/* Internal definitions for libdw.

   Copyright (C) 2002-2011, 2013-2018 Red Hat, Inc.

   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify

   it under the terms of either

     * the GNU Lesser General Public License as published by the Free

       Software Foundation; either version 3 of the License, or (at

       your option) any later version

   or

     * 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

   or both in parallel, as here.

   elfutils 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 copies of the GNU General Public License and

   the GNU Lesser General Public License along with this program.  If

   not, see <http://www.gnu.org/licenses/>.  */

#ifndef _LIBDWP_H

#define _LIBDWP_H 1

#include <libintl.h>

#include <stdbool.h>

#include <pthread.h>

#include <libdw.h>

#include <dwarf.h>

#include "atomics.h"

/* gettext helper macros.  */

#define _(Str) dgettext ("elfutils", Str)

/* Known location expressions already decoded.  */

struct loc_s

{

  void *addr;

  Dwarf_Op *loc;

  size_t nloc;

};

/* Known DW_OP_implicit_value blocks already decoded.

   This overlaps struct loc_s exactly, but only the

   first member really has to match.  */

struct loc_block_s

{

  void *addr;

  unsigned char *data;

  size_t length;

};

/* Already decoded .debug_line units.  */

struct files_lines_s

{

  Dwarf_Off debug_line_offset;

  Dwarf_Files *files;

  Dwarf_Lines *lines;

};

/* Valid indeces for the section data.  */

enum

  {

    IDX_debug_info = 0,

    IDX_debug_types,

    IDX_debug_abbrev,

    IDX_debug_aranges,

    IDX_debug_addr,

    IDX_debug_line,

    IDX_debug_line_str,

    IDX_debug_frame,

    IDX_debug_loc,

    IDX_debug_loclists,

    IDX_debug_pubnames,

    IDX_debug_str,

    IDX_debug_str_offsets,

    IDX_debug_macinfo,

    IDX_debug_macro,

    IDX_debug_ranges,

    IDX_debug_rnglists,

    IDX_gnu_debugaltlink,

    IDX_last

  };

/* Error values.  */

enum

{

  DWARF_E_NOERROR = 0,

  DWARF_E_UNKNOWN_ERROR,

  DWARF_E_INVALID_ACCESS,

  DWARF_E_NO_REGFILE,

  DWARF_E_IO_ERROR,

  DWARF_E_INVALID_ELF,

  DWARF_E_NO_DWARF,

  DWARF_E_COMPRESSED_ERROR,

  DWARF_E_NOELF,

  DWARF_E_GETEHDR_ERROR,

  DWARF_E_NOMEM,

  DWARF_E_UNIMPL,

  DWARF_E_INVALID_CMD,

  DWARF_E_INVALID_VERSION,

  DWARF_E_INVALID_FILE,

  DWARF_E_NO_ENTRY,

  DWARF_E_INVALID_DWARF,

  DWARF_E_NO_STRING,

  DWARF_E_NO_DEBUG_STR,

  DWARF_E_NO_DEBUG_LINE_STR,

  DWARF_E_NO_STR_OFFSETS,

  DWARF_E_NO_ADDR,

  DWARF_E_NO_CONSTANT,

  DWARF_E_NO_REFERENCE,

  DWARF_E_INVALID_REFERENCE,

  DWARF_E_NO_DEBUG_LINE,

  DWARF_E_INVALID_DEBUG_LINE,

  DWARF_E_TOO_BIG,

  DWARF_E_VERSION,

  DWARF_E_INVALID_DIR_IDX,

  DWARF_E_ADDR_OUTOFRANGE,

  DWARF_E_NO_DEBUG_LOC,

  DWARF_E_NO_DEBUG_LOCLISTS,

  DWARF_E_NO_LOC_VALUE,

  DWARF_E_NO_BLOCK,

  DWARF_E_INVALID_LINE_IDX,

  DWARF_E_INVALID_ARANGE_IDX,

  DWARF_E_NO_MATCH,

  DWARF_E_NO_FLAG,

  DWARF_E_INVALID_OFFSET,

  DWARF_E_NO_DEBUG_RANGES,

  DWARF_E_NO_DEBUG_RNGLISTS,

  DWARF_E_INVALID_CFI,

  DWARF_E_NO_ALT_DEBUGLINK,

  DWARF_E_INVALID_OPCODE,

  DWARF_E_NOT_CUDIE,

  DWARF_E_UNKNOWN_LANGUAGE,

  DWARF_E_NO_DEBUG_ADDR,

};

