/*      $NetBSD: buffer_iocp.c,v 1.1.1.3 2021/04/07 02:43:13 christos Exp $     */
/*
* Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
*    derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/**
  @file buffer_iocp.c

  This module implements overlapped read and write functions for evbuffer
  objects on Windows.
*/
#include "event2/event-config.h"
#include <sys/cdefs.h>
__RCSID("$NetBSD: buffer_iocp.c,v 1.1.1.3 2021/04/07 02:43:13 christos Exp $");
#include "evconfig-private.h"

#include "event2/buffer.h"
#include "event2/buffer_compat.h"
#include "event2/util.h"
#include "event2/thread.h"
#include "util-internal.h"
#include "evthread-internal.h"
#include "evbuffer-internal.h"
#include "iocp-internal.h"
#include "mm-internal.h"

#include <winsock2.h>
#include <winerror.h>
#include <windows.h>
#include <stdio.h>

#define MAX_WSABUFS 16

/** An evbuffer that can handle overlapped IO. */
struct evbuffer_overlapped {
       struct evbuffer buffer;
       /** The socket that we're doing overlapped IO on. */
       evutil_socket_t fd;

       /** pending I/O type */
       unsigned read_in_progress : 1;
       unsigned write_in_progress : 1;

       /** The first pinned chain in the buffer. */
       struct evbuffer_chain *first_pinned;

       /** How many chains are pinned; how many of the fields in buffers
        * are we using. */
       int n_buffers;
       WSABUF buffers[MAX_WSABUFS];
};

/** Given an evbuffer, return the correponding evbuffer structure, or NULL if
* the evbuffer isn't overlapped. */
static inline struct evbuffer_overlapped *
upcast_evbuffer(struct evbuffer *buf)
{
       if (!buf || !buf->is_overlapped)
               return NULL;
       return EVUTIL_UPCAST(buf, struct evbuffer_overlapped, buffer);
}

/** Unpin all the chains noted as pinned in 'eo'. */
static void
pin_release(struct evbuffer_overlapped *eo, unsigned flag)
{
       int i;
       struct evbuffer_chain *next, *chain = eo->first_pinned;

       for (i = 0; i < eo->n_buffers; ++i) {
               EVUTIL_ASSERT(chain);
               next = chain->next;
               evbuffer_chain_unpin_(chain, flag);
               chain = next;
       }
}

void
evbuffer_commit_read_(struct evbuffer *evbuf, ev_ssize_t nBytes)
{
       struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
       struct evbuffer_chain **chainp;
       size_t remaining, len;
       unsigned i;

       EVBUFFER_LOCK(evbuf);
       EVUTIL_ASSERT(buf->read_in_progress && !buf->write_in_progress);
       EVUTIL_ASSERT(nBytes >= 0); /* XXXX Can this be false? */

       evbuffer_unfreeze(evbuf, 0);

       chainp = evbuf->last_with_datap;
       if (!((*chainp)->flags & EVBUFFER_MEM_PINNED_R))
               chainp = &(*chainp)->next;
       remaining = nBytes;
       for (i = 0; remaining > 0 && i < (unsigned)buf->n_buffers; ++i) {
               EVUTIL_ASSERT(*chainp);
               len = buf->buffers[i].len;
               if (remaining < len)
                       len = remaining;
               (*chainp)->off += len;
               evbuf->last_with_datap = chainp;
               remaining -= len;
               chainp = &(*chainp)->next;
       }

       pin_release(buf, EVBUFFER_MEM_PINNED_R);

       buf->read_in_progress = 0;

       evbuf->total_len += nBytes;
       evbuf->n_add_for_cb += nBytes;

       evbuffer_invoke_callbacks_(evbuf);

       evbuffer_decref_and_unlock_(evbuf);
}

void
evbuffer_commit_write_(struct evbuffer *evbuf, ev_ssize_t nBytes)
{
       struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);

       EVBUFFER_LOCK(evbuf);
       EVUTIL_ASSERT(buf->write_in_progress && !buf->read_in_progress);
       evbuffer_unfreeze(evbuf, 1);
       evbuffer_drain(evbuf, nBytes);
       pin_release(buf,EVBUFFER_MEM_PINNED_W);
       buf->write_in_progress = 0;
       evbuffer_decref_and_unlock_(evbuf);
}

struct evbuffer *
evbuffer_overlapped_new_(evutil_socket_t fd)
{
       struct evbuffer_overlapped *evo;

       evo = mm_calloc(1, sizeof(struct evbuffer_overlapped));
       if (!evo)
               return NULL;

       LIST_INIT(&evo->buffer.callbacks);
       evo->buffer.refcnt = 1;
       evo->buffer.last_with_datap = &evo->buffer.first;

       evo->buffer.is_overlapped = 1;
       evo->fd = fd;

       return &evo->buffer;
}

int
evbuffer_launch_write_(struct evbuffer *buf, ev_ssize_t at_most,
               struct event_overlapped *ol)
{
       struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
       int r = -1;
       int i;
       struct evbuffer_chain *chain;
       DWORD bytesSent;

       if (!buf) {
               /* No buffer, or it isn't overlapped */
               return -1;
       }

