dwarf_util.c   [plain text]


  Copyright (C) 2000,2004,2005 Silicon Graphics, Inc.  All Rights Reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of version 2.1 of the GNU Lesser General Public License 
  as published by the Free Software Foundation.

  This program is distributed in the hope that it would be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of

  Further, this software is distributed without any warranty that it is
  free of the rightful claim of any third person regarding infringement 
  or the like.  Any license provided herein, whether implied or 
  otherwise, applies only to this software file.  Patent licenses, if
  any, provided herein do not apply to combinations of this program with 
  other software, or any other product whatsoever.  

  You should have received a copy of the GNU Lesser General Public 
  License along with this program; if not, write the Free Software 
  Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, 

  Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
  Mountain View, CA 94043, or:


  For further information regarding this notice, see:



#include "config.h"
#include "dwarf_incl.h"
#include <stdio.h>
#include "dwarf_die_deliv.h"

    Given a form, and a pointer to the bytes encoding 
    a value of that form, val_ptr, this function returns
    the length, in bytes, of a value of that form.
    When using this function, check for a return of 0
    a recursive DW_FORM_INDIRECT value.
_dwarf_get_size_of_val(Dwarf_Debug dbg,
		       Dwarf_Unsigned form,
		       Dwarf_Small * val_ptr, int v_length_size)
    Dwarf_Unsigned length = 0;
    Dwarf_Word leb128_length = 0;
    Dwarf_Unsigned form_indirect = 0;
    Dwarf_Unsigned ret_value = 0;

    switch (form) {

    default:			/* Handles form = 0. */
	return (form);

    case DW_FORM_addr:
	return (dbg->de_pointer_size);

    case DW_FORM_ref_addr:
	return (v_length_size);

    case DW_FORM_block1:
	return (*(Dwarf_Small *) val_ptr + 1);

    case DW_FORM_block2:
	READ_UNALIGNED(dbg, ret_value, Dwarf_Unsigned,
		       val_ptr, sizeof(Dwarf_Half));
	return (ret_value + sizeof(Dwarf_Half));

    case DW_FORM_block4:
	READ_UNALIGNED(dbg, ret_value, Dwarf_Unsigned,
		       val_ptr, sizeof(Dwarf_ufixed));
	return (ret_value + sizeof(Dwarf_ufixed));

    case DW_FORM_data1:
	return (1);

    case DW_FORM_data2:
	return (2);

    case DW_FORM_data4:
	return (4);

    case DW_FORM_data8:
	return (8);

    case DW_FORM_string:
	return (strlen((char *) val_ptr) + 1);

    case DW_FORM_block:
    case DW_FORM_exprloc:
        length = _dwarf_decode_u_leb128(val_ptr, &leb128_length);
        return (length + leb128_length);

        /* According to the DWARF4 documentation, there is nothing to read. */
    case DW_FORM_flag_present:
        return (0);
    case DW_FORM_flag:
        return (1);

    case DW_FORM_sec_offset:
        /* If 32bit dwarf, is 4. Else is 64bit dwarf and is 8. */
        return (v_length_size);

    case DW_FORM_ref_udata:
	_dwarf_decode_u_leb128(val_ptr, &leb128_length);
	return (leb128_length);

    case DW_FORM_indirect:
	    Dwarf_Word indir_len = 0;

	    form_indirect = _dwarf_decode_u_leb128(val_ptr, &indir_len);
	    if (form_indirect == DW_FORM_indirect) {
		return (0);	/* We are in big trouble: The true form 
				   of DW_FORM_indirect is
				   DW_FORM_indirect? Nonsense. Should
				   never happen. */
	    return (indir_len + _dwarf_get_size_of_val(dbg,
						       val_ptr +

    case DW_FORM_ref1:
	return (1);

    case DW_FORM_ref2:
	return (2);

    case DW_FORM_ref4:
	return (4);

    case DW_FORM_ref8:
	return (8);

    case DW_FORM_sdata:
	_dwarf_decode_s_leb128(val_ptr, &leb128_length);
	return (leb128_length);

    case DW_FORM_strp:
	return (v_length_size);

    case DW_FORM_udata:
	_dwarf_decode_u_leb128(val_ptr, &leb128_length);
	return (leb128_length);