#include "dwarf_sig8_hash.h"

/* This is the structure representing the debugging state.  */

struct Dwarf

{

  /* The underlying ELF file.  */

  Elf *elf;

  /* The (absolute) path to the ELF dir, if known.  To help locating

     alt and dwo files.  */

  char *debugdir;

  /* dwz alternate DWARF file.  */

  Dwarf *alt_dwarf;

  /* The section data.  */

  Elf_Data *sectiondata[IDX_last];

  /* True if the file has a byte order different from the host.  */

  bool other_byte_order;

  /* If true, we allocated the ELF descriptor ourselves.  */

  bool free_elf;

  /* If >= 0, we allocated the alt_dwarf ourselves and must end it and

     close this file descriptor.  */

  int alt_fd;

  /* Information for traversing the .debug_pubnames section.  This is

     an array and separately allocated with malloc.  */

  struct pubnames_s

  {

    Dwarf_Off cu_offset;

    Dwarf_Off set_start;

    unsigned int cu_header_size;

    int address_len;

  } *pubnames_sets;

  size_t pubnames_nsets;

  /* Search tree for the CUs.  */

  void *cu_tree;

  Dwarf_Off next_cu_offset;

  /* Search tree and sig8 hash table for .debug_types type units.  */

  void *tu_tree;

  Dwarf_Off next_tu_offset;

  Dwarf_Sig8_Hash sig8_hash;

  /* Search tree for split Dwarf associated with CUs in this debug.  */

  void *split_tree;

  /* Search tree for .debug_macro operator tables.  */

  void *macro_ops;

  /* Search tree for decoded .debug_line units.  */

  void *files_lines;

  /* Address ranges.  */

  Dwarf_Aranges *aranges;

  /* Cached info from the CFI section.  */

  struct Dwarf_CFI_s *cfi;

  /* Fake loc CU.  Used when synthesizing attributes for Dwarf_Ops that

     came from a location list entry in dwarf_getlocation_attr.

     Depending on version this is the .debug_loc or .debug_loclists

     section (could be both if mixing CUs with different DWARF versions).  */

  struct Dwarf_CU *fake_loc_cu;

  struct Dwarf_CU *fake_loclists_cu;

  /* Similar for addrx/constx, which will come from .debug_addr section.  */

  struct Dwarf_CU *fake_addr_cu;

  /* Supporting lock for internal memory handling.  Ensures threads that have

     an entry in the mem_tails array are not disturbed by new threads doing

     allocations for this Dwarf.  */

  pthread_rwlock_t mem_rwl;

  /* Internal memory handling.  This is basically a simplified thread-local

     reimplementation of obstacks.  Unfortunately the standard obstack

     implementation is not usable in libraries.  */

  size_t mem_stacks;

  struct libdw_memblock

  {

    size_t size;

    size_t remaining;

    struct libdw_memblock *prev;

    char mem[0];

  } **mem_tails;

  /* Default size of allocated memory blocks.  */

  size_t mem_default_size;

  /* Registered OOM handler.  */

  Dwarf_OOM oom_handler;

};

/* Abbreviation representation.  */

struct Dwarf_Abbrev

{

  Dwarf_Off offset;	  /* Offset to start of abbrev into .debug_abbrev.  */

  unsigned char *attrp;   /* Pointer to start of attribute name/form pairs. */

  bool has_children : 1;  /* Whether or not the DIE has children. */

  unsigned int code : 31; /* The (unique) abbrev code.  */

  unsigned int tag;	  /* The tag of the DIE. */

} attribute_packed;

#include "dwarf_abbrev_hash.h"

/* Files in line information records.  */

struct Dwarf_Files_s

  {

    unsigned int ndirs;

    unsigned int nfiles;

    struct Dwarf_Fileinfo_s

    {

      char *name;

      Dwarf_Word mtime;

      Dwarf_Word length;

    } info[0];

    /* nfiles of those, followed by char *[ndirs].  */

  };

typedef struct Dwarf_Fileinfo_s Dwarf_Fileinfo;

/* Representation of a row in the line table.  */

struct Dwarf_Line_s

{

  Dwarf_Files *files;

  Dwarf_Addr addr;

  unsigned int file;

  int line;

  unsigned short int column;

  unsigned int is_stmt:1;

  unsigned int basic_block:1;

  unsigned int end_sequence:1;

  unsigned int prologue_end:1;

  unsigned int epilogue_begin:1;

