libelf/elf_getshstrndx.c - platform/external/elfutils - Git at Google

 /* Return section index of section header string table.
    Copyright (C) 2002, 2005 Red Hat, Inc.
    This file is part of Red Hat elfutils.
    Written by Ulrich Drepper <drepper@redhat.com>, 2002.

    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 <assert.h>
 #include <errno.h>
 #include <gelf.h>
 #include <stddef.h>
 #include <unistd.h>

 #include <system.h>
 #include "libelfP.h"
 #include "common.h"


 int
 elf_getshstrndx (elf, dst)
      Elf *elf;
      size_t *dst;
 {
   int result = 0;

   if (elf == NULL)
     return -1;

   if (unlikely (elf->kind != ELF_K_ELF))
     {
       __libelf_seterrno (ELF_E_INVALID_HANDLE);
       return -1;
     }

   rwlock_rdlock (elf->lock);

   /* We rely here on the fact that the `elf' element is a common prefix
      of `elf32' and `elf64'.  */
   assert (offsetof (struct Elf, state.elf.ehdr)
 	  == offsetof (struct Elf, state.elf32.ehdr));
   assert (sizeof (elf->state.elf.ehdr)
 	  == sizeof (elf->state.elf32.ehdr));
   assert (offsetof (struct Elf, state.elf.ehdr)
 	  == offsetof (struct Elf, state.elf64.ehdr));
   assert (sizeof (elf->state.elf.ehdr)
 	  == sizeof (elf->state.elf64.ehdr));

   if (unlikely (elf->state.elf.ehdr == NULL))
     {
       __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
       result = -1;
     }
   else
     {
       Elf32_Word num;

       num = (elf->class == ELFCLASS32
 	     ? elf->state.elf32.ehdr->e_shstrndx
 	     : elf->state.elf64.ehdr->e_shstrndx);

       /* Determine whether the index is too big to fit in the ELF
 	 header.  */
       if (unlikely (num == SHN_XINDEX))
 	{
 	  /* Yes.  Search the zeroth section header.  */
 	  if (elf->class == ELFCLASS32)
 	    {
 	      size_t offset;

 	      if (elf->state.elf32.scns.data[0].shdr.e32 != NULL)
 		{
 		  num = elf->state.elf32.scns.data[0].shdr.e32->sh_link;
 		  goto success;
 		}

 	      offset = elf->state.elf32.ehdr->e_shoff;

 	      if (elf->map_address != NULL
 		  && elf->state.elf32.ehdr->e_ident[EI_DATA] == MY_ELFDATA
 		  && (ALLOW_UNALIGNED
 		      || (((size_t) ((char *) elf->map_address + offset))
 			  & (__alignof__ (Elf32_Shdr) - 1)) == 0))
 		/* We can directly access the memory.  */
 		num = ((Elf32_Shdr *) (elf->map_address + offset))->sh_link;
 	      else
 		{
 		  /* We avoid reading in all the section headers.  Just read
 		     the first one.  */
 		  Elf32_Shdr shdr_mem;

 		  if (unlikely (pread_retry (elf->fildes, &shdr_mem,
 					     sizeof (Elf32_Shdr), offset)
 				!= sizeof (Elf32_Shdr)))
 		    {
 		      /* We must be able to read this ELF section header.  */
 		      __libelf_seterrno (ELF_E_INVALID_FILE);
 		      result = -1;
 		      goto out;
 		    }

 		  if (elf->state.elf32.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
 		    CONVERT (shdr_mem.sh_link);
 		  num = shdr_mem.sh_link;
 		}
 	    }
 	  else
 	    {
 	      if (elf->state.elf64.scns.data[0].shdr.e64 != NULL)
 		{
 		  num = elf->state.elf64.scns.data[0].shdr.e64->sh_link;
 		  goto success;
 		}

 	      size_t offset = elf->state.elf64.ehdr->e_shoff;

 	      if (elf->map_address != NULL
 		  && elf->state.elf64.ehdr->e_ident[EI_DATA] == MY_ELFDATA
 		  && (ALLOW_UNALIGNED
 		      || (((size_t) ((char *) elf->map_address + offset))
 			  & (__alignof__ (Elf64_Shdr) - 1)) == 0))
 		/* We can directly access the memory.  */
 		num = ((Elf64_Shdr *) (elf->map_address + offset))->sh_link;
 	      else
 		{
 		  /* We avoid reading in all the section headers.  Just read
 		     the first one.  */
 		  Elf64_Shdr shdr_mem;

 		  if (unlikely (pread_retry (elf->fildes, &shdr_mem,
 					     sizeof (Elf64_Shdr), offset)
 				!= sizeof (Elf64_Shdr)))
 		    {
 		      /* We must be able to read this ELF section header.  */
 		      __libelf_seterrno (ELF_E_INVALID_FILE);
 		      result = -1;
 		      goto out;
 		    }

 		  if (elf->state.elf64.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
 		    CONVERT (shdr_mem.sh_link);
 		  num = shdr_mem.sh_link;
 		}
 	    }
 	}

       /* Store the result.  */
     success:
       *dst = num;
     }

  out:
   rwlock_unlock (elf->lock);

   return result;
 }
 INTDEF(elf_getshstrndx)
	/* Return section index of section header string table.
	Copyright (C) 2002, 2005 Red Hat, Inc.
	This file is part of Red Hat elfutils.
	Written by Ulrich Drepper <drepper@redhat.com>, 2002.

