslash, because, if
 233                          the linker is hashing stabs strings, we may
 234                          see the same string more than once.  */
 235                       *p = '\\';
 236
 237                       free (f);
 238                       f = s;
 239                     }
 240
 241                   save_stab (type, desc, value, s);
 242
 243                   if (! parse_stab (dhandle, shandle, type, desc, value, s))
 244                     {
 245                       stab_context ();
 246                       free_saved_stabs ();
 247                       free (f);
 248                       free (shandle);
 249                       free (stabs);
 250                       free (strings);
 251                       return false;
 252                     }
 253
 254                   /* Don't free f, since I think the stabs code
 255                      expects strings to hang around.  This should be
 256                      straightened out.  FIXME.  */
 257                 }
 258             }
 259
 260           free_saved_stabs ();
 261           free (stabs);
 262
 263           /* Don't free strings, since I think the stabs code expects
 264              the strings to hang around.  This should be straightened
 265              out.  FIXME.  */
 266         }
 267     }
 268
 269   if (shandle != NULL)
 270     {
 271       if (! finish_stab (dhandle, shandle))
 272         return false;
 273     }
 274
 275   return true;
 276 }
 277
 278 /* Read stabs in the symbol table.  */
 279
 280 static bool
 281 read_symbol_stabs_debugging_info (bfd *abfd, asymbol **syms, long symcount,
 282                                   void *dhandle, bool *pfound)
 283 {
 284   void *shandle;
 285   asymbol **ps, **symend;
 286
 287   shandle = NULL;
 288   symend = syms + symcount;
 289   for (ps = syms; ps < symend; ps++)
 290     {
 291       symbol_info i;
 292
 293       bfd_get_symbol_info (abfd, *ps, &i);
 294
 295       if (i.type == '-')
 296         {
 297           const char *s;
 298           char *f;
 299
 300           if (shandle == NULL)
 301             {
 302               shandle = start_stab (dhandle, abfd, false, syms, symcount);
 303               if (shandle == NULL)
 304                 return false;
 305             }
 306
 307           *pfound = true;
 308
 309           s = i.name;
 310           if (s == NULL || strlen (s) < 1)
 311             return false;
 312           f = NULL;
 313
 314           while (strlen (s) > 0
 315                  && s[strlen (s) - 1] == '\\'
 316                  && ps + 1 < symend)
 317             {
 318               char *sc, *n;
 319
 320               ++ps;
 321               sc = xstrdup (s);
 322               sc[strlen (sc) - 1] = '\0';
 323               n = concat (sc, bfd_asymbol_name (*ps), (const char *) NULL);
 324               free (sc);
 325               free (f);
 326               f = n;
 327               s = n;
 328             }
 329
 330           save_stab (i.stab_type, i.stab_desc, i.value, s);
 331
 332           if (! parse_stab (dhandle, shandle, i.stab_type, i.stab_desc,
 333                             i.value, s))
 334             {
 335               stab_context ();
 336               free_saved_stabs ();
 337               return false;
 338             }
 339
 340           /* Don't free f, since I think the stabs code expects
 341              strings to hang around.  This should be straightened out.
 342              FIXME.  */
 343         }
 344     }
 345
 346   free_saved_stabs ();
 347
 348   if (shandle != NULL)
 349     {
 350       if (! finish_stab (dhandle, shandle))
 351         return false;
 352     }
 353
 354   return true;
 355 }
 356 \f
 357 /* Record stabs strings, so that we can give some context for errors.  */
 358
 359 #define SAVE_STABS_COUNT (16)
 360
 361 struct saved_stab
 362 {
 363   int type;
 364   int desc;
 365   bfd_vma value;
 366   char *string;
 367 };
 368
 369 static struct saved_stab saved_stabs[SAVE_STABS_COUNT];
 370 static int saved_stabs_index;
 371
 372 /* Save a stabs string.  */
 373
 374 static void
 375 save_stab (int type, int desc, bfd_vma value, const char *string)
 376 {
 377   free (saved_stabs[saved_stabs_index].string);
 378   saved_stabs[saved_stabs_index].type = type;
 379   saved_stabs[saved_stabs_index].desc = desc;
 380   saved_stabs[saved_stabs_index].value = value;
 381   saved_stabs[saved_stabs_index].string = xstrdup (string);
 382   saved_stabs_index = (saved_stabs_index + 1) % SAVE_STABS_COUNT;
 383 }
 384
 385 /* Provide context for an error.  */
 386
 387 static void
 388 stab_context (void)
 389 {
 390   int i;
 391
 392   fprintf (stderr, _("Last stabs entries before error:\n"));
 393   fprintf (stderr, "n_type n_desc n_value  string\n");
 394
 395   i = saved_stabs_index;
 396   do
 397     {
 398       struct saved_stab *stabp;
 399
 400       stabp = saved_stabs + i;
 401       if (stabp->string != NULL)
 402         {
 403           const char *s;
 404
 405           s = bfd_get_stab_name (stabp->type);
 406           if (s != NULL)
 407             fprintf (stderr, "%-6s", s);
 408           else if (stabp->type == 0)
 409             fprintf (stderr, "HdrSym");
 410           else
 411             fprintf (stderr, "%-6d", stabp->type);
 412           fprintf (stderr, " %-6d ", stabp->desc);
 413           fprintf (stderr, "%08" PRIx64, (uint64_t) stabp->value);
 414           if (stabp->type != 0)
 415             fprintf (stderr, " %s", stabp->string);
 416           fprintf (stderr, "\n");
 417         }
 418       i = (i + 1) % SAVE_STABS_COUNT;
 419     }
 420   while (i != saved_stabs_index);
 421 }
 422
 423 /* Free the saved stab strings.  */
 424
 425 static void
 426 free_saved_stabs (void)
 427 {
 428   int i;
 429
 430   for (i = 0; i < SAVE_STABS_COUNT; i++)
 431     {
 432       free (saved_stabs[i].string);
 433       saved_stabs[i].string = NULL;
 434     }
 435
 436   saved_stabs_index = 0;
 437 }