src/elf32_offscn.c

   1 /* Get section at specific index.
   2    Copyright (C) 2005, 2008 Red Hat, Inc.
   3    This file is part of elfutils.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 2005.
   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 <assert.h>
  35 #include <stddef.h>
  36 #include <stdlib.h>
  37
  38 #include "libelfP.h"
  39
  40 #ifndef LIBELFBITS
  41 # define LIBELFBITS 32
  42 #endif
  43
  44
  45 Elf_Scn *
  46 elfw2(LIBELFBITS,offscn) (elf, offset)
  47      Elf *elf;
  48      ElfW2(LIBELFBITS,Off) offset;
  49 {
  50   if (elf == NULL)
  51     return NULL;
  52
  53   if (unlikely (elf->kind != ELF_K_ELF))
  54     {
  55       __libelf_seterrno (ELF_E_INVALID_HANDLE);
  56       return NULL;
  57     }
  58
  59   Elf_ScnList *runp = &elf->state.ELFW(elf,LIBELFBITS).scns;
  60
  61   /* If we have not looked at section headers before,
  62      we might need to read them in first.  */
  63   if (runp->cnt > 0
  64       && unlikely (runp->data[0].shdr.ELFW(e,LIBELFBITS) == NULL)
  65       && unlikely (elfw2(LIBELFBITS,getshdr) (&runp->data[0]) == NULL))
  66     return NULL;
  67
  68   rwlock_rdlock (elf->lock);
  69
  70   Elf_Scn *result = NULL;
  71
  72   /* Find the section in the list.  */
  73   while (1)
  74     {
  75       for (unsigned int i = 0; i < runp->cnt; ++i)
  76         if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_offset == offset)
  77           {
  78             result = &runp->data[i];
  79
  80             /* If this section is empty, the following one has the same
  81                sh_offset.  We presume the caller is looking for a nonempty
  82                section, so keep looking if this one is empty.  */
  83             if (runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_size != 0
  84                 && runp->data[i].shdr.ELFW(e,LIBELFBITS)->sh_type != SHT_NOBITS)
  85               goto out;
  86           }
  87
  88       runp = runp->next;
  89       if (runp == NULL)
  90         {
  91           __libelf_seterrno (ELF_E_INVALID_OFFSET);
  92           break;
  93         }
  94     }
  95
  96  out:
  97   rwlock_unlock (elf->lock);
  98
  99   return result;
 100 }
 101 INTDEF(elfw2(LIBELFBITS,offscn))