	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 <assert.h>
	#include <errno.h>
	#include <gelf.h>
	#include <stddef.h>
	#include <unistd.h>

	#include <system.h>
	#include "libelfP.h"
	#include "common.h"


	int
	elf_getshstrndx (elf, dst)
	Elf *elf;
	size_t *dst;
	{
	int result = 0;

	if (elf == NULL)
	return -1;

	if (unlikely (elf->kind != ELF_K_ELF))
	{
	__libelf_seterrno (ELF_E_INVALID_HANDLE);
	return -1;
	}

	rwlock_rdlock (elf->lock);

	/* We rely here on the fact that the `elf' element is a common prefix
	of `elf32' and `elf64'. */
	assert (offsetof (struct Elf, state.elf.ehdr)
	== offsetof (struct Elf, state.elf32.ehdr));
	assert (sizeof (elf->state.elf.ehdr)
	== sizeof (elf->state.elf32.ehdr));
	assert (offsetof (struct Elf, state.elf.ehdr)
	== offsetof (struct Elf, state.elf64.ehdr));
	assert (sizeof (elf->state.elf.ehdr)
	== sizeof (elf->state.elf64.ehdr));

	if (unlikely (elf->state.elf.ehdr == NULL))
	{
	__libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
	result = -1;
	}
	else
	{
	Elf32_Word num;

	num = (elf->class == ELFCLASS32
	? elf->state.elf32.ehdr->e_shstrndx
	: elf->state.elf64.ehdr->e_shstrndx);

	/* Determine whether the index is too big to fit in the ELF
	header. */
	if (unlikely (num == SHN_XINDEX))
	{
	/* Yes. Search the zeroth section header. */
	if (elf->class == ELFCLASS32)
	{
	size_t offset;

	if (elf->state.elf32.scns.data[0].shdr.e32 != NULL)
	{
	num = elf->state.elf32.scns.data[0].shdr.e32->sh_link;
	goto success;
	}

	offset = elf->state.elf32.ehdr->e_shoff;

	if (elf->map_address != NULL
	&& elf->state.elf32.ehdr->e_ident[EI_DATA] == MY_ELFDATA
	&& (ALLOW_UNALIGNED
	\|\| (((size_t) ((char *) elf->map_address + offset))
	& (__alignof__ (Elf32_Shdr) - 1)) == 0))
	/* We can directly access the memory. */
	num = ((Elf32_Shdr *) (elf->map_address + offset))->sh_link;
	else
	{
	/* We avoid reading in all the section headers. Just read
	the first one. */
	Elf32_Shdr shdr_mem;

	if (unlikely (pread_retry (elf->fildes, &shdr_mem,
	sizeof (Elf32_Shdr), offset)
	!= sizeof (Elf32_Shdr)))
	{
	/* We must be able to read this ELF section header. */
	__libelf_seterrno (ELF_E_INVALID_FILE);
	result = -1;
	goto out;
	}

	if (elf->state.elf32.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
	CONVERT (shdr_mem.sh_link);
	num = shdr_mem.sh_link;
	}
	}
	else
	{
	if (elf->state.elf64.scns.data[0].shdr.e64 != NULL)
	{
	num = elf->state.elf64.scns.data[0].shdr.e64->sh_link;
	goto success;
	}

	size_t offset = elf->state.elf64.ehdr->e_shoff;

	if (elf->map_address != NULL
	&& elf->state.elf64.ehdr->e_ident[EI_DATA] == MY_ELFDATA
	&& (ALLOW_UNALIGNED
	\|\| (((size_t) ((char *) elf->map_address + offset))
	& (__alignof__ (Elf64_Shdr) - 1)) == 0))
	/* We can directly access the memory. */
	num = ((Elf64_Shdr *) (elf->map_address + offset))->sh_link;
	else
	{
	/* We avoid reading in all the section headers. Just read
	the first one. */
	Elf64_Shdr shdr_mem;

	if (unlikely (pread_retry (elf->fildes, &shdr_mem,
	sizeof (Elf64_Shdr), offset)
	!= sizeof (Elf64_Shdr)))
	{
	/* We must be able to read this ELF section header. */
	__libelf_seterrno (ELF_E_INVALID_FILE);
	result = -1;
	goto out;
	}

	if (elf->state.elf64.ehdr->e_ident[EI_DATA] != MY_ELFDATA)
	CONVERT (shdr_mem.sh_link);
	num = shdr_mem.sh_link;
	}
	}
	}

	/* Store the result. */
	success:
	*dst = num;
	}

	out:
	rwlock_unlock (elf->lock);

	return result;
	}
	INTDEF(elf_getshstrndx)