/*

  This file is part of libmicrohttpd

  Copyright (C) 2016 Karlson2k (Evgeny Grin)

  This library is free software; you can redistribute it and/or

  modify it under the terms of the GNU Lesser General Public

  License as published by the Free Software Foundation; either

  version 2.1 of the License, or (at your option) any later version.

  This library 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

  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public

  License along with this library; if not, write to the Free Software

  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

*/

/**

 * @file microhttpd/mhd_itc.h

 * @brief  Header for platform-independent inter-thread communication

 * @author Karlson2k (Evgeny Grin)

 * @author Christian Grothoff

 *

 * Provides basic abstraction for inter-thread communication.

 * Any functions can be implemented as macro on some platforms

 * unless explicitly marked otherwise.

 * Any function argument can be skipped in macro, so avoid

 * variable modification in function parameters.

 */

#ifndef MHD_ITC_H

#define MHD_ITC_H 1

#include "mhd_itc_types.h"

#include <fcntl.h>

#ifndef MHD_PANIC

#  include <stdio.h>

#  include <stdlib.h>

/* Simple implementation of MHD_PANIC, to be used outside lib */

#  define MHD_PANIC(msg) do { fprintf (stderr,           \

     "Abnormal termination at %d line in file %s: %s\n", \

     (int)__LINE__, __FILE__, msg); abort();} while(0)

#endif /* ! MHD_PANIC */

#if defined(_MHD_ITC_EVENTFD)

/* **************** Optimized GNU/Linux ITC implementation by eventfd ********** */

#include <sys/eventfd.h>

#include <stdint.h>      /* for uint64_t */

#ifdef HAVE_UNISTD_H

#include <unistd.h>      /* for read(), write(), errno */

#endif /* HAVE_UNISTD_H */

#ifdef HAVE_STRING_H

#include <string.h> /* for strerror() */

#endif

/**

 * Initialise ITC by generating eventFD

 * @param itc the itc to initialise

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_init_(itc) (-1 != ((itc).fd = eventfd (0, EFD_CLOEXEC | EFD_NONBLOCK)))

/**

 * Get description string of last errno for itc operations.

 */

#define MHD_itc_last_strerror_() strerror(errno)

/**

 * Internal static const helper for MHD_itc_activate_()

 */

static const uint64_t _MHD_itc_wr_data = 1;

/**

 * Activate signal on @a itc

 * @param itc the itc to use

 * @param str ignored

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_activate_(itc, str) \

  ((write((itc).fd, (const void*)&_MHD_itc_wr_data, 8) > 0) || (EAGAIN == errno))

/**

 * Return read FD of @a itc which can be used for poll(), select() etc.

 * @param itc the itc to get FD

 * @return FD of read side

 */

#define MHD_itc_r_fd_(itc) ((itc).fd)

/**

 * Return write FD of @a itc

 * @param itc the itc to get FD

 * @return FD of write side

 */

#define MHD_itc_w_fd_(itc) ((itc).fd)

/**

 * Clear signaled state on @a itc

 * @param itc the itc to clear

 */

#define MHD_itc_clear_(itc)                  \

  do { uint64_t __b; int __r;                \

       __r = read((itc).fd, &__b, sizeof(__b)); \

       (void)__r; } while(0)

/**

 * Destroy previously initialised ITC

 * @param itc the itc to destroy

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_destroy_(itc) ((0 != close ((itc).fd)) || (EBADF != errno))

/**

 * Check whether ITC has valid value.

 *

 * Macro check whether @a itc value is valid (allowed),

 * macro does not check whether @a itc was really initialised.

 * @param itc the itc to check

 * @return boolean true if @a itc has valid value,

 *         boolean false otherwise.

 */

#define MHD_ITC_IS_VALID_(itc)  (-1 != ((itc).fd))

/**

 * Set @a itc to invalid value.

