bfd/dwarf1.c

   1 /* DWARF 1 find nearest line (_bfd_dwarf1_find_nearest_line).
   2    Copyright 1998, 1999, 2000 Free Software Foundation, Inc.
   3
   4 Written by Gavin Romig-Koch of Cygnus Solutions (gavin@cygnus.com).
   5
   6 This file is part of BFD.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or (at
  11 your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 #include "bfd.h"
  23 #include "sysdep.h"
  24 #include "libiberty.h"
  25 #include "libbfd.h"
  26 #include "elf-bfd.h"
  27 #include "elf/dwarf.h"
  28
  29 /* dwarf1_debug is the starting point for all dwarf1 info.  */
  30
  31 struct dwarf1_debug {
  32
  33   /* The bfd we are working with.  */
  34   bfd* abfd;
  35
  36   /* List of already parsed compilation units.  */
  37   struct dwarf1_unit* lastUnit;
  38
  39   /* The buffer for the .debug section.
  40      Zero indicates that the .debug section failed to load.  */
  41   char* debug_section;
  42
  43   /* Pointer to the end of the .debug_info section memory buffer.  */
  44   char* debug_section_end;
  45
  46   /* The buffer for the .line section.  */
  47   char* line_section;
  48
  49   /* End of that buffer.  */
  50   char* line_section_end;
  51
  52   /* The current or next unread die within the .debug section.  */
  53   char* currentDie;
  54 };
  55
  56 /* One dwarf1_unit for each parsed compilation unit die.  */
  57
  58 struct dwarf1_unit {
  59   /* Linked starting from stash->lastUnit.  */
  60   struct dwarf1_unit* prev;
  61
  62   /* Name of the compilation unit.  */
  63   char* name;
  64
  65   /* The highest and lowest address used in the compilation unit.  */
  66   unsigned long low_pc;
  67   unsigned long high_pc;
  68
  69   /* Does this unit have a statement list? */
  70   int has_stmt_list;
  71
  72   /* If any, the offset of the line number table in the .line section.  */
  73   unsigned long stmt_list_offset;
  74
  75   /* If non-zero, a pointer to the first child of this unit.  */
  76   char* first_child;
  77
  78   /* How many line entries? */
  79   unsigned long line_count;
  80
  81   /* The decoded line number table (line_count entries).  */
  82   struct linenumber* linenumber_table;
  83
  84   /* The list of functions in this unit.  */
  85   struct dwarf1_func* func_list;
  86 };
  87
  88 /* One dwarf1_func for each parsed function die.  */
  89
  90 struct dwarf1_func {
  91   /* Linked starting from aUnit->func_list.  */
  92   struct dwarf1_func* prev;
  93
  94   /* Name of function.  */
  95   char* name;
  96
  97   /* The highest and lowest address used in the compilation unit.  */
  98   unsigned long low_pc;
  99   unsigned long high_pc;
 100 };
 101
 102 /* Used to return info about a parsed die.  */
 103 struct die_info {
 104   unsigned long length;
 105   unsigned long sibling;
 106   unsigned long low_pc;
 107   unsigned long high_pc;
 108   unsigned long stmt_list_offset;
 109
 110   char* name;
 111
 112   int has_stmt_list;
 113
 114   unsigned short tag;
 115 };
 116
 117 /* Parsed line number information.  */
 118 struct linenumber {
 119   /* First address in the line.  */
 120   unsigned long addr;
 121
 122   /* The line number.  */
 123   unsigned long linenumber;
 124 };
 125
 126 /* Find the form of an attr, from the attr field.  */
 127 #define FORM_FROM_ATTR(attr)    ((attr) & 0xF)  /* Implicitly specified */
 128
 129 /* Return a newly allocated dwarf1_unit.  It should be cleared and
 130    then attached into the 'stash' at 'stash->lastUnit'.  */
 131
 132 static struct dwarf1_unit*
 133 alloc_dwarf1_unit (stash)
 134   struct dwarf1_debug* stash;
 135 {
 136   struct dwarf1_unit* x =
 137     (struct dwarf1_unit*) bfd_zalloc (stash->abfd,
 138                                       sizeof (struct dwarf1_unit));
 139   x->prev = stash->lastUnit;
 140   stash->lastUnit = x;
 141
 142   return x;
 143 }
 144
 145 /* Return a newly allocated dwarf1_func.  It must be cleared and
 146    attached into 'aUnit' at 'aUnit->func_list'.  */
 147
 148 static struct dwarf1_func*
 149 alloc_dwarf1_func (stash, aUnit)
 150      struct dwarf1_debug* stash;
 151      struct dwarf1_unit* aUnit;
 152 {
 153   struct dwarf1_func* x =
 154     (struct dwarf1_func*) bfd_zalloc (stash->abfd,
 155                                       sizeof (struct dwarf1_func));
 156   x->prev = aUnit->func_list;
 157   aUnit->func_list = x;
 158
 159   return x;
 160 }
 161
 162 /* parse_die - parse a Dwarf1 die.