       EVBUFFER_LOCK(buf);
       EVUTIL_ASSERT(!buf_o->read_in_progress);
       if (buf->freeze_start || buf_o->write_in_progress)
               goto done;
       if (!buf->total_len) {
               /* Nothing to write */
               r = 0;
               goto done;
       } else if (at_most < 0 || (size_t)at_most > buf->total_len) {
               at_most = buf->total_len;
       }
       evbuffer_freeze(buf, 1);

       buf_o->first_pinned = NULL;
       buf_o->n_buffers = 0;
       memset(buf_o->buffers, 0, sizeof(buf_o->buffers));

       chain = buf_o->first_pinned = buf->first;

       for (i=0; i < MAX_WSABUFS && chain; ++i, chain=chain->next) {
               WSABUF *b = &buf_o->buffers[i];
               b->buf = (char*)( chain->buffer + chain->misalign );
               evbuffer_chain_pin_(chain, EVBUFFER_MEM_PINNED_W);

               if ((size_t)at_most > chain->off) {
                       /* XXXX Cast is safe for now, since win32 has no
                          mmaped chains.  But later, we need to have this
                          add more WSAbufs if chain->off is greater than
                          ULONG_MAX */
                       b->len = (unsigned long)chain->off;
                       at_most -= chain->off;
               } else {
                       b->len = (unsigned long)at_most;
                       ++i;
                       break;
               }
       }

       buf_o->n_buffers = i;
       evbuffer_incref_(buf);
       if (WSASend(buf_o->fd, buf_o->buffers, i, &bytesSent, 0,
               &ol->overlapped, NULL)) {
               int error = WSAGetLastError();
               if (error != WSA_IO_PENDING) {
                       /* An actual error. */
                       pin_release(buf_o, EVBUFFER_MEM_PINNED_W);
                       evbuffer_unfreeze(buf, 1);
                       evbuffer_free(buf); /* decref */
                       goto done;
               }
       }

       buf_o->write_in_progress = 1;
       r = 0;
done:
       EVBUFFER_UNLOCK(buf);
       return r;
}

int
evbuffer_launch_read_(struct evbuffer *buf, size_t at_most,
               struct event_overlapped *ol)
{
       struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
       int r = -1, i;
       int nvecs;
       int npin=0;
       struct evbuffer_chain *chain=NULL, **chainp;
       DWORD bytesRead;
       DWORD flags = 0;
       struct evbuffer_iovec vecs[MAX_WSABUFS];

       if (!buf_o)
               return -1;
       EVBUFFER_LOCK(buf);
       EVUTIL_ASSERT(!buf_o->write_in_progress);
       if (buf->freeze_end || buf_o->read_in_progress)
               goto done;

       buf_o->first_pinned = NULL;
       buf_o->n_buffers = 0;
       memset(buf_o->buffers, 0, sizeof(buf_o->buffers));

       if (evbuffer_expand_fast_(buf, at_most, MAX_WSABUFS) == -1)
               goto done;
       evbuffer_freeze(buf, 0);

       nvecs = evbuffer_read_setup_vecs_(buf, at_most,
           vecs, MAX_WSABUFS, &chainp, 1);
       for (i=0;i<nvecs;++i) {
               WSABUF_FROM_EVBUFFER_IOV(
                       &buf_o->buffers[i],
                       &vecs[i]);
       }

       buf_o->n_buffers = nvecs;
       buf_o->first_pinned = chain = *chainp;

       npin=0;
       for ( ; chain; chain = chain->next) {
               evbuffer_chain_pin_(chain, EVBUFFER_MEM_PINNED_R);
               ++npin;
       }
       EVUTIL_ASSERT(npin == nvecs);

       evbuffer_incref_(buf);
       if (WSARecv(buf_o->fd, buf_o->buffers, nvecs, &bytesRead, &flags,
                   &ol->overlapped, NULL)) {
               int error = WSAGetLastError();
               if (error != WSA_IO_PENDING) {
                       /* An actual error. */
                       pin_release(buf_o, EVBUFFER_MEM_PINNED_R);
                       evbuffer_unfreeze(buf, 0);
                       evbuffer_free(buf); /* decref */
                       goto done;
               }
       }

       buf_o->read_in_progress = 1;
       r = 0;
done:
       EVBUFFER_UNLOCK(buf);
       return r;
}

evutil_socket_t
evbuffer_overlapped_get_fd_(struct evbuffer *buf)
{
       struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
       return buf_o ? buf_o->fd : -1;
}

void
evbuffer_overlapped_set_fd_(struct evbuffer *buf, evutil_socket_t fd)
{
       struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
       EVBUFFER_LOCK(buf);
       /* XXX is this right?, should it cancel current I/O operations? */
       if (buf_o)
               buf_o->fd = fd;
       EVBUFFER_UNLOCK(buf);
}

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