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       1                 :            : /* Get information from auxiliary vector at the given index.
       2                 :            :    Copyright (C) 2007 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                 :         56 : gelf_getauxv (data, ndx, dst)
      42                 :            :      Elf_Data *data;
      43                 :            :      int ndx;
      44                 :            :      GElf_auxv_t *dst;
      45                 :            : {
      46                 :         56 :   Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;
      47                 :         56 :   GElf_auxv_t *result = NULL;
      48                 :            :   Elf *elf;
      49                 :            : 
      50         [ +  - ]:         56 :   if (data_scn == NULL)
      51                 :            :     return NULL;
      52                 :            : 
      53         [ -  + ]:         56 :   if (unlikely (data_scn->d.d_type != ELF_T_AUXV))
      54                 :            :     {
      55                 :          0 :       __libelf_seterrno (ELF_E_INVALID_HANDLE);
      56                 :          0 :       return NULL;
      57                 :            :     }
      58                 :            : 
      59                 :         56 :   elf = data_scn->s->elf;
      60                 :            : 
      61                 :            :   rwlock_rdlock (elf->lock);
      62                 :            : 
      63                 :            :   /* This is the one place where we have to take advantage of the fact
      64                 :            :      that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.
      65                 :            :      The interface is broken so that it requires this hack.  */
      66         [ +  + ]:         56 :   if (elf->class == ELFCLASS32)
      67                 :            :     {
      68                 :            :       Elf32_auxv_t *src;
      69                 :            : 
      70                 :            :       /* Here it gets a bit more complicated.  The format of the vector
      71                 :            :          entries has to be converted.  The user better have provided a
      72                 :            :          buffer where we can store the information.  While copying the data
      73                 :            :          we convert the format.  */
      74         [ -  + ]:         37 :       if (unlikely ((ndx + 1) * sizeof (Elf32_auxv_t) > data_scn->d.d_size))
      75                 :            :         {
      76                 :          0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      77                 :          0 :           goto out;
      78                 :            :         }
      79                 :            : 
      80                 :         37 :       src = &((Elf32_auxv_t *) data_scn->d.d_buf)[ndx];
      81                 :            : 
      82                 :            :       /* This might look like a simple copy operation but it's
      83                 :            :          not.  There are zero- and sign-extensions going on.  */
      84                 :         37 :       dst->a_type = src->a_type;
      85                 :         37 :       dst->a_un.a_val = src->a_un.a_val;
      86                 :            :     }
      87                 :            :   else
      88                 :            :     {
      89                 :            :       /* If this is a 64 bit object it's easy.  */
      90                 :            :       assert (sizeof (GElf_auxv_t) == sizeof (Elf64_auxv_t));
      91                 :            : 
      92                 :            :       /* The data is already in the correct form.  Just make sure the
      93                 :            :          index is OK.  */
      94         [ -  + ]:         19 :       if (unlikely ((ndx + 1) * sizeof (GElf_auxv_t) > data_scn->d.d_size))
      95                 :            :         {
      96                 :          0 :           __libelf_seterrno (ELF_E_INVALID_INDEX);
      97                 :          0 :           goto out;
      98                 :            :         }
      99                 :            : 
     100                 :         19 :       *dst = ((GElf_auxv_t *) data_scn->d.d_buf)[ndx];
     101                 :            :     }
     102                 :            : 
     103                 :         56 :   result = dst;
     104                 :            : 
     105                 :            :  out:
     106                 :            :   rwlock_unlock (elf->lock);
     107                 :            : 
     108                 :         56 :   return result;
     109                 :            : }