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dwfl_error.c

/* Error handling in libdwfl.
   Copyright (C) 2005, 2006 Red Hat, Inc.
   This file is part of Red Hat elfutils.

   Red Hat elfutils 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 of the License.

   Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

   In addition, as a special exception, Red Hat, Inc. gives You the
   additional right to link the code of Red Hat elfutils with code licensed
   under any Open Source Initiative certified open source license
   (http://www.opensource.org/licenses/index.php) which requires the
   distribution of source code with any binary distribution and to
   distribute linked combinations of the two.  Non-GPL Code permitted under
   this exception must only link to the code of Red Hat elfutils through
   those well defined interfaces identified in the file named EXCEPTION
   found in the source code files (the "Approved Interfaces").  The files
   of Non-GPL Code may instantiate templates or use macros or inline
   functions from the Approved Interfaces without causing the resulting
   work to be covered by the GNU General Public License.  Only Red Hat,
   Inc. may make changes or additions to the list of Approved Interfaces.
   Red Hat's grant of this exception is conditioned upon your not adding
   any new exceptions.  If you wish to add a new Approved Interface or
   exception, please contact Red Hat.  You must obey the GNU General Public
   License in all respects for all of the Red Hat elfutils code and other
   code used in conjunction with Red Hat elfutils except the Non-GPL Code
   covered by this exception.  If you modify this file, you may extend this
   exception to your version of the file, but you are not obligated to do
   so.  If you do not wish to provide this exception without modification,
   you must delete this exception statement from your version and license
   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
   license is granted, either expressly or impliedly, by designation as an
   included package.  Should you wish to participate in the Open Invention
   Network licensing program, please visit www.openinventionnetwork.com
   <http://www.openinventionnetwork.com>.  */

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

#include <assert.h>
#include <libintl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>

#include "libdwflP.h"


#ifdef USE_TLS
/* The error number.  */
static __thread int global_error;
#else
/* This is the key for the thread specific memory.  */
static tls_key_t key;

/* The error number.  Used in non-threaded programs.  */
static int global_error;
static bool threaded;
/* We need to initialize the thread-specific data.  */
once_define (static, once);

/* The initialization and destruction functions.  */
static void init (void);
static void free_key_mem (void *mem);
#endif      /* TLS */


int
dwfl_errno (void)
{
  int result;

#ifndef USE_TLS
  /* If we have not yet initialized the buffer do it now.  */
  once_execute (once, init);

  if (threaded)
    {
      /* We do not allocate memory for the data.  It is only a word.
       We can store it in place of the pointer.  */
      result = (intptr_t) getspecific (key);

      setspecific (key, (void *) (intptr_t) DWFL_E_NOERROR);
      return result;
    }
#endif      /* TLS */

  result = global_error;
  global_error = DWFL_E_NOERROR;
  return result;
}


static const struct msgtable
{
#define DWFL_ERROR(name, text) char msg_##name[sizeof text];
  DWFL_ERRORS
#undef      DWFL_ERROR
} msgtable =
  {
#define DWFL_ERROR(name, text) text,
  DWFL_ERRORS
#undef      DWFL_ERROR
  };
#define msgstr (&msgtable.msg_NOERROR[0])

static const uint_fast16_t msgidx[] =
{
#define DWFL_ERROR(name, text) \
  [DWFL_E_##name] = offsetof (struct msgtable, msg_##name),
  DWFL_ERRORS
#undef      DWFL_ERROR
};
#define nmsgidx (sizeof msgidx / sizeof msgidx[0])


static inline int
canonicalize (Dwfl_Error error)
{
  unsigned int value;

  switch (error)
    {
    default:
      value = error;
      if ((value &~ 0xffff) != 0)
      break;
      assert (value < nmsgidx);
      break;
    case DWFL_E_ERRNO:
      value = DWFL_E (ERRNO, errno);
      break;
    case DWFL_E_LIBELF:
      value = DWFL_E (LIBELF, elf_errno ());
      break;
    case DWFL_E_LIBDW:
      value = DWFL_E (LIBDW, INTUSE(dwarf_errno) ());
      break;
#if 0
    DWFL_E_LIBEBL:
      value = DWFL_E (LIBEBL, ebl_errno ());
      break;
#endif
    }

  return value;
}

int
internal_function
__libdwfl_canon_error (Dwfl_Error error)
{
  return canonicalize (error);
}

void
internal_function
__libdwfl_seterrno (Dwfl_Error error)
{
  int value = canonicalize (error);

#ifndef USE_TLS
  /* If we have not yet initialized the buffer do it now.  */
  once_execute (once, init);

  if (threaded)
    /* We do not allocate memory for the data.  It is only a word.
       We can store it in place of the pointer.  */
    setspecific (key, (void *) (intptr_t) value);
#endif      /* TLS */

  global_error = value;
}


const char *
dwfl_errmsg (error)
     int error;
{
  if (error == 0 || error == -1)
    {
      int last_error;

#ifndef USE_TLS
      /* If we have not yet initialized the buffer do it now.  */
      once_execute (once, init);

      if (threaded)
      /* We do not allocate memory for the data.  It is only a word.
         We can store it in place of the pointer.  */
      last_error = (intptr_t) getspecific (key);
      else
#endif      /* TLS */
      last_error = global_error;

      if (error == 0 && last_error == 0)
      return NULL;

      error = last_error;
      global_error = DWFL_E_NOERROR;
    }

  switch (error &~ 0xffff)
    {
    case OTHER_ERROR (ERRNO):
      return strerror_r (error & 0xffff, "bad", 0);
    case OTHER_ERROR (LIBELF):
      return elf_errmsg (error & 0xffff);
    case OTHER_ERROR (LIBDW):
      return INTUSE(dwarf_errmsg) (error & 0xffff);
#if 0
    case OTHER_ERROR (LIBEBL):
      return ebl_errmsg (error & 0xffff);
#endif
    }

  return _(&msgstr[msgidx[(unsigned int) error < nmsgidx
                    ? error : DWFL_E_UNKNOWN_ERROR]]);
}
INTDEF (dwfl_errmsg)


#ifndef USE_TLS
/* Free the thread specific data, this is done if a thread terminates.  */
static void
free_key_mem (void *mem __attribute__ ((unused)))
{
  setspecific (key, NULL);
}


/* Initialize the key for the global variable.  */
static void
init (void)
{
  // XXX Screw you, gcc4, the unused function attribute does not work.
  __asm ("" :: "r" (free_key_mem));

  if (key_create (&key, free_key_mem) == 0)
    /* Creating the key succeeded.  */
    threaded = true;
}
#endif      /* TLS */

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