dwarf2.c

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/* DWARF 2 support.
   Copyright 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001
   Free Software Foundation, Inc.

   Adapted from gdb/dwarf2read.c by Gavin Koch of Cygnus Solutions
   ([e-mail]).

   From the dwarf2read.c header:
   Adapted by Gary Funck ([e-mail]), Intrepid Technology,
   Inc.  with support from Florida State University (under contract
   with the Ada Joint Program Office), and Silicon Graphics, Inc.
   Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
   based on Fred Fish's (Cygnus Support) implementation of DWARF 1
   support in dwarfread.c

This file is part of BFD.

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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "bfd.h"
#include "sysdep.h"
#include "libiberty.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/dwarf2.h"

/* The data in the .debug_line statement prologue looks like this.  */

struct line_head
{
  unsigned int total_length;
  unsigned short version;
  unsigned int prologue_length;
  unsigned char minimum_instruction_length;
  unsigned char default_is_stmt;
  int line_base;
  unsigned char line_range;
  unsigned char opcode_base;
  unsigned char *standard_opcode_lengths;
};

/* Attributes have a name and a value.  */

struct attribute
{
  enum dwarf_attribute name;
  enum dwarf_form form;
  union
  {
    char *str;
    struct dwarf_block *blk;
    unsigned int unsnd;
    int snd;
    bfd_vma addr;
  }
  u;
};

/* Get at parts of an attribute structure.  */

#define DW_STRING(attr)    ((attr)->u.str)
#define DW_UNSND(attr)     ((attr)->u.unsnd)
#define DW_BLOCK(attr)     ((attr)->u.blk)
#define DW_SND(attr)       ((attr)->u.snd)
#define DW_ADDR(attr)	   ((attr)->u.addr)

/* Blocks are a bunch of untyped bytes.  */
struct dwarf_block
{
  unsigned int size;
  char *data;
};

struct dwarf2_debug
{
  /* A list of all previously read comp_units.  */
  struct comp_unit* all_comp_units;

  /* The next unread compilation unit within the .debug_info section.
     Zero indicates that the .debug_info section has not been loaded
     into a buffer yet.  */
  char* info_ptr;

  /* Pointer to the end of the .debug_info section memory buffer.  */
  char* info_ptr_end;

  /* Pointer to the .debug_abbrev section loaded into memory.  */
  char* dwarf_abbrev_buffer;

  /* Length of the loaded .debug_abbrev section.  */
  unsigned long dwarf_abbrev_size;

  /* Buffer for decode_line_info.  */
  char *dwarf_line_buffer;

  /* Length of the loaded .debug_line section.  */
  unsigned long dwarf_line_size;
};

struct arange
{
  struct arange *next;
  bfd_vma low;
  bfd_vma high;
};

/* A minimal decoding of DWARF2 compilation units.  We only decode
   what's needed to get to the line number information.  */

struct comp_unit
{
  /* Chain the previously read compilation units.  */
  struct comp_unit* next_unit;

  /* Keep the bdf convenient (for memory allocation).  */
  bfd* abfd;

  /* The lowest and higest addresses contained in this compilation
     unit as specified in the compilation unit header.  */
  struct arange arange;

  /* The DW_AT_name attribute (for error messages).  */
  char* name;

  /* The abbrev hash table.  */
  struct abbrev_info** abbrevs;

  /* Note that an error was found by comp_unit_find_nearest_line.  */
  int error;

  /* The DW_AT_comp_dir attribute.  */
  char* comp_dir;

  /* True if there is a line number table associated with this comp. unit.  */
  int stmtlist;

  /* The offset into .debug_line of the line number table.  */
  unsigned long line_offset;

  /* Pointer to the first child die for the comp unit.  */
  char *first_child_die_ptr;

  /* The end of the comp unit.  */
  char *end_ptr;

  /* The decoded line number, NULL if not yet decoded.  */
  struct line_info_table* line_table;

  /* A list of the functions found in this comp. unit.  */
  struct funcinfo* function_table;

  /* Address size for this unit - from unit header.  */
  unsigned char addr_size;
};

/* VERBATIM
   The following function up to the END VERBATIM mark are
   copied directly from dwarf2read.c.  */

/* Read dwarf information from a buffer.  */

static unsigned int
read_1_byte (abfd, buf)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
{
  return bfd_get_8 (abfd, (bfd_byte *) buf);
}

static int
read_1_signed_byte (abfd, buf)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
{
  return bfd_get_signed_8 (abfd, (bfd_byte *) buf);
}

static unsigned int
read_2_bytes (abfd, buf)
     bfd *abfd;
     char *buf;
{
  return bfd_get_16 (abfd, (bfd_byte *) buf);
}

#if 0  /* This is not used.  */

static int
read_2_signed_bytes (abfd, buf)
     bfd *abfd;
     char *buf;
{
  return bfd_get_signed_16 (abfd, (bfd_byte *) buf);
}

#endif

static unsigned int
read_4_bytes (abfd, buf)
     bfd *abfd;
     char *buf;
{
  return bfd_get_32 (abfd, (bfd_byte *) buf);
}

