libelf/elf_newscn.c

/* Append new section.
   Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 1998.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, version 2.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include "libelfP.h"


Elf_Scn *
elf_newscn (elf)
     Elf *elf;
{
  Elf_Scn *result = NULL;
  bool first = false;

  if (elf == NULL)
    return NULL;

  /* We rely on the prefix of the `elf', `elf32', and `elf64' element
     being the same.  */
  assert (offsetof (Elf, state.elf.scns_last)
	  == offsetof (Elf, state.elf32.scns_last));
  assert (offsetof (Elf, state.elf.scns_last)
	  == offsetof (Elf, state.elf64.scns_last));
  assert (offsetof (Elf, state.elf32.scns)
	  == offsetof (Elf, state.elf64.scns));

  rwlock_wrlock (elf->lock);

 again:
  if (elf->state.elf.scns_last->cnt < elf->state.elf.scns_last->max)
    {
      result = &elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt];

      if (++elf->state.elf.scns_last->cnt == 1
	  && (elf->state.elf.scns_last
	      == (elf->class == ELFCLASS32
		  || (offsetof (Elf, state.elf32.scns)
		      == offsetof (Elf, state.elf64.scns))
		  ? &elf->state.elf32.scns : &elf->state.elf64.scns)))
	/* This is zeroth section.  */
	first = true;
      else
	{
	  assert (elf->state.elf.scns_last->cnt > 1);
	  result->index = result[-1].index + 1;
	}
    }
  else
    {
      /* We must allocate a new element.  */
      Elf_ScnList *newp;

      assert (elf->state.elf.scnincr > 0);

      newp = (Elf_ScnList *) calloc (sizeof (Elf_ScnList)
				     + ((elf->state.elf.scnincr *= 2)
					* sizeof (Elf_Scn)), 1);
      if (newp == NULL)
	{
	  __libelf_seterrno (ELF_E_NOMEM);
	  goto out;
	}

      result = &newp->data[0];

      /* One section used.  */
      ++newp->cnt;

      /* This is the number of sections we allocated.  */
      newp->max = elf->state.elf.scnincr;

      /* Remember the index for the first section in this block.  */
      newp->data[0].index
	= 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->max - 1].index;

      /* Enqueue the new list element.  */
      elf->state.elf.scns_last = elf->state.elf.scns_last->next = newp;
    }

  /* Create a section header for this section.  */
  if (elf->class == ELFCLASS32)
    {
      result->shdr.e32 = (Elf32_Shdr *) calloc (1, sizeof (Elf32_Shdr));
      if (result->shdr.e32 == NULL)
	{
	  __libelf_seterrno (ELF_E_NOMEM);
	  goto out;
	}
    }
  else
    {
      result->shdr.e64 = (Elf64_Shdr *) calloc (1, sizeof (Elf64_Shdr));
      if (result->shdr.e64 == NULL)
	{
	  __libelf_seterrno (ELF_E_NOMEM);
	  goto out;
	}
    }

  result->elf = elf;
  result->shdr_flags = ELF_F_DIRTY | ELF_F_MALLOCED;
  result->list = elf->state.elf.scns_last;

  /* Initialize the data part.  */
  result->data_read = 1;
  if (unlikely (first))
    {
      /* For the first section we mark the data as already available.  */
      //result->data_list_rear = &result->data_list;
      first = false;
      goto again;
    }

  result->flags |= ELF_F_DIRTY;

 out:
  rwlock_unlock (elf->lock);

  return result;
}