 163    Parse the die starting at 'aDiePtr' into 'aDieInfo'.
 164    'abfd' must be the bfd from which the section that 'aDiePtr'
 165    points to was pulled from.
 166
 167    Return false if the die is invalidly formatted; true otherwise.  */
 168
 169 static boolean
 170 parse_die (abfd, aDieInfo, aDiePtr)
 171      bfd* abfd;
 172      struct die_info* aDieInfo;
 173      char*            aDiePtr;
 174 {
 175   char* this_die = aDiePtr;
 176   char* xptr = this_die;
 177
 178   memset (aDieInfo,0,sizeof (*aDieInfo));
 179
 180   /* First comes the length.  */
 181   aDieInfo->length = bfd_get_32 (abfd, (bfd_byte *) xptr);
 182   xptr += 4;
 183   if (aDieInfo->length == 0)
 184     return false;
 185   if (aDieInfo->length < 6)
 186     {
 187       /* Just padding bytes.  */
 188       aDieInfo->tag = TAG_padding;
 189       return true;
 190     }
 191
 192   /* Then the tag.  */
 193   aDieInfo->tag = bfd_get_16 (abfd, (bfd_byte *) xptr);
 194   xptr += 2;
 195
 196   /* Then the attributes.  */
 197   while (xptr < (this_die + aDieInfo->length))
 198     {
 199       unsigned short attr;
 200
 201       /* Parse the attribute based on its form.  This section
 202          must handle all dwarf1 forms, but need only handle the
 203          actual attributes that we care about.  */
 204
 205       attr = bfd_get_16 (abfd, (bfd_byte *) xptr);
 206       xptr += 2;
 207
 208       switch (FORM_FROM_ATTR (attr))
 209         {
 210         case FORM_DATA2:
 211           xptr += 2;
 212           break;
 213         case FORM_DATA4:
 214         case FORM_REF:
 215           if (attr == AT_sibling)
 216             aDieInfo->sibling = bfd_get_32 (abfd, (bfd_byte *) xptr);
 217           else if (attr == AT_stmt_list)
 218             {
 219               aDieInfo->stmt_list_offset = bfd_get_32 (abfd, (bfd_byte *) xptr);
 220               aDieInfo->has_stmt_list = 1;
 221             }
 222           xptr += 4;
 223           break;
 224         case FORM_DATA8:
 225           xptr += 8;
 226           break;
 227         case FORM_ADDR:
 228           if (attr == AT_low_pc)
 229             aDieInfo->low_pc = bfd_get_32 (abfd, (bfd_byte *) xptr);
 230           else if (attr == AT_high_pc)
 231             aDieInfo->high_pc = bfd_get_32 (abfd, (bfd_byte *) xptr);
 232           xptr += 4;
 233           break;
 234         case FORM_BLOCK2:
 235           xptr += 2 + bfd_get_16 (abfd, (bfd_byte *) xptr);
 236           break;
 237         case FORM_BLOCK4:
 238           xptr += 4 + bfd_get_32 (abfd, (bfd_byte *) xptr);
 239           break;
 240         case FORM_STRING:
 241           if (attr == AT_name)
 242             aDieInfo->name = xptr;
 243           xptr += strlen (xptr) + 1;
 244           break;
 245         }
 246     }
 247
 248   return true;
 249 }
 250
 251 /* Parse a dwarf1 line number table for 'aUnit->stmt_list_offset'
 252    into 'aUnit->linenumber_table'.  Return false if an error
 253    occurs; true otherwise.  */
 254
 255 static boolean
 256 parse_line_table (stash, aUnit)
 257   struct dwarf1_debug* stash;
 258   struct dwarf1_unit* aUnit;
 259 {
 260   char* xptr;
 261
 262   /* Load the ".line" section from the bfd if we haven't already.  */
 263   if (stash->line_section == 0)
 264     {
 265       asection *msec;
 266       unsigned long size;
 267
 268       msec = bfd_get_section_by_name (stash->abfd, ".line");
 269       if (! msec)
 270         return false;
 271
 272       size = bfd_get_section_size_before_reloc (msec);
 273       stash->line_section = (char *) bfd_alloc (stash->abfd, size);
 274
 275       if (! stash->line_section)
 276         return false;
 277
 278       if (! bfd_get_section_contents (stash->abfd, msec, stash->line_section, 0, size))
 279         {
 280           stash->line_section = 0;
 281           return false;
 282         }
 283
 284       stash->line_section_end = stash->line_section + size;
 285     }
 286
 287   xptr = stash->line_section + aUnit->stmt_list_offset;
 288   if (xptr < stash->line_section_end)
 289     {
 290       unsigned long eachLine;
 291
 292       char* tblend;
 293       unsigned long base;
 294
 295       /* First comes the length.  */
 296       tblend = bfd_get_32 (stash->abfd, (bfd_byte *) xptr) + xptr;
 297       xptr += 4;
 298
 299       /* Then the base address for each address in the table.  */
 300       base = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 301       xptr += 4;
 302
 303       /* How many line entrys?