  /* The remaining bit fields are not flags, but hold values presumed to be

     small.  All the flags and other bit fields should add up to 48 bits

     to give the whole struct a nice round size.  */

  unsigned int op_index:8;

  unsigned int isa:8;

  unsigned int discriminator:24;

};

struct Dwarf_Lines_s

{

  size_t nlines;

  struct Dwarf_Line_s info[0];

};

/* Representation of address ranges.  */

struct Dwarf_Aranges_s

{

  Dwarf *dbg;

  size_t naranges;

  struct Dwarf_Arange_s

  {

    Dwarf_Addr addr;

    Dwarf_Word length;

    Dwarf_Off offset;

  } info[0];

};

/* CU representation.  */

struct Dwarf_CU

{

  Dwarf *dbg;

  Dwarf_Off start;

  Dwarf_Off end;

  uint8_t address_size;

  uint8_t offset_size;

  uint16_t version;

  size_t sec_idx; /* Normally .debug_info, could be .debug_type or "fake". */

  /* The unit type if version >= 5.  Otherwise 0 for normal CUs (from

     .debug_info) or 1 for v4 type units (from .debug_types).  */

  uint8_t unit_type;

  /* Zero if the unit type doesn't support a die/type offset and/or id/sig.

     Nonzero if it is a v4 type unit or for DWARFv5 units depending on

     unit_type.  */

  size_t subdie_offset;

  uint64_t unit_id8;

  /* If this is a skeleton unit this points to the split compile unit.

     Or the other way around if this is a split compile unit.  Set to -1

     if not yet searched.  Always use __libdw_find_split_unit to access

     this field.  */

  struct Dwarf_CU *split;

  /* Hash table for the abbreviations.  */

  Dwarf_Abbrev_Hash abbrev_hash;

  /* Offset of the first abbreviation.  */

  size_t orig_abbrev_offset;

  /* Offset past last read abbreviation.  */

  size_t last_abbrev_offset;

  /* The srcline information.  */

  Dwarf_Lines *lines;

  /* The source file information.  */

  Dwarf_Files *files;

  /* Known location lists.  */

  void *locs;

  /* Base address for use with ranges and locs.

     Don't access directly, call __libdw_cu_base_address.  */

  Dwarf_Addr base_address;

  /* The offset into the .debug_addr section where index zero begins.

     Don't access directly, call __libdw_cu_addr_base.  */

  Dwarf_Off addr_base;

  /* The offset into the .debug_str_offsets section where index zero begins.

     Don't access directly, call __libdw_cu_str_off_base.  */

  Dwarf_Off str_off_base;

  /* The offset into the .debug_ranges section to use for GNU

     DebugFission split units.  Don't access directly, call

     __libdw_cu_ranges_base.  */

  Dwarf_Off ranges_base;

  /* The start of the offset table in .debug_loclists.

     Don't access directly, call __libdw_cu_locs_base.  */

  Dwarf_Off locs_base;

  /* Memory boundaries of this CU.  */

  void *startp;

  void *endp;

};

#define ISV4TU(cu) ((cu)->version == 4 && (cu)->sec_idx == IDX_debug_types)

/* Compute the offset of a CU's first DIE from the CU offset.

   CU must be a valid/known version/unit_type.  */

static inline Dwarf_Off

__libdw_first_die_from_cu_start (Dwarf_Off cu_start,

				 uint8_t offset_size,

				 uint16_t version,

				 uint8_t unit_type)

{

/*

  assert (offset_size == 4 || offset_size == 8);

  assert (version >= 2 && version <= 5);

  assert (unit_type == DW_UT_compile

	  || unit_type == DW_UT_partial

	  || unit_type == DW_UT_skeleton

	  || unit_type == DW_UT_split_compile

	  || unit_type == DW_UT_type

	  || unit_type == DW_UT_split_type);

*/

  Dwarf_Off off = cu_start;

  if (version < 5)

    {

   /*

        LEN       VER     OFFSET    ADDR

      4-bytes + 2-bytes + 4-bytes + 1-byte  for 32-bit dwarf

     12-bytes + 2-bytes + 8-bytes + 1-byte  for 64-bit dwarf

   or in .debug_types, 			     SIGNATURE TYPE-OFFSET

      4-bytes + 2-bytes + 4-bytes + 1-byte + 8-bytes + 4-bytes  for 32-bit

     12-bytes + 2-bytes + 8-bytes + 1-byte + 8-bytes + 8-bytes  for 64-bit

   Note the trick in the computation.  If the offset_size is 4

   the '- 4' term changes the '3 *' (or '4 *') into a '2 *' (or '3 *).

