/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 *********************************************************************
 *
 * Pollable events
 *
 * Pollable events are implemented using layered I/O.  The only
 * I/O methods that are implemented for pollable events are poll
 * and close.  No other methods can be invoked on a pollable
 * event.
 *
 * A pipe or socket pair is created and the pollable event layer
 * is pushed onto the read end.  A pointer to the write end is
 * saved in the PRFilePrivate structure of the pollable event.
 *
 *********************************************************************
 */

#include "prinit.h"
#include "prio.h"
#include "prmem.h"
#include "prerror.h"
#include "prlog.h"

/*
 * These internal functions are declared in primpl.h,
 * but we can't include primpl.h because the definition
 * of struct PRFilePrivate in this file (for the pollable
 * event layer) will conflict with the definition of
 * struct PRFilePrivate in primpl.h (for the NSPR layer).
 */
extern PRIntn _PR_InvalidInt(void);
extern PRInt64 _PR_InvalidInt64(void);
extern PRStatus _PR_InvalidStatus(void);
extern PRFileDesc* _PR_InvalidDesc(void);

/*
 * PRFilePrivate structure for the NSPR pollable events layer
 */
struct PRFilePrivate {
  PRFileDesc* writeEnd; /* the write end of the pipe/socketpair */
};

static PRStatus PR_CALLBACK _pr_PolEvtClose(PRFileDesc* fd);

static PRInt16 PR_CALLBACK _pr_PolEvtPoll(PRFileDesc* fd, PRInt16 in_flags,
                                          PRInt16* out_flags);

static PRIOMethods _pr_polevt_methods = {PR_DESC_LAYERED,
                                         _pr_PolEvtClose,
                                         (PRReadFN)_PR_InvalidInt,
                                         (PRWriteFN)_PR_InvalidInt,
                                         (PRAvailableFN)_PR_InvalidInt,
                                         (PRAvailable64FN)_PR_InvalidInt64,
                                         (PRFsyncFN)_PR_InvalidStatus,
                                         (PRSeekFN)_PR_InvalidInt,
                                         (PRSeek64FN)_PR_InvalidInt64,
                                         (PRFileInfoFN)_PR_InvalidStatus,
                                         (PRFileInfo64FN)_PR_InvalidStatus,
                                         (PRWritevFN)_PR_InvalidInt,
                                         (PRConnectFN)_PR_InvalidStatus,
                                         (PRAcceptFN)_PR_InvalidDesc,
                                         (PRBindFN)_PR_InvalidStatus,
                                         (PRListenFN)_PR_InvalidStatus,
                                         (PRShutdownFN)_PR_InvalidStatus,
                                         (PRRecvFN)_PR_InvalidInt,
                                         (PRSendFN)_PR_InvalidInt,
                                         (PRRecvfromFN)_PR_InvalidInt,
                                         (PRSendtoFN)_PR_InvalidInt,
                                         _pr_PolEvtPoll,
                                         (PRAcceptreadFN)_PR_InvalidInt,
                                         (PRTransmitfileFN)_PR_InvalidInt,
                                         (PRGetsocknameFN)_PR_InvalidStatus,
                                         (PRGetpeernameFN)_PR_InvalidStatus,
                                         (PRReservedFN)_PR_InvalidInt,
                                         (PRReservedFN)_PR_InvalidInt,
                                         (PRGetsocketoptionFN)_PR_InvalidStatus,
                                         (PRSetsocketoptionFN)_PR_InvalidStatus,
                                         (PRSendfileFN)_PR_InvalidInt,
                                         (PRConnectcontinueFN)_PR_InvalidStatus,
                                         (PRReservedFN)_PR_InvalidInt,
                                         (PRReservedFN)_PR_InvalidInt,
                                         (PRReservedFN)_PR_InvalidInt,
                                         (PRReservedFN)_PR_InvalidInt};

static PRDescIdentity _pr_polevt_id;
static PRCallOnceType _pr_polevt_once_control;
static PRStatus PR_CALLBACK _pr_PolEvtInit(void);

static PRInt16 PR_CALLBACK _pr_PolEvtPoll(PRFileDesc* fd, PRInt16 in_flags,
                                          PRInt16* out_flags) {
  return (fd->lower->methods->poll)(fd->lower, in_flags, out_flags);
}

static PRStatus PR_CALLBACK _pr_PolEvtInit(void) {
  _pr_polevt_id = PR_GetUniqueIdentity("NSPR pollable events");
  if (PR_INVALID_IO_LAYER == _pr_polevt_id) {
    return PR_FAILURE;
  }
  return PR_SUCCESS;
}

