src/elf_newscn.c

   1 /* Append new section.
   2    Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
   3    This file is part of elfutils.
   4    Written 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 <assert.h>
  35 #include <stdbool.h>
  36 #include <stddef.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39
  40 #include "libelfP.h"
  41
  42
  43 Elf_Scn *
  44 elf_newscn (elf)
  45      Elf *elf;
  46 {
  47   Elf_Scn *result = NULL;
  48   bool first = false;
  49
  50   if (elf == NULL)
  51     return NULL;
  52
  53   /* We rely on the prefix of the `elf', `elf32', and `elf64' element
  54      being the same.  */
  55   assert (offsetof (Elf, state.elf.scns_last)
  56           == offsetof (Elf, state.elf32.scns_last));
  57   assert (offsetof (Elf, state.elf.scns_last)
  58           == offsetof (Elf, state.elf64.scns_last));
  59   assert (offsetof (Elf, state.elf32.scns)
  60           == offsetof (Elf, state.elf64.scns));
  61
  62   rwlock_wrlock (elf->lock);
  63
  64  again:
  65   if (elf->state.elf.scns_last->cnt < elf->state.elf.scns_last->max)
  66     {
  67       result = &elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt];
  68
  69       if (++elf->state.elf.scns_last->cnt == 1
  70           && (elf->state.elf.scns_last
  71               == (elf->class == ELFCLASS32
  72                   || (offsetof (Elf, state.elf32.scns)
  73                       == offsetof (Elf, state.elf64.scns))
  74                   ? &elf->state.elf32.scns : &elf->state.elf64.scns)))
  75         /* This is zeroth section.  */
  76         first = true;
  77       else
  78         {
  79           assert (elf->state.elf.scns_last->cnt > 1);
  80           result->index = result[-1].index + 1;
  81         }
  82     }
  83   else
  84     {
  85       /* We must allocate a new element.  */
  86       Elf_ScnList *newp;
  87
  88       assert (elf->state.elf.scnincr > 0);
  89
  90       newp = (Elf_ScnList *) calloc (sizeof (Elf_ScnList)
  91                                      + ((elf->state.elf.scnincr *= 2)
  92                                         * sizeof (Elf_Scn)), 1);
  93       if (newp == NULL)
  94         {
  95           __libelf_seterrno (ELF_E_NOMEM);
  96           goto out;
  97         }
  98
  99       result = &newp->data[0];
 100
 101       /* One section used.  */
 102       ++newp->cnt;
 103
 104       /* This is the number of sections we allocated.  */
 105       newp->max = elf->state.elf.scnincr;
 106
 107       /* Remember the index for the first section in this block.  */
 108       newp->data[0].index
 109         = 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->max - 1].index;
 110
 111       /* Enqueue the new list element.  */
 112       elf->state.elf.scns_last = elf->state.elf.scns_last->next = newp;
 113     }
 114
 115   /* Create a section header for this section.  */
 116   if (elf->class == ELFCLASS32)
 117     {
 118       result->shdr.e32 = (Elf32_Shdr *) calloc (1, sizeof (Elf32_Shdr));
 119       if (result->shdr.e32 == NULL)
 120         {
 121           __libelf_seterrno (ELF_E_NOMEM);
 122           goto out;
 123         }
 124     }
 125   else
 126     {
 127       result->shdr.e64 = (Elf64_Shdr *) calloc (1, sizeof (Elf64_Shdr));
 128       if (result->shdr.e64 == NULL)
 129         {
 130           __libelf_seterrno (ELF_E_NOMEM);
 131           goto out;
 132         }
 133     }
 134
 135   result->elf = elf;
 136   result->shdr_flags = ELF_F_DIRTY | ELF_F_MALLOCED;
 137   result->list = elf->state.elf.scns_last;
 138
 139   /* Initialize the data part.  */
 140   result->data_read = 1;
 141   if (unlikely (first))
 142     {
 143       /* For the first section we mark the data as already available.  */
 144       //result->data_list_rear = &result->data_list;
 145       first = false;
 146       goto again;
 147     }
 148
 149   result->flags |= ELF_F_DIRTY;
 150
 151  out:
 152   rwlock_unlock (elf->lock);
 153
 154   return result;
 155 }