 304          10 = 4 (line number) + 2 (pos in line) + 4 (address in line) */
 305       aUnit->line_count = (tblend - xptr) / 10;
 306
 307       /* Allocate an array for the entries.  */
 308       aUnit->linenumber_table = (struct linenumber *)
 309         bfd_alloc (stash->abfd,
 310                    sizeof (struct linenumber) * aUnit->line_count);
 311
 312       for (eachLine = 0; eachLine < aUnit->line_count; eachLine++)
 313         {
 314           /* A line number.  */
 315           aUnit->linenumber_table[eachLine].linenumber
 316             = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 317           xptr += 4;
 318
 319           /* Skip the position within the line.  */
 320           xptr += 2;
 321
 322           /* And finally the address.  */
 323           aUnit->linenumber_table[eachLine].addr
 324             = base + bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 325           xptr += 4;
 326         }
 327     }
 328
 329   return true;
 330 }
 331
 332 /* Parse each function die in a compilation unit 'aUnit'.
 333    The first child die of 'aUnit' should be in 'aUnit->first_child',
 334    the result is placed in 'aUnit->func_list'.
 335    Return false if error; true otherwise.  */
 336
 337 static boolean
 338 parse_functions_in_unit (stash, aUnit)
 339      struct dwarf1_debug* stash;
 340      struct dwarf1_unit* aUnit;
 341 {
 342   char* eachDie;
 343
 344   if (aUnit->first_child)
 345     for (eachDie = aUnit->first_child;
 346          eachDie < stash->debug_section_end;
 347          )
 348       {
 349         struct die_info eachDieInfo;
 350
 351         if (! parse_die (stash->abfd, &eachDieInfo, eachDie))
 352           return false;
 353
 354         if (eachDieInfo.tag == TAG_global_subroutine
 355             || eachDieInfo.tag == TAG_subroutine
 356             || eachDieInfo.tag == TAG_inlined_subroutine
 357             || eachDieInfo.tag == TAG_entry_point)
 358           {
 359             struct dwarf1_func* aFunc = alloc_dwarf1_func (stash,aUnit);
 360
 361             aFunc->name = eachDieInfo.name;
 362             aFunc->low_pc = eachDieInfo.low_pc;
 363             aFunc->high_pc = eachDieInfo.high_pc;
 364           }
 365
 366         /* Move to next sibling, if none, end loop */
 367         if (eachDieInfo.sibling)
 368           eachDie = stash->debug_section + eachDieInfo.sibling;
 369         else
 370           break;
 371       }
 372
 373   return true;
 374 }
 375
 376 /* Find the nearest line to 'addr' in 'aUnit'.
 377    Return whether we found the line (or a function) without error.  */
 378
 379 static boolean
 380 dwarf1_unit_find_nearest_line (stash, aUnit, addr,
 381                        filename_ptr, functionname_ptr,
 382                        linenumber_ptr)
 383   struct dwarf1_debug* stash;
 384   struct dwarf1_unit* aUnit;
 385   unsigned long addr;
 386   const char **filename_ptr;
 387   const char **functionname_ptr;
 388   unsigned int *linenumber_ptr;
 389 {
 390   int line_p = false;
 391   int func_p = false;
 392
 393   if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
 394     {
 395       if (aUnit->has_stmt_list)
 396         {
 397           unsigned long i;
 398           struct dwarf1_func* eachFunc;
 399
 400           if (! aUnit->linenumber_table)
 401             {
 402               if (! parse_line_table (stash, aUnit))
 403                 return false;
 404             }
 405
 406           if (! aUnit->func_list)
 407             {
 408               if (! parse_functions_in_unit (stash, aUnit))
 409                 return false;
 410             }
 411
 412           for (i = 0; i < aUnit->line_count; i++)
 413             {
 414               if (aUnit->linenumber_table[i].addr <= addr
 415                   && addr < aUnit->linenumber_table[i+1].addr)
 416                 {
 417                   *filename_ptr = aUnit->name;
 418                   *linenumber_ptr = aUnit->linenumber_table[i].linenumber;
 419                   line_p = true;
 420                   break;
 421                 }
 422             }
 423
 424           for (eachFunc = aUnit->func_list;
 425                eachFunc;
 426                eachFunc = eachFunc->prev)
 427             {
 428               if (eachFunc->low_pc <= addr
 429                   && addr < eachFunc->high_pc)
 430                 {
 431                   *functionname_ptr = eachFunc->name;
 432                   func_p = true;
 433                   break;
 434                 }
 435             }
 436         }
 437     }
 438
 439   return line_p || func_p;
 440 }
 441
 442 /* The DWARF 1 version of find_nearest line.