   If the offset_size is 8 it accounts for the 4-byte escape value

   used at the start of the length.  */

      if (unit_type != DW_UT_type)

	off += 3 * offset_size - 4 + 3;

      else

	off += 4 * offset_size - 4 + 3 + 8;

    }

  else

    {

     /*

        LEN       VER      TYPE     ADDR     OFFSET   SIGNATURE  TYPE-OFFSET

      4-bytes + 2-bytes + 1-byte + 1-byte + 4-bytes + 8-bytes + 4-bytes 32-bit

     12-bytes + 2-bytes + 1-byte + 1-byte + 8-bytes + 8-bytes + 8-bytes 64-bit

        Both signature and type offset are optional.

        Note same 4/8 offset size trick as above.

        We explicitly ignore unknow unit types (see asserts above).  */

      off += 3 * offset_size - 4 + 4;

      if (unit_type == DW_UT_skeleton || unit_type == DW_UT_split_compile

	  || unit_type == DW_UT_type || unit_type == DW_UT_split_type)

	{

	  off += 8;

	  if (unit_type == DW_UT_type || unit_type == DW_UT_split_type)

	    off += offset_size;

	}

    }

  return off;

}

static inline Dwarf_Off

__libdw_first_die_off_from_cu (struct Dwarf_CU *cu)

{

  return __libdw_first_die_from_cu_start (cu->start,

					  cu->offset_size,

					  cu->version,

					  cu->unit_type);

}

#define CUDIE(fromcu)							      \

  ((Dwarf_Die)								      \

   {									      \

     .cu = (fromcu),							      \

     .addr = ((char *) (fromcu)->dbg->sectiondata[cu_sec_idx (fromcu)]->d_buf \

	      + __libdw_first_die_off_from_cu (fromcu))			      \

   })

#define SUBDIE(fromcu)							      \

  ((Dwarf_Die)								      \

   {									      \

     .cu = (fromcu),							      \

     .addr = ((char *) (fromcu)->dbg->sectiondata[cu_sec_idx (fromcu)]->d_buf \

	      + (fromcu)->start + (fromcu)->subdie_offset)		      \

   })

/* Prototype of a single .debug_macro operator.  */

typedef struct

{

  Dwarf_Word nforms;

  unsigned char const *forms;

} Dwarf_Macro_Op_Proto;

/* Prototype table.  */

typedef struct

{

  /* Offset of .debug_macro section.  */

  Dwarf_Off offset;

  /* Offset of associated .debug_line section.  */

  Dwarf_Off line_offset;

  /* The source file information.  */

  Dwarf_Files *files;

  /* If this macro unit was opened through dwarf_getmacros or

     dwarf_getmacros_die, this caches value of DW_AT_comp_dir, if

     present.  */

  const char *comp_dir;

  /* Header length.  */

  Dwarf_Half header_len;

  uint16_t version;

  bool is_64bit;

  uint8_t sec_index;	/* IDX_debug_macro or IDX_debug_macinfo.  */

  /* Shows where in TABLE each opcode is defined.  Since opcode 0 is

     never used, it stores index of opcode X in X-1'th element.  The

     value of 0xff means not stored at all.  */

  unsigned char opcodes[255];

  /* Individual opcode prototypes.  */

  Dwarf_Macro_Op_Proto table[];

} Dwarf_Macro_Op_Table;

struct Dwarf_Macro_s

{

  Dwarf_Macro_Op_Table *table;

  Dwarf_Attribute *attributes;

  uint8_t opcode;

};

static inline Dwarf_Word

libdw_macro_nforms (Dwarf_Macro *macro)

{

  return macro->table->table[macro->table->opcodes[macro->opcode - 1]].nforms;

}

/* Returns true for any allowed FORM in the opcode_operands_table as

   mentioned in the DWARF5 spec (6.3.1 Macro Information Header).

