Line data    Source code

       1             : /* Get information from auxiliary vector at the given index.
       2             :    Copyright (C) 2007, 2015 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             : 
       5             :    This file is free software; you can redistribute it and/or modify
       6             :    it under the terms of either
       7             : 
       8             :      * the GNU Lesser General Public License as published by the Free
       9             :        Software Foundation; either version 3 of the License, or (at
      10             :        your option) any later version
      11             : 
      12             :    or
      13             : 
      14             :      * the GNU General Public License as published by the Free
      15             :        Software Foundation; either version 2 of the License, or (at
      16             :        your option) any later version
      17             : 
      18             :    or both in parallel, as here.
      19             : 
      20             :    elfutils is distributed in the hope that it will be useful, but
      21             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23             :    General Public License for more details.
      24             : 
      25             :    You should have received copies of the GNU General Public License and
      26             :    the GNU Lesser General Public License along with this program.  If
      27             :    not, see <http://www.gnu.org/licenses/>.  */
      28             : 
      29             : #ifdef HAVE_CONFIG_H
      30             : # include <config.h>
      31             : #endif
      32             : 
      33             : #include <assert.h>
      34             : #include <gelf.h>
      35             : #include <string.h>
      36             : 
      37             : #include "libelfP.h"
      38             : 
      39             : 
      40             : GElf_auxv_t *
      41         168 : gelf_getauxv (Elf_Data *data, int ndx, GElf_auxv_t *dst)
      42             : {
      43         168 :   Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
      44         168 :   GElf_auxv_t *result = NULL;
      45             :   Elf *elf;
      46             : 
      47         168 :   if (data_scn == NULL)
      48             :     return NULL;
      49             : 
      50         168 :   if (unlikely (data_scn->d.d_type != ELF_T_AUXV))
      51             :     {
      52           0 :       __libelf_seterrno (ELF_E_INVALID_HANDLE);
      53           0 :       return NULL;
      54             :     }
      55             : 
      56         168 :   elf = data_scn->s->elf;
      57             : 
      58             :   rwlock_rdlock (elf->lock);
      59             : 
      60             :   /* This is the one place where we have to take advantage of the fact
      61             :      that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
      62             :      The interface is broken so that it requires this hack.  */
      63         168 :   if (elf->class == ELFCLASS32)
      64             :     {
      65             :       Elf32_auxv_t *src;
      66             : 
      67             :       /* Here it gets a bit more complicated.  The format of the vector
      68             :          entries has to be converted.  The user better have provided a
      69             :          buffer where we can store the information.  While copying the data
      70             :          we convert the format.  */
      71          93 :       if (unlikely ((ndx + 1) * sizeof (Elf32_auxv_t) > data_scn->d.d_size))
      72             :         {
      73           0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      74           0 :           goto out;
      75             :         }
      76             : 
      77          93 :       src = &((Elf32_auxv_t *) data_scn->d.d_buf)[ndx];
      78             : 
      79             :       /* This might look like a simple copy operation but it's
      80             :          not.  There are zero- and sign-extensions going on.  */
      81          93 :       dst->a_type = src->a_type;
      82          93 :       dst->a_un.a_val = src->a_un.a_val;
      83             :     }
      84             :   else
      85             :     {
      86             :       /* If this is a 64 bit object it's easy.  */
      87             :       assert (sizeof (GElf_auxv_t) == sizeof (Elf64_auxv_t));
      88             : 
      89             :       /* The data is already in the correct form.  Just make sure the
      90             :          index is OK.  */
      91          75 :       if (unlikely ((ndx + 1) * sizeof (GElf_auxv_t) > data_scn->d.d_size))
      92             :         {
      93           0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      94           0 :           goto out;
      95             :         }
      96             : 
      97          75 :       memcpy (dst, data_scn->d.d_buf + ndx * sizeof (GElf_auxv_t),
      98             :               sizeof (GElf_auxv_t));
      99             :     }
     100             : 
     101             :   result = dst;
     102             : 
     103             :  out:
     104             :   rwlock_unlock (elf->lock);
     105             : 
     106             :   return result;
     107             : }