 * @param itc the itc to set

 */

#define MHD_itc_set_invalid_(itc) ((itc).fd = -1)

#elif defined(_MHD_ITC_PIPE)

/* **************** Standard UNIX ITC implementation by pipe ********** */

#if defined(HAVE_PIPE2_FUNC) && defined(HAVE_FCNTL_H)

#  include <fcntl.h>     /* for O_CLOEXEC, O_NONBLOCK */

#endif /* HAVE_PIPE2_FUNC && HAVE_FCNTL_H */

#ifdef HAVE_UNISTD_H

#include <unistd.h>      /* for read(), write(), errno */

#endif /* HAVE_UNISTD_H */

#ifdef HAVE_STRING_H

#include <string.h> /* for strerror() */

#endif

/**

 * Initialise ITC by generating pipe

 * @param itc the itc to initialise

 * @return non-zero if succeeded, zero otherwise

 */

#ifdef HAVE_PIPE2_FUNC

#  define MHD_itc_init_(itc) (!pipe2((itc).fd, O_CLOEXEC | O_NONBLOCK))

#else  /* ! HAVE_PIPE2_FUNC */

#  define MHD_itc_init_(itc)              \

     ( (!pipe((itc).fd)) ?                \

         (MHD_itc_nonblocking_((itc)) ?   \

           (!0) :                         \

           (MHD_itc_destroy_((itc)), 0) ) \

         : (0) )

#endif /* ! HAVE_PIPE2_FUNC */

/**

 * Get description string of last errno for itc operations.

 */

#define MHD_itc_last_strerror_() strerror(errno)

/**

 * Activate signal on @a itc

 * @param itc the itc to use

 * @param str one-symbol string, useful only for strace debug

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_activate_(itc, str) \

  ((write((itc).fd[1], (const void*)(str), 1) > 0) || (EAGAIN == errno))

/**

 * Return read FD of @a itc which can be used for poll(), select() etc.

 * @param itc the itc to get FD

 * @return FD of read side

 */

#define MHD_itc_r_fd_(itc) ((itc).fd[0])

/**

 * Return write FD of @a itc

 * @param itc the itc to get FD

 * @return FD of write side

 */

#define MHD_itc_w_fd_(itc) ((itc).fd[1])

/**

 * Clear signaled state on @a itc

 * @param itc the itc to clear

 */

#define MHD_itc_clear_(itc) do                      \

  { long __b;                                       \

    while(0 < read((itc).fd[0], &__b, sizeof(__b))) \

    {} } while(0)

/**

 * Destroy previously initialised ITC

 * @param itc the itc to destroy

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_destroy_(itc)      \

  ( (0 == close ((itc).fd[0])) ?   \

      (0 == close ((itc).fd[1])) : \

      ((close ((itc).fd[1])), 0) )

/**

 * Check whether ITC has valid value.

 *

 * Macro check whether @a itc value is valid (allowed),

 * macro does not check whether @a itc was really initialised.

 * @param itc the itc to check

 * @return boolean true if @a itc has valid value,

 *         boolean false otherwise.

 */

#define MHD_ITC_IS_VALID_(itc)  (-1 != (itc).fd[0])

/**

 * Set @a itc to invalid value.

 * @param itc the itc to set

 */

#define MHD_itc_set_invalid_(itc) ((itc).fd[0] = (itc).fd[1] = -1)

#ifndef HAVE_PIPE2_FUNC

  /**

   * Change itc FD options to be non-blocking.

