src/libdw/dwarf_next_cfi.c - fp2-dev/platform/external/elfutils - Gitiles

 /* Advance to next CFI entry.
    Copyright (C) 2009-2010 Red Hat, Inc.
    This file is part of Red Hat elfutils.

    Red Hat elfutils 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; version 2 of the License.

    Red Hat 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 a copy of the GNU General Public License along
    with Red Hat elfutils; if not, write to the Free Software Foundation,
    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

    In addition, as a special exception, Red Hat, Inc. gives You the
    additional right to link the code of Red Hat elfutils with code licensed
    under any Open Source Initiative certified open source license
    (http://www.opensource.org/licenses/index.php) which requires the
    distribution of source code with any binary distribution and to
    distribute linked combinations of the two.  Non-GPL Code permitted under
    this exception must only link to the code of Red Hat elfutils through
    those well defined interfaces identified in the file named EXCEPTION
    found in the source code files (the "Approved Interfaces").  The files
    of Non-GPL Code may instantiate templates or use macros or inline
    functions from the Approved Interfaces without causing the resulting
    work to be covered by the GNU General Public License.  Only Red Hat,
    Inc. may make changes or additions to the list of Approved Interfaces.
    Red Hat's grant of this exception is conditioned upon your not adding
    any new exceptions.  If you wish to add a new Approved Interface or
    exception, please contact Red Hat.  You must obey the GNU General Public
    License in all respects for all of the Red Hat elfutils code and other
    code used in conjunction with Red Hat elfutils except the Non-GPL Code
    covered by this exception.  If you modify this file, you may extend this
    exception to your version of the file, but you are not obligated to do
    so.  If you do not wish to provide this exception without modification,
    you must delete this exception statement from your version and license
    this file solely under the GPL without exception.

    Red Hat elfutils is an included package of the Open Invention Network.
    An included package of the Open Invention Network is a package for which
    Open Invention Network licensees cross-license their patents.  No patent
    license is granted, either expressly or impliedly, by designation as an
    included package.  Should you wish to participate in the Open Invention
    Network licensing program, please visit www.openinventionnetwork.com
    <http://www.openinventionnetwork.com>.  */

 #ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif

 #include "cfi.h"
 #include "encoded-value.h"

 #include <string.h>


 int
 dwarf_next_cfi (e_ident, data, eh_frame_p, off, next_off, entry)
      const unsigned char e_ident[];
      Elf_Data *data;
      bool eh_frame_p;
      Dwarf_Off off;
      Dwarf_Off *next_off;
      Dwarf_CFI_Entry *entry;
 {
   /* Dummy struct for memory-access.h macros.  */
   BYTE_ORDER_DUMMY (dw, e_ident);

   /* If we reached the end before don't do anything.  */
   if (off == (Dwarf_Off) -1l
       /* Make sure there is enough space in the .debug_frame section
 	 for at least the initial word.  We cannot test the rest since
 	 we don't know yet whether this is a 64-bit object or not.  */
       || unlikely (off + 4 >= data->d_size))
     {
       *next_off = (Dwarf_Off) -1l;
       return 1;
     }

   /* This points into the .debug_frame section at the start of the entry.  */
   const uint8_t *bytes = data->d_buf + off;
   const uint8_t *limit = data->d_buf + data->d_size;

   /* The format of a CFI entry is described in DWARF3 6.4.1:
    */

   uint64_t length = read_4ubyte_unaligned_inc (&dw, bytes);
   size_t offset_size = 4;
   if (length == DWARF3_LENGTH_64_BIT)
     {
       /* This is the 64-bit DWARF format.  */
       offset_size = 8;
       if (unlikely (limit - bytes < 8))
 	{
 	invalid:
 	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
 	  return -1;
 	}
       length = read_8ubyte_unaligned_inc (&dw, bytes);
     }
   if (unlikely ((uint64_t) (limit - bytes) < length)
       || unlikely (length < offset_size + 1))
     goto invalid;

   /* Now we know how large the entry is.  Note the trick in the
      computation.  If the offset_size is 4 the '- 4' term undoes the
      '2 *'.  If offset_size is 8 this term computes the size of the
      escape value plus the 8 byte offset.  */
   *next_off = off + (2 * offset_size - 4) + length;

   limit = bytes + length;