#if 0  /* This is not used.  */

static int
read_4_signed_bytes (abfd, buf)
     bfd *abfd;
     char *buf;
{
  return bfd_get_signed_32 (abfd, (bfd_byte *) buf);
}

#endif

static unsigned int
read_8_bytes (abfd, buf)
     bfd *abfd;
     char *buf;
{
  return bfd_get_64 (abfd, (bfd_byte *) buf);
}

static char *
read_n_bytes (abfd, buf, size)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int size ATTRIBUTE_UNUSED;
{
  /* If the size of a host char is 8 bits, we can return a pointer
     to the buffer, otherwise we have to copy the data to a buffer
     allocated on the temporary obstack.  */
  return buf;
}

static char *
read_string (abfd, buf, bytes_read_ptr)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int *bytes_read_ptr;
{
  /* If the size of a host char is 8 bits, we can return a pointer
     to the string, otherwise we have to copy the string to a buffer
     allocated on the temporary obstack.  */
  if (*buf == '\0')
    {
      *bytes_read_ptr = 1;
      return NULL;
    }

  *bytes_read_ptr = strlen (buf) + 1;
  return buf;
}

static unsigned int
read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int *bytes_read_ptr;
{
  unsigned int  result;
  unsigned int  num_read;
  int           shift;
  unsigned char byte;

  result   = 0;
  shift    = 0;
  num_read = 0;

  do
    {
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
      buf ++;
      num_read ++;
      result |= ((byte & 0x7f) << shift);
      shift += 7;
    }
  while (byte & 0x80);

  * bytes_read_ptr = num_read;

  return result;
}

static int
read_signed_leb128 (abfd, buf, bytes_read_ptr)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int * bytes_read_ptr;
{
  int           result;
  int           shift;
  int           num_read;
  unsigned char byte;

  result = 0;
  shift = 0;
  num_read = 0;

  do
    {
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
      buf ++;
      num_read ++;
      result |= ((byte & 0x7f) << shift);
      shift += 7;
    }
  while (byte & 0x80);

  if ((shift < 32) && (byte & 0x40))
    result |= -(1 << shift);

  * bytes_read_ptr = num_read;

  return result;
}

/* END VERBATIM */

static bfd_vma
read_address (unit, buf)
     struct comp_unit* unit;
     char *buf;
{
  switch (unit->addr_size)
    {
    case 8:
      return bfd_get_64 (unit->abfd, (bfd_byte *) buf);
    case 4:
      return bfd_get_32 (unit->abfd, (bfd_byte *) buf);
    case 2:
      return bfd_get_16 (unit->abfd, (bfd_byte *) buf);
    default:
      abort ();
    }
}

/* This data structure holds the information of an abbrev.  */
struct abbrev_info
{
  unsigned int number;		/* Number identifying abbrev.  */
  enum dwarf_tag tag;		/* DWARF tag.  */
  int has_children;		/* Boolean.  */
  unsigned int num_attrs;	/* Number of attributes.  */
  struct attr_abbrev *attrs;	/* An array of attribute descriptions.  */
  struct abbrev_info *next;	/* Next in chain.  */
};

struct attr_abbrev
{
  enum dwarf_attribute name;
  enum dwarf_form form;
};

#ifndef ABBREV_HASH_SIZE
#define ABBREV_HASH_SIZE 121
#endif
#ifndef ATTR_ALLOC_CHUNK
#define ATTR_ALLOC_CHUNK 4
#endif

/* Lookup an abbrev_info structure in the abbrev hash table.  */

static struct abbrev_info *
lookup_abbrev (number,abbrevs)
     unsigned int number;
     struct abbrev_info **abbrevs;
{
  unsigned int hash_number;
  struct abbrev_info *abbrev;

  hash_number = number % ABBREV_HASH_SIZE;
  abbrev = abbrevs[hash_number];

  while (abbrev)
    {
      if (abbrev->number == number)
	return abbrev;
      else
	abbrev = abbrev->next;
    }

  return NULL;
}

/* In DWARF version 2, the description of the debugging information is
   stored in a separate .debug_abbrev section.  Before we read any
   dies from a section we read in all abbreviations and install them
   in a hash table.  */

static struct abbrev_info**
read_abbrevs (abfd, offset, stash)
     bfd * abfd;
     unsigned int offset;
     struct dwarf2_debug *stash;
{
  struct abbrev_info **abbrevs;
  char *abbrev_ptr;
  struct abbrev_info *cur_abbrev;
  unsigned int abbrev_number, bytes_read, abbrev_name;
  unsigned int abbrev_form, hash_number;

  if (! stash->dwarf_abbrev_buffer)
    {
      asection *msec;

      msec = bfd_get_section_by_name (abfd, ".debug_abbrev");
      if (! msec)
	{
	  (*_bfd_error_handler) (_("Dwarf Error: Can't find .debug_abbrev section."));
	  bfd_set_error (bfd_error_bad_value);
	  return 0;
	}

