libelf/common.h

/* Common definitions for handling files in memory or only on disk.
   Copyright (C) 1998, 1999, 2000, 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.  */

#ifndef _COMMON_H
#define _COMMON_H       1

#include <ar.h>
//#include <byteswap.h>
//#include <endian.h>
#include <stdlib.h>
#include <string.h>


static inline Elf_Kind
determine_kind (void *buf, size_t len)
{
  /* First test for an archive.  */
  if (len >= SARMAG && memcmp (buf, ARMAG, SARMAG) == 0)
    return ELF_K_AR;

  /* Next try ELF files.  */
  if (len >= EI_NIDENT && memcmp (buf, ELFMAG, SELFMAG) == 0)
    {
      /* Could be an ELF file.  */
      int eclass = (int) ((unsigned char *) buf)[EI_CLASS];
      int data = (int) ((unsigned char *) buf)[EI_DATA];
      int version = (int) ((unsigned char *) buf)[EI_VERSION];

      if (eclass > ELFCLASSNONE && eclass < ELFCLASSNUM
	  && data > ELFDATANONE && data < ELFDATANUM
	  && version > EV_NONE && version < EV_NUM)
	return ELF_K_ELF;
    }

  /* We do not know this file type.  */
  return ELF_K_NONE;
}


/* Allocate an Elf descriptor and fill in the generic information.  */
static inline Elf *
allocate_elf (int fildes, void *map_address, off_t offset, size_t maxsize,
              Elf_Cmd cmd, Elf *parent, Elf_Kind kind, size_t extra)
{
  Elf *result = (Elf *) calloc (1, sizeof (Elf) + extra);
  if (result == NULL)
    __libelf_seterrno (ELF_E_NOMEM);
  else
    {
      result->kind = kind;
      result->ref_count = 1;
      result->cmd = cmd;
      result->fildes = fildes;
      result->start_offset = offset;
      result->maximum_size = maxsize;
      result->map_address = map_address;
      result->parent = parent;

      rwlock_init (result->lock);
    }

  return result;
}


/* Acquire lock for the descriptor and all children.  */
static void
libelf_acquire_all (Elf *elf)
{
  rwlock_wrlock (elf->lock);

  if (elf->kind == ELF_K_AR)
    {
      Elf *child = elf->state.ar.children;

      while (child != NULL)
	{
	  if (child->ref_count != 0)
	    libelf_acquire_all (child);
	  child = child->next;
	}
    }
}

/* Release own lock and those of the children.  */
static void
libelf_release_all (Elf *elf)
{
  if (elf->kind == ELF_K_AR)
    {
      Elf *child = elf->state.ar.children;

      while (child != NULL)
	{
	  if (child->ref_count != 0)
	    libelf_release_all (child);
	  child = child->next;
	}
    }

  rwlock_unlock (elf->lock);
}


/* Macro to convert endianess in place.  It determines the function it
   has to use itself.  */
#define CONVERT(Var) \
  (Var) = (sizeof (Var) == 1						      \
	   ? (Var)							      \
	   : (sizeof (Var) == 2						      \
	      ? bswap_16 (Var)						      \
	      : (sizeof (Var) == 4					      \
		 ? bswap_32 (Var)					      \
		 : bswap_64 (Var))))

#define CONVERT_TO(Dst, Var) \
  (Dst) = (sizeof (Var) == 1						      \
	   ? (Var)							      \
	   : (sizeof (Var) == 2						      \
	      ? bswap_16 (Var)						      \
	      : (sizeof (Var) == 4					      \
		 ? bswap_32 (Var)					      \
		 : bswap_64 (Var))))


#if __BYTE_ORDER == __LITTLE_ENDIAN
# define MY_ELFDATA	ELFDATA2LSB
#else
# define MY_ELFDATA	ELFDATA2MSB
#endif

#endif	/* common.h */