   Or those mentioned in DWARF5 spec (6.2.4.2 Vendor-defined Content

   Descriptions) for the directory/file table (plus DW_FORM_strp_sup).  */

static inline bool

libdw_valid_user_form (int form)

{

  switch (form)

    {

      case DW_FORM_block:

      case DW_FORM_block1:

      case DW_FORM_block2:

      case DW_FORM_block4:

      case DW_FORM_data1:

      case DW_FORM_data2:

      case DW_FORM_data4:

      case DW_FORM_data8:

      case DW_FORM_data16:

      case DW_FORM_flag:

      case DW_FORM_line_strp:

      case DW_FORM_sdata:

      case DW_FORM_sec_offset:

      case DW_FORM_string:

      case DW_FORM_strp:

      case DW_FORM_strp_sup:

      case DW_FORM_strx:

      case DW_FORM_strx1:

      case DW_FORM_strx2:

      case DW_FORM_strx3:

      case DW_FORM_strx4:

      case DW_FORM_udata:

	return true;

      default:

	return false;

    }

}

/* We have to include the file at this point because the inline

   functions access internals of the Dwarf structure.  */

#include "memory-access.h"

/* Set error value.  */

extern void __libdw_seterrno (int value) internal_function;

/* Memory handling, the easy parts.  */

#define libdw_alloc(dbg, type, tsize, cnt) \

  ({ struct libdw_memblock *_tail = __libdw_alloc_tail(dbg);		      \

     size_t _required = (tsize) * (cnt);				      \

     type *_result = (type *) (_tail->mem + (_tail->size - _tail->remaining));\

     size_t _padding = ((__alignof (type)				      \

			 - ((uintptr_t) _result & (__alignof (type) - 1)))    \

			& (__alignof (type) - 1));			      \

     if (unlikely (_tail->remaining < _required + _padding))		      \

       _result = (type *) __libdw_allocate (dbg, _required, __alignof (type));\

     else								      \

       {								      \

	 _required += _padding;						      \

	 _result = (type *) ((char *) _result + _padding);		      \

	 _tail->remaining -= _required;					      \

       }								      \

     _result; })

#define libdw_typed_alloc(dbg, type) \

  libdw_alloc (dbg, type, sizeof (type), 1)

/* Can only be used to undo the last libdw_alloc.  */

#define libdw_unalloc(dbg, type, tsize, cnt) \

  ({ struct libdw_memblock *_tail = __libdw_thread_tail (dbg);		      \

     size_t _required = (tsize) * (cnt);				      \

     /* We cannot know the padding, it is lost.  */			      \

     _tail->remaining += _required; })					      \

#define libdw_typed_unalloc(dbg, type) \

  libdw_unalloc (dbg, type, sizeof (type), 1)

/* Callback to choose a thread-local memory allocation stack.  */

extern struct libdw_memblock *__libdw_alloc_tail (Dwarf* dbg)

     __nonnull_attribute__ (1);

extern struct libdw_memblock *__libdw_thread_tail (Dwarf* dbg)

     __nonnull_attribute__ (1);

/* Callback to allocate more.  */

extern void *__libdw_allocate (Dwarf *dbg, size_t minsize, size_t align)

     __attribute__ ((__malloc__)) __nonnull_attribute__ (1);

/* Default OOM handler.  */

extern void __libdw_oom (void) __attribute ((noreturn)) attribute_hidden;

/* Read next unit (or v4 debug type) and return next offset.  Doesn't

   create an actual Dwarf_CU just provides necessary header fields.  */

extern int

internal_function

__libdw_next_unit (Dwarf *dbg, bool v4_debug_types, Dwarf_Off off,

		   Dwarf_Off *next_off, size_t *header_sizep,

		   Dwarf_Half *versionp, uint8_t *unit_typep,

		   Dwarf_Off *abbrev_offsetp, uint8_t *address_sizep,

		   uint8_t *offset_sizep, uint64_t *unit_id8p,

		   Dwarf_Off *subdie_offsetp)

     __nonnull_attribute__ (4) internal_function;

/* Allocate the internal data for a unit not seen before.  */

extern struct Dwarf_CU *__libdw_intern_next_unit (Dwarf *dbg, bool debug_types)

     __nonnull_attribute__ (1) internal_function;

/* Find CU for given offset.  */

extern struct Dwarf_CU *__libdw_findcu (Dwarf *dbg, Dwarf_Off offset, bool tu)

     __nonnull_attribute__ (1) internal_function;

/* Find CU for given DIE address.  */

extern struct Dwarf_CU *__libdw_findcu_addr (Dwarf *dbg, void *addr)