   const uint8_t *const cie_pointer_start = bytes;
   if (offset_size == 8)
     entry->cie.CIE_id = read_8ubyte_unaligned_inc (&dw, bytes);
   else
     {
       entry->cie.CIE_id = read_4ubyte_unaligned_inc (&dw, bytes);
       /* Canonicalize the 32-bit CIE_ID value to 64 bits.  */
       if (!eh_frame_p && entry->cie.CIE_id == DW_CIE_ID_32)
 	entry->cie.CIE_id = DW_CIE_ID_64;
     }
   if (eh_frame_p)
     {
       /* Canonicalize the .eh_frame CIE pointer to .debug_frame format.  */
       if (entry->cie.CIE_id == 0)
 	entry->cie.CIE_id = DW_CIE_ID_64;
       else
 	{
 	  /* In .eh_frame format, a CIE pointer is the distance from where
 	     it appears back to the beginning of the CIE.  */
 	  ptrdiff_t pos = cie_pointer_start - (const uint8_t *) data->d_buf;
 	  if (unlikely (entry->cie.CIE_id > (Dwarf_Off) pos)
 	      || unlikely (pos <= (ptrdiff_t) offset_size))
 	    goto invalid;
 	  entry->cie.CIE_id = pos - entry->cie.CIE_id;
 	}
     }

   if (entry->cie.CIE_id == DW_CIE_ID_64)
     {
       /* Read the version stamp.  Always an 8-bit value.  */
       uint8_t version = *bytes++;

       if (version != 1 && (unlikely (version < 3) || unlikely (version > 4)))
 	goto invalid;

       entry->cie.augmentation = (const char *) bytes;

       bytes = memchr (bytes, '\0', limit - bytes);
       if (unlikely (bytes == NULL))
 	goto invalid;
       ++bytes;

       /* The address size for CFI is implicit in the ELF class.  */
       uint_fast8_t address_size = e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
       uint_fast8_t segment_size = 0;
       if (version >= 4)
 	{
 	  if (unlikely (limit - bytes < 5))
 	    goto invalid;
 	  /* XXX We don't actually support address_size not matching the class.
 	     To do so, we'd have to return it here so that intern_new_cie
 	     could use it choose a specific fde_encoding.  */
 	  if (unlikely (*bytes != address_size))
 	    {
 	      __libdw_seterrno (DWARF_E_VERSION);
 	      return -1;
 	    }
 	  address_size = *bytes++;
 	  segment_size = *bytes++;
 	  /* We don't actually support segment selectors.  We'd have to
 	     roll this into the fde_encoding bits or something.  */
 	  if (unlikely (segment_size != 0))
 	    {
 	      __libdw_seterrno (DWARF_E_VERSION);
 	      return -1;
 	    }
 	}

       const char *ap = entry->cie.augmentation;

       /* g++ v2 "eh" has pointer immediately following augmentation string,
 	 so it must be handled first.  */
       if (unlikely (ap[0] == 'e' && ap[1] == 'h'))
 	{
 	  ap += 2;
 	  bytes += address_size;
 	}

       get_uleb128 (entry->cie.code_alignment_factor, bytes);
       get_sleb128 (entry->cie.data_alignment_factor, bytes);

       if (version >= 3)		/* DWARF 3+ */
 	get_uleb128 (entry->cie.return_address_register, bytes);
       else			/* DWARF 2 */
 	entry->cie.return_address_register = *bytes++;

       /* If we have sized augmentation data,
 	 we don't need to grok it all.  */
       entry->cie.fde_augmentation_data_size = 0;
       bool sized_augmentation = *ap == 'z';
       if (sized_augmentation)
 	{
 	  get_uleb128 (entry->cie.augmentation_data_size, bytes);
 	  if ((Dwarf_Word) (limit - bytes) < entry->cie.augmentation_data_size)
 	    goto invalid;
 	  entry->cie.augmentation_data = bytes;
 	  bytes += entry->cie.augmentation_data_size;
 	}
       else
 	{
 	  entry->cie.augmentation_data = bytes;

 	  for (; *ap != '\0'; ++ap)
 	    {
 	      uint8_t encoding;
 	      switch (*ap)
 		{
 		case 'L':		/* Skip LSDA pointer encoding byte.  */
 		case 'R':		/* Skip FDE address encoding byte.  */
 		  encoding = *bytes++;
 		  entry->cie.fde_augmentation_data_size
 		    += encoded_value_size (data, e_ident, encoding, NULL);
 		  continue;
 		case 'P':   /* Skip encoded personality routine pointer. */
 		  encoding = *bytes++;
 		  bytes += encoded_value_size (data, e_ident, encoding, bytes);
 		  continue;
 		case 'S':		/* Skip signal-frame flag.  */
 		  continue;
 		default:
 		  /* Unknown augmentation string.  initial_instructions might
 		     actually start with some augmentation data.  */
 		  break;
 		}
 	      break;
 	    }
 	  entry->cie.augmentation_data_size
 	    = bytes - entry->cie.augmentation_data;
 	}

       entry->cie.initial_instructions = bytes;
       entry->cie.initial_instructions_end = limit;
     }
   else
     {
       entry->fde.start = bytes;
       entry->fde.end = limit;
     }

   return 0;
 }
 INTDEF (dwarf_next_cfi)
	/* Advance to next CFI entry.
	Copyright (C) 2009-2010 Red Hat, Inc.
	This file is part of Red Hat elfutils.