    This function returns a pointer to a Dwarf_Abbrev_List_s
    struct for the abbrev with the given code.  It puts the
    struct on the appropriate hash table.  It also adds all
    the abbrev between the last abbrev added and this one to
    the hash table.  In other words, the .debug_abbrev section
    is scanned sequentially from the top for an abbrev with
    the given code.  All intervening abbrevs are also put 
    into the hash table.

    This function hashes the given code, and checks the chain
    at that hash table entry to see if a Dwarf_Abbrev_List_s
    with the given code exists.  If yes, it returns a pointer
    to that struct.  Otherwise, it scans the .debug_abbrev
    section from the last byte scanned for that CU till either
    an abbrev with the given code is found, or an abbrev code
    of 0 is read.  It puts Dwarf_Abbrev_List_s entries for all
    abbrev's read till that point into the hash table.  The
    hash table contains both a head pointer and a tail pointer
    for each entry.

    Returns NULL on error.
_dwarf_get_abbrev_for_code(Dwarf_CU_Context cu_context, Dwarf_Word code)
    Dwarf_Debug dbg = cu_context->cc_dbg;
    Dwarf_Hash_Table hash_table = cu_context->cc_abbrev_hash_table;
    Dwarf_Word hash_num;
    Dwarf_Abbrev_List hash_abbrev_list;
    Dwarf_Abbrev_List abbrev_list;
    Dwarf_Byte_Ptr abbrev_ptr;
    Dwarf_Half abbrev_code, abbrev_tag;
    Dwarf_Half attr_name, attr_form;

    hash_num = code % ABBREV_HASH_TABLE_SIZE;
    for (hash_abbrev_list = hash_table[hash_num].at_head;
	 hash_abbrev_list != NULL && hash_abbrev_list->ab_code != code;
	 hash_abbrev_list = hash_abbrev_list->ab_next);
    if (hash_abbrev_list != NULL)
	return (hash_abbrev_list);

    abbrev_ptr = cu_context->cc_last_abbrev_ptr != NULL ?
	cu_context->cc_last_abbrev_ptr :
	dbg->de_debug_abbrev + cu_context->cc_abbrev_offset;

    /* End of abbrev's for this cu, since abbrev code is 0. */
    if (*abbrev_ptr == 0) {
	return (NULL);

    do {
	Dwarf_Unsigned utmp;

	DECODE_LEB128_UWORD(abbrev_ptr, utmp)
	    abbrev_code = (Dwarf_Half) utmp;
	DECODE_LEB128_UWORD(abbrev_ptr, utmp)
	    abbrev_tag = (Dwarf_Half) utmp;

	abbrev_list = (Dwarf_Abbrev_List)
	    _dwarf_get_alloc(cu_context->cc_dbg, DW_DLA_ABBREV_LIST, 1);
	if (abbrev_list == NULL)
	    return (NULL);

	hash_num = abbrev_code % ABBREV_HASH_TABLE_SIZE;
	if (hash_table[hash_num].at_head == NULL) {
	    hash_table[hash_num].at_head =
		hash_table[hash_num].at_tail = abbrev_list;
	} else {
	    hash_table[hash_num].at_tail->ab_next = abbrev_list;
	    hash_table[hash_num].at_tail = abbrev_list;

	abbrev_list->ab_code = abbrev_code;
	abbrev_list->ab_tag = abbrev_tag;

	abbrev_list->ab_has_child = *(abbrev_ptr++);
	abbrev_list->ab_abbrev_ptr = abbrev_ptr;

	/* Cycle thru the abbrev content, ignoring the content except
	   to find the end of the content. */
	do {
	    Dwarf_Unsigned utmp3;

