Line data    Source code

       1             : /* Create new, empty section data.
       2             :    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2015 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             :    Contributed by Ulrich Drepper <drepper@redhat.com>, 1998.
       5             : 
       6             :    This file is free software; you can redistribute it and/or modify
       7             :    it under the terms of either
       8             : 
       9             :      * the GNU Lesser General Public License as published by the Free
      10             :        Software Foundation; either version 3 of the License, or (at
      11             :        your option) any later version
      12             : 
      13             :    or
      14             : 
      15             :      * the GNU General Public License as published by the Free
      16             :        Software Foundation; either version 2 of the License, or (at
      17             :        your option) any later version
      18             : 
      19             :    or both in parallel, as here.
      20             : 
      21             :    elfutils is distributed in the hope that it will be useful, but
      22             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      23             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      24             :    General Public License for more details.
      25             : 
      26             :    You should have received copies of the GNU General Public License and
      27             :    the GNU Lesser General Public License along with this program.  If
      28             :    not, see <http://www.gnu.org/licenses/>.  */
      29             : 
      30             : #ifdef HAVE_CONFIG_H
      31             : # include <config.h>
      32             : #endif
      33             : 
      34             : #include <stddef.h>
      35             : #include <stdlib.h>
      36             : 
      37             : #include "libelfP.h"
      38             : 
      39             : 
      40             : Elf_Data *
      41     2632184 : elf_newdata (Elf_Scn *scn)
      42             : {
      43     2632184 :   Elf_Data_List *result = NULL;
      44             : 
      45     2632184 :   if (scn == NULL)
      46             :     return NULL;
      47             : 
      48     2632184 :   if (unlikely (scn->index == 0))
      49             :     {
      50             :       /* It is not allowed to add something to the 0th section.  */
      51           0 :       __libelf_seterrno (ELF_E_NOT_NUL_SECTION);
      52           0 :       return NULL;
      53             :     }
      54             : 
      55     2632184 :   if (scn->elf->class == ELFCLASS32
      56             :       || (offsetof (struct Elf, state.elf32.ehdr)
      57             :           == offsetof (struct Elf, state.elf64.ehdr))
      58     2632184 :       ? scn->elf->state.elf32.ehdr == NULL
      59             :       : scn->elf->state.elf64.ehdr == NULL)
      60             :     {
      61           0 :       __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
      62           0 :       return NULL;
      63             :     }
      64             : 
      65             :   rwlock_wrlock (scn->elf->lock);
      66             : 
      67             :   /* data_read is set when data has been read from the ELF image or
      68             :      when a new section has been created by elf_newscn.  If data has
      69             :      been read from the ELF image, then rawdata_base will point to raw
      70             :      data.  If data_read has been set by elf_newscn, then rawdata_base
      71             :      will be NULL.  data_list_rear will be set by elf_getdata if the
      72             :      data has been converted, or by this function, elf_newdata, when
      73             :      new data has been added.
      74             : 
      75             :      Currently elf_getdata and elf_update rely on the fact that when
      76             :      data_list_read is not NULL all they have to do is walk the data
      77             :      list. They will ignore any (unread) raw data in that case.
      78             : 
      79             :      So we need to make sure the data list is setup if there is
      80             :      already data available.  */
      81     2632184 :   if (scn->data_read
      82     2632179 :       && scn->rawdata_base != NULL
      83          31 :       && scn->data_list_rear == NULL)
      84           7 :     __libelf_set_data_list_rdlock (scn, 1);
      85             : 
      86     2632184 :   if (scn->data_read && scn->data_list_rear == NULL)
      87             :     {
      88             :       /* This means the section was created by the user and this is the
      89             :          first data.  */
      90     2632090 :       result = &scn->data_list;
      91     2632090 :       result->flags = ELF_F_DIRTY;
      92             :     }
      93             :   else
      94             :     {
      95             :       /* It would be more efficient to create new data without
      96             :          reading/converting the data from the file.  But then we
      97             :          have to remember this.  Currently elf_getdata and
      98             :          elf_update rely on the fact that they don't have to
      99             :          load/convert any data if data_list_rear is set.  */
     100          94 :       if (scn->data_read == 0)
     101             :         {
     102           5 :           if (__libelf_set_rawdata_wrlock (scn) != 0)
     103             :             /* Something went wrong.  The error value is already set.  */
     104             :             goto out;
     105           5 :           __libelf_set_data_list_rdlock (scn, 1);
     106             :         }
     107             : 
     108             :       /* Create a new, empty data descriptor.  */
     109          94 :       result = (Elf_Data_List *) calloc (1, sizeof (Elf_Data_List));
     110          94 :       if (result == NULL)
     111             :         {
     112           0 :           __libelf_seterrno (ELF_E_NOMEM);
     113           0 :           goto out;
     114             :         }
     115             : 
     116          94 :       result->flags = ELF_F_DIRTY | ELF_F_MALLOCED;
     117             :     }
     118             : 
     119             :   /* Set the predefined values.  */
     120     2632184 :   result->data.d.d_version = __libelf_version;
     121             : 
     122     2632184 :   result->data.s = scn;
     123             : 
     124             :   /* Add to the end of the list.  */
     125     2632184 :   if (scn->data_list_rear != NULL)
     126          94 :     scn->data_list_rear->next = result;
     127             : 
     128     2632184 :   scn->data_list_rear = result;
     129             : 
     130     2632184 :  out:
     131             :   rwlock_unlock (scn->elf->lock);
     132             : 
     133             :   /* Please note that the following is thread safe and is also defined
     134             :      for RESULT == NULL since it still return NULL.  */
     135     2632184 :   return &result->data.d;
     136             : }