 443    Return true if the line is found without error.  */
 444
 445 boolean
 446 _bfd_dwarf1_find_nearest_line (abfd, section, symbols, offset,
 447                               filename_ptr, functionname_ptr, linenumber_ptr)
 448      bfd *abfd;
 449      asection *section;
 450      asymbol **symbols ATTRIBUTE_UNUSED;
 451      bfd_vma offset;
 452      const char **filename_ptr;
 453      const char **functionname_ptr;
 454      unsigned int *linenumber_ptr;
 455 {
 456   struct dwarf1_debug *stash = elf_tdata (abfd)->dwarf1_find_line_info;
 457
 458   struct dwarf1_unit* eachUnit;
 459
 460   /* What address are we looking for? */
 461   bfd_vma addr = offset + section->vma;
 462
 463   *filename_ptr = NULL;
 464   *functionname_ptr = NULL;
 465   *linenumber_ptr = 0;
 466
 467   if (! stash)
 468     {
 469       asection *msec;
 470       unsigned long size;
 471
 472       stash = elf_tdata (abfd)->dwarf1_find_line_info =
 473         (struct dwarf1_debug*) bfd_zalloc (abfd, sizeof (struct dwarf1_debug));
 474
 475       if (! stash)
 476         return false;
 477
 478       msec = bfd_get_section_by_name (abfd, ".debug");
 479       if (! msec)
 480         {
 481           /* No dwarf1 info.  Note that at this point the stash
 482              has been allocated, but contains zeros, this lets
 483              future calls to this function fail quicker.  */
 484           return false;
 485         }
 486
 487       size = bfd_get_section_size_before_reloc (msec);
 488       stash->debug_section = (char *) bfd_alloc (abfd, size);
 489
 490       if (! stash->debug_section)
 491         return false;
 492
 493       if (! bfd_get_section_contents (abfd, msec, stash->debug_section, 0, size))
 494         {
 495           stash->debug_section = 0;
 496           return false;
 497         }
 498
 499       stash->debug_section_end = stash->debug_section + size;
 500       stash->currentDie = stash->debug_section;
 501       stash->abfd = abfd;
 502     }
 503
 504   /* A null debug_section indicates that there was no dwarf1 info
 505      or that an error occured while setting up the stash.  */
 506
 507   if (! stash->debug_section)
 508     return false;
 509
 510   /* Look at the previously parsed units to see if any contain
 511      the addr.  */
 512   for (eachUnit = stash->lastUnit; eachUnit; eachUnit = eachUnit->prev)
 513     {
 514       if (eachUnit->low_pc <= addr && addr < eachUnit->high_pc)
 515         return dwarf1_unit_find_nearest_line (stash, eachUnit, addr,
 516                                               filename_ptr,
 517                                               functionname_ptr,
 518                                               linenumber_ptr);
 519     }
 520
 521   while (stash->currentDie < stash->debug_section_end)
 522     {
 523       struct die_info aDieInfo;
 524
 525       if (! parse_die (stash->abfd, &aDieInfo, stash->currentDie))
 526         return false;
 527
 528       if (aDieInfo.tag == TAG_compile_unit)
 529         {
 530           struct dwarf1_unit* aUnit
 531             = alloc_dwarf1_unit (stash);
 532
 533           aUnit->name = aDieInfo.name;
 534           aUnit->low_pc = aDieInfo.low_pc;
 535           aUnit->high_pc = aDieInfo.high_pc;
 536           aUnit->has_stmt_list = aDieInfo.has_stmt_list;
 537           aUnit->stmt_list_offset = aDieInfo.stmt_list_offset;
 538
 539           /* A die has a child if it's followed by a die that is
 540              not it's sibling.  */
 541           if (aDieInfo.sibling
 542               && stash->currentDie + aDieInfo.length
 543                     < stash->debug_section_end
 544               && stash->currentDie + aDieInfo.length
 545                     != stash->debug_section + aDieInfo.sibling)
 546             aUnit->first_child = stash->currentDie + aDieInfo.length;
 547           else
 548             aUnit->first_child = 0;
 549
 550           if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
 551             return dwarf1_unit_find_nearest_line (stash, aUnit, addr,
 552                                                   filename_ptr,
 553                                                   functionname_ptr,
 554                                                   linenumber_ptr);
 555         }
 556
 557       if (aDieInfo.sibling != 0)
 558         stash->currentDie = stash->debug_section + aDieInfo.sibling;
 559       else
 560         stash->currentDie += aDieInfo.length;
 561     }
 562
 563   return false;
 564 }
 565
 566 /* EOF */