     __nonnull_attribute__ (1) internal_function;

/* Find split Dwarf for given DIE address.  */

extern struct Dwarf *__libdw_find_split_dbg_addr (Dwarf *dbg, void *addr)

     __nonnull_attribute__ (1) internal_function;

/* Find the split (or skeleton) unit.  */

extern struct Dwarf_CU *__libdw_find_split_unit (Dwarf_CU *cu)

     internal_function;

/* Get abbreviation with given code.  */

extern Dwarf_Abbrev *__libdw_findabbrev (struct Dwarf_CU *cu,

					 unsigned int code)

     __nonnull_attribute__ (1) internal_function;

/* Get abbreviation at given offset.  */

extern Dwarf_Abbrev *__libdw_getabbrev (Dwarf *dbg, struct Dwarf_CU *cu,

					Dwarf_Off offset, size_t *lengthp,

					Dwarf_Abbrev *result)

     __nonnull_attribute__ (1) internal_function;

/* Get abbreviation of given DIE, and optionally set *READP to the DIE memory

   just past the abbreviation code.  */

static inline Dwarf_Abbrev *

__nonnull_attribute__ (1)

__libdw_dieabbrev (Dwarf_Die *die, const unsigned char **readp)

{

  /* Do we need to get the abbreviation, or need to read after the code?  */

  if (die->abbrev == NULL || readp != NULL)

    {

      /* Get the abbreviation code.  */

      unsigned int code;

      const unsigned char *addr = die->addr;

      if (unlikely (die->cu == NULL

		    || addr >= (const unsigned char *) die->cu->endp))

	return die->abbrev = DWARF_END_ABBREV;

      get_uleb128 (code, addr, die->cu->endp);

      if (readp != NULL)

	*readp = addr;

      /* Find the abbreviation.  */

      if (die->abbrev == NULL)

	die->abbrev = __libdw_findabbrev (die->cu, code);

    }

  return die->abbrev;

}

/* Helper functions for form handling.  */

extern size_t __libdw_form_val_compute_len (struct Dwarf_CU *cu,

					    unsigned int form,

					    const unsigned char *valp)

     __nonnull_attribute__ (1, 3) internal_function;

/* Find the length of a form attribute in DIE/info data.  */

static inline size_t

__nonnull_attribute__ (1, 3)

__libdw_form_val_len (struct Dwarf_CU *cu, unsigned int form,

		      const unsigned char *valp)

{

  /* Small lookup table of forms with fixed lengths.  Absent indexes are

     initialized 0, so any truly desired 0 is set to 0x80 and masked.  */

  static const uint8_t form_lengths[] =

    {

      [DW_FORM_flag_present] = 0x80,

      [DW_FORM_implicit_const] = 0x80, /* Value is in abbrev, not in info.  */

      [DW_FORM_flag] = 1,

      [DW_FORM_data1] = 1, [DW_FORM_ref1] = 1,

      [DW_FORM_addrx1] = 1, [DW_FORM_strx1] = 1,

      [DW_FORM_data2] = 2, [DW_FORM_ref2] = 2,

      [DW_FORM_addrx2] = 2, [DW_FORM_strx2] = 2,

      [DW_FORM_addrx3] = 3, [DW_FORM_strx3] = 3,

      [DW_FORM_data4] = 4, [DW_FORM_ref4] = 4, [DW_FORM_ref_sup4] = 4,

      [DW_FORM_addrx4] = 4, [DW_FORM_strx4] = 4,

      [DW_FORM_ref_sig8] = 8,

      [DW_FORM_data8] = 8, [DW_FORM_ref8] = 8, [DW_FORM_ref_sup8] = 8,

      [DW_FORM_data16] = 16,

    };

  /* Return immediately for forms with fixed lengths.  */

  if (form < sizeof form_lengths / sizeof form_lengths[0])

    {

      uint8_t len = form_lengths[form];

      if (len != 0)

	{

	  const unsigned char *endp = cu->endp;

	  len &= 0x7f; /* Mask to allow 0x80 -> 0.  */

	  if (unlikely (len > (size_t) (endp - valp)))

	    {

	      __libdw_seterrno (DWARF_E_INVALID_DWARF);

	      return -1;

	    }

	  return len;

	}

    }

  /* Other forms require some computation.  */

  return __libdw_form_val_compute_len (cu, form, valp);

