Blame libdw/dwarf_getabbrev.c

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/* Get abbreviation at given offset.
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   Copyright (C) 2003, 2004, 2005, 2006, 2014, 2017 Red Hat, Inc.
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   This file is part of elfutils.
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   Written by Ulrich Drepper <drepper@redhat.com>, 2003.
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   This file is free software; you can redistribute it and/or modify
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   it under the terms of either
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     * the GNU Lesser General Public License as published by the Free
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       Software Foundation; either version 3 of the License, or (at
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       your option) any later version
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   or
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     * the GNU General Public License as published by the Free
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       Software Foundation; either version 2 of the License, or (at
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       your option) any later version
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   or both in parallel, as here.
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   elfutils is distributed in the hope that it will be useful, but
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   WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   General Public License for more details.
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   You should have received copies of the GNU General Public License and
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   the GNU Lesser General Public License along with this program.  If
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   not, see <http://www.gnu.org/licenses/>.  */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <dwarf.h>
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#include "libdwP.h"
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Dwarf_Abbrev *
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internal_function
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__libdw_getabbrev (Dwarf *dbg, struct Dwarf_CU *cu, Dwarf_Off offset,
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		   size_t *lengthp, Dwarf_Abbrev *result)
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{
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  /* Don't fail if there is not .debug_abbrev section.  */
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  if (dbg->sectiondata[IDX_debug_abbrev] == NULL)
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    return NULL;
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  if (offset >= dbg->sectiondata[IDX_debug_abbrev]->d_size)
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    {
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      __libdw_seterrno (DWARF_E_INVALID_OFFSET);
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      return NULL;
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    }
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  const unsigned char *abbrevp
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    = (unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf + offset;
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  if (*abbrevp == '\0')
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    /* We are past the last entry.  */
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    return DWARF_END_ABBREV;
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  /* 7.5.3 Abbreviations Tables
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     [...] Each declaration begins with an unsigned LEB128 number
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     representing the abbreviation code itself.  [...]  The
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     abbreviation code is followed by another unsigned LEB128
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     number that encodes the entry's tag.  [...]
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     [...] Following the tag encoding is a 1-byte value that
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     determines whether a debugging information entry using this
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     abbreviation has child entries or not. [...]
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     [...] Finally, the child encoding is followed by a series of
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     attribute specifications. Each attribute specification
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     consists of two parts. The first part is an unsigned LEB128
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     number representing the attribute's name. The second part is
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     an unsigned LEB128 number representing the attribute's form.  */
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  const unsigned char *end = (dbg->sectiondata[IDX_debug_abbrev]->d_buf
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			      + dbg->sectiondata[IDX_debug_abbrev]->d_size);
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  const unsigned char *start_abbrevp = abbrevp;
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  unsigned int code;
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  get_uleb128 (code, abbrevp, end);
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  /* Check whether this code is already in the hash table.  */
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  bool foundit = false;
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  Dwarf_Abbrev *abb = NULL;
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  if (cu == NULL
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      || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code)) == NULL)
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    {
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      if (result == NULL)
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	abb = libdw_typed_alloc (dbg, Dwarf_Abbrev);
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      else
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	abb = result;
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    }
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  else
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    {
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      foundit = true;
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      if (unlikely (abb->offset != offset))
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	{
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	  /* A duplicate abbrev code at a different offset,
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	     that should never happen.  */
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	invalid:
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	  if (! foundit)
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	    libdw_typed_unalloc (dbg, Dwarf_Abbrev);
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	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
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	  return NULL;
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	}
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      /* If the caller doesn't need the length we are done.  */
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      if (lengthp == NULL)
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	goto out;
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    }
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  /* If there is already a value in the hash table we are going to
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     overwrite its content.  This must not be a problem, since the
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     content better be the same.  */
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  abb->code = code;
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  if (abbrevp >= end)
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    goto invalid;
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  get_uleb128 (abb->tag, abbrevp, end);
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  if (abbrevp + 1 >= end)
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    goto invalid;
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  abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
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  abb->attrp = (unsigned char *) abbrevp;
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  abb->offset = offset;
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  /* Skip over all the attributes and check rest of the abbrev is valid.  */
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  unsigned int attrname;
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  unsigned int attrform;
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  do
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    {
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      if (abbrevp >= end)
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	goto invalid;
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      get_uleb128 (attrname, abbrevp, end);
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      if (abbrevp >= end)
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	goto invalid;
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      get_uleb128 (attrform, abbrevp, end);
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      if (attrform == DW_FORM_implicit_const)
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	{
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	  int64_t formval __attribute__((__unused__));
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	  if (abbrevp >= end)
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	    goto invalid;
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	  get_sleb128 (formval, abbrevp, end);
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	}
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    }
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  while (attrname != 0 || attrform != 0);
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  /* Return the length to the caller if she asked for it.  */
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  if (lengthp != NULL)
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    *lengthp = abbrevp - start_abbrevp;
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  /* Add the entry to the hash table.  */
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  if (cu != NULL && ! foundit)
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    if (Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb) == -1)
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      {
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	/* The entry was already in the table, remove the one we just
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	   created and get the one already inserted.  */
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	libdw_typed_unalloc (dbg, Dwarf_Abbrev);
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	abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code);
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      }
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 out:
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  return abb;
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}
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Dwarf_Abbrev *
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dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp)
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{
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  if (die == NULL || die->cu == NULL)
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    return NULL;
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  Dwarf_CU *cu = die->cu;
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  Dwarf *dbg = cu->dbg;
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  Dwarf_Off abbrev_offset = cu->orig_abbrev_offset;
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  Elf_Data *data = dbg->sectiondata[IDX_debug_abbrev];
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  if (data == NULL)
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    return NULL;
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  if (offset >= data->d_size - abbrev_offset)
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    {
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      __libdw_seterrno (DWARF_E_INVALID_OFFSET);
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      return NULL;
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    }
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  return __libdw_getabbrev (dbg, cu, abbrev_offset + offset, lengthp, NULL);
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}