libelf/elf_getshdrstrndx.c - external/elfutils - Git at Google

 /* Return section index of section header string table.
    Copyright (C) 2002, 2005, 2009, 2014, 2015 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <drepper@redhat.com>, 2002.

    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/>.  */

 #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_getshdrstrndx (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 (unlikely (elf->state.elf32.scns.cnt == 0))
 		{
 		  /* Cannot use SHN_XINDEX without section headers.  */
 		  __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
 		  result = -1;
 		  goto out;
 		}

 	      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
 			   + elf->start_offset + offset))
 			  & (__alignof__ (Elf32_Shdr) - 1)) == 0))
 		{
 		  /* First see whether the information in the ELF header is
 		     valid and it does not ask for too much.  */
 		  if (unlikely (elf->maximum_size - offset
 				< sizeof (Elf32_Shdr)))
 		    {
 		      /* Something is wrong.  */
 		      __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
 		      result = -1;
 		      goto out;
 		    }

 		  /* We can directly access the memory.  */
 		  num = ((Elf32_Shdr *) (elf->map_address + elf->start_offset
 					 + offset))->sh_link;
 		}
 	      else
 		{
 		  /* We avoid reading in all the section headers.  Just read
 		     the first one.  */
 		  Elf32_Shdr shdr_mem;
 		  ssize_t r;

 		  if (unlikely ((r = pread_retry (elf->fildes, &shdr_mem,
 						  sizeof (Elf32_Shdr), offset))
 				!= sizeof (Elf32_Shdr)))
 		    {
 		      /* We must be able to read this ELF section header.  */
 		      if (r < 0)
 			__libelf_seterrno (ELF_E_INVALID_FILE);
 		      else
 			__libelf_seterrno (ELF_E_INVALID_ELF);
 		      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 (unlikely (elf->state.elf64.scns.cnt == 0))
 		{
 		  /* Cannot use SHN_XINDEX without section headers.  */
 		  __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
 		  result = -1;
 		  goto out;
 		}

 	      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
 			   + elf->start_offset + offset))
 			  & (__alignof__ (Elf64_Shdr) - 1)) == 0))
 		{
 		  /* First see whether the information in the ELF header is
 		     valid and it does not ask for too much.  */
 		  if (unlikely (elf->maximum_size - offset
 				< sizeof (Elf64_Shdr)))
 		    {
 		      /* Something is wrong.  */
 		      __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
 		      result = -1;
 		      goto out;
 		    }

 		  /* We can directly access the memory.  */
 		  num = ((Elf64_Shdr *) (elf->map_address + elf->start_offset
 					 + offset))->sh_link;
 		}
 	      else
 		{
 		  /* We avoid reading in all the section headers.  Just read
 		     the first one.  */
 		  Elf64_Shdr shdr_mem;
 		  ssize_t r;

 		  if (unlikely ((r = pread_retry (elf->fildes, &shdr_mem,
 						  sizeof (Elf64_Shdr), offset))
 				!= sizeof (Elf64_Shdr)))
 		    {
 		      /* We must be able to read this ELF section header.  */
 		      if (r < 0)
 			__libelf_seterrno (ELF_E_INVALID_FILE);
 		      else
 			__libelf_seterrno (ELF_E_INVALID_ELF);
 		      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_getshdrstrndx)
 /* Alias for the deprecated name.  */
 strong_alias (elf_getshdrstrndx, elf_getshstrndx)
	/* Return section index of section header string table.
	Copyright (C) 2002, 2005, 2009, 2014, 2015 Red Hat, Inc.
	This file is part of elfutils.
	Written by Ulrich Drepper <drepper@redhat.com>, 2002.

	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/>. */

	#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_getshdrstrndx (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 (unlikely (elf->state.elf32.scns.cnt == 0))
	{
	/* Cannot use SHN_XINDEX without section headers. */
	__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
	result = -1;
	goto out;
	}

	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
	+ elf->start_offset + offset))
	& (__alignof__ (Elf32_Shdr) - 1)) == 0))
	{
	/* First see whether the information in the ELF header is
	valid and it does not ask for too much. */
	if (unlikely (elf->maximum_size - offset
	< sizeof (Elf32_Shdr)))
	{
	/* Something is wrong. */
	__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
	result = -1;
	goto out;
	}

	/* We can directly access the memory. */
	num = ((Elf32_Shdr *) (elf->map_address + elf->start_offset
	+ offset))->sh_link;
	}
	else
	{
	/* We avoid reading in all the section headers. Just read
	the first one. */
	Elf32_Shdr shdr_mem;
	ssize_t r;

	if (unlikely ((r = pread_retry (elf->fildes, &shdr_mem,
	sizeof (Elf32_Shdr), offset))
	!= sizeof (Elf32_Shdr)))
	{
	/* We must be able to read this ELF section header. */
	if (r < 0)
	__libelf_seterrno (ELF_E_INVALID_FILE);
	else
	__libelf_seterrno (ELF_E_INVALID_ELF);
	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 (unlikely (elf->state.elf64.scns.cnt == 0))
	{
	/* Cannot use SHN_XINDEX without section headers. */
	__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
	result = -1;
	goto out;
	}

	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
	+ elf->start_offset + offset))
	& (__alignof__ (Elf64_Shdr) - 1)) == 0))
	{
	/* First see whether the information in the ELF header is
	valid and it does not ask for too much. */
	if (unlikely (elf->maximum_size - offset
	< sizeof (Elf64_Shdr)))
	{
	/* Something is wrong. */
	__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
	result = -1;
	goto out;
	}

	/* We can directly access the memory. */
	num = ((Elf64_Shdr *) (elf->map_address + elf->start_offset
	+ offset))->sh_link;
	}
	else
	{
	/* We avoid reading in all the section headers. Just read
	the first one. */
	Elf64_Shdr shdr_mem;
	ssize_t r;

	if (unlikely ((r = pread_retry (elf->fildes, &shdr_mem,
	sizeof (Elf64_Shdr), offset))
	!= sizeof (Elf64_Shdr)))
	{
	/* We must be able to read this ELF section header. */
	if (r < 0)
	__libelf_seterrno (ELF_E_INVALID_FILE);
	else
	__libelf_seterrno (ELF_E_INVALID_ELF);
	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_getshdrstrndx)
	/* Alias for the deprecated name. */
	strong_alias (elf_getshdrstrndx, elf_getshstrndx)