	Red Hat elfutils 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; version 2 of the License.

	Red Hat 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 a copy of the GNU General Public License along
	with Red Hat elfutils; if not, write to the Free Software Foundation,
	Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

	In addition, as a special exception, Red Hat, Inc. gives You the
	additional right to link the code of Red Hat elfutils with code licensed
	under any Open Source Initiative certified open source license
	(http://www.opensource.org/licenses/index.php) which requires the
	distribution of source code with any binary distribution and to
	distribute linked combinations of the two. Non-GPL Code permitted under
	this exception must only link to the code of Red Hat elfutils through
	those well defined interfaces identified in the file named EXCEPTION
	found in the source code files (the "Approved Interfaces"). The files
	of Non-GPL Code may instantiate templates or use macros or inline
	functions from the Approved Interfaces without causing the resulting
	work to be covered by the GNU General Public License. Only Red Hat,
	Inc. may make changes or additions to the list of Approved Interfaces.
	Red Hat's grant of this exception is conditioned upon your not adding
	any new exceptions. If you wish to add a new Approved Interface or
	exception, please contact Red Hat. You must obey the GNU General Public
	License in all respects for all of the Red Hat elfutils code and other
	code used in conjunction with Red Hat elfutils except the Non-GPL Code
	covered by this exception. If you modify this file, you may extend this
	exception to your version of the file, but you are not obligated to do
	so. If you do not wish to provide this exception without modification,
	you must delete this exception statement from your version and license
	this file solely under the GPL without exception.

	Red Hat elfutils is an included package of the Open Invention Network.
	An included package of the Open Invention Network is a package for which
	Open Invention Network licensees cross-license their patents. No patent
	license is granted, either expressly or impliedly, by designation as an
	included package. Should you wish to participate in the Open Invention
	Network licensing program, please visit www.openinventionnetwork.com
	<http://www.openinventionnetwork.com>. */

	#ifdef HAVE_CONFIG_H
	# include <config.h>
	#endif

	#include "cfi.h"
	#include "encoded-value.h"

	#include <string.h>


	int
	dwarf_next_cfi (e_ident, data, eh_frame_p, off, next_off, entry)
	const unsigned char e_ident[];
	Elf_Data *data;
	bool eh_frame_p;
	Dwarf_Off off;
	Dwarf_Off *next_off;
	Dwarf_CFI_Entry *entry;
	{
	/* Dummy struct for memory-access.h macros. */
	BYTE_ORDER_DUMMY (dw, e_ident);

	/* If we reached the end before don't do anything. */
	if (off == (Dwarf_Off) -1l
	/* Make sure there is enough space in the .debug_frame section
	for at least the initial word. We cannot test the rest since
	we don't know yet whether this is a 64-bit object or not. */
	\|\| unlikely (off + 4 >= data->d_size))
	{
	*next_off = (Dwarf_Off) -1l;
	return 1;
	}

	/* This points into the .debug_frame section at the start of the entry. */
	const uint8_t *bytes = data->d_buf + off;
	const uint8_t *limit = data->d_buf + data->d_size;

	/* The format of a CFI entry is described in DWARF3 6.4.1:
	*/

	uint64_t length = read_4ubyte_unaligned_inc (&dw, bytes);
	size_t offset_size = 4;
	if (length == DWARF3_LENGTH_64_BIT)
	{
	/* This is the 64-bit DWARF format. */
	offset_size = 8;
	if (unlikely (limit - bytes < 8))
	{
	invalid:
	__libdw_seterrno (DWARF_E_INVALID_DWARF);
	return -1;
	}
	length = read_8ubyte_unaligned_inc (&dw, bytes);
	}
	if (unlikely ((uint64_t) (limit - bytes) < length)
	\|\| unlikely (length < offset_size + 1))
	goto invalid;