}

/* Helper function for DW_FORM_ref* handling.  */

extern int __libdw_formref (Dwarf_Attribute *attr, Dwarf_Off *return_offset)

     __nonnull_attribute__ (1, 2) internal_function;

/* Helper function to locate attribute.  */

extern unsigned char *__libdw_find_attr (Dwarf_Die *die,

					 unsigned int search_name,

					 unsigned int *codep,

					 unsigned int *formp)

     __nonnull_attribute__ (1) internal_function;

/* Helper function to access integer attribute.  */

extern int __libdw_attr_intval (Dwarf_Die *die, int *valp, int attval)

     __nonnull_attribute__ (1, 2) internal_function;

/* Helper function to walk scopes.  */

struct Dwarf_Die_Chain

{

  Dwarf_Die die;

  struct Dwarf_Die_Chain *parent;

  bool prune;			/* The PREVISIT function can set this.  */

};

extern int __libdw_visit_scopes (unsigned int depth,

				 struct Dwarf_Die_Chain *root,

				 struct Dwarf_Die_Chain *imports,

				 int (*previsit) (unsigned int depth,

						  struct Dwarf_Die_Chain *,

						  void *arg),

				 int (*postvisit) (unsigned int depth,

						   struct Dwarf_Die_Chain *,

						   void *arg),

				 void *arg)

  __nonnull_attribute__ (2, 4) internal_function;

/* Parse a DWARF Dwarf_Block into an array of Dwarf_Op's,

   and cache the result (via tsearch).  */

extern int __libdw_intern_expression (Dwarf *dbg,

				      bool other_byte_order,

				      unsigned int address_size,

				      unsigned int ref_size,

				      void **cache, const Dwarf_Block *block,

				      bool cfap, bool valuep,

				      Dwarf_Op **llbuf, size_t *listlen,

				      int sec_index)

  __nonnull_attribute__ (5, 6, 9, 10) internal_function;

extern Dwarf_Die *__libdw_offdie (Dwarf *dbg, Dwarf_Off offset,

				  Dwarf_Die *result, bool debug_types)

  internal_function;

/* Return error code of last failing function call.  This value is kept

   separately for each thread.  */

extern int __dwarf_errno_internal (void);

/* Reader hooks.  */

/* Relocation hooks return -1 on error (in that case the error code

   must already have been set), 0 if there is no relocation and 1 if a

   relocation was present.*/

static inline int

__libdw_relocate_address (Dwarf *dbg __attribute__ ((unused)),

			  int sec_index __attribute__ ((unused)),

			  const void *addr __attribute__ ((unused)),

			  int width __attribute__ ((unused)),

			  Dwarf_Addr *val __attribute__ ((unused)))

{

  return 0;

}

static inline int

__libdw_relocate_offset (Dwarf *dbg __attribute__ ((unused)),

			 int sec_index __attribute__ ((unused)),

			 const void *addr __attribute__ ((unused)),

			 int width __attribute__ ((unused)),

			 Dwarf_Off *val __attribute__ ((unused)))

{

  return 0;

}

static inline Elf_Data *

__libdw_checked_get_data (Dwarf *dbg, int sec_index)

{

  Elf_Data *data = dbg->sectiondata[sec_index];

  if (unlikely (data == NULL)

      || unlikely (data->d_buf == NULL))

    {

      __libdw_seterrno (DWARF_E_INVALID_DWARF);

      return NULL;

    }

  return data;

}

static inline int

__libdw_offset_in_section (Dwarf *dbg, int sec_index,

			   Dwarf_Off offset, size_t size)

{

  Elf_Data *data = __libdw_checked_get_data (dbg, sec_index);

  if (data == NULL)

    return -1;

  if (unlikely (offset > data->d_size)

      || unlikely (data->d_size < size)

      || unlikely (offset > data->d_size - size))

    {

      __libdw_seterrno (DWARF_E_INVALID_OFFSET);

      return -1;

    }

  return 0;

}

static inline bool

__libdw_in_section (Dwarf *dbg, int sec_index,

		    const void *addr, size_t size)

{

  Elf_Data *data = __libdw_checked_get_data (dbg, sec_index);

  if (data == NULL)

    return false;

  if (unlikely (addr < data->d_buf)

      || unlikely (data->d_size < size)

      || unlikely ((size_t)(addr - data->d_buf) > data->d_size - size))

    {

      __libdw_seterrno (DWARF_E_INVALID_OFFSET);

      return false;

    }