      stash->dwarf_abbrev_size = msec->_raw_size;
      stash->dwarf_abbrev_buffer = (char*) bfd_alloc (abfd, stash->dwarf_abbrev_size);
      if (! stash->dwarf_abbrev_buffer)
	  return 0;

      if (! bfd_get_section_contents (abfd, msec,
				      stash->dwarf_abbrev_buffer, 0,
				      stash->dwarf_abbrev_size))
	return 0;
    }

  if (offset >= stash->dwarf_abbrev_size)
    {
      (*_bfd_error_handler) (_("Dwarf Error: Abbrev offset (%u) greater than or equal to abbrev size (%u)."),
			     offset, stash->dwarf_abbrev_size );
      bfd_set_error (bfd_error_bad_value);
      return 0;
    }

  abbrevs = (struct abbrev_info**) bfd_zalloc (abfd, sizeof (struct abbrev_info*) * ABBREV_HASH_SIZE);

  abbrev_ptr = stash->dwarf_abbrev_buffer + offset;
  abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
  abbrev_ptr += bytes_read;

  /* Loop until we reach an abbrev number of 0.  */
  while (abbrev_number)
    {
      cur_abbrev = (struct abbrev_info*)bfd_zalloc (abfd, sizeof (struct abbrev_info));

      /* Read in abbrev header.  */
      cur_abbrev->number = abbrev_number;
      cur_abbrev->tag = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
      abbrev_ptr += bytes_read;
      cur_abbrev->has_children = read_1_byte (abfd, abbrev_ptr);
      abbrev_ptr += 1;

      /* Now read in declarations.  */
      abbrev_name = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
      abbrev_ptr += bytes_read;
      abbrev_form = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
      abbrev_ptr += bytes_read;

      while (abbrev_name)
	{
	  if ((cur_abbrev->num_attrs % ATTR_ALLOC_CHUNK) == 0)
	    {
	      cur_abbrev->attrs = (struct attr_abbrev *)
		bfd_realloc (cur_abbrev->attrs,
			     (cur_abbrev->num_attrs + ATTR_ALLOC_CHUNK)
			     * sizeof (struct attr_abbrev));
	      if (! cur_abbrev->attrs)
		return 0;
	    }

	  cur_abbrev->attrs[cur_abbrev->num_attrs].name = abbrev_name;
	  cur_abbrev->attrs[cur_abbrev->num_attrs++].form = abbrev_form;
	  abbrev_name = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
	  abbrev_ptr += bytes_read;
	  abbrev_form = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
	  abbrev_ptr += bytes_read;
	}

      hash_number = abbrev_number % ABBREV_HASH_SIZE;
      cur_abbrev->next = abbrevs[hash_number];
      abbrevs[hash_number] = cur_abbrev;

      /* Get next abbreviation.
         Under Irix6 the abbreviations for a compilation unit are not
	 always properly terminated with an abbrev number of 0.
	 Exit loop if we encounter an abbreviation which we have
	 already read (which means we are about to read the abbreviations
	 for the next compile unit) or if the end of the abbreviation
	 table is reached.  */
      if ((unsigned int) (abbrev_ptr - stash->dwarf_abbrev_buffer)
	    >= stash->dwarf_abbrev_size)
	break;
      abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
      abbrev_ptr += bytes_read;
      if (lookup_abbrev (abbrev_number,abbrevs) != NULL)
	break;
    }

  return abbrevs;
}

/* Read an attribute described by an abbreviated attribute.  */

static char *
read_attribute (attr, abbrev, unit, info_ptr)
     struct attribute   *attr;
     struct attr_abbrev *abbrev;
     struct comp_unit   *unit;
     char               *info_ptr;
{
  bfd *abfd = unit->abfd;
  unsigned int bytes_read;
  struct dwarf_block *blk;

  attr->name = abbrev->name;
  attr->form = abbrev->form;

  switch (abbrev->form)
    {
    case DW_FORM_addr:
    case DW_FORM_ref_addr:
      DW_ADDR (attr) = read_address (unit, info_ptr);
      info_ptr += unit->addr_size;
      break;
    case DW_FORM_block2:
      blk = (struct dwarf_block *) bfd_alloc (abfd, sizeof (struct dwarf_block));
      blk->size = read_2_bytes (abfd, info_ptr);
      info_ptr += 2;
      blk->data = read_n_bytes (abfd, info_ptr, blk->size);
      info_ptr += blk->size;
      DW_BLOCK (attr) = blk;
      break;
    case DW_FORM_block4:
      blk = (struct dwarf_block *) bfd_alloc (abfd, sizeof (struct dwarf_block));
      blk->size = read_4_bytes (abfd, info_ptr);
      info_ptr += 4;
      blk->data = read_n_bytes (abfd, info_ptr, blk->size);
      info_ptr += blk->size;
      DW_BLOCK (attr) = blk;
      break;
    case DW_FORM_data2:
      DW_UNSND (attr) = read_2_bytes (abfd, info_ptr);
      info_ptr += 2;
      break;