   *

   * @param fd the FD to manipulate

   * @return non-zero if succeeded, zero otherwise

   */

  int

  MHD_itc_nonblocking_ (struct MHD_itc_ itc);

#endif /* ! HAVE_PIPE2_FUNC */

#elif defined(_MHD_ITC_SOCKETPAIR)

/* **************** ITC implementation by socket pair ********** */

#include "mhd_sockets.h"

/**

 * Initialise ITC by generating socketpair

 * @param itc the itc to initialise

 * @return non-zero if succeeded, zero otherwise

 */

#ifdef MHD_socket_pair_nblk_

#  define MHD_itc_init_(itc) MHD_socket_pair_nblk_((itc).sk)

#else  /* ! MHD_socket_pair_nblk_ */

#  define MHD_itc_init_(itc)            \

     (MHD_socket_pair_((itc).sk) ?      \

       (MHD_itc_nonblocking_((itc)) ?   \

         (!0) :                         \

         (MHD_itc_destroy_((itc)), 0) ) \

       : (0))

#endif /* ! MHD_socket_pair_nblk_ */

/**

 * Get description string of last error for itc operations.

 */

#define MHD_itc_last_strerror_() MHD_socket_last_strerr_()

/**

 * Activate signal on @a itc

 * @param itc the itc to use

 * @param str one-symbol string, useful only for strace debug

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_activate_(itc, str)          \

  ((MHD_send_((itc).sk[1], (str), 1) > 0) || \

   (MHD_SCKT_ERR_IS_EAGAIN_(MHD_socket_get_error_())))

/**

 * Return read FD of @a itc which can be used for poll(), select() etc.

 * @param itc the itc to get FD

 * @return FD of read side

 */

#define MHD_itc_r_fd_(itc) ((itc).sk[0])

/**

 * Return write FD of @a itc

 * @param itc the itc to get FD

 * @return FD of write side

 */

#define MHD_itc_w_fd_(itc) ((itc).sk[1])

/**

 * Clear signaled state on @a itc

 * @param itc the itc to clear

 */

#define MHD_itc_clear_(itc) do      \

  { long __b;                       \

    while(0 < recv((itc).sk[0],     \

                   (char*)&__b,     \

                   sizeof(__b), 0)) \

    {} } while(0)

/**

 * Destroy previously initialised ITC

 * @param itc the itc to destroy

 * @return non-zero if succeeded, zero otherwise

 */

#define MHD_itc_destroy_(itc)          \

  ( MHD_socket_close_((itc).sk[0]) ?   \

      MHD_socket_close_((itc).sk[1]) : \

      ((void)MHD_socket_close_((itc).sk[1]), 0) )

/**

 * Check whether ITC has valid value.

 *

 * Macro check whether @a itc value is valid (allowed),

 * macro does not check whether @a itc was really initialised.

 * @param itc the itc to check

 * @return boolean true if @a itc has valid value,

 *         boolean false otherwise.

 */

#define MHD_ITC_IS_VALID_(itc)  (MHD_INVALID_SOCKET != (itc).sk[0])

/**

 * Set @a itc to invalid value.

 * @param itc the itc to set

 */

#define MHD_itc_set_invalid_(itc) ((itc).sk[0] = (itc).sk[1] = MHD_INVALID_SOCKET)

#ifndef MHD_socket_pair_nblk_

#  define MHD_itc_nonblocking_(pip) (MHD_socket_nonblocking_((pip).sk[0]) && MHD_socket_nonblocking_((pip).sk[1]))

#endif /* ! MHD_socket_pair_nblk_ */

#endif /* _MHD_ITC_SOCKETPAIR */

/**

 * Destroy previously initialised ITC and abort execution

 * if error is detected.

 * @param itc the itc to destroy

 */

#define MHD_itc_destroy_chk_(itc) do {          \

    if (!MHD_itc_destroy_(itc))                 \

      MHD_PANIC(_("Failed to destroy ITC.\n")); \

  } while(0)

/**

 * Check whether ITC has invalid value.

 *

 * Macro check whether @a itc value is invalid,

 * macro does not check whether @a itc was destroyed.

 * @param itc the itc to check

 * @return boolean true if @a itc has invalid value,

 *         boolean false otherwise.

 */

#define MHD_ITC_IS_INVALID_(itc)  (! MHD_ITC_IS_VALID_(itc))

#endif /* MHD_ITC_H */