/*

 * Copyright (C) 2012-2014 Tobias Brunner

 *

 * Copyright (C) secunet Security Networks AG

 *

 * 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; either version 2 of the License, or (at your

 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.

 *

 * 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.

 */

#include <stdlib.h>

#include <string.h>

#include <library.h>

#include <threading/thread_value.h>

#include <threading/spinlock.h>

#include "strerror.h"

/**

 * The size of the thread-specific error buffer

 */

#define STRERROR_BUF_LEN 256

/**

 * Thread specific strerror buffer, as char*

 */

static thread_value_t *strerror_buf;

#ifndef HAVE_STRERROR_R

/**

 * Lock to access strerror() safely

 */

static spinlock_t *strerror_lock;

#endif /* HAVE_STRERROR_R */

/**

 * Retrieve the error buffer assigned to the current thread (or create it)

 */

static inline char *get_strerror_buf()

{

  char *buf;

  bool old = FALSE;

  if (!strerror_buf)

  {

    return NULL;

  }

  buf = strerror_buf->get(strerror_buf);

  if (!buf)

  {

    if (lib->leak_detective)

    {

      old = lib->leak_detective->set_state(lib->leak_detective, FALSE);

    }

    buf = malloc(STRERROR_BUF_LEN);

    strerror_buf->set(strerror_buf, buf);

    if (lib->leak_detective)

    {

      lib->leak_detective->set_state(lib->leak_detective, old);

    }

  }

  return buf;

}

/**

 * Use real strerror() below

 */

#undef strerror

/*

 * Described in header.

 */

const char *strerror_safe(int errnum)

{

  char *buf, *msg;

  buf = get_strerror_buf();

  if (!buf)

  {

    /* library not initialized? fallback */

    return strerror(errnum);

  }

#ifdef HAVE_STRERROR_R

# ifdef STRERROR_R_CHAR_P

  /* char* version which may or may not return the original buffer */

  msg = strerror_r(errnum, buf, STRERROR_BUF_LEN);

# else

  /* int version returns 0 on success */

  msg = strerror_r(errnum, buf, STRERROR_BUF_LEN) ? "Unknown error" : buf;

# endif

#else /* HAVE_STRERROR_R */

  /* use a lock to ensure calling strerror(3) is thread-safe */

  strerror_lock->lock(strerror_lock);

  msg = strncpy(buf, strerror(errnum), STRERROR_BUF_LEN);

  strerror_lock->unlock(strerror_lock);

  buf[STRERROR_BUF_LEN - 1] = '\0';

#endif /* HAVE_STRERROR_R */

  return msg;

}

/**

 * free() with disabled leak detective

 */

static void free_no_ld(void *buf)

{

  bool old = FALSE;

  if (lib->leak_detective)

  {

    old = lib->leak_detective->set_state(lib->leak_detective, FALSE);

  }

  free(buf);

  if (lib->leak_detective)

  {

    lib->leak_detective->set_state(lib->leak_detective, old);

  }

}

/**

 * See header

 */

void strerror_init()

{

  strerror_buf = thread_value_create(free_no_ld);

#ifndef HAVE_STRERROR_R

  strerror_lock = spinlock_create();

#endif

}

/**

 * See header

 */

void strerror_deinit()

{

  strerror_buf->destroy(strerror_buf);

  strerror_buf = NULL;

#ifndef HAVE_STRERROR_R

  strerror_lock->destroy(strerror_lock);

#endif

}