	/* Now we know how large the entry is. Note the trick in the
	computation. If the offset_size is 4 the '- 4' term undoes the
	'2 *'. If offset_size is 8 this term computes the size of the
	escape value plus the 8 byte offset. */
	next_off = off + (2 offset_size - 4) + length;

	limit = bytes + length;

	const uint8_t *const cie_pointer_start = bytes;
	if (offset_size == 8)
	entry->cie.CIE_id = read_8ubyte_unaligned_inc (&dw, bytes);
	else
	{
	entry->cie.CIE_id = read_4ubyte_unaligned_inc (&dw, bytes);
	/* Canonicalize the 32-bit CIE_ID value to 64 bits. */
	if (!eh_frame_p && entry->cie.CIE_id == DW_CIE_ID_32)
	entry->cie.CIE_id = DW_CIE_ID_64;
	}
	if (eh_frame_p)
	{
	/* Canonicalize the .eh_frame CIE pointer to .debug_frame format. */
	if (entry->cie.CIE_id == 0)
	entry->cie.CIE_id = DW_CIE_ID_64;
	else
	{
	/* In .eh_frame format, a CIE pointer is the distance from where
	it appears back to the beginning of the CIE. */
	ptrdiff_t pos = cie_pointer_start - (const uint8_t *) data->d_buf;
	if (unlikely (entry->cie.CIE_id > (Dwarf_Off) pos)
	\|\| unlikely (pos <= (ptrdiff_t) offset_size))
	goto invalid;
	entry->cie.CIE_id = pos - entry->cie.CIE_id;
	}
	}

	if (entry->cie.CIE_id == DW_CIE_ID_64)
	{
	/* Read the version stamp. Always an 8-bit value. */
	uint8_t version = *bytes++;

	if (version != 1 && (unlikely (version < 3) \|\| unlikely (version > 4)))
	goto invalid;

	entry->cie.augmentation = (const char *) bytes;

	bytes = memchr (bytes, '\0', limit - bytes);
	if (unlikely (bytes == NULL))
	goto invalid;
	++bytes;

	/* The address size for CFI is implicit in the ELF class. */
	uint_fast8_t address_size = e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
	uint_fast8_t segment_size = 0;
	if (version >= 4)
	{
	if (unlikely (limit - bytes < 5))
	goto invalid;
	/* XXX We don't actually support address_size not matching the class.
	To do so, we'd have to return it here so that intern_new_cie
	could use it choose a specific fde_encoding. */
	if (unlikely (*bytes != address_size))
	{
	__libdw_seterrno (DWARF_E_VERSION);
	return -1;
	}
	address_size = *bytes++;
	segment_size = *bytes++;
	/* We don't actually support segment selectors. We'd have to
	roll this into the fde_encoding bits or something. */
	if (unlikely (segment_size != 0))
	{
	__libdw_seterrno (DWARF_E_VERSION);
	return -1;
	}
	}

	const char *ap = entry->cie.augmentation;

	/* g++ v2 "eh" has pointer immediately following augmentation string,
	so it must be handled first. */
	if (unlikely (ap[0] == 'e' && ap[1] == 'h'))
	{
	ap += 2;
	bytes += address_size;
	}

	get_uleb128 (entry->cie.code_alignment_factor, bytes);
	get_sleb128 (entry->cie.data_alignment_factor, bytes);

	if (version >= 3) /* DWARF 3+ */
	get_uleb128 (entry->cie.return_address_register, bytes);
	else /* DWARF 2 */
	entry->cie.return_address_register = *bytes++;

	/* If we have sized augmentation data,
	we don't need to grok it all. */
	entry->cie.fde_augmentation_data_size = 0;
	bool sized_augmentation = *ap == 'z';
	if (sized_augmentation)
	{
	get_uleb128 (entry->cie.augmentation_data_size, bytes);
	if ((Dwarf_Word) (limit - bytes) < entry->cie.augmentation_data_size)
	goto invalid;
	entry->cie.augmentation_data = bytes;
	bytes += entry->cie.augmentation_data_size;
	}
	else
	{
	entry->cie.augmentation_data = bytes;

	for (; *ap != '\0'; ++ap)
	{
	uint8_t encoding;
	switch (*ap)
	{
	case 'L': /* Skip LSDA pointer encoding byte. */
	case 'R': /* Skip FDE address encoding byte. */
	encoding = *bytes++;
	entry->cie.fde_augmentation_data_size
	+= encoded_value_size (data, e_ident, encoding, NULL);
	continue;
	case 'P': /* Skip encoded personality routine pointer. */
	encoding = *bytes++;
	bytes += encoded_value_size (data, e_ident, encoding, bytes);
	continue;
	case 'S': /* Skip signal-frame flag. */
	continue;
	default:
	/* Unknown augmentation string. initial_instructions might
	actually start with some augmentation data. */
	break;
	}
	break;
	}
	entry->cie.augmentation_data_size
	= bytes - entry->cie.augmentation_data;
	}

	entry->cie.initial_instructions = bytes;
	entry->cie.initial_instructions_end = limit;
	}
	else
	{
	entry->fde.start = bytes;
	entry->fde.end = limit;
	}

	return 0;
	}
	INTDEF (dwarf_next_cfi)