/* 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)