#if !defined(XP_UNIX)
#  define USE_TCP_SOCKETPAIR
#endif

PR_IMPLEMENT(PRFileDesc*) PR_NewPollableEvent(void) {
  PRFileDesc* event;
  PRFileDesc* fd[2]; /* fd[0] is the read end; fd[1] is the write end */
#ifdef USE_TCP_SOCKETPAIR
  PRSocketOptionData socket_opt;
  PRStatus rv;
#endif

  fd[0] = fd[1] = NULL;

  if (PR_CallOnce(&_pr_polevt_once_control, _pr_PolEvtInit) == PR_FAILURE) {
    return NULL;
  }

  event = PR_CreateIOLayerStub(_pr_polevt_id, &_pr_polevt_methods);
  if (NULL == event) {
    goto errorExit;
  }
  event->secret = PR_NEW(PRFilePrivate);
  if (event->secret == NULL) {
    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
    goto errorExit;
  }

#ifndef USE_TCP_SOCKETPAIR
  if (PR_CreatePipe(&fd[0], &fd[1]) == PR_FAILURE) {
    fd[0] = fd[1] = NULL;
    goto errorExit;
  }
#else
  if (PR_NewTCPSocketPair(fd) == PR_FAILURE) {
    fd[0] = fd[1] = NULL;
    goto errorExit;
  }
  /*
   * set the TCP_NODELAY option to reduce notification latency
   */
  socket_opt.option = PR_SockOpt_NoDelay;
  socket_opt.value.no_delay = PR_TRUE;
  rv = PR_SetSocketOption(fd[1], &socket_opt);
  PR_ASSERT(PR_SUCCESS == rv);
#endif

  event->secret->writeEnd = fd[1];
  if (PR_PushIOLayer(fd[0], PR_TOP_IO_LAYER, event) == PR_FAILURE) {
    goto errorExit;
  }

  return fd[0];

errorExit:
  if (fd[0]) {
    PR_Close(fd[0]);
    PR_Close(fd[1]);
  }
  if (event) {
    PR_DELETE(event->secret);
    event->dtor(event);
  }
  return NULL;
}

static PRStatus PR_CALLBACK _pr_PolEvtClose(PRFileDesc* fd) {
  PRFileDesc* event;

  event = PR_PopIOLayer(fd, PR_TOP_IO_LAYER);
  PR_ASSERT(NULL == event->higher && NULL == event->lower);
  PR_Close(fd);
  PR_Close(event->secret->writeEnd);
  PR_DELETE(event->secret);
  event->dtor(event);
  return PR_SUCCESS;
}

PR_IMPLEMENT(PRStatus) PR_DestroyPollableEvent(PRFileDesc* event) {
  return PR_Close(event);
}

static const char magicChar = '\x38';

PR_IMPLEMENT(PRStatus) PR_SetPollableEvent(PRFileDesc* event) {
  if (PR_Write(event->secret->writeEnd, &magicChar, 1) != 1) {
    return PR_FAILURE;
  }
  return PR_SUCCESS;
}

PR_IMPLEMENT(PRStatus) PR_WaitForPollableEvent(PRFileDesc* event) {
  char buf[1024];
  PRInt32 nBytes;
#ifdef DEBUG
  PRIntn i;
#endif

  nBytes = PR_Read(event->lower, buf, sizeof(buf));
  if (nBytes == -1) {
    return PR_FAILURE;
  }

#ifdef DEBUG
  /*
   * Make sure people do not write to the pollable event fd
   * directly.
   */
  for (i = 0; i < nBytes; i++) {
    PR_ASSERT(buf[i] == magicChar);
  }
#endif

  return PR_SUCCESS;
}