	    DECODE_LEB128_UWORD(abbrev_ptr, utmp3)
		attr_name = (Dwarf_Half) utmp3;
	    DECODE_LEB128_UWORD(abbrev_ptr, utmp3)
		attr_form = (Dwarf_Half) utmp3;
	} while (attr_name != 0 && attr_form != 0);

    } while (*abbrev_ptr != 0 && abbrev_code != code);

    cu_context->cc_last_abbrev_ptr = abbrev_ptr;
    return (abbrev_code == code ? abbrev_list : NULL);

/* return 1 if string ends before 'endptr' else
** return 0 meaning string is not properly terminated.
** Presumption is the 'endptr' pts to end of some dwarf section data.
_dwarf_string_valid(void *startptr, void *endptr)

    char *start = startptr;
    char *end = endptr;

    while (start < end) {
	if (*start == 0) {
	    return 1;		/* OK! */
    return 0;			/* FAIL! bad string! */

  A byte-swapping version of memcpy
  for cross-endian use.
  Only 2,4,8 should be lengths passed in.
void *
_dwarf_memcpy_swap_bytes(void *s1, const void *s2, size_t len)
    void *orig_s1 = s1;
    unsigned char *targ = (unsigned char *) s1;
    unsigned char *src = (unsigned char *) s2;

    if (len == 4) {
	targ[3] = src[0];
	targ[2] = src[1];
	targ[1] = src[2];
	targ[0] = src[3];
    } else if (len == 8) {
	targ[7] = src[0];
	targ[6] = src[1];
	targ[5] = src[2];
	targ[4] = src[3];
	targ[3] = src[4];
	targ[2] = src[5];
	targ[1] = src[6];
	targ[0] = src[7];
    } else if (len == 2) {
	targ[1] = src[0];
	targ[0] = src[1];
/* should NOT get below here: is not the intended use */
    else if (len == 1) {
	targ[0] = src[0];
    } else {
	memcpy(s1, s2, len);

    return orig_s1;

  This calculation used to be sprinkled all over.
  Now brought to one place.

  We try to accurately compute the size of a cu header
  given a known cu header location ( an offset in .debug_info).

_dwarf_length_of_cu_header(Dwarf_Debug dbg, Dwarf_Unsigned offset)
    int local_length_size = 0;
    int local_extension_size = 0;
    Dwarf_Unsigned length = 0;
    Dwarf_Small *cuptr = dbg->de_debug_info + offset;

    READ_AREA_LENGTH(dbg, length, Dwarf_Unsigned,
		     cuptr, local_length_size, local_extension_size);

    return local_extension_size +	/* initial extesion, if present 
	local_length_size +	/* Size of cu length field. */
	sizeof(Dwarf_Half) +	/* Size of version stamp field. */
	local_length_size +	/* Size of abbrev offset field. */
	sizeof(Dwarf_Small);	/* Size of address size field. */


	Pretend we know nothing about the CU
	and just roughly compute the result. 
_dwarf_length_of_cu_header_simple(Dwarf_Debug dbg)
    return dbg->de_length_size +	/* Size of cu length field. */
	sizeof(Dwarf_Half) +	/* Size of version stamp field. */
	dbg->de_length_size +	/* Size of abbrev offset field. */
	sizeof(Dwarf_Small);	/* Size of address size field. */

/* Now that we delay loading .debug_info, we need to do the
   load in more places. So putting the load
   code in one place now instead of replicating it in multiple

_dwarf_load_debug_info(Dwarf_Debug dbg, Dwarf_Error * error)
    int res;

    /* Testing de_debug_info allows us to avoid testing
       de_debug_abbrev. One test instead of 2. .debug_info is useless
       without .debug_abbrev. */
    if (dbg->de_debug_info) {
	return DW_DLV_OK;

    res = _dwarf_load_section(dbg, dbg->de_debug_abbrev_index,
			      &dbg->de_debug_abbrev, error);
    if (res != DW_DLV_OK) {
	return res;
    res = _dwarf_load_section(dbg, dbg->de_debug_info_index,
			      &dbg->de_debug_info, error);
    return res;